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

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! The top-level routing/network map tracking logic lives here.
  11 //!
  12 //! You probably want to create a NetGraphMsgHandler and use that as your RoutingMessageHandler and then
  13 //! interrogate it to get routes for your own payments.
  14
  15 use bitcoin::secp256k1::key::PublicKey;
  16
  17 use ln::channelmanager::ChannelDetails;
  18 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
  19 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
  20 use routing::network_graph::{NetworkGraph, RoutingFees};
  21 use util::ser::{Writeable, Readable};
  22 use util::logger::Logger;
  23
  24 use io;
  25 use prelude::*;
  26 use alloc::collections::BinaryHeap;
  27 use core::cmp;
  28 use core::ops::Deref;
  29
  30 /// A hop in a route
  31 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  32 pub struct RouteHop {
  33         /// The node_id of the node at this hop.
  34         pub pubkey: PublicKey,
  35         /// The node_announcement features of the node at this hop. For the last hop, these may be
  36         /// amended to match the features present in the invoice this node generated.
  37         pub node_features: NodeFeatures,
  38         /// The channel that should be used from the previous hop to reach this node.
  39         pub short_channel_id: u64,
  40         /// The channel_announcement features of the channel that should be used from the previous hop
  41         /// to reach this node.
  42         pub channel_features: ChannelFeatures,
  43         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  44         /// For the last hop, this should be the full value of the payment (might be more than
  45         /// requested if we had to match htlc_minimum_msat).
  46         pub fee_msat: u64,
  47         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  48         /// expected at the destination, in excess of the current block height.
  49         pub cltv_expiry_delta: u32,
  50 }
  51
  52 impl_writeable_tlv_based!(RouteHop, {
  53         (0, pubkey, required),
  54         (2, node_features, required),
  55         (4, short_channel_id, required),
  56         (6, channel_features, required),
  57         (8, fee_msat, required),
  58         (10, cltv_expiry_delta, required),
  59 });
  60
  61 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  62 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  63 #[derive(Clone, Hash, PartialEq, Eq)]
  64 pub struct Route {
  65         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  66         /// last RouteHop in each path must be the same.
  67         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  68         /// destination. Thus, this must always be at least length one. While the maximum length of any
  69         /// given path is variable, keeping the length of any path to less than 20 should currently
  70         /// ensure it is viable.
  71         pub paths: Vec<Vec<RouteHop>>,
  72 }
  73
  74 impl Route {
  75         /// Returns the total amount of fees paid on this Route.
  76         /// This doesn't include any extra payment made to the recipient,
  77         /// which can happen in excess of the amount passed to `get_route`'s `final_value_msat`.
  78         pub fn get_total_fees(&self) -> u64 {
  79                 // Do not count last hop of each path since that's the full value of the payment
  80                 return self.paths.iter()
  81                         .flat_map(|path| path.split_last().unwrap().1)
  82                         .map(|hop| &hop.fee_msat)
  83                         .sum();
  84         }
  85         /// Returns the total amount paid on this Route, excluding the fees.
  86         pub fn get_total_amount(&self) -> u64 {
  87                 return self.paths.iter()
  88                         .map(|path| path.split_last().unwrap().0)
  89                         .map(|hop| &hop.fee_msat)
  90                         .sum();
  91         }
  92 }
  93
  94 const SERIALIZATION_VERSION: u8 = 1;
  95 const MIN_SERIALIZATION_VERSION: u8 = 1;
  96
  97 impl Writeable for Route {
  98         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
  99                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
 100                 (self.paths.len() as u64).write(writer)?;
 101                 for hops in self.paths.iter() {
 102                         (hops.len() as u8).write(writer)?;
 103                         for hop in hops.iter() {
 104                                 hop.write(writer)?;
 105                         }
 106                 }
 107                 write_tlv_fields!(writer, {});
 108                 Ok(())
 109         }
 110 }
 111
 112 impl Readable for Route {
 113         fn read<R: io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 114                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 115                 let path_count: u64 = Readable::read(reader)?;
 116                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 117                 for _ in 0..path_count {
 118                         let hop_count: u8 = Readable::read(reader)?;
 119                         let mut hops = Vec::with_capacity(hop_count as usize);
 120                         for _ in 0..hop_count {
 121                                 hops.push(Readable::read(reader)?);
 122                         }
 123                         paths.push(hops);
 124                 }
 125                 read_tlv_fields!(reader, {});
 126                 Ok(Route { paths })
 127         }
 128 }
 129
 130 /// A list of hops along a payment path terminating with a channel to the recipient.
 131 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 132 pub struct RouteHint(pub Vec<RouteHintHop>);
 133
 134 /// A channel descriptor for a hop along a payment path.
 135 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 136 pub struct RouteHintHop {
 137         /// The node_id of the non-target end of the route
 138         pub src_node_id: PublicKey,
 139         /// The short_channel_id of this channel
 140         pub short_channel_id: u64,
 141         /// The fees which must be paid to use this channel
 142         pub fees: RoutingFees,
 143         /// The difference in CLTV values between this node and the next node.
 144         pub cltv_expiry_delta: u16,
 145         /// The minimum value, in msat, which must be relayed to the next hop.
 146         pub htlc_minimum_msat: Option<u64>,
 147         /// The maximum value in msat available for routing with a single HTLC.
 148         pub htlc_maximum_msat: Option<u64>,
 149 }
 150
 151 #[derive(Eq, PartialEq)]
 152 struct RouteGraphNode {
 153         pubkey: PublicKey,
 154         lowest_fee_to_peer_through_node: u64,
 155         lowest_fee_to_node: u64,
 156         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 157         // This value is upper-bounded by us by:
 158         // - how much is needed for a path being constructed
 159         // - how much value can channels following this node (up to the destination) can contribute,
 160         //   considering their capacity and fees
 161         value_contribution_msat: u64,
 162         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 163         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 164         path_htlc_minimum_msat: u64,
 165 }
 166
 167 impl cmp::Ord for RouteGraphNode {
 168         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 169                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 170                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 171                 other_score.cmp(&self_score).then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 172         }
 173 }
 174
 175 impl cmp::PartialOrd for RouteGraphNode {
 176         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 177                 Some(self.cmp(other))
 178         }
 179 }
 180
 181 struct DummyDirectionalChannelInfo {
 182         cltv_expiry_delta: u32,
 183         htlc_minimum_msat: u64,
 184         htlc_maximum_msat: Option<u64>,
 185         fees: RoutingFees,
 186 }
 187
 188 /// It's useful to keep track of the hops associated with the fees required to use them,
 189 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 190 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 191 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 192 #[derive(Clone, Debug)]
 193 struct PathBuildingHop<'a> {
 194         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 195         // Note that node_features is calculated separately after our initial graph walk.
 196         pubkey: PublicKey,
 197         short_channel_id: u64,
 198         channel_features: &'a ChannelFeatures,
 199         fee_msat: u64,
 200         cltv_expiry_delta: u32,
 201
 202         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 203         src_lowest_inbound_fees: RoutingFees,
 204         /// Fees of the channel used in this hop.
 205         channel_fees: RoutingFees,
 206         /// All the fees paid *after* this channel on the way to the destination
 207         next_hops_fee_msat: u64,
 208         /// Fee paid for the use of the current channel (see channel_fees).
 209         /// The value will be actually deducted from the counterparty balance on the previous link.
 210         hop_use_fee_msat: u64,
 211         /// Used to compare channels when choosing the for routing.
 212         /// Includes paying for the use of a hop and the following hops, as well as
 213         /// an estimated cost of reaching this hop.
 214         /// Might get stale when fees are recomputed. Primarily for internal use.
 215         total_fee_msat: u64,
 216         /// This is useful for update_value_and_recompute_fees to make sure
 217         /// we don't fall below the minimum. Should not be updated manually and
 218         /// generally should not be accessed.
 219         htlc_minimum_msat: u64,
 220         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 221         /// walk and may be invalid thereafter.
 222         path_htlc_minimum_msat: u64,
 223         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 224         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 225         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 226         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 227         /// avoid processing them again.
 228         was_processed: bool,
 229         #[cfg(any(test, feature = "fuzztarget"))]
 230         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 231         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 232         // value_contribution_msat, which requires tracking it here. See comments below where it is
 233         // used for more info.
 234         value_contribution_msat: u64,
 235 }
 236
 237 // Instantiated with a list of hops with correct data in them collected during path finding,
 238 // an instance of this struct should be further modified only via given methods.
 239 #[derive(Clone)]
 240 struct PaymentPath<'a> {
 241         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 242 }
 243
 244 impl<'a> PaymentPath<'a> {
 245         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 246         fn get_value_msat(&self) -> u64 {
 247                 self.hops.last().unwrap().0.fee_msat
 248         }
 249
 250         fn get_total_fee_paid_msat(&self) -> u64 {
 251                 if self.hops.len() < 1 {
 252                         return 0;
 253                 }
 254                 let mut result = 0;
 255                 // Can't use next_hops_fee_msat because it gets outdated.
 256                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 257                         if i != self.hops.len() - 1 {
 258                                 result += hop.fee_msat;
 259                         }
 260                 }
 261                 return result;
 262         }
 263
 264         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 265         // to change fees may result in an inconsistency.
 266         //
 267         // Sometimes we call this function right after constructing a path which is inconsistent in
 268         // that it the value being transferred has decreased while we were doing path finding, leading
 269         // to the fees being paid not lining up with the actual limits.
 270         //
 271         // Note that this function is not aware of the available_liquidity limit, and thus does not
 272         // support increasing the value being transferred.
 273         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 274                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 275
 276                 let mut total_fee_paid_msat = 0 as u64;
 277                 for i in (0..self.hops.len()).rev() {
 278                         let last_hop = i == self.hops.len() - 1;
 279
 280                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 281                         // will consist of the fees for the use of the next hop, and extra fees to match
 282                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 283                         let mut cur_hop_fees_msat = 0;
 284                         if !last_hop {
 285                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 286                         }
 287
 288                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 289                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 290                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 291                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 292                         // set it too high just to maliciously take more fees by exploiting this
 293                         // match htlc_minimum_msat logic.
 294                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 295                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 296                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 297                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 298                                 //
 299                                 // This might make us end up with a broken route, although this should be super-rare
 300                                 // in practice, both because of how healthy channels look like, and how we pick
 301                                 // channels in add_entry.
 302                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 303                                 // all payments*.
 304                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 305                                 total_fee_paid_msat += extra_fees_msat;
 306                                 cur_hop_fees_msat += extra_fees_msat;
 307                         }
 308
 309                         if last_hop {
 310                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 311                                 // it still could overpay for the htlc_minimum_msat.
 312                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 313                         } else {
 314                                 // Propagate updated fees for the use of the channels to one hop back, where they
 315                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 316                                 cur_hop.fee_msat = cur_hop_fees_msat;
 317                         }
 318
 319                         // Fee for the use of the current hop which will be deducted on the previous hop.
 320                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 321                         // this channel is free for us.
 322                         if i != 0 {
 323                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 324                                         cur_hop.hop_use_fee_msat = new_fee;
 325                                         total_fee_paid_msat += new_fee;
 326                                 } else {
 327                                         // It should not be possible because this function is called only to reduce the
 328                                         // value. In that case, compute_fee was already called with the same fees for
 329                                         // larger amount and there was no overflow.
 330                                         unreachable!();
 331                                 }
 332                         }
 333                 }
 334         }
 335 }
 336
 337 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 338         let proportional_fee_millions =
 339                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 340         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 341                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 342
 343                 Some(new_fee)
 344         } else {
 345                 // This function may be (indirectly) called without any verification,
 346                 // with channel_fees provided by a caller. We should handle it gracefully.
 347                 None
 348         }
 349 }
 350
 351 /// Gets a keysend route from us (payer) to the given target node (payee). This is needed because
 352 /// keysend payments do not have an invoice from which to pull the payee's supported features, which
 353 /// makes it tricky to otherwise supply the `payee_features` parameter of `get_route`.
 354 pub fn get_keysend_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee:
 355                        &PublicKey, first_hops: Option<&[&ChannelDetails]>, last_hops: &[&RouteHint],
 356                        final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route,
 357                        LightningError> where L::Target: Logger {
 358         let invoice_features = InvoiceFeatures::for_keysend();
 359         get_route(our_node_id, network, payee, Some(invoice_features), first_hops, last_hops,
 360             final_value_msat, final_cltv, logger)
 361 }
 362
 363 /// Gets a route from us (payer) to the given target node (payee).
 364 ///
 365 /// If the payee provided features in their invoice, they should be provided via payee_features.
 366 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 367 ///
 368 /// Private routing paths between a public node and the target may be included in `last_hops`.
 369 /// Currently, only the last hop in each path is considered.
 370 ///
 371 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 372 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 373 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 374 /// in first_hops will be used.
 375 ///
 376 /// Panics if first_hops contains channels without short_channel_ids
 377 /// (ChannelManager::list_usable_channels will never include such channels).
 378 ///
 379 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 380 /// equal), however the enabled/disabled bit on such channels as well as the
 381 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 382 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 383         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 384         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 385         // uptime/success in using a node in the past.
 386         if *payee == *our_node_id {
 387                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 388         }
 389
 390         if final_value_msat > MAX_VALUE_MSAT {
 391                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 392         }
 393
 394         if final_value_msat == 0 {
 395                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 396         }
 397
 398         for route in last_hops.iter() {
 399                 for hop in &route.0 {
 400                         if hop.src_node_id == *payee {
 401                                 return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 402                         }
 403                 }
 404         }
 405
 406         // The general routing idea is the following:
 407         // 1. Fill first/last hops communicated by the caller.
 408         // 2. Attempt to construct a path from payer to payee for transferring
 409         //    any ~sufficient (described later) value.
 410         //    If succeed, remember which channels were used and how much liquidity they have available,
 411         //    so that future paths don't rely on the same liquidity.
 412         // 3. Prooceed to the next step if:
 413         //    - we hit the recommended target value;
 414         //    - OR if we could not construct a new path. Any next attempt will fail too.
 415         //    Otherwise, repeat step 2.
 416         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 417         //    (not recommended value). If yes, proceed. If not, fail routing.
 418         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 419         // 6. Of all the found paths, select only those with the lowest total fee.
 420         // 7. The last path in every selected route is likely to be more than we need.
 421         //    Reduce its value-to-transfer and recompute fees.
 422         // 8. Choose the best route by the lowest total fee.
 423
 424         // As for the actual search algorithm,
 425         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 426         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 427         //
 428         // We are not a faithful Dijkstra's implementation because we can change values which impact
 429         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 430         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 431         // the value we are currently attempting to send over a path, we simply reduce the value being
 432         // sent along the path for any hops after that channel. This may imply that later fees (which
 433         // we've already tabulated) are lower because a smaller value is passing through the channels
 434         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 435         // channels which were selected earlier (and which may still be used for other paths without a
 436         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 437         // de-preferenced.
 438         //
 439         // One potentially problematic case for this algorithm would be if there are many
 440         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 441         // graph walking), we may never find a path which is not liquidity-limited and has lower
 442         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 443         // Because we only consider paths with at least 5% of the total value being sent, the damage
 444         // from such a case should be limited, however this could be further reduced in the future by
 445         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 446         // limits for the purposes of fee calculation.
 447         //
 448         // Alternatively, we could store more detailed path information in the heap (targets, below)
 449         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 450         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 451         // and practically (as we would need to store dynamically-allocated path information in heap
 452         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 453         // results of such an algorithm would likely be biased towards lower-value paths.
 454         //
 455         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 456         // outside of our current search value, running a path search more times to gather candidate
 457         // paths at different values. While this may be acceptable, further path searches may increase
 458         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 459         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 460         // the same time, remaining generic across different payment values.
 461         //
 462         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 463         // to use as the A* heuristic beyond just the cost to get one node further than the current
 464         // one.
 465
 466         let network_graph = network.read_only();
 467         let network_channels = network_graph.channels();
 468         let network_nodes = network_graph.nodes();
 469         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 470                 cltv_expiry_delta: 0,
 471                 htlc_minimum_msat: 0,
 472                 htlc_maximum_msat: None,
 473                 fees: RoutingFees {
 474                         base_msat: 0,
 475                         proportional_millionths: 0,
 476                 }
 477         };
 478
 479         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 480         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 481         // work reliably.
 482         let allow_mpp = if let Some(features) = &payee_features {
 483                 features.supports_basic_mpp()
 484         } else if let Some(node) = network_nodes.get(&payee) {
 485                 if let Some(node_info) = node.announcement_info.as_ref() {
 486                         node_info.features.supports_basic_mpp()
 487                 } else { false }
 488         } else { false };
 489
 490         // Step (1).
 491         // Prepare the data we'll use for payee-to-payer search by
 492         // inserting first hops suggested by the caller as targets.
 493         // Our search will then attempt to reach them while traversing from the payee node.
 494         let mut first_hop_targets: HashMap<_, (_, ChannelFeatures, _, NodeFeatures)> =
 495                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 496         if let Some(hops) = first_hops {
 497                 for chan in hops {
 498                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 499                         if chan.counterparty.node_id == *our_node_id {
 500                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 501                         }
 502                         first_hop_targets.insert(chan.counterparty.node_id, (short_channel_id, chan.counterparty.features.to_context(), chan.outbound_capacity_msat, chan.counterparty.features.to_context()));
 503                 }
 504                 if first_hop_targets.is_empty() {
 505                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 506                 }
 507         }
 508
 509         let empty_channel_features = ChannelFeatures::empty();
 510
 511         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 512         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 513         // adding duplicate entries when we find a better path to a given node.
 514         let mut targets = BinaryHeap::new();
 515
 516         // Map from node_id to information about the best current path to that node, including feerate
 517         // information.
 518         let mut dist = HashMap::with_capacity(network_nodes.len());
 519
 520         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 521         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 522         // htlc_minimum with extra fees while still finding a cheaper path.
 523         let mut hit_minimum_limit;
 524
 525         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 526         // We start with a path_value of the exact amount we want, and if that generates a route we may
 527         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 528         // amount we want in total across paths, selecting the best subset at the end.
 529         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 530         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 531         let mut path_value_msat = final_value_msat;
 532
 533         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 534         // This map allows paths to be aware of the channel use by other paths in the same call.
 535         // This would help to make a better path finding decisions and not "overbook" channels.
 536         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 537         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network_nodes.len());
 538
 539         // Keeping track of how much value we already collected across other paths. Helps to decide:
 540         // - how much a new path should be transferring (upper bound);
 541         // - whether a channel should be disregarded because
 542         //   it's available liquidity is too small comparing to how much more we need to collect;
 543         // - when we want to stop looking for new paths.
 544         let mut already_collected_value_msat = 0;
 545
 546         log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payee, our_node_id, final_value_msat);
 547
 548         macro_rules! add_entry {
 549                 // Adds entry which goes from $src_node_id to $dest_node_id
 550                 // over the channel with id $chan_id with fees described in
 551                 // $directional_info.
 552                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 553                 // since that value has to be transferred over this channel.
 554                 // Returns whether this channel caused an update to `targets`.
 555                 ( $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,
 556                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => { {
 557                         // We "return" whether we updated the path at the end, via this:
 558                         let mut did_add_update_path_to_src_node = false;
 559                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 560                         // practice these cases should be caught earlier:
 561                         // - for regular channels at channel announcement (TODO)
 562                         // - for first and last hops early in get_route
 563                         if $src_node_id != $dest_node_id.clone() {
 564                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 565                                         let mut initial_liquidity_available_msat = None;
 566                                         if let Some(capacity_sats) = $capacity_sats {
 567                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 568                                         }
 569
 570                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 571                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 572                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 573                                                 } else {
 574                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 575                                                 }
 576                                         }
 577
 578                                         match initial_liquidity_available_msat {
 579                                                 Some(available_msat) => available_msat,
 580                                                 // We assume channels with unknown balance have
 581                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 582                                                 None => 250_000 * 1000
 583                                         }
 584                                 });
 585
 586                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 587                                 // It may be misleading because we might later choose to reduce the value transferred
 588                                 // over these channels, and the channel which was insufficient might become sufficient.
 589                                 // Worst case: we drop a good channel here because it can't cover the high following
 590                                 // fees caused by one expensive channel, but then this channel could have been used
 591                                 // if the amount being transferred over this path is lower.
 592                                 // We do this for now, but this is a subject for removal.
 593                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 594
 595                                         // Routing Fragmentation Mitigation heuristic:
 596                                         //
 597                                         // Routing fragmentation across many payment paths increases the overall routing
 598                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 599                                         // Taking too many smaller paths also increases the chance of payment failure.
 600                                         // Thus to avoid this effect, we require from our collected links to provide
 601                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 602                                         //
 603                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 604                                         // This means as we successfully advance in our collection,
 605                                         // the absolute liquidity contribution is lowered,
 606                                         // thus increasing the number of potential channels to be selected.
 607
 608                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 609                                         // or 100% if we're not allowed to do multipath payments.
 610                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 611                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 612                                         } else {
 613                                                 final_value_msat
 614                                         };
 615                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 616                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 617
 618                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 619                                         // Includes paying fees for the use of the following channels.
 620                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 621                                                 Some(result) => result,
 622                                                 // Can't overflow due to how the values were computed right above.
 623                                                 None => unreachable!(),
 624                                         };
 625                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 626                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 627                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 628
 629                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 630                                         // bother considering this channel.
 631                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 632                                         // be only reduced later (not increased), so this channel should just be skipped
 633                                         // as not sufficient.
 634                                         if !over_path_minimum_msat {
 635                                                 hit_minimum_limit = true;
 636                                         } else if contributes_sufficient_value {
 637                                                 // Note that low contribution here (limited by available_liquidity_msat)
 638                                                 // might violate htlc_minimum_msat on the hops which are next along the
 639                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 640                                                 // path fees knowing the final path contribution after constructing it.
 641                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 642                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 643                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 644                                                         _ => u64::max_value()
 645                                                 };
 646                                                 let hm_entry = dist.entry(&$src_node_id);
 647                                                 let old_entry = hm_entry.or_insert_with(|| {
 648                                                         // If there was previously no known way to access
 649                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 650                                                         // a semi-dummy record just to compute the fees to reach the source node.
 651                                                         // This will affect our decision on selecting $chan_id
 652                                                         // as a way to reach the $dest_node_id.
 653                                                         let mut fee_base_msat = u32::max_value();
 654                                                         let mut fee_proportional_millionths = u32::max_value();
 655                                                         if let Some(Some(fees)) = network_nodes.get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 656                                                                 fee_base_msat = fees.base_msat;
 657                                                                 fee_proportional_millionths = fees.proportional_millionths;
 658                                                         }
 659                                                         PathBuildingHop {
 660                                                                 pubkey: $dest_node_id.clone(),
 661                                                                 short_channel_id: 0,
 662                                                                 channel_features: $chan_features,
 663                                                                 fee_msat: 0,
 664                                                                 cltv_expiry_delta: 0,
 665                                                                 src_lowest_inbound_fees: RoutingFees {
 666                                                                         base_msat: fee_base_msat,
 667                                                                         proportional_millionths: fee_proportional_millionths,
 668                                                                 },
 669                                                                 channel_fees: $directional_info.fees,
 670                                                                 next_hops_fee_msat: u64::max_value(),
 671                                                                 hop_use_fee_msat: u64::max_value(),
 672                                                                 total_fee_msat: u64::max_value(),
 673                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 674                                                                 path_htlc_minimum_msat,
 675                                                                 was_processed: false,
 676                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 677                                                                 value_contribution_msat,
 678                                                         }
 679                                                 });
 680
 681                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 682                                                 let mut should_process = !old_entry.was_processed;
 683                                                 #[cfg(any(test, feature = "fuzztarget"))]
 684                                                 {
 685                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 686                                                         // of already-seen nodes only happens in cases we expect (see below).
 687                                                         if !should_process { should_process = true; }
 688                                                 }
 689
 690                                                 if should_process {
 691                                                         let mut hop_use_fee_msat = 0;
 692                                                         let mut total_fee_msat = $next_hops_fee_msat;
 693
 694                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 695                                                         // will have the same effective-fee
 696                                                         if $src_node_id != *our_node_id {
 697                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 698                                                                         // max_value means we'll always fail
 699                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 700                                                                         None => total_fee_msat = u64::max_value(),
 701                                                                         Some(fee_msat) => {
 702                                                                                 hop_use_fee_msat = fee_msat;
 703                                                                                 total_fee_msat += hop_use_fee_msat;
 704                                                                                 // When calculating the lowest inbound fees to a node, we
 705                                                                                 // calculate fees here not based on the actual value we think
 706                                                                                 // will flow over this channel, but on the minimum value that
 707                                                                                 // we'll accept flowing over it. The minimum accepted value
 708                                                                                 // is a constant through each path collection run, ensuring
 709                                                                                 // consistent basis. Otherwise we may later find a
 710                                                                                 // different path to the source node that is more expensive,
 711                                                                                 // but which we consider to be cheaper because we are capacity
 712                                                                                 // constrained and the relative fee becomes lower.
 713                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 714                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 715                                                                                         Some(Some(v)) => {
 716                                                                                                 total_fee_msat = v;
 717                                                                                         },
 718                                                                                         _ => {
 719                                                                                                 total_fee_msat = u64::max_value();
 720                                                                                         }
 721                                                                                 };
 722                                                                         }
 723                                                                 }
 724                                                         }
 725
 726                                                         let new_graph_node = RouteGraphNode {
 727                                                                 pubkey: $src_node_id,
 728                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 729                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 730                                                                 value_contribution_msat: value_contribution_msat,
 731                                                                 path_htlc_minimum_msat,
 732                                                         };
 733
 734                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 735                                                         // if this way is cheaper than the already known
 736                                                         // (considering the cost to "reach" this channel from the route destination,
 737                                                         // the cost of using this channel,
 738                                                         // and the cost of routing to the source node of this channel).
 739                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 740                                                         // paying it. Consider the following exploit:
 741                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 742                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 743                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 744                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 745                                                         // to this channel.
 746                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 747                                                         // but it may require additional tracking - we don't want to double-count
 748                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 749                                                         // can't use something that may decrease on future hops.
 750                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 751                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 752
 753                                                         if !old_entry.was_processed && new_cost < old_cost {
 754                                                                 targets.push(new_graph_node);
 755                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 756                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 757                                                                 old_entry.total_fee_msat = total_fee_msat;
 758                                                                 old_entry.pubkey = $dest_node_id.clone();
 759                                                                 old_entry.short_channel_id = $chan_id.clone();
 760                                                                 old_entry.channel_features = $chan_features;
 761                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 762                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 763                                                                 old_entry.channel_fees = $directional_info.fees;
 764                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 765                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 766                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 767                                                                 {
 768                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 769                                                                 }
 770                                                                 did_add_update_path_to_src_node = true;
 771                                                         } else if old_entry.was_processed && new_cost < old_cost {
 772                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 773                                                                 {
 774                                                                         // If we're skipping processing a node which was previously
 775                                                                         // processed even though we found another path to it with a
 776                                                                         // cheaper fee, check that it was because the second path we
 777                                                                         // found (which we are processing now) has a lower value
 778                                                                         // contribution due to an HTLC minimum limit.
 779                                                                         //
 780                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 781                                                                         // through channel A, and one through channel B. Channel A and
 782                                                                         // B are both in the to-process heap, with their scores set by
 783                                                                         // a higher htlc_minimum than fee.
 784                                                                         // Channel A is processed first, and the channels onwards from
 785                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 786                                                                         // Channel B off of the heap, note that it has a much more
 787                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 788                                                                         // all of node 1's channels using the new, reduced, amount.
 789                                                                         //
 790                                                                         // This would be bogus - we'd be selecting a higher-fee path
 791                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 792                                                                         // already decided to use.
 793                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 794                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 795                                                                 }
 796                                                         }
 797                                                 }
 798                                         }
 799                                 }
 800                         }
 801                         did_add_update_path_to_src_node
 802                 } }
 803         }
 804
 805         let empty_node_features = NodeFeatures::empty();
 806         // Find ways (channels with destination) to reach a given node and store them
 807         // in the corresponding data structures (routing graph etc).
 808         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 809         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 810         // This data can later be helpful to optimize routing (pay lower fees).
 811         macro_rules! add_entries_to_cheapest_to_target_node {
 812                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 813                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 814                                 let was_processed = elem.was_processed;
 815                                 elem.was_processed = true;
 816                                 was_processed
 817                         } else {
 818                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 819                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 820                                 // If we're processing any other node, it is always be the result of a channel from it.
 821                                 assert_eq!($node_id, payee);
 822                                 false
 823                         };
 824
 825                         if !skip_node {
 826                                 if first_hops.is_some() {
 827                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&$node_id) {
 828                                                 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);
 829                                         }
 830                                 }
 831
 832                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 833                                         &node_info.features
 834                                 } else {
 835                                         &empty_node_features
 836                                 };
 837
 838                                 if !features.requires_unknown_bits() {
 839                                         for chan_id in $node.channels.iter() {
 840                                                 let chan = network_channels.get(chan_id).unwrap();
 841                                                 if !chan.features.requires_unknown_bits() {
 842                                                         if chan.node_one == *$node_id {
 843                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 844                                                                 if first_hops.is_none() || chan.node_two != *our_node_id {
 845                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 846                                                                                 if two_to_one.enabled {
 847                                                                                         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);
 848                                                                                 }
 849                                                                         }
 850                                                                 }
 851                                                         } else {
 852                                                                 if first_hops.is_none() || chan.node_one != *our_node_id {
 853                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 854                                                                                 if one_to_two.enabled {
 855                                                                                         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);
 856                                                                                 }
 857                                                                         }
 858                                                                 }
 859                                                         }
 860                                                 }
 861                                         }
 862                                 }
 863                         }
 864                 };
 865         }
 866
 867         let mut payment_paths = Vec::<PaymentPath>::new();
 868
 869         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 870         'paths_collection: loop {
 871                 // For every new path, start from scratch, except
 872                 // bookkeeped_channels_liquidity_available_msat, which will improve
 873                 // the further iterations of path finding. Also don't erase first_hop_targets.
 874                 targets.clear();
 875                 dist.clear();
 876                 hit_minimum_limit = false;
 877
 878                 // If first hop is a private channel and the only way to reach the payee, this is the only
 879                 // place where it could be added.
 880                 if first_hops.is_some() {
 881                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&payee) {
 882                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 883                         }
 884                 }
 885
 886                 // Add the payee as a target, so that the payee-to-payer
 887                 // search algorithm knows what to start with.
 888                 match network_nodes.get(payee) {
 889                         // The payee is not in our network graph, so nothing to add here.
 890                         // There is still a chance of reaching them via last_hops though,
 891                         // so don't yet fail the payment here.
 892                         // If not, targets.pop() will not even let us enter the loop in step 2.
 893                         None => {},
 894                         Some(node) => {
 895                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 896                         },
 897                 }
 898
 899                 // Step (1).
 900                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 901                 // earlier than general path finding, they will be somewhat prioritized, although currently
 902                 // it matters only if the fees are exactly the same.
 903                 for route in last_hops.iter().filter(|route| !route.0.is_empty()) {
 904                         let first_hop_in_route = &(route.0)[0];
 905                         let have_hop_src_in_graph =
 906                                 // Only add the hops in this route to our candidate set if either
 907                                 // we have a direct channel to the first hop or the first hop is
 908                                 // in the regular network graph.
 909                                 first_hop_targets.get(&first_hop_in_route.src_node_id).is_some() ||
 910                                 network_nodes.get(&first_hop_in_route.src_node_id).is_some();
 911                         if have_hop_src_in_graph {
 912                                 // We start building the path from reverse, i.e., from payee
 913                                 // to the first RouteHintHop in the path.
 914                                 let hop_iter = route.0.iter().rev();
 915                                 let prev_hop_iter = core::iter::once(payee).chain(
 916                                         route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
 917                                 let mut hop_used = true;
 918                                 let mut aggregate_next_hops_fee_msat: u64 = 0;
 919                                 let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
 920
 921                                 for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
 922                                         // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 923                                         // really sucks, cause we're gonna need that eventually.
 924                                         let hop_htlc_minimum_msat: u64 = hop.htlc_minimum_msat.unwrap_or(0);
 925
 926                                         let directional_info = DummyDirectionalChannelInfo {
 927                                                 cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 928                                                 htlc_minimum_msat: hop_htlc_minimum_msat,
 929                                                 htlc_maximum_msat: hop.htlc_maximum_msat,
 930                                                 fees: hop.fees,
 931                                         };
 932
 933                                         let reqd_channel_cap = if let Some (val) = final_value_msat.checked_add(match idx {
 934                                                 0 => 999,
 935                                                 _ => aggregate_next_hops_fee_msat.checked_add(999).unwrap_or(u64::max_value())
 936                                         }) { Some( val / 1000 ) } else { break; }; // converting from msat or breaking if max ~ infinity
 937
 938
 939                                         // We assume that the recipient only included route hints for routes which had
 940                                         // sufficient value to route `final_value_msat`. Note that in the case of "0-value"
 941                                         // invoices where the invoice does not specify value this may not be the case, but
 942                                         // better to include the hints than not.
 943                                         if !add_entry!(hop.short_channel_id, hop.src_node_id, prev_hop_id, directional_info, reqd_channel_cap, &empty_channel_features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat) {
 944                                                 // If this hop was not used then there is no use checking the preceding hops
 945                                                 // in the RouteHint. We can break by just searching for a direct channel between
 946                                                 // last checked hop and first_hop_targets
 947                                                 hop_used = false;
 948                                         }
 949
 950                                         // Searching for a direct channel between last checked hop and first_hop_targets
 951                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&prev_hop_id) {
 952                                                 add_entry!(first_hop, *our_node_id , prev_hop_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat);
 953                                         }
 954
 955                                         if !hop_used {
 956                                                 break;
 957                                         }
 958
 959                                         // In the next values of the iterator, the aggregate fees already reflects
 960                                         // the sum of value sent from payer (final_value_msat) and routing fees
 961                                         // for the last node in the RouteHint. We need to just add the fees to
 962                                         // route through the current node so that the preceeding node (next iteration)
 963                                         // can use it.
 964                                         let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
 965                                                 .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
 966                                         aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
 967
 968                                         let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
 969                                         let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
 970                                                 .checked_add(hop_htlc_minimum_msat_inc);
 971                                         aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
 972
 973                                         if idx == route.0.len() - 1 {
 974                                                 // The last hop in this iterator is the first hop in
 975                                                 // overall RouteHint.
 976                                                 // If this hop connects to a node with which we have a direct channel,
 977                                                 // ignore the network graph and, if the last hop was added, add our
 978                                                 // direct channel to the candidate set.
 979                                                 //
 980                                                 // Note that we *must* check if the last hop was added as `add_entry`
 981                                                 // always assumes that the third argument is a node to which we have a
 982                                                 // path.
 983                                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
 984                                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat);
 985                                                 }
 986                                         }
 987                                 }
 988                         }
 989                 }
 990
 991                 log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
 992
 993                 // At this point, targets are filled with the data from first and
 994                 // last hops communicated by the caller, and the payment receiver.
 995                 let mut found_new_path = false;
 996
 997                 // Step (2).
 998                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 999                 // - not enough outgoing liquidity:
1000                 //   0 < already_collected_value_msat < final_value_msat
1001                 // - enough outgoing liquidity:
1002                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
1003                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
1004                 // paths_collection will be stopped because found_new_path==false.
1005                 // This is not necessarily a routing failure.
1006                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
1007
1008                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
1009                         // traversing the graph and arrange the path out of what we found.
1010                         if pubkey == *our_node_id {
1011                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
1012                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
1013
1014                                 'path_walk: loop {
1015                                         if let Some(&(_, _, _, ref features)) = first_hop_targets.get(&ordered_hops.last().unwrap().0.pubkey) {
1016                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
1017                                         } else if let Some(node) = network_nodes.get(&ordered_hops.last().unwrap().0.pubkey) {
1018                                                 if let Some(node_info) = node.announcement_info.as_ref() {
1019                                                         ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
1020                                                 } else {
1021                                                         ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
1022                                                 }
1023                                         } else {
1024                                                 // We should be able to fill in features for everything except the last
1025                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
1026                                                 // should be able to extend it further as BOLT 11 does have feature
1027                                                 // flags for the last hop node itself).
1028                                                 assert!(ordered_hops.last().unwrap().0.pubkey == *payee);
1029                                         }
1030
1031                                         // Means we succesfully traversed from the payer to the payee, now
1032                                         // save this path for the payment route. Also, update the liquidity
1033                                         // remaining on the used hops, so that we take them into account
1034                                         // while looking for more paths.
1035                                         if ordered_hops.last().unwrap().0.pubkey == *payee {
1036                                                 break 'path_walk;
1037                                         }
1038
1039                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.pubkey) {
1040                                                 Some(payment_hop) => payment_hop,
1041                                                 // We can't arrive at None because, if we ever add an entry to targets,
1042                                                 // we also fill in the entry in dist (see add_entry!).
1043                                                 None => unreachable!(),
1044                                         };
1045                                         // We "propagate" the fees one hop backward (topologically) here,
1046                                         // so that fees paid for a HTLC forwarding on the current channel are
1047                                         // associated with the previous channel (where they will be subtracted).
1048                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
1049                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
1050                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
1051                                 }
1052                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
1053                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
1054                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
1055
1056                                 log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
1057                                         ordered_hops.len(), value_contribution_msat, ordered_hops);
1058
1059                                 let mut payment_path = PaymentPath {hops: ordered_hops};
1060
1061                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
1062                                 // value being transferred along the way, we could have violated htlc_minimum_msat
1063                                 // on some channels we already passed (assuming dest->source direction). Here, we
1064                                 // recompute the fees again, so that if that's the case, we match the currently
1065                                 // underpaid htlc_minimum_msat with fees.
1066                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
1067
1068                                 // Since a path allows to transfer as much value as
1069                                 // the smallest channel it has ("bottleneck"), we should recompute
1070                                 // the fees so sender HTLC don't overpay fees when traversing
1071                                 // larger channels than the bottleneck. This may happen because
1072                                 // when we were selecting those channels we were not aware how much value
1073                                 // this path will transfer, and the relative fee for them
1074                                 // might have been computed considering a larger value.
1075                                 // Remember that we used these channels so that we don't rely
1076                                 // on the same liquidity in future paths.
1077                                 let mut prevented_redundant_path_selection = false;
1078                                 for (payment_hop, _) in payment_path.hops.iter() {
1079                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
1080                                         let mut spent_on_hop_msat = value_contribution_msat;
1081                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
1082                                         spent_on_hop_msat += next_hops_fee_msat;
1083                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
1084                                                 // If this path used all of this channel's available liquidity, we know
1085                                                 // this path will not be selected again in the next loop iteration.
1086                                                 prevented_redundant_path_selection = true;
1087                                         }
1088                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
1089                                 }
1090                                 if !prevented_redundant_path_selection {
1091                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
1092                                         // we'll probably end up picking the same path again on the next iteration.
1093                                         // Decrease the available liquidity of a hop in the middle of the path.
1094                                         let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
1095                                         log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
1096                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
1097                                         *victim_liquidity = 0;
1098                                 }
1099
1100                                 // Track the total amount all our collected paths allow to send so that we:
1101                                 // - know when to stop looking for more paths
1102                                 // - know which of the hops are useless considering how much more sats we need
1103                                 //   (contributes_sufficient_value)
1104                                 already_collected_value_msat += value_contribution_msat;
1105
1106                                 payment_paths.push(payment_path);
1107                                 found_new_path = true;
1108                                 break 'path_construction;
1109                         }
1110
1111                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1112                         // the equivalent of the `elem.was_processed` check in
1113                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1114                         if pubkey == *payee { continue 'path_construction; }
1115
1116                         // Otherwise, since the current target node is not us,
1117                         // keep "unrolling" the payment graph from payee to payer by
1118                         // finding a way to reach the current target from the payer side.
1119                         match network_nodes.get(&pubkey) {
1120                                 None => {},
1121                                 Some(node) => {
1122                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1123                                 },
1124                         }
1125                 }
1126
1127                 if !allow_mpp {
1128                         // If we don't support MPP, no use trying to gather more value ever.
1129                         break 'paths_collection;
1130                 }
1131
1132                 // Step (3).
1133                 // Stop either when the recommended value is reached or if no new path was found in this
1134                 // iteration.
1135                 // In the latter case, making another path finding attempt won't help,
1136                 // because we deterministically terminated the search due to low liquidity.
1137                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1138                         log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
1139                                 already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
1140                         break 'paths_collection;
1141                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1142                         // Further, if this was our first walk of the graph, and we weren't limited by an
1143                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1144                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1145                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1146                         // still keeping a lower total fee than this path.
1147                         if !hit_minimum_limit {
1148                                 log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
1149                                 break 'paths_collection;
1150                         }
1151                         log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
1152                         path_value_msat = recommended_value_msat;
1153                 }
1154         }
1155
1156         // Step (4).
1157         if payment_paths.len() == 0 {
1158                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1159         }
1160
1161         if already_collected_value_msat < final_value_msat {
1162                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1163         }
1164
1165         // Sort by total fees and take the best paths.
1166         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1167         if payment_paths.len() > 50 {
1168                 payment_paths.truncate(50);
1169         }
1170
1171         // Draw multiple sufficient routes by randomly combining the selected paths.
1172         let mut drawn_routes = Vec::new();
1173         for i in 0..payment_paths.len() {
1174                 let mut cur_route = Vec::<PaymentPath>::new();
1175                 let mut aggregate_route_value_msat = 0;
1176
1177                 // Step (5).
1178                 // TODO: real random shuffle
1179                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1180                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1181
1182                 // Step (6).
1183                 for payment_path in cur_payment_paths {
1184                         cur_route.push(payment_path.clone());
1185                         aggregate_route_value_msat += payment_path.get_value_msat();
1186                         if aggregate_route_value_msat > final_value_msat {
1187                                 // Last path likely overpaid. Substract it from the most expensive
1188                                 // (in terms of proportional fee) path in this route and recompute fees.
1189                                 // This might be not the most economically efficient way, but fewer paths
1190                                 // also makes routing more reliable.
1191                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1192
1193                                 // First, drop some expensive low-value paths entirely if possible.
1194                                 // Sort by value so that we drop many really-low values first, since
1195                                 // fewer paths is better: the payment is less likely to fail.
1196                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1197                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1198                                 cur_route.sort_by_key(|path| path.get_value_msat());
1199                                 // We should make sure that at least 1 path left.
1200                                 let mut paths_left = cur_route.len();
1201                                 cur_route.retain(|path| {
1202                                         if paths_left == 1 {
1203                                                 return true
1204                                         }
1205                                         let mut keep = true;
1206                                         let path_value_msat = path.get_value_msat();
1207                                         if path_value_msat <= overpaid_value_msat {
1208                                                 keep = false;
1209                                                 overpaid_value_msat -= path_value_msat;
1210                                                 paths_left -= 1;
1211                                         }
1212                                         keep
1213                                 });
1214
1215                                 if overpaid_value_msat == 0 {
1216                                         break;
1217                                 }
1218
1219                                 assert!(cur_route.len() > 0);
1220
1221                                 // Step (7).
1222                                 // Now, substract the overpaid value from the most-expensive path.
1223                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1224                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1225                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1226                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1227                                 // We already dropped all the small channels above, meaning all the
1228                                 // remaining channels are larger than remaining overpaid_value_msat.
1229                                 // Thus, this can't be negative.
1230                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1231                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1232                                 break;
1233                         }
1234                 }
1235                 drawn_routes.push(cur_route);
1236         }
1237
1238         // Step (8).
1239         // Select the best route by lowest total fee.
1240         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1241         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1242         for payment_path in drawn_routes.first().unwrap() {
1243                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1244                         RouteHop {
1245                                 pubkey: payment_hop.pubkey,
1246                                 node_features: node_features.clone(),
1247                                 short_channel_id: payment_hop.short_channel_id,
1248                                 channel_features: payment_hop.channel_features.clone(),
1249                                 fee_msat: payment_hop.fee_msat,
1250                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1251                         }
1252                 }).collect());
1253         }
1254
1255         if let Some(features) = &payee_features {
1256                 for path in selected_paths.iter_mut() {
1257                         path.last_mut().unwrap().node_features = features.to_context();
1258                 }
1259         }
1260
1261         let route = Route { paths: selected_paths };
1262         log_info!(logger, "Got route to {}: {}", payee, log_route!(route));
1263         Ok(route)
1264 }
1265
1266 #[cfg(test)]
1267 mod tests {
1268         use routing::router::{get_route, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
1269         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1270         use chain::transaction::OutPoint;
1271         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1272         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1273            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1274         use ln::channelmanager;
1275         use util::test_utils;
1276         use util::ser::Writeable;
1277
1278         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1279         use bitcoin::hashes::Hash;
1280         use bitcoin::network::constants::Network;
1281         use bitcoin::blockdata::constants::genesis_block;
1282         use bitcoin::blockdata::script::Builder;
1283         use bitcoin::blockdata::opcodes;
1284         use bitcoin::blockdata::transaction::TxOut;
1285
1286         use hex;
1287
1288         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1289         use bitcoin::secp256k1::{Secp256k1, All};
1290
1291         use prelude::*;
1292         use sync::{self, Arc};
1293
1294         fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
1295                         features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
1296                 channelmanager::ChannelDetails {
1297                         channel_id: [0; 32],
1298                         counterparty: channelmanager::ChannelCounterparty {
1299                                 features,
1300                                 node_id,
1301                                 unspendable_punishment_reserve: 0,
1302                                 forwarding_info: None,
1303                         },
1304                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1305                         short_channel_id,
1306                         channel_value_satoshis: 0,
1307                         user_id: 0,
1308                         outbound_capacity_msat,
1309                         inbound_capacity_msat: 42,
1310                         unspendable_punishment_reserve: None,
1311                         confirmations_required: None,
1312                         force_close_spend_delay: None,
1313                         is_outbound: true, is_funding_locked: true,
1314                         is_usable: true, is_public: true,
1315                 }
1316         }
1317
1318         // Using the same keys for LN and BTC ids
1319         fn add_channel(
1320                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1321                 secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey, node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64
1322         ) {
1323                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1324                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1325
1326                 let unsigned_announcement = UnsignedChannelAnnouncement {
1327                         features,
1328                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1329                         short_channel_id,
1330                         node_id_1,
1331                         node_id_2,
1332                         bitcoin_key_1: node_id_1,
1333                         bitcoin_key_2: node_id_2,
1334                         excess_data: Vec::new(),
1335                 };
1336
1337                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1338                 let valid_announcement = ChannelAnnouncement {
1339                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1340                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1341                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1342                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1343                         contents: unsigned_announcement.clone(),
1344                 };
1345                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1346                         Ok(res) => assert!(res),
1347                         _ => panic!()
1348                 };
1349         }
1350
1351         fn update_channel(
1352                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1353                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate
1354         ) {
1355                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1356                 let valid_channel_update = ChannelUpdate {
1357                         signature: secp_ctx.sign(&msghash, node_privkey),
1358                         contents: update.clone()
1359                 };
1360
1361                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1362                         Ok(res) => assert!(res),
1363                         Err(_) => panic!()
1364                 };
1365         }
1366
1367         fn add_or_update_node(
1368                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1369                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, features: NodeFeatures, timestamp: u32
1370         ) {
1371                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1372                 let unsigned_announcement = UnsignedNodeAnnouncement {
1373                         features,
1374                         timestamp,
1375                         node_id,
1376                         rgb: [0; 3],
1377                         alias: [0; 32],
1378                         addresses: Vec::new(),
1379                         excess_address_data: Vec::new(),
1380                         excess_data: Vec::new(),
1381                 };
1382                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1383                 let valid_announcement = NodeAnnouncement {
1384                         signature: secp_ctx.sign(&msghash, node_privkey),
1385                         contents: unsigned_announcement.clone()
1386                 };
1387
1388                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1389                         Ok(_) => (),
1390                         Err(_) => panic!()
1391                 };
1392         }
1393
1394         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1395                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1396                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1397                 }).collect();
1398
1399                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1400
1401                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1402                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1403
1404                 (our_privkey, our_id, privkeys, pubkeys)
1405         }
1406
1407         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1408                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1409                 // test for it later.
1410                 let idx = (id - 1) * 2 + 1;
1411                 if idx > 8*3 {
1412                         vec![1 << (idx - 8*3), 0, 0, 0]
1413                 } else if idx > 8*2 {
1414                         vec![1 << (idx - 8*2), 0, 0]
1415                 } else if idx > 8*1 {
1416                         vec![1 << (idx - 8*1), 0]
1417                 } else {
1418                         vec![1 << idx]
1419                 }
1420         }
1421
1422         fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>, sync::Arc<test_utils::TestChainSource>, sync::Arc<test_utils::TestLogger>) {
1423                 let secp_ctx = Secp256k1::new();
1424                 let logger = Arc::new(test_utils::TestLogger::new());
1425                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1426                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
1427                 let net_graph_msg_handler = NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger));
1428                 // Build network from our_id to node6:
1429                 //
1430                 //        -1(1)2-  node0  -1(3)2-
1431                 //       /                       \
1432                 // our_id -1(12)2- node7 -1(13)2--- node2
1433                 //       \                       /
1434                 //        -1(2)2-  node1  -1(4)2-
1435                 //
1436                 //
1437                 // chan1  1-to-2: disabled
1438                 // chan1  2-to-1: enabled, 0 fee
1439                 //
1440                 // chan2  1-to-2: enabled, ignored fee
1441                 // chan2  2-to-1: enabled, 0 fee
1442                 //
1443                 // chan3  1-to-2: enabled, 0 fee
1444                 // chan3  2-to-1: enabled, 100 msat fee
1445                 //
1446                 // chan4  1-to-2: enabled, 100% fee
1447                 // chan4  2-to-1: enabled, 0 fee
1448                 //
1449                 // chan12 1-to-2: enabled, ignored fee
1450                 // chan12 2-to-1: enabled, 0 fee
1451                 //
1452                 // chan13 1-to-2: enabled, 200% fee
1453                 // chan13 2-to-1: enabled, 0 fee
1454                 //
1455                 //
1456                 //       -1(5)2- node3 -1(8)2--
1457                 //       |         2          |
1458                 //       |       (11)         |
1459                 //      /          1           \
1460                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1461                 //      \                      /
1462                 //       -1(7)2- node5 -1(10)2-
1463                 //
1464                 // Channels 5, 8, 9 and 10 are private channels.
1465                 //
1466                 // chan5  1-to-2: enabled, 100 msat fee
1467                 // chan5  2-to-1: enabled, 0 fee
1468                 //
1469                 // chan6  1-to-2: enabled, 0 fee
1470                 // chan6  2-to-1: enabled, 0 fee
1471                 //
1472                 // chan7  1-to-2: enabled, 100% fee
1473                 // chan7  2-to-1: enabled, 0 fee
1474                 //
1475                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1476                 // chan8  2-to-1: enabled, 0 fee
1477                 //
1478                 // chan9  1-to-2: enabled, 1001 msat fee
1479                 // chan9  2-to-1: enabled, 0 fee
1480                 //
1481                 // chan10 1-to-2: enabled, 0 fee
1482                 // chan10 2-to-1: enabled, 0 fee
1483                 //
1484                 // chan11 1-to-2: enabled, 0 fee
1485                 // chan11 2-to-1: enabled, 0 fee
1486
1487                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1488
1489                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1490                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1491                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1492                         short_channel_id: 1,
1493                         timestamp: 1,
1494                         flags: 1,
1495                         cltv_expiry_delta: 0,
1496                         htlc_minimum_msat: 0,
1497                         htlc_maximum_msat: OptionalField::Absent,
1498                         fee_base_msat: 0,
1499                         fee_proportional_millionths: 0,
1500                         excess_data: Vec::new()
1501                 });
1502
1503                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1504
1505                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1506                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1507                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1508                         short_channel_id: 2,
1509                         timestamp: 1,
1510                         flags: 0,
1511                         cltv_expiry_delta: u16::max_value(),
1512                         htlc_minimum_msat: 0,
1513                         htlc_maximum_msat: OptionalField::Absent,
1514                         fee_base_msat: u32::max_value(),
1515                         fee_proportional_millionths: u32::max_value(),
1516                         excess_data: Vec::new()
1517                 });
1518                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1519                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1520                         short_channel_id: 2,
1521                         timestamp: 1,
1522                         flags: 1,
1523                         cltv_expiry_delta: 0,
1524                         htlc_minimum_msat: 0,
1525                         htlc_maximum_msat: OptionalField::Absent,
1526                         fee_base_msat: 0,
1527                         fee_proportional_millionths: 0,
1528                         excess_data: Vec::new()
1529                 });
1530
1531                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1532
1533                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1534                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1535                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1536                         short_channel_id: 12,
1537                         timestamp: 1,
1538                         flags: 0,
1539                         cltv_expiry_delta: u16::max_value(),
1540                         htlc_minimum_msat: 0,
1541                         htlc_maximum_msat: OptionalField::Absent,
1542                         fee_base_msat: u32::max_value(),
1543                         fee_proportional_millionths: u32::max_value(),
1544                         excess_data: Vec::new()
1545                 });
1546                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1547                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1548                         short_channel_id: 12,
1549                         timestamp: 1,
1550                         flags: 1,
1551                         cltv_expiry_delta: 0,
1552                         htlc_minimum_msat: 0,
1553                         htlc_maximum_msat: OptionalField::Absent,
1554                         fee_base_msat: 0,
1555                         fee_proportional_millionths: 0,
1556                         excess_data: Vec::new()
1557                 });
1558
1559                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1560
1561                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1562                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1563                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1564                         short_channel_id: 3,
1565                         timestamp: 1,
1566                         flags: 0,
1567                         cltv_expiry_delta: (3 << 8) | 1,
1568                         htlc_minimum_msat: 0,
1569                         htlc_maximum_msat: OptionalField::Absent,
1570                         fee_base_msat: 0,
1571                         fee_proportional_millionths: 0,
1572                         excess_data: Vec::new()
1573                 });
1574                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1575                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1576                         short_channel_id: 3,
1577                         timestamp: 1,
1578                         flags: 1,
1579                         cltv_expiry_delta: (3 << 8) | 2,
1580                         htlc_minimum_msat: 0,
1581                         htlc_maximum_msat: OptionalField::Absent,
1582                         fee_base_msat: 100,
1583                         fee_proportional_millionths: 0,
1584                         excess_data: Vec::new()
1585                 });
1586
1587                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1588                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1589                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1590                         short_channel_id: 4,
1591                         timestamp: 1,
1592                         flags: 0,
1593                         cltv_expiry_delta: (4 << 8) | 1,
1594                         htlc_minimum_msat: 0,
1595                         htlc_maximum_msat: OptionalField::Absent,
1596                         fee_base_msat: 0,
1597                         fee_proportional_millionths: 1000000,
1598                         excess_data: Vec::new()
1599                 });
1600                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1601                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1602                         short_channel_id: 4,
1603                         timestamp: 1,
1604                         flags: 1,
1605                         cltv_expiry_delta: (4 << 8) | 2,
1606                         htlc_minimum_msat: 0,
1607                         htlc_maximum_msat: OptionalField::Absent,
1608                         fee_base_msat: 0,
1609                         fee_proportional_millionths: 0,
1610                         excess_data: Vec::new()
1611                 });
1612
1613                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1614                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1615                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1616                         short_channel_id: 13,
1617                         timestamp: 1,
1618                         flags: 0,
1619                         cltv_expiry_delta: (13 << 8) | 1,
1620                         htlc_minimum_msat: 0,
1621                         htlc_maximum_msat: OptionalField::Absent,
1622                         fee_base_msat: 0,
1623                         fee_proportional_millionths: 2000000,
1624                         excess_data: Vec::new()
1625                 });
1626                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1627                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1628                         short_channel_id: 13,
1629                         timestamp: 1,
1630                         flags: 1,
1631                         cltv_expiry_delta: (13 << 8) | 2,
1632                         htlc_minimum_msat: 0,
1633                         htlc_maximum_msat: OptionalField::Absent,
1634                         fee_base_msat: 0,
1635                         fee_proportional_millionths: 0,
1636                         excess_data: Vec::new()
1637                 });
1638
1639                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1640
1641                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1642                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1643                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1644                         short_channel_id: 6,
1645                         timestamp: 1,
1646                         flags: 0,
1647                         cltv_expiry_delta: (6 << 8) | 1,
1648                         htlc_minimum_msat: 0,
1649                         htlc_maximum_msat: OptionalField::Absent,
1650                         fee_base_msat: 0,
1651                         fee_proportional_millionths: 0,
1652                         excess_data: Vec::new()
1653                 });
1654                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1655                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1656                         short_channel_id: 6,
1657                         timestamp: 1,
1658                         flags: 1,
1659                         cltv_expiry_delta: (6 << 8) | 2,
1660                         htlc_minimum_msat: 0,
1661                         htlc_maximum_msat: OptionalField::Absent,
1662                         fee_base_msat: 0,
1663                         fee_proportional_millionths: 0,
1664                         excess_data: Vec::new(),
1665                 });
1666
1667                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1668                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1669                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1670                         short_channel_id: 11,
1671                         timestamp: 1,
1672                         flags: 0,
1673                         cltv_expiry_delta: (11 << 8) | 1,
1674                         htlc_minimum_msat: 0,
1675                         htlc_maximum_msat: OptionalField::Absent,
1676                         fee_base_msat: 0,
1677                         fee_proportional_millionths: 0,
1678                         excess_data: Vec::new()
1679                 });
1680                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1681                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1682                         short_channel_id: 11,
1683                         timestamp: 1,
1684                         flags: 1,
1685                         cltv_expiry_delta: (11 << 8) | 2,
1686                         htlc_minimum_msat: 0,
1687                         htlc_maximum_msat: OptionalField::Absent,
1688                         fee_base_msat: 0,
1689                         fee_proportional_millionths: 0,
1690                         excess_data: Vec::new()
1691                 });
1692
1693                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1694
1695                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1696
1697                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1698                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1699                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1700                         short_channel_id: 7,
1701                         timestamp: 1,
1702                         flags: 0,
1703                         cltv_expiry_delta: (7 << 8) | 1,
1704                         htlc_minimum_msat: 0,
1705                         htlc_maximum_msat: OptionalField::Absent,
1706                         fee_base_msat: 0,
1707                         fee_proportional_millionths: 1000000,
1708                         excess_data: Vec::new()
1709                 });
1710                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1711                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1712                         short_channel_id: 7,
1713                         timestamp: 1,
1714                         flags: 1,
1715                         cltv_expiry_delta: (7 << 8) | 2,
1716                         htlc_minimum_msat: 0,
1717                         htlc_maximum_msat: OptionalField::Absent,
1718                         fee_base_msat: 0,
1719                         fee_proportional_millionths: 0,
1720                         excess_data: Vec::new()
1721                 });
1722
1723                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1724
1725                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1726         }
1727
1728         #[test]
1729         fn simple_route_test() {
1730                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1731                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1732
1733                 // Simple route to 2 via 1
1734
1735                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger)) {
1736                         assert_eq!(err, "Cannot send a payment of 0 msat");
1737                 } else { panic!(); }
1738
1739                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1740                 assert_eq!(route.paths[0].len(), 2);
1741
1742                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1743                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1744                 assert_eq!(route.paths[0][0].fee_msat, 100);
1745                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1746                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1747                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1748
1749                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1750                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1751                 assert_eq!(route.paths[0][1].fee_msat, 100);
1752                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1753                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1754                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1755         }
1756
1757         #[test]
1758         fn invalid_first_hop_test() {
1759                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1760                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1761
1762                 // Simple route to 2 via 1
1763
1764                 let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
1765
1766                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
1767                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1768                 } else { panic!(); }
1769
1770                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1771                 assert_eq!(route.paths[0].len(), 2);
1772         }
1773
1774         #[test]
1775         fn htlc_minimum_test() {
1776                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1777                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1778
1779                 // Simple route to 2 via 1
1780
1781                 // Disable other paths
1782                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1783                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1784                         short_channel_id: 12,
1785                         timestamp: 2,
1786                         flags: 2, // to disable
1787                         cltv_expiry_delta: 0,
1788                         htlc_minimum_msat: 0,
1789                         htlc_maximum_msat: OptionalField::Absent,
1790                         fee_base_msat: 0,
1791                         fee_proportional_millionths: 0,
1792                         excess_data: Vec::new()
1793                 });
1794                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1795                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1796                         short_channel_id: 3,
1797                         timestamp: 2,
1798                         flags: 2, // to disable
1799                         cltv_expiry_delta: 0,
1800                         htlc_minimum_msat: 0,
1801                         htlc_maximum_msat: OptionalField::Absent,
1802                         fee_base_msat: 0,
1803                         fee_proportional_millionths: 0,
1804                         excess_data: Vec::new()
1805                 });
1806                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1807                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1808                         short_channel_id: 13,
1809                         timestamp: 2,
1810                         flags: 2, // to disable
1811                         cltv_expiry_delta: 0,
1812                         htlc_minimum_msat: 0,
1813                         htlc_maximum_msat: OptionalField::Absent,
1814                         fee_base_msat: 0,
1815                         fee_proportional_millionths: 0,
1816                         excess_data: Vec::new()
1817                 });
1818                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1819                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1820                         short_channel_id: 6,
1821                         timestamp: 2,
1822                         flags: 2, // to disable
1823                         cltv_expiry_delta: 0,
1824                         htlc_minimum_msat: 0,
1825                         htlc_maximum_msat: OptionalField::Absent,
1826                         fee_base_msat: 0,
1827                         fee_proportional_millionths: 0,
1828                         excess_data: Vec::new()
1829                 });
1830                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1831                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1832                         short_channel_id: 7,
1833                         timestamp: 2,
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                 // Check against amount_to_transfer_over_msat.
1844                 // Set minimal HTLC of 200_000_000 msat.
1845                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1846                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1847                         short_channel_id: 2,
1848                         timestamp: 3,
1849                         flags: 0,
1850                         cltv_expiry_delta: 0,
1851                         htlc_minimum_msat: 200_000_000,
1852                         htlc_maximum_msat: OptionalField::Absent,
1853                         fee_base_msat: 0,
1854                         fee_proportional_millionths: 0,
1855                         excess_data: Vec::new()
1856                 });
1857
1858                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1859                 // be used.
1860                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1861                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1862                         short_channel_id: 4,
1863                         timestamp: 3,
1864                         flags: 0,
1865                         cltv_expiry_delta: 0,
1866                         htlc_minimum_msat: 0,
1867                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1868                         fee_base_msat: 0,
1869                         fee_proportional_millionths: 0,
1870                         excess_data: Vec::new()
1871                 });
1872
1873                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1874                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)) {
1875                         assert_eq!(err, "Failed to find a path to the given destination");
1876                 } else { panic!(); }
1877
1878                 // Lift the restriction on the first hop.
1879                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1880                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1881                         short_channel_id: 2,
1882                         timestamp: 4,
1883                         flags: 0,
1884                         cltv_expiry_delta: 0,
1885                         htlc_minimum_msat: 0,
1886                         htlc_maximum_msat: OptionalField::Absent,
1887                         fee_base_msat: 0,
1888                         fee_proportional_millionths: 0,
1889                         excess_data: Vec::new()
1890                 });
1891
1892                 // A payment above the minimum should pass
1893                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)).unwrap();
1894                 assert_eq!(route.paths[0].len(), 2);
1895         }
1896
1897         #[test]
1898         fn htlc_minimum_overpay_test() {
1899                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1900                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1901
1902                 // A route to node#2 via two paths.
1903                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1904                 // Thus, they can't send 60 without overpaying.
1905                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1906                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1907                         short_channel_id: 2,
1908                         timestamp: 2,
1909                         flags: 0,
1910                         cltv_expiry_delta: 0,
1911                         htlc_minimum_msat: 35_000,
1912                         htlc_maximum_msat: OptionalField::Present(40_000),
1913                         fee_base_msat: 0,
1914                         fee_proportional_millionths: 0,
1915                         excess_data: Vec::new()
1916                 });
1917                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1918                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1919                         short_channel_id: 12,
1920                         timestamp: 3,
1921                         flags: 0,
1922                         cltv_expiry_delta: 0,
1923                         htlc_minimum_msat: 35_000,
1924                         htlc_maximum_msat: OptionalField::Present(40_000),
1925                         fee_base_msat: 0,
1926                         fee_proportional_millionths: 0,
1927                         excess_data: Vec::new()
1928                 });
1929
1930                 // Make 0 fee.
1931                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1932                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1933                         short_channel_id: 13,
1934                         timestamp: 2,
1935                         flags: 0,
1936                         cltv_expiry_delta: 0,
1937                         htlc_minimum_msat: 0,
1938                         htlc_maximum_msat: OptionalField::Absent,
1939                         fee_base_msat: 0,
1940                         fee_proportional_millionths: 0,
1941                         excess_data: Vec::new()
1942                 });
1943                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1944                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1945                         short_channel_id: 4,
1946                         timestamp: 2,
1947                         flags: 0,
1948                         cltv_expiry_delta: 0,
1949                         htlc_minimum_msat: 0,
1950                         htlc_maximum_msat: OptionalField::Absent,
1951                         fee_base_msat: 0,
1952                         fee_proportional_millionths: 0,
1953                         excess_data: Vec::new()
1954                 });
1955
1956                 // Disable other paths
1957                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1958                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1959                         short_channel_id: 1,
1960                         timestamp: 3,
1961                         flags: 2, // to disable
1962                         cltv_expiry_delta: 0,
1963                         htlc_minimum_msat: 0,
1964                         htlc_maximum_msat: OptionalField::Absent,
1965                         fee_base_msat: 0,
1966                         fee_proportional_millionths: 0,
1967                         excess_data: Vec::new()
1968                 });
1969
1970                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
1971                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1972                 // Overpay fees to hit htlc_minimum_msat.
1973                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1974                 // TODO: this could be better balanced to overpay 10k and not 15k.
1975                 assert_eq!(overpaid_fees, 15_000);
1976
1977                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1978                 // while taking even more fee to match htlc_minimum_msat.
1979                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1980                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1981                         short_channel_id: 12,
1982                         timestamp: 4,
1983                         flags: 0,
1984                         cltv_expiry_delta: 0,
1985                         htlc_minimum_msat: 65_000,
1986                         htlc_maximum_msat: OptionalField::Present(80_000),
1987                         fee_base_msat: 0,
1988                         fee_proportional_millionths: 0,
1989                         excess_data: Vec::new()
1990                 });
1991                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1992                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1993                         short_channel_id: 2,
1994                         timestamp: 3,
1995                         flags: 0,
1996                         cltv_expiry_delta: 0,
1997                         htlc_minimum_msat: 0,
1998                         htlc_maximum_msat: OptionalField::Absent,
1999                         fee_base_msat: 0,
2000                         fee_proportional_millionths: 0,
2001                         excess_data: Vec::new()
2002                 });
2003                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2004                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2005                         short_channel_id: 4,
2006                         timestamp: 4,
2007                         flags: 0,
2008                         cltv_expiry_delta: 0,
2009                         htlc_minimum_msat: 0,
2010                         htlc_maximum_msat: OptionalField::Absent,
2011                         fee_base_msat: 0,
2012                         fee_proportional_millionths: 100_000,
2013                         excess_data: Vec::new()
2014                 });
2015
2016                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2017                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
2018                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
2019                 assert_eq!(route.paths.len(), 1);
2020                 assert_eq!(route.paths[0][0].short_channel_id, 12);
2021                 let fees = route.paths[0][0].fee_msat;
2022                 assert_eq!(fees, 5_000);
2023
2024                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2025                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2026                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
2027                 // the other channel.
2028                 assert_eq!(route.paths.len(), 1);
2029                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2030                 let fees = route.paths[0][0].fee_msat;
2031                 assert_eq!(fees, 5_000);
2032         }
2033
2034         #[test]
2035         fn disable_channels_test() {
2036                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2037                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2038
2039                 // // Disable channels 4 and 12 by flags=2
2040                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2041                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2042                         short_channel_id: 4,
2043                         timestamp: 2,
2044                         flags: 2, // to disable
2045                         cltv_expiry_delta: 0,
2046                         htlc_minimum_msat: 0,
2047                         htlc_maximum_msat: OptionalField::Absent,
2048                         fee_base_msat: 0,
2049                         fee_proportional_millionths: 0,
2050                         excess_data: Vec::new()
2051                 });
2052                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2053                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2054                         short_channel_id: 12,
2055                         timestamp: 2,
2056                         flags: 2, // to disable
2057                         cltv_expiry_delta: 0,
2058                         htlc_minimum_msat: 0,
2059                         htlc_maximum_msat: OptionalField::Absent,
2060                         fee_base_msat: 0,
2061                         fee_proportional_millionths: 0,
2062                         excess_data: Vec::new()
2063                 });
2064
2065                 // If all the channels require some features we don't understand, route should fail
2066                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
2067                         assert_eq!(err, "Failed to find a path to the given destination");
2068                 } else { panic!(); }
2069
2070                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2071                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2072                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2073                 assert_eq!(route.paths[0].len(), 2);
2074
2075                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2076                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2077                 assert_eq!(route.paths[0][0].fee_msat, 200);
2078                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2079                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2080                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2081
2082                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2083                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2084                 assert_eq!(route.paths[0][1].fee_msat, 100);
2085                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2086                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2087                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2088         }
2089
2090         #[test]
2091         fn disable_node_test() {
2092                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2093                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2094
2095                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
2096                 let unknown_features = NodeFeatures::known().set_unknown_feature_required();
2097                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
2098                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
2099                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
2100
2101                 // If all nodes require some features we don't understand, route should fail
2102                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
2103                         assert_eq!(err, "Failed to find a path to the given destination");
2104                 } else { panic!(); }
2105
2106                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2107                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2108                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2109                 assert_eq!(route.paths[0].len(), 2);
2110
2111                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2112                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2113                 assert_eq!(route.paths[0][0].fee_msat, 200);
2114                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2115                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2116                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2117
2118                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2119                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2120                 assert_eq!(route.paths[0][1].fee_msat, 100);
2121                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2122                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2123                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2124
2125                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2126                 // naively) assume that the user checked the feature bits on the invoice, which override
2127                 // the node_announcement.
2128         }
2129
2130         #[test]
2131         fn our_chans_test() {
2132                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2133                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2134
2135                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2136                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2137                 assert_eq!(route.paths[0].len(), 3);
2138
2139                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2140                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2141                 assert_eq!(route.paths[0][0].fee_msat, 200);
2142                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2143                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2144                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2145
2146                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2147                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2148                 assert_eq!(route.paths[0][1].fee_msat, 100);
2149                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2150                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2151                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2152
2153                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2154                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2155                 assert_eq!(route.paths[0][2].fee_msat, 100);
2156                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2157                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2158                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2159
2160                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2161                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2162                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2163                 assert_eq!(route.paths[0].len(), 2);
2164
2165                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2166                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2167                 assert_eq!(route.paths[0][0].fee_msat, 200);
2168                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2169                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2170                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2171
2172                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2173                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2174                 assert_eq!(route.paths[0][1].fee_msat, 100);
2175                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2176                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2177                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2178         }
2179
2180         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2181                 let zero_fees = RoutingFees {
2182                         base_msat: 0,
2183                         proportional_millionths: 0,
2184                 };
2185                 vec![RouteHint(vec![RouteHintHop {
2186                         src_node_id: nodes[3].clone(),
2187                         short_channel_id: 8,
2188                         fees: zero_fees,
2189                         cltv_expiry_delta: (8 << 8) | 1,
2190                         htlc_minimum_msat: None,
2191                         htlc_maximum_msat: None,
2192                 }
2193                 ]), RouteHint(vec![RouteHintHop {
2194                         src_node_id: nodes[4].clone(),
2195                         short_channel_id: 9,
2196                         fees: RoutingFees {
2197                                 base_msat: 1001,
2198                                 proportional_millionths: 0,
2199                         },
2200                         cltv_expiry_delta: (9 << 8) | 1,
2201                         htlc_minimum_msat: None,
2202                         htlc_maximum_msat: None,
2203                 }]), RouteHint(vec![RouteHintHop {
2204                         src_node_id: nodes[5].clone(),
2205                         short_channel_id: 10,
2206                         fees: zero_fees,
2207                         cltv_expiry_delta: (10 << 8) | 1,
2208                         htlc_minimum_msat: None,
2209                         htlc_maximum_msat: None,
2210                 }])]
2211         }
2212
2213         fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2214                 let zero_fees = RoutingFees {
2215                         base_msat: 0,
2216                         proportional_millionths: 0,
2217                 };
2218                 vec![RouteHint(vec![RouteHintHop {
2219                         src_node_id: nodes[2].clone(),
2220                         short_channel_id: 5,
2221                         fees: RoutingFees {
2222                                 base_msat: 100,
2223                                 proportional_millionths: 0,
2224                         },
2225                         cltv_expiry_delta: (5 << 8) | 1,
2226                         htlc_minimum_msat: None,
2227                         htlc_maximum_msat: None,
2228                 }, RouteHintHop {
2229                         src_node_id: nodes[3].clone(),
2230                         short_channel_id: 8,
2231                         fees: zero_fees,
2232                         cltv_expiry_delta: (8 << 8) | 1,
2233                         htlc_minimum_msat: None,
2234                         htlc_maximum_msat: None,
2235                 }
2236                 ]), RouteHint(vec![RouteHintHop {
2237                         src_node_id: nodes[4].clone(),
2238                         short_channel_id: 9,
2239                         fees: RoutingFees {
2240                                 base_msat: 1001,
2241                                 proportional_millionths: 0,
2242                         },
2243                         cltv_expiry_delta: (9 << 8) | 1,
2244                         htlc_minimum_msat: None,
2245                         htlc_maximum_msat: None,
2246                 }]), RouteHint(vec![RouteHintHop {
2247                         src_node_id: nodes[5].clone(),
2248                         short_channel_id: 10,
2249                         fees: zero_fees,
2250                         cltv_expiry_delta: (10 << 8) | 1,
2251                         htlc_minimum_msat: None,
2252                         htlc_maximum_msat: None,
2253                 }])]
2254         }
2255
2256         #[test]
2257         fn partial_route_hint_test() {
2258                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2259                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2260
2261                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2262                 // Tests the behaviour when the RouteHint contains a suboptimal hop.
2263                 // RouteHint may be partially used by the algo to build the best path.
2264
2265                 // First check that last hop can't have its source as the payee.
2266                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2267                         src_node_id: nodes[6],
2268                         short_channel_id: 8,
2269                         fees: RoutingFees {
2270                                 base_msat: 1000,
2271                                 proportional_millionths: 0,
2272                         },
2273                         cltv_expiry_delta: (8 << 8) | 1,
2274                         htlc_minimum_msat: None,
2275                         htlc_maximum_msat: None,
2276                 }]);
2277
2278                 let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
2279                 invalid_last_hops.push(invalid_last_hop);
2280                 {
2281                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)) {
2282                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2283                         } else { panic!(); }
2284                 }
2285
2286                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops_multi_private_channels(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2287                 assert_eq!(route.paths[0].len(), 5);
2288
2289                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2290                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2291                 assert_eq!(route.paths[0][0].fee_msat, 100);
2292                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2293                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2294                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2295
2296                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2297                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2298                 assert_eq!(route.paths[0][1].fee_msat, 0);
2299                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2300                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2301                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2302
2303                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2304                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2305                 assert_eq!(route.paths[0][2].fee_msat, 0);
2306                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2307                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2308                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2309
2310                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2311                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2312                 assert_eq!(route.paths[0][3].fee_msat, 0);
2313                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2314                 // If we have a peer in the node map, we'll use their features here since we don't have
2315                 // a way of figuring out their features from the invoice:
2316                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2317                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2318
2319                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2320                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2321                 assert_eq!(route.paths[0][4].fee_msat, 100);
2322                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2323                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2324                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2325         }
2326
2327         fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2328                 let zero_fees = RoutingFees {
2329                         base_msat: 0,
2330                         proportional_millionths: 0,
2331                 };
2332                 vec![RouteHint(vec![RouteHintHop {
2333                         src_node_id: nodes[3].clone(),
2334                         short_channel_id: 8,
2335                         fees: zero_fees,
2336                         cltv_expiry_delta: (8 << 8) | 1,
2337                         htlc_minimum_msat: None,
2338                         htlc_maximum_msat: None,
2339                 }]), RouteHint(vec![
2340
2341                 ]), RouteHint(vec![RouteHintHop {
2342                         src_node_id: nodes[5].clone(),
2343                         short_channel_id: 10,
2344                         fees: zero_fees,
2345                         cltv_expiry_delta: (10 << 8) | 1,
2346                         htlc_minimum_msat: None,
2347                         htlc_maximum_msat: None,
2348                 }])]
2349         }
2350
2351         #[test]
2352         fn ignores_empty_last_hops_test() {
2353                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2354                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2355
2356                 // Test handling of an empty RouteHint passed in Invoice.
2357
2358                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &empty_last_hop(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2359                 assert_eq!(route.paths[0].len(), 5);
2360
2361                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2362                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2363                 assert_eq!(route.paths[0][0].fee_msat, 100);
2364                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2365                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2366                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2367
2368                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2369                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2370                 assert_eq!(route.paths[0][1].fee_msat, 0);
2371                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2372                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2373                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2374
2375                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2376                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2377                 assert_eq!(route.paths[0][2].fee_msat, 0);
2378                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2379                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2380                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2381
2382                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2383                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2384                 assert_eq!(route.paths[0][3].fee_msat, 0);
2385                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2386                 // If we have a peer in the node map, we'll use their features here since we don't have
2387                 // a way of figuring out their features from the invoice:
2388                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2389                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2390
2391                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2392                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2393                 assert_eq!(route.paths[0][4].fee_msat, 100);
2394                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2395                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2396                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2397         }
2398
2399         fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2400                 let zero_fees = RoutingFees {
2401                         base_msat: 0,
2402                         proportional_millionths: 0,
2403                 };
2404                 vec![RouteHint(vec![RouteHintHop {
2405                         src_node_id: nodes[2].clone(),
2406                         short_channel_id: 5,
2407                         fees: RoutingFees {
2408                                 base_msat: 100,
2409                                 proportional_millionths: 0,
2410                         },
2411                         cltv_expiry_delta: (5 << 8) | 1,
2412                         htlc_minimum_msat: None,
2413                         htlc_maximum_msat: None,
2414                 }, RouteHintHop {
2415                         src_node_id: nodes[3].clone(),
2416                         short_channel_id: 8,
2417                         fees: zero_fees,
2418                         cltv_expiry_delta: (8 << 8) | 1,
2419                         htlc_minimum_msat: None,
2420                         htlc_maximum_msat: None,
2421                 }]), RouteHint(vec![RouteHintHop {
2422                         src_node_id: nodes[5].clone(),
2423                         short_channel_id: 10,
2424                         fees: zero_fees,
2425                         cltv_expiry_delta: (10 << 8) | 1,
2426                         htlc_minimum_msat: None,
2427                         htlc_maximum_msat: None,
2428                 }])]
2429         }
2430
2431         #[test]
2432         fn multi_hint_last_hops_test() {
2433                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2434                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2435                 // Test through channels 2, 3, 5, 8.
2436                 // Test shows that multiple hop hints are considered.
2437
2438                 // Disabling channels 6 & 7 by flags=2
2439                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2440                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2441                         short_channel_id: 6,
2442                         timestamp: 2,
2443                         flags: 2, // to disable
2444                         cltv_expiry_delta: 0,
2445                         htlc_minimum_msat: 0,
2446                         htlc_maximum_msat: OptionalField::Absent,
2447                         fee_base_msat: 0,
2448                         fee_proportional_millionths: 0,
2449                         excess_data: Vec::new()
2450                 });
2451                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2452                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2453                         short_channel_id: 7,
2454                         timestamp: 2,
2455                         flags: 2, // to disable
2456                         cltv_expiry_delta: 0,
2457                         htlc_minimum_msat: 0,
2458                         htlc_maximum_msat: OptionalField::Absent,
2459                         fee_base_msat: 0,
2460                         fee_proportional_millionths: 0,
2461                         excess_data: Vec::new()
2462                 });
2463
2464                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &multi_hint_last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2465                 assert_eq!(route.paths[0].len(), 4);
2466
2467                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2468                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2469                 assert_eq!(route.paths[0][0].fee_msat, 200);
2470                 assert_eq!(route.paths[0][0].cltv_expiry_delta, 1025);
2471                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2472                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2473
2474                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2475                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2476                 assert_eq!(route.paths[0][1].fee_msat, 100);
2477                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 1281);
2478                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2479                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2480
2481                 assert_eq!(route.paths[0][2].pubkey, nodes[3]);
2482                 assert_eq!(route.paths[0][2].short_channel_id, 5);
2483                 assert_eq!(route.paths[0][2].fee_msat, 0);
2484                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 2049);
2485                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
2486                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
2487
2488                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2489                 assert_eq!(route.paths[0][3].short_channel_id, 8);
2490                 assert_eq!(route.paths[0][3].fee_msat, 100);
2491                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2492                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2493                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2494         }
2495
2496         fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2497                 let zero_fees = RoutingFees {
2498                         base_msat: 0,
2499                         proportional_millionths: 0,
2500                 };
2501                 vec![RouteHint(vec![RouteHintHop {
2502                         src_node_id: nodes[4].clone(),
2503                         short_channel_id: 11,
2504                         fees: zero_fees,
2505                         cltv_expiry_delta: (11 << 8) | 1,
2506                         htlc_minimum_msat: None,
2507                         htlc_maximum_msat: None,
2508                 }, RouteHintHop {
2509                         src_node_id: nodes[3].clone(),
2510                         short_channel_id: 8,
2511                         fees: zero_fees,
2512                         cltv_expiry_delta: (8 << 8) | 1,
2513                         htlc_minimum_msat: None,
2514                         htlc_maximum_msat: None,
2515                 }]), RouteHint(vec![RouteHintHop {
2516                         src_node_id: nodes[4].clone(),
2517                         short_channel_id: 9,
2518                         fees: RoutingFees {
2519                                 base_msat: 1001,
2520                                 proportional_millionths: 0,
2521                         },
2522                         cltv_expiry_delta: (9 << 8) | 1,
2523                         htlc_minimum_msat: None,
2524                         htlc_maximum_msat: None,
2525                 }]), RouteHint(vec![RouteHintHop {
2526                         src_node_id: nodes[5].clone(),
2527                         short_channel_id: 10,
2528                         fees: zero_fees,
2529                         cltv_expiry_delta: (10 << 8) | 1,
2530                         htlc_minimum_msat: None,
2531                         htlc_maximum_msat: None,
2532                 }])]
2533         }
2534
2535         #[test]
2536         fn last_hops_with_public_channel_test() {
2537                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2538                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2539                 // This test shows that public routes can be present in the invoice
2540                 // which would be handled in the same manner.
2541
2542                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops_with_public_channel(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2543                 assert_eq!(route.paths[0].len(), 5);
2544
2545                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2546                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2547                 assert_eq!(route.paths[0][0].fee_msat, 100);
2548                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2549                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2550                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2551
2552                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2553                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2554                 assert_eq!(route.paths[0][1].fee_msat, 0);
2555                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2556                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2557                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2558
2559                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2560                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2561                 assert_eq!(route.paths[0][2].fee_msat, 0);
2562                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2563                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2564                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2565
2566                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2567                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2568                 assert_eq!(route.paths[0][3].fee_msat, 0);
2569                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2570                 // If we have a peer in the node map, we'll use their features here since we don't have
2571                 // a way of figuring out their features from the invoice:
2572                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2573                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new());
2574
2575                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2576                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2577                 assert_eq!(route.paths[0][4].fee_msat, 100);
2578                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2579                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2580                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2581         }
2582
2583         #[test]
2584         fn our_chans_last_hop_connect_test() {
2585                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2586                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2587
2588                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2589                 let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2590                 let mut last_hops = last_hops(&nodes);
2591                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2592                 assert_eq!(route.paths[0].len(), 2);
2593
2594                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2595                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2596                 assert_eq!(route.paths[0][0].fee_msat, 0);
2597                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2598                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2599                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2600
2601                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2602                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2603                 assert_eq!(route.paths[0][1].fee_msat, 100);
2604                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2605                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2606                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2607
2608                 last_hops[0].0[0].fees.base_msat = 1000;
2609
2610                 // Revert to via 6 as the fee on 8 goes up
2611                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2612                 assert_eq!(route.paths[0].len(), 4);
2613
2614                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2615                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2616                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2617                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2618                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2619                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2620
2621                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2622                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2623                 assert_eq!(route.paths[0][1].fee_msat, 100);
2624                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2625                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2626                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2627
2628                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2629                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2630                 assert_eq!(route.paths[0][2].fee_msat, 0);
2631                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2632                 // If we have a peer in the node map, we'll use their features here since we don't have
2633                 // a way of figuring out their features from the invoice:
2634                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2635                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2636
2637                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2638                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2639                 assert_eq!(route.paths[0][3].fee_msat, 100);
2640                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2641                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2642                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2643
2644                 // ...but still use 8 for larger payments as 6 has a variable feerate
2645                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger)).unwrap();
2646                 assert_eq!(route.paths[0].len(), 5);
2647
2648                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2649                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2650                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2651                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2652                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2653                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2654
2655                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2656                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2657                 assert_eq!(route.paths[0][1].fee_msat, 0);
2658                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2659                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2660                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2661
2662                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2663                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2664                 assert_eq!(route.paths[0][2].fee_msat, 0);
2665                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2666                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2667                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2668
2669                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2670                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2671                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2672                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2673                 // If we have a peer in the node map, we'll use their features here since we don't have
2674                 // a way of figuring out their features from the invoice:
2675                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2676                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2677
2678                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2679                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2680                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2681                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2682                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2683                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2684         }
2685
2686         fn do_unannounced_path_test(last_hop_htlc_max: Option<u64>, last_hop_fee_prop: u32, outbound_capacity_msat: u64, route_val: u64) -> Result<Route, LightningError> {
2687                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2688                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2689                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2690
2691                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2692                 let last_hops = RouteHint(vec![RouteHintHop {
2693                         src_node_id: middle_node_id,
2694                         short_channel_id: 8,
2695                         fees: RoutingFees {
2696                                 base_msat: 1000,
2697                                 proportional_millionths: last_hop_fee_prop,
2698                         },
2699                         cltv_expiry_delta: (8 << 8) | 1,
2700                         htlc_minimum_msat: None,
2701                         htlc_maximum_msat: last_hop_htlc_max,
2702                 }]);
2703                 let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
2704                 get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &vec![&last_hops], route_val, 42, Arc::new(test_utils::TestLogger::new()))
2705         }
2706
2707         #[test]
2708         fn unannounced_path_test() {
2709                 // We should be able to send a payment to a destination without any help of a routing graph
2710                 // if we have a channel with a common counterparty that appears in the first and last hop
2711                 // hints.
2712                 let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
2713
2714                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2715                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2716                 assert_eq!(route.paths[0].len(), 2);
2717
2718                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2719                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2720                 assert_eq!(route.paths[0][0].fee_msat, 1001);
2721                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2722                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2723                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2724
2725                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2726                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2727                 assert_eq!(route.paths[0][1].fee_msat, 1000000);
2728                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2729                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2730                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2731         }
2732
2733         #[test]
2734         fn overflow_unannounced_path_test_liquidity_underflow() {
2735                 // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
2736                 // the last-hop had a fee which overflowed a u64, we'd panic.
2737                 // This was due to us adding the first-hop from us unconditionally, causing us to think
2738                 // we'd built a path (as our node is in the "best candidate" set), when we had not.
2739                 // In this test, we previously hit a subtraction underflow due to having less available
2740                 // liquidity at the last hop than 0.
2741                 assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 0, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
2742         }
2743
2744         #[test]
2745         fn overflow_unannounced_path_test_feerate_overflow() {
2746                 // This tests for the same case as above, except instead of hitting a subtraction
2747                 // underflow, we hit a case where the fee charged at a hop overflowed.
2748                 assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 50000, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
2749         }
2750
2751         #[test]
2752         fn available_amount_while_routing_test() {
2753                 // Tests whether we choose the correct available channel amount while routing.
2754
2755                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2756                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2757
2758                 // We will use a simple single-path route from
2759                 // our node to node2 via node0: channels {1, 3}.
2760
2761                 // First disable all other paths.
2762                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2763                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2764                         short_channel_id: 2,
2765                         timestamp: 2,
2766                         flags: 2,
2767                         cltv_expiry_delta: 0,
2768                         htlc_minimum_msat: 0,
2769                         htlc_maximum_msat: OptionalField::Present(100_000),
2770                         fee_base_msat: 0,
2771                         fee_proportional_millionths: 0,
2772                         excess_data: Vec::new()
2773                 });
2774                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2775                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2776                         short_channel_id: 12,
2777                         timestamp: 2,
2778                         flags: 2,
2779                         cltv_expiry_delta: 0,
2780                         htlc_minimum_msat: 0,
2781                         htlc_maximum_msat: OptionalField::Present(100_000),
2782                         fee_base_msat: 0,
2783                         fee_proportional_millionths: 0,
2784                         excess_data: Vec::new()
2785                 });
2786
2787                 // Make the first channel (#1) very permissive,
2788                 // and we will be testing all limits on the second channel.
2789                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2790                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2791                         short_channel_id: 1,
2792                         timestamp: 2,
2793                         flags: 0,
2794                         cltv_expiry_delta: 0,
2795                         htlc_minimum_msat: 0,
2796                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2797                         fee_base_msat: 0,
2798                         fee_proportional_millionths: 0,
2799                         excess_data: Vec::new()
2800                 });
2801
2802                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2803                 // In this case, it should be set to 250_000 sats.
2804                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2805                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2806                         short_channel_id: 3,
2807                         timestamp: 2,
2808                         flags: 0,
2809                         cltv_expiry_delta: 0,
2810                         htlc_minimum_msat: 0,
2811                         htlc_maximum_msat: OptionalField::Absent,
2812                         fee_base_msat: 0,
2813                         fee_proportional_millionths: 0,
2814                         excess_data: Vec::new()
2815                 });
2816
2817                 {
2818                         // Attempt to route more than available results in a failure.
2819                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2820                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2821                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2822                         } else { panic!(); }
2823                 }
2824
2825                 {
2826                         // Now, attempt to route an exact amount we have should be fine.
2827                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2828                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2829                         assert_eq!(route.paths.len(), 1);
2830                         let path = route.paths.last().unwrap();
2831                         assert_eq!(path.len(), 2);
2832                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2833                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2834                 }
2835
2836                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2837                 // Disable channel #1 and use another first hop.
2838                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2839                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2840                         short_channel_id: 1,
2841                         timestamp: 3,
2842                         flags: 2,
2843                         cltv_expiry_delta: 0,
2844                         htlc_minimum_msat: 0,
2845                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2846                         fee_base_msat: 0,
2847                         fee_proportional_millionths: 0,
2848                         excess_data: Vec::new()
2849                 });
2850
2851                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2852                 let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
2853
2854                 {
2855                         // Attempt to route more than available results in a failure.
2856                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2857                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2858                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2859                         } else { panic!(); }
2860                 }
2861
2862                 {
2863                         // Now, attempt to route an exact amount we have should be fine.
2864                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2865                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2866                         assert_eq!(route.paths.len(), 1);
2867                         let path = route.paths.last().unwrap();
2868                         assert_eq!(path.len(), 2);
2869                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2870                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2871                 }
2872
2873                 // Enable channel #1 back.
2874                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2875                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2876                         short_channel_id: 1,
2877                         timestamp: 4,
2878                         flags: 0,
2879                         cltv_expiry_delta: 0,
2880                         htlc_minimum_msat: 0,
2881                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2882                         fee_base_msat: 0,
2883                         fee_proportional_millionths: 0,
2884                         excess_data: Vec::new()
2885                 });
2886
2887
2888                 // Now let's see if routing works if we know only htlc_maximum_msat.
2889                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2890                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2891                         short_channel_id: 3,
2892                         timestamp: 3,
2893                         flags: 0,
2894                         cltv_expiry_delta: 0,
2895                         htlc_minimum_msat: 0,
2896                         htlc_maximum_msat: OptionalField::Present(15_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, &nodes[2],
2905                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 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 an exact amount we have should be fine.
2912                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2913                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2914                         assert_eq!(route.paths.len(), 1);
2915                         let path = route.paths.last().unwrap();
2916                         assert_eq!(path.len(), 2);
2917                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2918                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2919                 }
2920
2921                 // Now let's see if routing works if we know only capacity from the UTXO.
2922
2923                 // We can't change UTXO capacity on the fly, so we'll disable
2924                 // the existing channel and add another one with the capacity we need.
2925                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2926                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2927                         short_channel_id: 3,
2928                         timestamp: 4,
2929                         flags: 2,
2930                         cltv_expiry_delta: 0,
2931                         htlc_minimum_msat: 0,
2932                         htlc_maximum_msat: OptionalField::Absent,
2933                         fee_base_msat: 0,
2934                         fee_proportional_millionths: 0,
2935                         excess_data: Vec::new()
2936                 });
2937
2938                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2939                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2940                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2941                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2942                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2943
2944                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2945                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2946
2947                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2948                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2949                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2950                         short_channel_id: 333,
2951                         timestamp: 1,
2952                         flags: 0,
2953                         cltv_expiry_delta: (3 << 8) | 1,
2954                         htlc_minimum_msat: 0,
2955                         htlc_maximum_msat: OptionalField::Absent,
2956                         fee_base_msat: 0,
2957                         fee_proportional_millionths: 0,
2958                         excess_data: Vec::new()
2959                 });
2960                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2961                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2962                         short_channel_id: 333,
2963                         timestamp: 1,
2964                         flags: 1,
2965                         cltv_expiry_delta: (3 << 8) | 2,
2966                         htlc_minimum_msat: 0,
2967                         htlc_maximum_msat: OptionalField::Absent,
2968                         fee_base_msat: 100,
2969                         fee_proportional_millionths: 0,
2970                         excess_data: Vec::new()
2971                 });
2972
2973                 {
2974                         // Attempt to route more than available results in a failure.
2975                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2976                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2977                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2978                         } else { panic!(); }
2979                 }
2980
2981                 {
2982                         // Now, attempt to route an exact amount we have should be fine.
2983                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2984                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2985                         assert_eq!(route.paths.len(), 1);
2986                         let path = route.paths.last().unwrap();
2987                         assert_eq!(path.len(), 2);
2988                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2989                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2990                 }
2991
2992                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2993                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2994                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2995                         short_channel_id: 333,
2996                         timestamp: 6,
2997                         flags: 0,
2998                         cltv_expiry_delta: 0,
2999                         htlc_minimum_msat: 0,
3000                         htlc_maximum_msat: OptionalField::Present(10_000),
3001                         fee_base_msat: 0,
3002                         fee_proportional_millionths: 0,
3003                         excess_data: Vec::new()
3004                 });
3005
3006                 {
3007                         // Attempt to route more than available results in a failure.
3008                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3009                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
3010                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3011                         } else { panic!(); }
3012                 }
3013
3014                 {
3015                         // Now, attempt to route an exact amount we have should be fine.
3016                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3017                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
3018                         assert_eq!(route.paths.len(), 1);
3019                         let path = route.paths.last().unwrap();
3020                         assert_eq!(path.len(), 2);
3021                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3022                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
3023                 }
3024         }
3025
3026         #[test]
3027         fn available_liquidity_last_hop_test() {
3028                 // Check that available liquidity properly limits the path even when only
3029                 // one of the latter hops is limited.
3030                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3031                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3032
3033                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3034                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
3035                 // Total capacity: 50 sats.
3036
3037                 // Disable other potential paths.
3038                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3039                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3040                         short_channel_id: 2,
3041                         timestamp: 2,
3042                         flags: 2,
3043                         cltv_expiry_delta: 0,
3044                         htlc_minimum_msat: 0,
3045                         htlc_maximum_msat: OptionalField::Present(100_000),
3046                         fee_base_msat: 0,
3047                         fee_proportional_millionths: 0,
3048                         excess_data: Vec::new()
3049                 });
3050                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3051                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3052                         short_channel_id: 7,
3053                         timestamp: 2,
3054                         flags: 2,
3055                         cltv_expiry_delta: 0,
3056                         htlc_minimum_msat: 0,
3057                         htlc_maximum_msat: OptionalField::Present(100_000),
3058                         fee_base_msat: 0,
3059                         fee_proportional_millionths: 0,
3060                         excess_data: Vec::new()
3061                 });
3062
3063                 // Limit capacities
3064
3065                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3066                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3067                         short_channel_id: 12,
3068                         timestamp: 2,
3069                         flags: 0,
3070                         cltv_expiry_delta: 0,
3071                         htlc_minimum_msat: 0,
3072                         htlc_maximum_msat: OptionalField::Present(100_000),
3073                         fee_base_msat: 0,
3074                         fee_proportional_millionths: 0,
3075                         excess_data: Vec::new()
3076                 });
3077                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3078                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3079                         short_channel_id: 13,
3080                         timestamp: 2,
3081                         flags: 0,
3082                         cltv_expiry_delta: 0,
3083                         htlc_minimum_msat: 0,
3084                         htlc_maximum_msat: OptionalField::Present(100_000),
3085                         fee_base_msat: 0,
3086                         fee_proportional_millionths: 0,
3087                         excess_data: Vec::new()
3088                 });
3089
3090                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3091                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3092                         short_channel_id: 6,
3093                         timestamp: 2,
3094                         flags: 0,
3095                         cltv_expiry_delta: 0,
3096                         htlc_minimum_msat: 0,
3097                         htlc_maximum_msat: OptionalField::Present(50_000),
3098                         fee_base_msat: 0,
3099                         fee_proportional_millionths: 0,
3100                         excess_data: Vec::new()
3101                 });
3102                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3103                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3104                         short_channel_id: 11,
3105                         timestamp: 2,
3106                         flags: 0,
3107                         cltv_expiry_delta: 0,
3108                         htlc_minimum_msat: 0,
3109                         htlc_maximum_msat: OptionalField::Present(100_000),
3110                         fee_base_msat: 0,
3111                         fee_proportional_millionths: 0,
3112                         excess_data: Vec::new()
3113                 });
3114                 {
3115                         // Attempt to route more than available results in a failure.
3116                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3117                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
3118                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3119                         } else { panic!(); }
3120                 }
3121
3122                 {
3123                         // Now, attempt to route 49 sats (just a bit below the capacity).
3124                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3125                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
3126                         assert_eq!(route.paths.len(), 1);
3127                         let mut total_amount_paid_msat = 0;
3128                         for path in &route.paths {
3129                                 assert_eq!(path.len(), 4);
3130                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3131                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3132                         }
3133                         assert_eq!(total_amount_paid_msat, 49_000);
3134                 }
3135
3136                 {
3137                         // Attempt to route an exact amount is also fine
3138                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3139                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
3140                         assert_eq!(route.paths.len(), 1);
3141                         let mut total_amount_paid_msat = 0;
3142                         for path in &route.paths {
3143                                 assert_eq!(path.len(), 4);
3144                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3145                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3146                         }
3147                         assert_eq!(total_amount_paid_msat, 50_000);
3148                 }
3149         }
3150
3151         #[test]
3152         fn ignore_fee_first_hop_test() {
3153                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3154                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3155
3156                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3157                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3158                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3159                         short_channel_id: 1,
3160                         timestamp: 2,
3161                         flags: 0,
3162                         cltv_expiry_delta: 0,
3163                         htlc_minimum_msat: 0,
3164                         htlc_maximum_msat: OptionalField::Present(100_000),
3165                         fee_base_msat: 1_000_000,
3166                         fee_proportional_millionths: 0,
3167                         excess_data: Vec::new()
3168                 });
3169                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3170                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3171                         short_channel_id: 3,
3172                         timestamp: 2,
3173                         flags: 0,
3174                         cltv_expiry_delta: 0,
3175                         htlc_minimum_msat: 0,
3176                         htlc_maximum_msat: OptionalField::Present(50_000),
3177                         fee_base_msat: 0,
3178                         fee_proportional_millionths: 0,
3179                         excess_data: Vec::new()
3180                 });
3181
3182                 {
3183                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
3184                         assert_eq!(route.paths.len(), 1);
3185                         let mut total_amount_paid_msat = 0;
3186                         for path in &route.paths {
3187                                 assert_eq!(path.len(), 2);
3188                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3189                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3190                         }
3191                         assert_eq!(total_amount_paid_msat, 50_000);
3192                 }
3193         }
3194
3195         #[test]
3196         fn simple_mpp_route_test() {
3197                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3198                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3199
3200                 // We need a route consisting of 3 paths:
3201                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3202                 // To achieve this, the amount being transferred should be around
3203                 // the total capacity of these 3 paths.
3204
3205                 // First, we set limits on these (previously unlimited) channels.
3206                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
3207
3208                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3209                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3210                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3211                         short_channel_id: 1,
3212                         timestamp: 2,
3213                         flags: 0,
3214                         cltv_expiry_delta: 0,
3215                         htlc_minimum_msat: 0,
3216                         htlc_maximum_msat: OptionalField::Present(100_000),
3217                         fee_base_msat: 0,
3218                         fee_proportional_millionths: 0,
3219                         excess_data: Vec::new()
3220                 });
3221                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3222                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3223                         short_channel_id: 3,
3224                         timestamp: 2,
3225                         flags: 0,
3226                         cltv_expiry_delta: 0,
3227                         htlc_minimum_msat: 0,
3228                         htlc_maximum_msat: OptionalField::Present(50_000),
3229                         fee_base_msat: 0,
3230                         fee_proportional_millionths: 0,
3231                         excess_data: Vec::new()
3232                 });
3233
3234                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
3235                 // (total limit 60).
3236                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3237                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3238                         short_channel_id: 12,
3239                         timestamp: 2,
3240                         flags: 0,
3241                         cltv_expiry_delta: 0,
3242                         htlc_minimum_msat: 0,
3243                         htlc_maximum_msat: OptionalField::Present(60_000),
3244                         fee_base_msat: 0,
3245                         fee_proportional_millionths: 0,
3246                         excess_data: Vec::new()
3247                 });
3248                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3249                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3250                         short_channel_id: 13,
3251                         timestamp: 2,
3252                         flags: 0,
3253                         cltv_expiry_delta: 0,
3254                         htlc_minimum_msat: 0,
3255                         htlc_maximum_msat: OptionalField::Present(60_000),
3256                         fee_base_msat: 0,
3257                         fee_proportional_millionths: 0,
3258                         excess_data: Vec::new()
3259                 });
3260
3261                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
3262                 // (total capacity 180 sats).
3263                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3264                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3265                         short_channel_id: 2,
3266                         timestamp: 2,
3267                         flags: 0,
3268                         cltv_expiry_delta: 0,
3269                         htlc_minimum_msat: 0,
3270                         htlc_maximum_msat: OptionalField::Present(200_000),
3271                         fee_base_msat: 0,
3272                         fee_proportional_millionths: 0,
3273                         excess_data: Vec::new()
3274                 });
3275                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3276                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3277                         short_channel_id: 4,
3278                         timestamp: 2,
3279                         flags: 0,
3280                         cltv_expiry_delta: 0,
3281                         htlc_minimum_msat: 0,
3282                         htlc_maximum_msat: OptionalField::Present(180_000),
3283                         fee_base_msat: 0,
3284                         fee_proportional_millionths: 0,
3285                         excess_data: Vec::new()
3286                 });
3287
3288                 {
3289                         // Attempt to route more than available results in a failure.
3290                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph,
3291                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
3292                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3293                         } else { panic!(); }
3294                 }
3295
3296                 {
3297                         // Now, attempt to route 250 sats (just a bit below the capacity).
3298                         // Our algorithm should provide us with these 3 paths.
3299                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3300                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
3301                         assert_eq!(route.paths.len(), 3);
3302                         let mut total_amount_paid_msat = 0;
3303                         for path in &route.paths {
3304                                 assert_eq!(path.len(), 2);
3305                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3306                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3307                         }
3308                         assert_eq!(total_amount_paid_msat, 250_000);
3309                 }
3310
3311                 {
3312                         // Attempt to route an exact amount is also fine
3313                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3314                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
3315                         assert_eq!(route.paths.len(), 3);
3316                         let mut total_amount_paid_msat = 0;
3317                         for path in &route.paths {
3318                                 assert_eq!(path.len(), 2);
3319                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3320                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3321                         }
3322                         assert_eq!(total_amount_paid_msat, 290_000);
3323                 }
3324         }
3325
3326         #[test]
3327         fn long_mpp_route_test() {
3328                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3329                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3330
3331                 // We need a route consisting of 3 paths:
3332                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3333                 // Note that these paths overlap (channels 5, 12, 13).
3334                 // We will route 300 sats.
3335                 // Each path will have 100 sats capacity, those channels which
3336                 // are used twice will have 200 sats capacity.
3337
3338                 // Disable other potential paths.
3339                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3340                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3341                         short_channel_id: 2,
3342                         timestamp: 2,
3343                         flags: 2,
3344                         cltv_expiry_delta: 0,
3345                         htlc_minimum_msat: 0,
3346                         htlc_maximum_msat: OptionalField::Present(100_000),
3347                         fee_base_msat: 0,
3348                         fee_proportional_millionths: 0,
3349                         excess_data: Vec::new()
3350                 });
3351                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3352                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3353                         short_channel_id: 7,
3354                         timestamp: 2,
3355                         flags: 2,
3356                         cltv_expiry_delta: 0,
3357                         htlc_minimum_msat: 0,
3358                         htlc_maximum_msat: OptionalField::Present(100_000),
3359                         fee_base_msat: 0,
3360                         fee_proportional_millionths: 0,
3361                         excess_data: Vec::new()
3362                 });
3363
3364                 // Path via {node0, node2} is channels {1, 3, 5}.
3365                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3366                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3367                         short_channel_id: 1,
3368                         timestamp: 2,
3369                         flags: 0,
3370                         cltv_expiry_delta: 0,
3371                         htlc_minimum_msat: 0,
3372                         htlc_maximum_msat: OptionalField::Present(100_000),
3373                         fee_base_msat: 0,
3374                         fee_proportional_millionths: 0,
3375                         excess_data: Vec::new()
3376                 });
3377                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3378                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3379                         short_channel_id: 3,
3380                         timestamp: 2,
3381                         flags: 0,
3382                         cltv_expiry_delta: 0,
3383                         htlc_minimum_msat: 0,
3384                         htlc_maximum_msat: OptionalField::Present(100_000),
3385                         fee_base_msat: 0,
3386                         fee_proportional_millionths: 0,
3387                         excess_data: Vec::new()
3388                 });
3389
3390                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3391                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3392                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3393                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3394                         short_channel_id: 5,
3395                         timestamp: 2,
3396                         flags: 0,
3397                         cltv_expiry_delta: 0,
3398                         htlc_minimum_msat: 0,
3399                         htlc_maximum_msat: OptionalField::Present(200_000),
3400                         fee_base_msat: 0,
3401                         fee_proportional_millionths: 0,
3402                         excess_data: Vec::new()
3403                 });
3404
3405                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3406                 // Add 100 sats to the capacities of {12, 13}, because these channels
3407                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3408                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3409                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3410                         short_channel_id: 12,
3411                         timestamp: 2,
3412                         flags: 0,
3413                         cltv_expiry_delta: 0,
3414                         htlc_minimum_msat: 0,
3415                         htlc_maximum_msat: OptionalField::Present(200_000),
3416                         fee_base_msat: 0,
3417                         fee_proportional_millionths: 0,
3418                         excess_data: Vec::new()
3419                 });
3420                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3421                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3422                         short_channel_id: 13,
3423                         timestamp: 2,
3424                         flags: 0,
3425                         cltv_expiry_delta: 0,
3426                         htlc_minimum_msat: 0,
3427                         htlc_maximum_msat: OptionalField::Present(200_000),
3428                         fee_base_msat: 0,
3429                         fee_proportional_millionths: 0,
3430                         excess_data: Vec::new()
3431                 });
3432
3433                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3434                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3435                         short_channel_id: 6,
3436                         timestamp: 2,
3437                         flags: 0,
3438                         cltv_expiry_delta: 0,
3439                         htlc_minimum_msat: 0,
3440                         htlc_maximum_msat: OptionalField::Present(100_000),
3441                         fee_base_msat: 0,
3442                         fee_proportional_millionths: 0,
3443                         excess_data: Vec::new()
3444                 });
3445                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3446                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3447                         short_channel_id: 11,
3448                         timestamp: 2,
3449                         flags: 0,
3450                         cltv_expiry_delta: 0,
3451                         htlc_minimum_msat: 0,
3452                         htlc_maximum_msat: OptionalField::Present(100_000),
3453                         fee_base_msat: 0,
3454                         fee_proportional_millionths: 0,
3455                         excess_data: Vec::new()
3456                 });
3457
3458                 // Path via {node7, node2} is channels {12, 13, 5}.
3459                 // We already limited them to 200 sats (they are used twice for 100 sats).
3460                 // Nothing to do here.
3461
3462                 {
3463                         // Attempt to route more than available results in a failure.
3464                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3465                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3466                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3467                         } else { panic!(); }
3468                 }
3469
3470                 {
3471                         // Now, attempt to route 300 sats (exact amount we can route).
3472                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3473                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3474                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3475                         assert_eq!(route.paths.len(), 3);
3476
3477                         let mut total_amount_paid_msat = 0;
3478                         for path in &route.paths {
3479                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3480                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3481                         }
3482                         assert_eq!(total_amount_paid_msat, 300_000);
3483                 }
3484
3485         }
3486
3487         #[test]
3488         fn mpp_cheaper_route_test() {
3489                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3490                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3491
3492                 // This test checks that if we have two cheaper paths and one more expensive path,
3493                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3494                 // two cheaper paths will be taken.
3495                 // These paths have equal available liquidity.
3496
3497                 // We need a combination of 3 paths:
3498                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3499                 // Note that these paths overlap (channels 5, 12, 13).
3500                 // Each path will have 100 sats capacity, those channels which
3501                 // are used twice will have 200 sats capacity.
3502
3503                 // Disable other potential paths.
3504                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3505                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3506                         short_channel_id: 2,
3507                         timestamp: 2,
3508                         flags: 2,
3509                         cltv_expiry_delta: 0,
3510                         htlc_minimum_msat: 0,
3511                         htlc_maximum_msat: OptionalField::Present(100_000),
3512                         fee_base_msat: 0,
3513                         fee_proportional_millionths: 0,
3514                         excess_data: Vec::new()
3515                 });
3516                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3517                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3518                         short_channel_id: 7,
3519                         timestamp: 2,
3520                         flags: 2,
3521                         cltv_expiry_delta: 0,
3522                         htlc_minimum_msat: 0,
3523                         htlc_maximum_msat: OptionalField::Present(100_000),
3524                         fee_base_msat: 0,
3525                         fee_proportional_millionths: 0,
3526                         excess_data: Vec::new()
3527                 });
3528
3529                 // Path via {node0, node2} is channels {1, 3, 5}.
3530                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3531                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3532                         short_channel_id: 1,
3533                         timestamp: 2,
3534                         flags: 0,
3535                         cltv_expiry_delta: 0,
3536                         htlc_minimum_msat: 0,
3537                         htlc_maximum_msat: OptionalField::Present(100_000),
3538                         fee_base_msat: 0,
3539                         fee_proportional_millionths: 0,
3540                         excess_data: Vec::new()
3541                 });
3542                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3543                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3544                         short_channel_id: 3,
3545                         timestamp: 2,
3546                         flags: 0,
3547                         cltv_expiry_delta: 0,
3548                         htlc_minimum_msat: 0,
3549                         htlc_maximum_msat: OptionalField::Present(100_000),
3550                         fee_base_msat: 0,
3551                         fee_proportional_millionths: 0,
3552                         excess_data: Vec::new()
3553                 });
3554
3555                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3556                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3557                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3558                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3559                         short_channel_id: 5,
3560                         timestamp: 2,
3561                         flags: 0,
3562                         cltv_expiry_delta: 0,
3563                         htlc_minimum_msat: 0,
3564                         htlc_maximum_msat: OptionalField::Present(200_000),
3565                         fee_base_msat: 0,
3566                         fee_proportional_millionths: 0,
3567                         excess_data: Vec::new()
3568                 });
3569
3570                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3571                 // Add 100 sats to the capacities of {12, 13}, because these channels
3572                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3573                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3574                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3575                         short_channel_id: 12,
3576                         timestamp: 2,
3577                         flags: 0,
3578                         cltv_expiry_delta: 0,
3579                         htlc_minimum_msat: 0,
3580                         htlc_maximum_msat: OptionalField::Present(200_000),
3581                         fee_base_msat: 0,
3582                         fee_proportional_millionths: 0,
3583                         excess_data: Vec::new()
3584                 });
3585                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3586                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3587                         short_channel_id: 13,
3588                         timestamp: 2,
3589                         flags: 0,
3590                         cltv_expiry_delta: 0,
3591                         htlc_minimum_msat: 0,
3592                         htlc_maximum_msat: OptionalField::Present(200_000),
3593                         fee_base_msat: 0,
3594                         fee_proportional_millionths: 0,
3595                         excess_data: Vec::new()
3596                 });
3597
3598                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3599                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3600                         short_channel_id: 6,
3601                         timestamp: 2,
3602                         flags: 0,
3603                         cltv_expiry_delta: 0,
3604                         htlc_minimum_msat: 0,
3605                         htlc_maximum_msat: OptionalField::Present(100_000),
3606                         fee_base_msat: 1_000,
3607                         fee_proportional_millionths: 0,
3608                         excess_data: Vec::new()
3609                 });
3610                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3611                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3612                         short_channel_id: 11,
3613                         timestamp: 2,
3614                         flags: 0,
3615                         cltv_expiry_delta: 0,
3616                         htlc_minimum_msat: 0,
3617                         htlc_maximum_msat: OptionalField::Present(100_000),
3618                         fee_base_msat: 0,
3619                         fee_proportional_millionths: 0,
3620                         excess_data: Vec::new()
3621                 });
3622
3623                 // Path via {node7, node2} is channels {12, 13, 5}.
3624                 // We already limited them to 200 sats (they are used twice for 100 sats).
3625                 // Nothing to do here.
3626
3627                 {
3628                         // Now, attempt to route 180 sats.
3629                         // Our algorithm should provide us with these 2 paths.
3630                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3631                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3632                         assert_eq!(route.paths.len(), 2);
3633
3634                         let mut total_value_transferred_msat = 0;
3635                         let mut total_paid_msat = 0;
3636                         for path in &route.paths {
3637                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3638                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3639                                 for hop in path {
3640                                         total_paid_msat += hop.fee_msat;
3641                                 }
3642                         }
3643                         // If we paid fee, this would be higher.
3644                         assert_eq!(total_value_transferred_msat, 180_000);
3645                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3646                         assert_eq!(total_fees_paid, 0);
3647                 }
3648         }
3649
3650         #[test]
3651         fn fees_on_mpp_route_test() {
3652                 // This test makes sure that MPP algorithm properly takes into account
3653                 // fees charged on the channels, by making the fees impactful:
3654                 // if the fee is not properly accounted for, the behavior is different.
3655                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3656                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3657
3658                 // We need a route consisting of 2 paths:
3659                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3660                 // We will route 200 sats, Each path will have 100 sats capacity.
3661
3662                 // This test is not particularly stable: e.g.,
3663                 // there's a way to route via {node0, node2, node4}.
3664                 // It works while pathfinding is deterministic, but can be broken otherwise.
3665                 // It's fine to ignore this concern for now.
3666
3667                 // Disable other potential paths.
3668                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3669                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3670                         short_channel_id: 2,
3671                         timestamp: 2,
3672                         flags: 2,
3673                         cltv_expiry_delta: 0,
3674                         htlc_minimum_msat: 0,
3675                         htlc_maximum_msat: OptionalField::Present(100_000),
3676                         fee_base_msat: 0,
3677                         fee_proportional_millionths: 0,
3678                         excess_data: Vec::new()
3679                 });
3680
3681                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3682                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3683                         short_channel_id: 7,
3684                         timestamp: 2,
3685                         flags: 2,
3686                         cltv_expiry_delta: 0,
3687                         htlc_minimum_msat: 0,
3688                         htlc_maximum_msat: OptionalField::Present(100_000),
3689                         fee_base_msat: 0,
3690                         fee_proportional_millionths: 0,
3691                         excess_data: Vec::new()
3692                 });
3693
3694                 // Path via {node0, node2} is channels {1, 3, 5}.
3695                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3696                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3697                         short_channel_id: 1,
3698                         timestamp: 2,
3699                         flags: 0,
3700                         cltv_expiry_delta: 0,
3701                         htlc_minimum_msat: 0,
3702                         htlc_maximum_msat: OptionalField::Present(100_000),
3703                         fee_base_msat: 0,
3704                         fee_proportional_millionths: 0,
3705                         excess_data: Vec::new()
3706                 });
3707                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3708                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3709                         short_channel_id: 3,
3710                         timestamp: 2,
3711                         flags: 0,
3712                         cltv_expiry_delta: 0,
3713                         htlc_minimum_msat: 0,
3714                         htlc_maximum_msat: OptionalField::Present(100_000),
3715                         fee_base_msat: 0,
3716                         fee_proportional_millionths: 0,
3717                         excess_data: Vec::new()
3718                 });
3719
3720                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3721                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3722                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3723                         short_channel_id: 5,
3724                         timestamp: 2,
3725                         flags: 0,
3726                         cltv_expiry_delta: 0,
3727                         htlc_minimum_msat: 0,
3728                         htlc_maximum_msat: OptionalField::Present(100_000),
3729                         fee_base_msat: 0,
3730                         fee_proportional_millionths: 0,
3731                         excess_data: Vec::new()
3732                 });
3733
3734                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3735                 // All channels should be 100 sats capacity. But for the fee experiment,
3736                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3737                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3738                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3739                 // so no matter how large are other channels,
3740                 // the whole path will be limited by 100 sats with just these 2 conditions:
3741                 // - channel 12 capacity is 250 sats
3742                 // - fee for channel 6 is 150 sats
3743                 // Let's test this by enforcing these 2 conditions and removing other limits.
3744                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3745                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3746                         short_channel_id: 12,
3747                         timestamp: 2,
3748                         flags: 0,
3749                         cltv_expiry_delta: 0,
3750                         htlc_minimum_msat: 0,
3751                         htlc_maximum_msat: OptionalField::Present(250_000),
3752                         fee_base_msat: 0,
3753                         fee_proportional_millionths: 0,
3754                         excess_data: Vec::new()
3755                 });
3756                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3757                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3758                         short_channel_id: 13,
3759                         timestamp: 2,
3760                         flags: 0,
3761                         cltv_expiry_delta: 0,
3762                         htlc_minimum_msat: 0,
3763                         htlc_maximum_msat: OptionalField::Absent,
3764                         fee_base_msat: 0,
3765                         fee_proportional_millionths: 0,
3766                         excess_data: Vec::new()
3767                 });
3768
3769                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3770                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3771                         short_channel_id: 6,
3772                         timestamp: 2,
3773                         flags: 0,
3774                         cltv_expiry_delta: 0,
3775                         htlc_minimum_msat: 0,
3776                         htlc_maximum_msat: OptionalField::Absent,
3777                         fee_base_msat: 150_000,
3778                         fee_proportional_millionths: 0,
3779                         excess_data: Vec::new()
3780                 });
3781                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3782                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3783                         short_channel_id: 11,
3784                         timestamp: 2,
3785                         flags: 0,
3786                         cltv_expiry_delta: 0,
3787                         htlc_minimum_msat: 0,
3788                         htlc_maximum_msat: OptionalField::Absent,
3789                         fee_base_msat: 0,
3790                         fee_proportional_millionths: 0,
3791                         excess_data: Vec::new()
3792                 });
3793
3794                 {
3795                         // Attempt to route more than available results in a failure.
3796                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3797                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3798                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3799                         } else { panic!(); }
3800                 }
3801
3802                 {
3803                         // Now, attempt to route 200 sats (exact amount we can route).
3804                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3805                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3806                         assert_eq!(route.paths.len(), 2);
3807
3808                         let mut total_amount_paid_msat = 0;
3809                         for path in &route.paths {
3810                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3811                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3812                         }
3813                         assert_eq!(total_amount_paid_msat, 200_000);
3814                         assert_eq!(route.get_total_fees(), 150_000);
3815                 }
3816
3817         }
3818
3819         #[test]
3820         fn drop_lowest_channel_mpp_route_test() {
3821                 // This test checks that low-capacity channel is dropped when after
3822                 // path finding we realize that we found more capacity than we need.
3823                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3824                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3825
3826                 // We need a route consisting of 3 paths:
3827                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3828
3829                 // The first and the second paths should be sufficient, but the third should be
3830                 // cheaper, so that we select it but drop later.
3831
3832                 // First, we set limits on these (previously unlimited) channels.
3833                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3834
3835                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3836                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3837                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3838                         short_channel_id: 1,
3839                         timestamp: 2,
3840                         flags: 0,
3841                         cltv_expiry_delta: 0,
3842                         htlc_minimum_msat: 0,
3843                         htlc_maximum_msat: OptionalField::Present(100_000),
3844                         fee_base_msat: 0,
3845                         fee_proportional_millionths: 0,
3846                         excess_data: Vec::new()
3847                 });
3848                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3849                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3850                         short_channel_id: 3,
3851                         timestamp: 2,
3852                         flags: 0,
3853                         cltv_expiry_delta: 0,
3854                         htlc_minimum_msat: 0,
3855                         htlc_maximum_msat: OptionalField::Present(50_000),
3856                         fee_base_msat: 100,
3857                         fee_proportional_millionths: 0,
3858                         excess_data: Vec::new()
3859                 });
3860
3861                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3862                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3863                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3864                         short_channel_id: 12,
3865                         timestamp: 2,
3866                         flags: 0,
3867                         cltv_expiry_delta: 0,
3868                         htlc_minimum_msat: 0,
3869                         htlc_maximum_msat: OptionalField::Present(60_000),
3870                         fee_base_msat: 100,
3871                         fee_proportional_millionths: 0,
3872                         excess_data: Vec::new()
3873                 });
3874                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3875                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3876                         short_channel_id: 13,
3877                         timestamp: 2,
3878                         flags: 0,
3879                         cltv_expiry_delta: 0,
3880                         htlc_minimum_msat: 0,
3881                         htlc_maximum_msat: OptionalField::Present(60_000),
3882                         fee_base_msat: 0,
3883                         fee_proportional_millionths: 0,
3884                         excess_data: Vec::new()
3885                 });
3886
3887                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3888                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3889                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3890                         short_channel_id: 2,
3891                         timestamp: 2,
3892                         flags: 0,
3893                         cltv_expiry_delta: 0,
3894                         htlc_minimum_msat: 0,
3895                         htlc_maximum_msat: OptionalField::Present(20_000),
3896                         fee_base_msat: 0,
3897                         fee_proportional_millionths: 0,
3898                         excess_data: Vec::new()
3899                 });
3900                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3901                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3902                         short_channel_id: 4,
3903                         timestamp: 2,
3904                         flags: 0,
3905                         cltv_expiry_delta: 0,
3906                         htlc_minimum_msat: 0,
3907                         htlc_maximum_msat: OptionalField::Present(20_000),
3908                         fee_base_msat: 0,
3909                         fee_proportional_millionths: 0,
3910                         excess_data: Vec::new()
3911                 });
3912
3913                 {
3914                         // Attempt to route more than available results in a failure.
3915                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3916                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3917                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3918                         } else { panic!(); }
3919                 }
3920
3921                 {
3922                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3923                         // Our algorithm should provide us with these 3 paths.
3924                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3925                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3926                         assert_eq!(route.paths.len(), 3);
3927                         let mut total_amount_paid_msat = 0;
3928                         for path in &route.paths {
3929                                 assert_eq!(path.len(), 2);
3930                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3931                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3932                         }
3933                         assert_eq!(total_amount_paid_msat, 125_000);
3934                 }
3935
3936                 {
3937                         // Attempt to route without the last small cheap channel
3938                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3939                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3940                         assert_eq!(route.paths.len(), 2);
3941                         let mut total_amount_paid_msat = 0;
3942                         for path in &route.paths {
3943                                 assert_eq!(path.len(), 2);
3944                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3945                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3946                         }
3947                         assert_eq!(total_amount_paid_msat, 90_000);
3948                 }
3949         }
3950
3951         #[test]
3952         fn min_criteria_consistency() {
3953                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3954                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3955                 // was updated with a different criterion from the heap sorting, resulting in loops in
3956                 // calculated paths. We test for that specific case here.
3957
3958                 // We construct a network that looks like this:
3959                 //
3960                 //            node2 -1(3)2- node3
3961                 //              2          2
3962                 //               (2)     (4)
3963                 //                  1   1
3964                 //    node1 -1(5)2- node4 -1(1)2- node6
3965                 //    2
3966                 //   (6)
3967                 //        1
3968                 // our_node
3969                 //
3970                 // We create a loop on the side of our real path - our destination is node 6, with a
3971                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3972                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3973                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3974                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3975                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3976                 // "previous hop" being set to node 3, creating a loop in the path.
3977                 let secp_ctx = Secp256k1::new();
3978                 let logger = Arc::new(test_utils::TestLogger::new());
3979                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
3980                 let net_graph_msg_handler = NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger));
3981                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3982
3983                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3984                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3985                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3986                         short_channel_id: 6,
3987                         timestamp: 1,
3988                         flags: 0,
3989                         cltv_expiry_delta: (6 << 8) | 0,
3990                         htlc_minimum_msat: 0,
3991                         htlc_maximum_msat: OptionalField::Absent,
3992                         fee_base_msat: 0,
3993                         fee_proportional_millionths: 0,
3994                         excess_data: Vec::new()
3995                 });
3996                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3997
3998                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3999                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4000                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4001                         short_channel_id: 5,
4002                         timestamp: 1,
4003                         flags: 0,
4004                         cltv_expiry_delta: (5 << 8) | 0,
4005                         htlc_minimum_msat: 0,
4006                         htlc_maximum_msat: OptionalField::Absent,
4007                         fee_base_msat: 100,
4008                         fee_proportional_millionths: 0,
4009                         excess_data: Vec::new()
4010                 });
4011                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
4012
4013                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
4014                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4015                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4016                         short_channel_id: 4,
4017                         timestamp: 1,
4018                         flags: 0,
4019                         cltv_expiry_delta: (4 << 8) | 0,
4020                         htlc_minimum_msat: 0,
4021                         htlc_maximum_msat: OptionalField::Absent,
4022                         fee_base_msat: 0,
4023                         fee_proportional_millionths: 0,
4024                         excess_data: Vec::new()
4025                 });
4026                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
4027
4028                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
4029                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
4030                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4031                         short_channel_id: 3,
4032                         timestamp: 1,
4033                         flags: 0,
4034                         cltv_expiry_delta: (3 << 8) | 0,
4035                         htlc_minimum_msat: 0,
4036                         htlc_maximum_msat: OptionalField::Absent,
4037                         fee_base_msat: 0,
4038                         fee_proportional_millionths: 0,
4039                         excess_data: Vec::new()
4040                 });
4041                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
4042
4043                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
4044                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4045                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4046                         short_channel_id: 2,
4047                         timestamp: 1,
4048                         flags: 0,
4049                         cltv_expiry_delta: (2 << 8) | 0,
4050                         htlc_minimum_msat: 0,
4051                         htlc_maximum_msat: OptionalField::Absent,
4052                         fee_base_msat: 0,
4053                         fee_proportional_millionths: 0,
4054                         excess_data: Vec::new()
4055                 });
4056
4057                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
4058                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4059                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4060                         short_channel_id: 1,
4061                         timestamp: 1,
4062                         flags: 0,
4063                         cltv_expiry_delta: (1 << 8) | 0,
4064                         htlc_minimum_msat: 100,
4065                         htlc_maximum_msat: OptionalField::Absent,
4066                         fee_base_msat: 0,
4067                         fee_proportional_millionths: 0,
4068                         excess_data: Vec::new()
4069                 });
4070                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
4071
4072                 {
4073                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
4074                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
4075                         assert_eq!(route.paths.len(), 1);
4076                         assert_eq!(route.paths[0].len(), 3);
4077
4078                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
4079                         assert_eq!(route.paths[0][0].short_channel_id, 6);
4080                         assert_eq!(route.paths[0][0].fee_msat, 100);
4081                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
4082                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
4083                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
4084
4085                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
4086                         assert_eq!(route.paths[0][1].short_channel_id, 5);
4087                         assert_eq!(route.paths[0][1].fee_msat, 0);
4088                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
4089                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
4090                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
4091
4092                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
4093                         assert_eq!(route.paths[0][2].short_channel_id, 1);
4094                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
4095                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
4096                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
4097                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
4098                 }
4099         }
4100
4101
4102         #[test]
4103         fn exact_fee_liquidity_limit() {
4104                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
4105                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
4106                 // we calculated fees on a higher value, resulting in us ignoring such paths.
4107                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4108                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
4109
4110                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
4111                 // send.
4112                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4113                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4114                         short_channel_id: 2,
4115                         timestamp: 2,
4116                         flags: 0,
4117                         cltv_expiry_delta: 0,
4118                         htlc_minimum_msat: 0,
4119                         htlc_maximum_msat: OptionalField::Present(85_000),
4120                         fee_base_msat: 0,
4121                         fee_proportional_millionths: 0,
4122                         excess_data: Vec::new()
4123                 });
4124
4125                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4126                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4127                         short_channel_id: 12,
4128                         timestamp: 2,
4129                         flags: 0,
4130                         cltv_expiry_delta: (4 << 8) | 1,
4131                         htlc_minimum_msat: 0,
4132                         htlc_maximum_msat: OptionalField::Present(270_000),
4133                         fee_base_msat: 0,
4134                         fee_proportional_millionths: 1000000,
4135                         excess_data: Vec::new()
4136                 });
4137
4138                 {
4139                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
4140                         // 200% fee charged channel 13 in the 1-to-2 direction.
4141                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
4142                         assert_eq!(route.paths.len(), 1);
4143                         assert_eq!(route.paths[0].len(), 2);
4144
4145                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4146                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4147                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4148                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4149                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4150                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4151
4152                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4153                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4154                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4155                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4156                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
4157                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4158                 }
4159         }
4160
4161         #[test]
4162         fn htlc_max_reduction_below_min() {
4163                 // Test that if, while walking the graph, we reduce the value being sent to meet an
4164                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
4165                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
4166                 // resulting in us thinking there is no possible path, even if other paths exist.
4167                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4168                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4169
4170                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
4171                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
4172                 // then try to send 90_000.
4173                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4174                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4175                         short_channel_id: 2,
4176                         timestamp: 2,
4177                         flags: 0,
4178                         cltv_expiry_delta: 0,
4179                         htlc_minimum_msat: 0,
4180                         htlc_maximum_msat: OptionalField::Present(80_000),
4181                         fee_base_msat: 0,
4182                         fee_proportional_millionths: 0,
4183                         excess_data: Vec::new()
4184                 });
4185                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4186                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4187                         short_channel_id: 4,
4188                         timestamp: 2,
4189                         flags: 0,
4190                         cltv_expiry_delta: (4 << 8) | 1,
4191                         htlc_minimum_msat: 90_000,
4192                         htlc_maximum_msat: OptionalField::Absent,
4193                         fee_base_msat: 0,
4194                         fee_proportional_millionths: 0,
4195                         excess_data: Vec::new()
4196                 });
4197
4198                 {
4199                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
4200                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
4201                         // expensive) channels 12-13 path.
4202                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
4203                         assert_eq!(route.paths.len(), 1);
4204                         assert_eq!(route.paths[0].len(), 2);
4205
4206                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4207                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4208                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4209                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4210                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4211                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4212
4213                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4214                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4215                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4216                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4217                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
4218                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4219                 }
4220         }
4221
4222         #[test]
4223         fn total_fees_single_path() {
4224                 let route = Route {
4225                         paths: vec![vec![
4226                                 RouteHop {
4227                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4228                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4229                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
4230                                 },
4231                                 RouteHop {
4232                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4233                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4234                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
4235                                 },
4236                                 RouteHop {
4237                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
4238                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4239                                         short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
4240                                 },
4241                         ]],
4242                 };
4243
4244                 assert_eq!(route.get_total_fees(), 250);
4245                 assert_eq!(route.get_total_amount(), 225);
4246         }
4247
4248         #[test]
4249         fn total_fees_multi_path() {
4250                 let route = Route {
4251                         paths: vec![vec![
4252                                 RouteHop {
4253                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4254                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4255                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
4256                                 },
4257                                 RouteHop {
4258                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4259                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4260                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
4261                                 },
4262                         ],vec![
4263                                 RouteHop {
4264                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4265                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4266                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
4267                                 },
4268                                 RouteHop {
4269                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4270                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4271                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0 // Test vectors are garbage and not generateble from a RouteHop, we fill in payloads manually
4272                                 },
4273                         ]],
4274                 };
4275
4276                 assert_eq!(route.get_total_fees(), 200);
4277                 assert_eq!(route.get_total_amount(), 300);
4278         }
4279
4280         #[cfg(not(feature = "no-std"))]
4281         pub(super) fn random_init_seed() -> u64 {
4282                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
4283                 use core::hash::{BuildHasher, Hasher};
4284                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
4285                 println!("Using seed of {}", seed);
4286                 seed
4287         }
4288         #[cfg(not(feature = "no-std"))]
4289         use util::ser::Readable;
4290
4291         #[test]
4292         #[cfg(not(feature = "no-std"))]
4293         fn generate_routes() {
4294                 let mut d = match super::test_utils::get_route_file() {
4295                         Ok(f) => f,
4296                         Err(e) => {
4297                                 eprintln!("{}", e);
4298                                 return;
4299                         },
4300                 };
4301                 let graph = NetworkGraph::read(&mut d).unwrap();
4302
4303                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4304                 let mut seed = random_init_seed() as usize;
4305                 let nodes = graph.read_only().nodes().clone();
4306                 'load_endpoints: for _ in 0..10 {
4307                         loop {
4308                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4309                                 let src = nodes.keys().skip(seed % nodes.len()).next().unwrap();
4310                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4311                                 let dst = nodes.keys().skip(seed % nodes.len()).next().unwrap();
4312                                 let amt = seed as u64 % 200_000_000;
4313                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
4314                                         continue 'load_endpoints;
4315                                 }
4316                         }
4317                 }
4318         }
4319
4320         #[test]
4321         #[cfg(not(feature = "no-std"))]
4322         fn generate_routes_mpp() {
4323                 let mut d = match super::test_utils::get_route_file() {
4324                         Ok(f) => f,
4325                         Err(e) => {
4326                                 eprintln!("{}", e);
4327                                 return;
4328                         },
4329                 };
4330                 let graph = NetworkGraph::read(&mut d).unwrap();
4331
4332                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4333                 let mut seed = random_init_seed() as usize;
4334                 let nodes = graph.read_only().nodes().clone();
4335                 'load_endpoints: for _ in 0..10 {
4336                         loop {
4337                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4338                                 let src = nodes.keys().skip(seed % nodes.len()).next().unwrap();
4339                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4340                                 let dst = nodes.keys().skip(seed % nodes.len()).next().unwrap();
4341                                 let amt = seed as u64 % 200_000_000;
4342                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
4343                                         continue 'load_endpoints;
4344                                 }
4345                         }
4346                 }
4347         }
4348 }
4349
4350 #[cfg(all(test, not(feature = "no-std")))]
4351 pub(crate) mod test_utils {
4352         use std::fs::File;
4353         /// Tries to open a network graph file, or panics with a URL to fetch it.
4354         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
4355                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
4356                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
4357                         .or_else(|_| { // Fall back to guessing based on the binary location
4358                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
4359                                 let mut path = std::env::current_exe().unwrap();
4360                                 path.pop(); // lightning-...
4361                                 path.pop(); // deps
4362                                 path.pop(); // debug
4363                                 path.pop(); // target
4364                                 path.push("lightning");
4365                                 path.push("net_graph-2021-05-31.bin");
4366                                 eprintln!("{}", path.to_str().unwrap());
4367                                 File::open(path)
4368                         })
4369                 .map_err(|_| "Please fetch https://bitcoin.ninja/ldk-net_graph-v0.0.15-2021-05-31.bin and place it at lightning/net_graph-2021-05-31.bin");
4370                 #[cfg(require_route_graph_test)]
4371                 return Ok(res.unwrap());
4372                 #[cfg(not(require_route_graph_test))]
4373                 return res;
4374         }
4375 }
4376
4377 #[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
4378 mod benches {
4379         use super::*;
4380         use util::logger::{Logger, Record};
4381
4382         use test::Bencher;
4383
4384         struct DummyLogger {}
4385         impl Logger for DummyLogger {
4386                 fn log(&self, _record: &Record) {}
4387         }
4388
4389         #[bench]
4390         fn generate_routes(bench: &mut Bencher) {
4391                 let mut d = test_utils::get_route_file().unwrap();
4392                 let graph = NetworkGraph::read(&mut d).unwrap();
4393                 let nodes = graph.read_only().nodes().clone();
4394
4395                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4396                 let mut path_endpoints = Vec::new();
4397                 let mut seed: usize = 0xdeadbeef;
4398                 'load_endpoints: for _ in 0..100 {
4399                         loop {
4400                                 seed *= 0xdeadbeef;
4401                                 let src = nodes.keys().skip(seed % nodes.len()).next().unwrap();
4402                                 seed *= 0xdeadbeef;
4403                                 let dst = nodes.keys().skip(seed % nodes.len()).next().unwrap();
4404                                 let amt = seed as u64 % 1_000_000;
4405                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
4406                                         path_endpoints.push((src, dst, amt));
4407                                         continue 'load_endpoints;
4408                                 }
4409                         }
4410                 }
4411
4412                 // ...then benchmark finding paths between the nodes we learned.
4413                 let mut idx = 0;
4414                 bench.iter(|| {
4415                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4416                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
4417                         idx += 1;
4418                 });
4419         }
4420
4421         #[bench]
4422         fn generate_mpp_routes(bench: &mut Bencher) {
4423                 let mut d = test_utils::get_route_file().unwrap();
4424                 let graph = NetworkGraph::read(&mut d).unwrap();
4425                 let nodes = graph.read_only().nodes().clone();
4426
4427                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4428                 let mut path_endpoints = Vec::new();
4429                 let mut seed: usize = 0xdeadbeef;
4430                 'load_endpoints: for _ in 0..100 {
4431                         loop {
4432                                 seed *= 0xdeadbeef;
4433                                 let src = nodes.keys().skip(seed % nodes.len()).next().unwrap();
4434                                 seed *= 0xdeadbeef;
4435                                 let dst = nodes.keys().skip(seed % nodes.len()).next().unwrap();
4436                                 let amt = seed as u64 % 1_000_000;
4437                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
4438                                         path_endpoints.push((src, dst, amt));
4439                                         continue 'load_endpoints;
4440                                 }
4441                         }
4442                 }
4443
4444                 // ...then benchmark finding paths between the nodes we learned.
4445                 let mut idx = 0;
4446                 bench.iter(|| {
4447                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4448                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
4449                         idx += 1;
4450                 });
4451         }
4452 }