_ 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 prelude::*;
  25 use alloc::collections::BinaryHeap;
  26 use core::cmp;
  27 use std::collections::HashMap;
  28 use core::ops::Deref;
  29
  30 /// A hop in a route
  31 #[derive(Clone, PartialEq)]
  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),
  54         (2, node_features),
  55         (4, short_channel_id),
  56         (6, channel_features),
  57         (8, fee_msat),
  58         (10, cltv_expiry_delta),
  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, PartialEq)]
  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 const SERIALIZATION_VERSION: u8 = 1;
  75 const MIN_SERIALIZATION_VERSION: u8 = 1;
  76
  77 impl Writeable for Route {
  78         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
  79                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
  80                 (self.paths.len() as u64).write(writer)?;
  81                 for hops in self.paths.iter() {
  82                         (hops.len() as u8).write(writer)?;
  83                         for hop in hops.iter() {
  84                                 hop.write(writer)?;
  85                         }
  86                 }
  87                 write_tlv_fields!(writer, {}, {});
  88                 Ok(())
  89         }
  90 }
  91
  92 impl Readable for Route {
  93         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
  94                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
  95                 let path_count: u64 = Readable::read(reader)?;
  96                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
  97                 for _ in 0..path_count {
  98                         let hop_count: u8 = Readable::read(reader)?;
  99                         let mut hops = Vec::with_capacity(hop_count as usize);
 100                         for _ in 0..hop_count {
 101                                 hops.push(Readable::read(reader)?);
 102                         }
 103                         paths.push(hops);
 104                 }
 105                 read_tlv_fields!(reader, {}, {});
 106                 Ok(Route { paths })
 107         }
 108 }
 109
 110 /// A channel descriptor which provides a last-hop route to get_route
 111 #[derive(Eq, PartialEq, Debug, Clone)]
 112 pub struct RouteHintHop {
 113         /// The node_id of the non-target end of the route
 114         pub src_node_id: PublicKey,
 115         /// The short_channel_id of this channel
 116         pub short_channel_id: u64,
 117         /// The fees which must be paid to use this channel
 118         pub fees: RoutingFees,
 119         /// The difference in CLTV values between this node and the next node.
 120         pub cltv_expiry_delta: u16,
 121         /// The minimum value, in msat, which must be relayed to the next hop.
 122         pub htlc_minimum_msat: Option<u64>,
 123         /// The maximum value in msat available for routing with a single HTLC.
 124         pub htlc_maximum_msat: Option<u64>,
 125 }
 126
 127 #[derive(Eq, PartialEq)]
 128 struct RouteGraphNode {
 129         pubkey: PublicKey,
 130         lowest_fee_to_peer_through_node: u64,
 131         lowest_fee_to_node: u64,
 132         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 133         // This value is upper-bounded by us by:
 134         // - how much is needed for a path being constructed
 135         // - how much value can channels following this node (up to the destination) can contribute,
 136         //   considering their capacity and fees
 137         value_contribution_msat: u64,
 138         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 139         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 140         path_htlc_minimum_msat: u64,
 141 }
 142
 143 impl cmp::Ord for RouteGraphNode {
 144         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 145                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 146                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 147                 other_score.cmp(&self_score).then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 148         }
 149 }
 150
 151 impl cmp::PartialOrd for RouteGraphNode {
 152         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 153                 Some(self.cmp(other))
 154         }
 155 }
 156
 157 struct DummyDirectionalChannelInfo {
 158         cltv_expiry_delta: u32,
 159         htlc_minimum_msat: u64,
 160         htlc_maximum_msat: Option<u64>,
 161         fees: RoutingFees,
 162 }
 163
 164 /// It's useful to keep track of the hops associated with the fees required to use them,
 165 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 166 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 167 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 168 #[derive(Clone)]
 169 struct PathBuildingHop<'a> {
 170         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 171         // Note that node_features is calculated separately after our initial graph walk.
 172         pubkey: PublicKey,
 173         short_channel_id: u64,
 174         channel_features: &'a ChannelFeatures,
 175         fee_msat: u64,
 176         cltv_expiry_delta: u32,
 177
 178         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 179         src_lowest_inbound_fees: RoutingFees,
 180         /// Fees of the channel used in this hop.
 181         channel_fees: RoutingFees,
 182         /// All the fees paid *after* this channel on the way to the destination
 183         next_hops_fee_msat: u64,
 184         /// Fee paid for the use of the current channel (see channel_fees).
 185         /// The value will be actually deducted from the counterparty balance on the previous link.
 186         hop_use_fee_msat: u64,
 187         /// Used to compare channels when choosing the for routing.
 188         /// Includes paying for the use of a hop and the following hops, as well as
 189         /// an estimated cost of reaching this hop.
 190         /// Might get stale when fees are recomputed. Primarily for internal use.
 191         total_fee_msat: u64,
 192         /// This is useful for update_value_and_recompute_fees to make sure
 193         /// we don't fall below the minimum. Should not be updated manually and
 194         /// generally should not be accessed.
 195         htlc_minimum_msat: u64,
 196         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 197         /// walk and may be invalid thereafter.
 198         path_htlc_minimum_msat: u64,
 199         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 200         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 201         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 202         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 203         /// avoid processing them again.
 204         was_processed: bool,
 205         #[cfg(any(test, feature = "fuzztarget"))]
 206         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 207         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 208         // value_contribution_msat, which requires tracking it here. See comments below where it is
 209         // used for more info.
 210         value_contribution_msat: u64,
 211 }
 212
 213 // Instantiated with a list of hops with correct data in them collected during path finding,
 214 // an instance of this struct should be further modified only via given methods.
 215 #[derive(Clone)]
 216 struct PaymentPath<'a> {
 217         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 218 }
 219
 220 impl<'a> PaymentPath<'a> {
 221         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 222         fn get_value_msat(&self) -> u64 {
 223                 self.hops.last().unwrap().0.fee_msat
 224         }
 225
 226         fn get_total_fee_paid_msat(&self) -> u64 {
 227                 if self.hops.len() < 1 {
 228                         return 0;
 229                 }
 230                 let mut result = 0;
 231                 // Can't use next_hops_fee_msat because it gets outdated.
 232                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 233                         if i != self.hops.len() - 1 {
 234                                 result += hop.fee_msat;
 235                         }
 236                 }
 237                 return result;
 238         }
 239
 240         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 241         // to change fees may result in an inconsistency.
 242         //
 243         // Sometimes we call this function right after constructing a path which is inconsistent in
 244         // that it the value being transferred has decreased while we were doing path finding, leading
 245         // to the fees being paid not lining up with the actual limits.
 246         //
 247         // Note that this function is not aware of the available_liquidity limit, and thus does not
 248         // support increasing the value being transferred.
 249         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 250                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 251
 252                 let mut total_fee_paid_msat = 0 as u64;
 253                 for i in (0..self.hops.len()).rev() {
 254                         let last_hop = i == self.hops.len() - 1;
 255
 256                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 257                         // will consist of the fees for the use of the next hop, and extra fees to match
 258                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 259                         let mut cur_hop_fees_msat = 0;
 260                         if !last_hop {
 261                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 262                         }
 263
 264                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 265                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 266                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 267                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 268                         // set it too high just to maliciously take more fees by exploiting this
 269                         // match htlc_minimum_msat logic.
 270                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 271                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 272                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 273                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 274                                 //
 275                                 // This might make us end up with a broken route, although this should be super-rare
 276                                 // in practice, both because of how healthy channels look like, and how we pick
 277                                 // channels in add_entry.
 278                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 279                                 // all payments*.
 280                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 281                                 total_fee_paid_msat += extra_fees_msat;
 282                                 cur_hop_fees_msat += extra_fees_msat;
 283                         }
 284
 285                         if last_hop {
 286                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 287                                 // it still could overpay for the htlc_minimum_msat.
 288                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 289                         } else {
 290                                 // Propagate updated fees for the use of the channels to one hop back, where they
 291                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 292                                 cur_hop.fee_msat = cur_hop_fees_msat;
 293                         }
 294
 295                         // Fee for the use of the current hop which will be deducted on the previous hop.
 296                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 297                         // this channel is free for us.
 298                         if i != 0 {
 299                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 300                                         cur_hop.hop_use_fee_msat = new_fee;
 301                                         total_fee_paid_msat += new_fee;
 302                                 } else {
 303                                         // It should not be possible because this function is called only to reduce the
 304                                         // value. In that case, compute_fee was already called with the same fees for
 305                                         // larger amount and there was no overflow.
 306                                         unreachable!();
 307                                 }
 308                         }
 309                 }
 310         }
 311 }
 312
 313 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 314         let proportional_fee_millions =
 315                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 316         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 317                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 318
 319                 Some(new_fee)
 320         } else {
 321                 // This function may be (indirectly) called without any verification,
 322                 // with channel_fees provided by a caller. We should handle it gracefully.
 323                 None
 324         }
 325 }
 326
 327 /// Gets a route from us (payer) to the given target node (payee).
 328 ///
 329 /// If the payee provided features in their invoice, they should be provided via payee_features.
 330 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 331 ///
 332 /// Extra routing hops between known nodes and the target will be used if they are included in
 333 /// last_hops.
 334 ///
 335 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 336 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 337 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 338 /// in first_hops will be used.
 339 ///
 340 /// Panics if first_hops contains channels without short_channel_ids
 341 /// (ChannelManager::list_usable_channels will never include such channels).
 342 ///
 343 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 344 /// equal), however the enabled/disabled bit on such channels as well as the
 345 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 346 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 347         last_hops: &[&RouteHintHop], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 348         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 349         // uptime/success in using a node in the past.
 350         if *payee == *our_node_id {
 351                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 352         }
 353
 354         if final_value_msat > MAX_VALUE_MSAT {
 355                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 356         }
 357
 358         if final_value_msat == 0 {
 359                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 360         }
 361
 362         for last_hop in last_hops {
 363                 if last_hop.src_node_id == *payee {
 364                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 365                 }
 366         }
 367
 368         // The general routing idea is the following:
 369         // 1. Fill first/last hops communicated by the caller.
 370         // 2. Attempt to construct a path from payer to payee for transferring
 371         //    any ~sufficient (described later) value.
 372         //    If succeed, remember which channels were used and how much liquidity they have available,
 373         //    so that future paths don't rely on the same liquidity.
 374         // 3. Prooceed to the next step if:
 375         //    - we hit the recommended target value;
 376         //    - OR if we could not construct a new path. Any next attempt will fail too.
 377         //    Otherwise, repeat step 2.
 378         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 379         //    (not recommended value). If yes, proceed. If not, fail routing.
 380         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 381         // 6. Of all the found paths, select only those with the lowest total fee.
 382         // 7. The last path in every selected route is likely to be more than we need.
 383         //    Reduce its value-to-transfer and recompute fees.
 384         // 8. Choose the best route by the lowest total fee.
 385
 386         // As for the actual search algorithm,
 387         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 388         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 389         //
 390         // We are not a faithful Dijkstra's implementation because we can change values which impact
 391         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 392         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 393         // the value we are currently attempting to send over a path, we simply reduce the value being
 394         // sent along the path for any hops after that channel. This may imply that later fees (which
 395         // we've already tabulated) are lower because a smaller value is passing through the channels
 396         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 397         // channels which were selected earlier (and which may still be used for other paths without a
 398         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 399         // de-preferenced.
 400         //
 401         // One potentially problematic case for this algorithm would be if there are many
 402         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 403         // graph walking), we may never find a path which is not liquidity-limited and has lower
 404         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 405         // Because we only consider paths with at least 5% of the total value being sent, the damage
 406         // from such a case should be limited, however this could be further reduced in the future by
 407         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 408         // limits for the purposes of fee calculation.
 409         //
 410         // Alternatively, we could store more detailed path information in the heap (targets, below)
 411         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 412         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 413         // and practically (as we would need to store dynamically-allocated path information in heap
 414         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 415         // results of such an algorithm would likely be biased towards lower-value paths.
 416         //
 417         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 418         // outside of our current search value, running a path search more times to gather candidate
 419         // paths at different values. While this may be acceptable, further path searches may increase
 420         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 421         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 422         // the same time, remaining generic across different payment values.
 423         //
 424         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 425         // to use as the A* heuristic beyond just the cost to get one node further than the current
 426         // one.
 427
 428         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 429                 cltv_expiry_delta: 0,
 430                 htlc_minimum_msat: 0,
 431                 htlc_maximum_msat: None,
 432                 fees: RoutingFees {
 433                         base_msat: 0,
 434                         proportional_millionths: 0,
 435                 }
 436         };
 437
 438         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 439         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 440         // work reliably.
 441         let allow_mpp = if let Some(features) = &payee_features {
 442                 features.supports_basic_mpp()
 443         } else if let Some(node) = network.get_nodes().get(&payee) {
 444                 if let Some(node_info) = node.announcement_info.as_ref() {
 445                         node_info.features.supports_basic_mpp()
 446                 } else { false }
 447         } else { false };
 448
 449         // Step (1).
 450         // Prepare the data we'll use for payee-to-payer search by
 451         // inserting first hops suggested by the caller as targets.
 452         // Our search will then attempt to reach them while traversing from the payee node.
 453         let mut first_hop_targets: HashMap<_, (_, ChannelFeatures, _, NodeFeatures)> =
 454                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 455         if let Some(hops) = first_hops {
 456                 for chan in hops {
 457                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 458                         if chan.remote_network_id == *our_node_id {
 459                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 460                         }
 461                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.to_context(), chan.outbound_capacity_msat, chan.counterparty_features.to_context()));
 462                 }
 463                 if first_hop_targets.is_empty() {
 464                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 465                 }
 466         }
 467
 468         let empty_channel_features = ChannelFeatures::empty();
 469
 470         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 471         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 472         // adding duplicate entries when we find a better path to a given node.
 473         let mut targets = BinaryHeap::new();
 474
 475         // Map from node_id to information about the best current path to that node, including feerate
 476         // information.
 477         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 478
 479         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 480         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 481         // htlc_minimum with extra fees while still finding a cheaper path.
 482         let mut hit_minimum_limit;
 483
 484         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 485         // We start with a path_value of the exact amount we want, and if that generates a route we may
 486         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 487         // amount we want in total across paths, selecting the best subset at the end.
 488         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 489         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 490         let mut path_value_msat = final_value_msat;
 491
 492         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 493         // This map allows paths to be aware of the channel use by other paths in the same call.
 494         // This would help to make a better path finding decisions and not "overbook" channels.
 495         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 496         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network.get_nodes().len());
 497
 498         // Keeping track of how much value we already collected across other paths. Helps to decide:
 499         // - how much a new path should be transferring (upper bound);
 500         // - whether a channel should be disregarded because
 501         //   it's available liquidity is too small comparing to how much more we need to collect;
 502         // - when we want to stop looking for new paths.
 503         let mut already_collected_value_msat = 0;
 504
 505         macro_rules! add_entry {
 506                 // Adds entry which goes from $src_node_id to $dest_node_id
 507                 // over the channel with id $chan_id with fees described in
 508                 // $directional_info.
 509                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 510                 // since that value has to be transferred over this channel.
 511                 ( $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,
 512                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 513                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 514                         // practice these cases should be caught earlier:
 515                         // - for regular channels at channel announcement (TODO)
 516                         // - for first and last hops early in get_route
 517                         if $src_node_id != $dest_node_id.clone() {
 518                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 519                                         let mut initial_liquidity_available_msat = None;
 520                                         if let Some(capacity_sats) = $capacity_sats {
 521                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 522                                         }
 523
 524                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 525                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 526                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 527                                                 } else {
 528                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 529                                                 }
 530                                         }
 531
 532                                         match initial_liquidity_available_msat {
 533                                                 Some(available_msat) => available_msat,
 534                                                 // We assume channels with unknown balance have
 535                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 536                                                 None => 250_000 * 1000
 537                                         }
 538                                 });
 539
 540                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 541                                 // It may be misleading because we might later choose to reduce the value transferred
 542                                 // over these channels, and the channel which was insufficient might become sufficient.
 543                                 // Worst case: we drop a good channel here because it can't cover the high following
 544                                 // fees caused by one expensive channel, but then this channel could have been used
 545                                 // if the amount being transferred over this path is lower.
 546                                 // We do this for now, but this is a subject for removal.
 547                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 548
 549                                         // Routing Fragmentation Mitigation heuristic:
 550                                         //
 551                                         // Routing fragmentation across many payment paths increases the overall routing
 552                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 553                                         // Taking too many smaller paths also increases the chance of payment failure.
 554                                         // Thus to avoid this effect, we require from our collected links to provide
 555                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 556                                         //
 557                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 558                                         // This means as we successfully advance in our collection,
 559                                         // the absolute liquidity contribution is lowered,
 560                                         // thus increasing the number of potential channels to be selected.
 561
 562                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 563                                         // or 100% if we're not allowed to do multipath payments.
 564                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 565                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 566                                         } else {
 567                                                 final_value_msat
 568                                         };
 569                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 570                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 571
 572                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 573                                         // Includes paying fees for the use of the following channels.
 574                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 575                                                 Some(result) => result,
 576                                                 // Can't overflow due to how the values were computed right above.
 577                                                 None => unreachable!(),
 578                                         };
 579                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 580                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 581                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 582
 583                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 584                                         // bother considering this channel.
 585                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 586                                         // be only reduced later (not increased), so this channel should just be skipped
 587                                         // as not sufficient.
 588                                         if !over_path_minimum_msat {
 589                                                 hit_minimum_limit = true;
 590                                         } else if contributes_sufficient_value {
 591                                                 // Note that low contribution here (limited by available_liquidity_msat)
 592                                                 // might violate htlc_minimum_msat on the hops which are next along the
 593                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 594                                                 // path fees knowing the final path contribution after constructing it.
 595                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 596                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 597                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 598                                                         _ => u64::max_value()
 599                                                 };
 600                                                 let hm_entry = dist.entry(&$src_node_id);
 601                                                 let old_entry = hm_entry.or_insert_with(|| {
 602                                                         // If there was previously no known way to access
 603                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 604                                                         // a semi-dummy record just to compute the fees to reach the source node.
 605                                                         // This will affect our decision on selecting $chan_id
 606                                                         // as a way to reach the $dest_node_id.
 607                                                         let mut fee_base_msat = u32::max_value();
 608                                                         let mut fee_proportional_millionths = u32::max_value();
 609                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 610                                                                 fee_base_msat = fees.base_msat;
 611                                                                 fee_proportional_millionths = fees.proportional_millionths;
 612                                                         }
 613                                                         PathBuildingHop {
 614                                                                 pubkey: $dest_node_id.clone(),
 615                                                                 short_channel_id: 0,
 616                                                                 channel_features: $chan_features,
 617                                                                 fee_msat: 0,
 618                                                                 cltv_expiry_delta: 0,
 619                                                                 src_lowest_inbound_fees: RoutingFees {
 620                                                                         base_msat: fee_base_msat,
 621                                                                         proportional_millionths: fee_proportional_millionths,
 622                                                                 },
 623                                                                 channel_fees: $directional_info.fees,
 624                                                                 next_hops_fee_msat: u64::max_value(),
 625                                                                 hop_use_fee_msat: u64::max_value(),
 626                                                                 total_fee_msat: u64::max_value(),
 627                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 628                                                                 path_htlc_minimum_msat,
 629                                                                 was_processed: false,
 630                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 631                                                                 value_contribution_msat,
 632                                                         }
 633                                                 });
 634
 635                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 636                                                 let mut should_process = !old_entry.was_processed;
 637                                                 #[cfg(any(test, feature = "fuzztarget"))]
 638                                                 {
 639                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 640                                                         // of already-seen nodes only happens in cases we expect (see below).
 641                                                         if !should_process { should_process = true; }
 642                                                 }
 643
 644                                                 if should_process {
 645                                                         let mut hop_use_fee_msat = 0;
 646                                                         let mut total_fee_msat = $next_hops_fee_msat;
 647
 648                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 649                                                         // will have the same effective-fee
 650                                                         if $src_node_id != *our_node_id {
 651                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 652                                                                         // max_value means we'll always fail
 653                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 654                                                                         None => total_fee_msat = u64::max_value(),
 655                                                                         Some(fee_msat) => {
 656                                                                                 hop_use_fee_msat = fee_msat;
 657                                                                                 total_fee_msat += hop_use_fee_msat;
 658                                                                                 // When calculating the lowest inbound fees to a node, we
 659                                                                                 // calculate fees here not based on the actual value we think
 660                                                                                 // will flow over this channel, but on the minimum value that
 661                                                                                 // we'll accept flowing over it. The minimum accepted value
 662                                                                                 // is a constant through each path collection run, ensuring
 663                                                                                 // consistent basis. Otherwise we may later find a
 664                                                                                 // different path to the source node that is more expensive,
 665                                                                                 // but which we consider to be cheaper because we are capacity
 666                                                                                 // constrained and the relative fee becomes lower.
 667                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 668                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 669                                                                                         Some(Some(v)) => {
 670                                                                                                 total_fee_msat = v;
 671                                                                                         },
 672                                                                                         _ => {
 673                                                                                                 total_fee_msat = u64::max_value();
 674                                                                                         }
 675                                                                                 };
 676                                                                         }
 677                                                                 }
 678                                                         }
 679
 680                                                         let new_graph_node = RouteGraphNode {
 681                                                                 pubkey: $src_node_id,
 682                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 683                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 684                                                                 value_contribution_msat: value_contribution_msat,
 685                                                                 path_htlc_minimum_msat,
 686                                                         };
 687
 688                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 689                                                         // if this way is cheaper than the already known
 690                                                         // (considering the cost to "reach" this channel from the route destination,
 691                                                         // the cost of using this channel,
 692                                                         // and the cost of routing to the source node of this channel).
 693                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 694                                                         // paying it. Consider the following exploit:
 695                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 696                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 697                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 698                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 699                                                         // to this channel.
 700                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 701                                                         // but it may require additional tracking - we don't want to double-count
 702                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 703                                                         // can't use something that may decrease on future hops.
 704                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 705                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 706
 707                                                         if !old_entry.was_processed && new_cost < old_cost {
 708                                                                 targets.push(new_graph_node);
 709                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 710                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 711                                                                 old_entry.total_fee_msat = total_fee_msat;
 712                                                                 old_entry.pubkey = $dest_node_id.clone();
 713                                                                 old_entry.short_channel_id = $chan_id.clone();
 714                                                                 old_entry.channel_features = $chan_features;
 715                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 716                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 717                                                                 old_entry.channel_fees = $directional_info.fees;
 718                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 719                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 720                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 721                                                                 {
 722                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 723                                                                 }
 724                                                         } else if old_entry.was_processed && new_cost < old_cost {
 725                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 726                                                                 {
 727                                                                         // If we're skipping processing a node which was previously
 728                                                                         // processed even though we found another path to it with a
 729                                                                         // cheaper fee, check that it was because the second path we
 730                                                                         // found (which we are processing now) has a lower value
 731                                                                         // contribution due to an HTLC minimum limit.
 732                                                                         //
 733                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 734                                                                         // through channel A, and one through channel B. Channel A and
 735                                                                         // B are both in the to-process heap, with their scores set by
 736                                                                         // a higher htlc_minimum than fee.
 737                                                                         // Channel A is processed first, and the channels onwards from
 738                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 739                                                                         // Channel B off of the heap, note that it has a much more
 740                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 741                                                                         // all of node 1's channels using the new, reduced, amount.
 742                                                                         //
 743                                                                         // This would be bogus - we'd be selecting a higher-fee path
 744                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 745                                                                         // already decided to use.
 746                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 747                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 748                                                                 }
 749                                                         }
 750                                                 }
 751                                         }
 752                                 }
 753                         }
 754                 };
 755         }
 756
 757         let empty_node_features = NodeFeatures::empty();
 758         // Find ways (channels with destination) to reach a given node and store them
 759         // in the corresponding data structures (routing graph etc).
 760         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 761         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 762         // This data can later be helpful to optimize routing (pay lower fees).
 763         macro_rules! add_entries_to_cheapest_to_target_node {
 764                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 765                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 766                                 let was_processed = elem.was_processed;
 767                                 elem.was_processed = true;
 768                                 was_processed
 769                         } else {
 770                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 771                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 772                                 // If we're processing any other node, it is always be the result of a channel from it.
 773                                 assert_eq!($node_id, payee);
 774                                 false
 775                         };
 776
 777                         if !skip_node {
 778                                 if first_hops.is_some() {
 779                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&$node_id) {
 780                                                 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);
 781                                         }
 782                                 }
 783
 784                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 785                                         &node_info.features
 786                                 } else {
 787                                         &empty_node_features
 788                                 };
 789
 790                                 if !features.requires_unknown_bits() {
 791                                         for chan_id in $node.channels.iter() {
 792                                                 let chan = network.get_channels().get(chan_id).unwrap();
 793                                                 if !chan.features.requires_unknown_bits() {
 794                                                         if chan.node_one == *$node_id {
 795                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 796                                                                 if first_hops.is_none() || chan.node_two != *our_node_id {
 797                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 798                                                                                 if two_to_one.enabled {
 799                                                                                         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);
 800                                                                                 }
 801                                                                         }
 802                                                                 }
 803                                                         } else {
 804                                                                 if first_hops.is_none() || chan.node_one != *our_node_id {
 805                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 806                                                                                 if one_to_two.enabled {
 807                                                                                         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);
 808                                                                                 }
 809                                                                         }
 810                                                                 }
 811                                                         }
 812                                                 }
 813                                         }
 814                                 }
 815                         }
 816                 };
 817         }
 818
 819         let mut payment_paths = Vec::<PaymentPath>::new();
 820
 821         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 822         'paths_collection: loop {
 823                 // For every new path, start from scratch, except
 824                 // bookkeeped_channels_liquidity_available_msat, which will improve
 825                 // the further iterations of path finding. Also don't erase first_hop_targets.
 826                 targets.clear();
 827                 dist.clear();
 828                 hit_minimum_limit = false;
 829
 830                 // If first hop is a private channel and the only way to reach the payee, this is the only
 831                 // place where it could be added.
 832                 if first_hops.is_some() {
 833                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&payee) {
 834                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 835                         }
 836                 }
 837
 838                 // Add the payee as a target, so that the payee-to-payer
 839                 // search algorithm knows what to start with.
 840                 match network.get_nodes().get(payee) {
 841                         // The payee is not in our network graph, so nothing to add here.
 842                         // There is still a chance of reaching them via last_hops though,
 843                         // so don't yet fail the payment here.
 844                         // If not, targets.pop() will not even let us enter the loop in step 2.
 845                         None => {},
 846                         Some(node) => {
 847                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 848                         },
 849                 }
 850
 851                 // Step (1).
 852                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 853                 // earlier than general path finding, they will be somewhat prioritized, although currently
 854                 // it matters only if the fees are exactly the same.
 855                 for hop in last_hops.iter() {
 856                         let have_hop_src_in_graph =
 857                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
 858                                         // If this hop connects to a node with which we have a direct channel, ignore
 859                                         // the network graph and add both the hop and our direct channel to
 860                                         // the candidate set.
 861                                         //
 862                                         // Currently there are no channel-context features defined, so we are a
 863                                         // bit lazy here. In the future, we should pull them out via our
 864                                         // ChannelManager, but there's no reason to waste the space until we
 865                                         // need them.
 866                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 867                                         true
 868                                 } else {
 869                                         // In any other case, only add the hop if the source is in the regular network
 870                                         // graph:
 871                                         network.get_nodes().get(&hop.src_node_id).is_some()
 872                                 };
 873                         if have_hop_src_in_graph {
 874                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 875                                 // really sucks, cause we're gonna need that eventually.
 876                                 let last_hop_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 877                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 878                                         None => 0
 879                                 };
 880                                 let directional_info = DummyDirectionalChannelInfo {
 881                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 882                                         htlc_minimum_msat: last_hop_htlc_minimum_msat,
 883                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 884                                         fees: hop.fees,
 885                                 };
 886                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, &empty_channel_features, 0, path_value_msat, 0);
 887                         }
 888                 }
 889
 890                 // At this point, targets are filled with the data from first and
 891                 // last hops communicated by the caller, and the payment receiver.
 892                 let mut found_new_path = false;
 893
 894                 // Step (2).
 895                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 896                 // - not enough outgoing liquidity:
 897                 //   0 < already_collected_value_msat < final_value_msat
 898                 // - enough outgoing liquidity:
 899                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 900                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 901                 // paths_collection will be stopped because found_new_path==false.
 902                 // This is not necessarily a routing failure.
 903                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 904
 905                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 906                         // traversing the graph and arrange the path out of what we found.
 907                         if pubkey == *our_node_id {
 908                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 909                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
 910
 911                                 'path_walk: loop {
 912                                         if let Some(&(_, _, _, ref features)) = first_hop_targets.get(&ordered_hops.last().unwrap().0.pubkey) {
 913                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
 914                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().0.pubkey) {
 915                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 916                                                         ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
 917                                                 } else {
 918                                                         ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
 919                                                 }
 920                                         } else {
 921                                                 // We should be able to fill in features for everything except the last
 922                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 923                                                 // should be able to extend it further as BOLT 11 does have feature
 924                                                 // flags for the last hop node itself).
 925                                                 assert!(ordered_hops.last().unwrap().0.pubkey == *payee);
 926                                         }
 927
 928                                         // Means we succesfully traversed from the payer to the payee, now
 929                                         // save this path for the payment route. Also, update the liquidity
 930                                         // remaining on the used hops, so that we take them into account
 931                                         // while looking for more paths.
 932                                         if ordered_hops.last().unwrap().0.pubkey == *payee {
 933                                                 break 'path_walk;
 934                                         }
 935
 936                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.pubkey) {
 937                                                 Some(payment_hop) => payment_hop,
 938                                                 // We can't arrive at None because, if we ever add an entry to targets,
 939                                                 // we also fill in the entry in dist (see add_entry!).
 940                                                 None => unreachable!(),
 941                                         };
 942                                         // We "propagate" the fees one hop backward (topologically) here,
 943                                         // so that fees paid for a HTLC forwarding on the current channel are
 944                                         // associated with the previous channel (where they will be subtracted).
 945                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
 946                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
 947                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
 948                                 }
 949                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
 950                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
 951                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
 952
 953                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 954
 955                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 956                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 957                                 // on some channels we already passed (assuming dest->source direction). Here, we
 958                                 // recompute the fees again, so that if that's the case, we match the currently
 959                                 // underpaid htlc_minimum_msat with fees.
 960                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
 961
 962                                 // Since a path allows to transfer as much value as
 963                                 // the smallest channel it has ("bottleneck"), we should recompute
 964                                 // the fees so sender HTLC don't overpay fees when traversing
 965                                 // larger channels than the bottleneck. This may happen because
 966                                 // when we were selecting those channels we were not aware how much value
 967                                 // this path will transfer, and the relative fee for them
 968                                 // might have been computed considering a larger value.
 969                                 // Remember that we used these channels so that we don't rely
 970                                 // on the same liquidity in future paths.
 971                                 let mut prevented_redundant_path_selection = false;
 972                                 for (payment_hop, _) in payment_path.hops.iter() {
 973                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
 974                                         let mut spent_on_hop_msat = value_contribution_msat;
 975                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 976                                         spent_on_hop_msat += next_hops_fee_msat;
 977                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
 978                                                 // If this path used all of this channel's available liquidity, we know
 979                                                 // this path will not be selected again in the next loop iteration.
 980                                                 prevented_redundant_path_selection = true;
 981                                         }
 982                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 983                                 }
 984                                 if !prevented_redundant_path_selection {
 985                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
 986                                         // we'll probably end up picking the same path again on the next iteration.
 987                                         // Decrease the available liquidity of a hop in the middle of the path.
 988                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(
 989                                                 &payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id).unwrap();
 990                                         *victim_liquidity = 0;
 991                                 }
 992
 993                                 // Track the total amount all our collected paths allow to send so that we:
 994                                 // - know when to stop looking for more paths
 995                                 // - know which of the hops are useless considering how much more sats we need
 996                                 //   (contributes_sufficient_value)
 997                                 already_collected_value_msat += value_contribution_msat;
 998
 999                                 payment_paths.push(payment_path);
1000                                 found_new_path = true;
1001                                 break 'path_construction;
1002                         }
1003
1004                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1005                         // the equivalent of the `elem.was_processed` check in
1006                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1007                         if pubkey == *payee { continue 'path_construction; }
1008
1009                         // Otherwise, since the current target node is not us,
1010                         // keep "unrolling" the payment graph from payee to payer by
1011                         // finding a way to reach the current target from the payer side.
1012                         match network.get_nodes().get(&pubkey) {
1013                                 None => {},
1014                                 Some(node) => {
1015                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1016                                 },
1017                         }
1018                 }
1019
1020                 if !allow_mpp {
1021                         // If we don't support MPP, no use trying to gather more value ever.
1022                         break 'paths_collection;
1023                 }
1024
1025                 // Step (3).
1026                 // Stop either when the recommended value is reached or if no new path was found in this
1027                 // iteration.
1028                 // In the latter case, making another path finding attempt won't help,
1029                 // because we deterministically terminated the search due to low liquidity.
1030                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1031                         break 'paths_collection;
1032                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1033                         // Further, if this was our first walk of the graph, and we weren't limited by an
1034                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1035                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1036                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1037                         // still keeping a lower total fee than this path.
1038                         if !hit_minimum_limit {
1039                                 break 'paths_collection;
1040                         }
1041                         path_value_msat = recommended_value_msat;
1042                 }
1043         }
1044
1045         // Step (4).
1046         if payment_paths.len() == 0 {
1047                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1048         }
1049
1050         if already_collected_value_msat < final_value_msat {
1051                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1052         }
1053
1054         // Sort by total fees and take the best paths.
1055         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1056         if payment_paths.len() > 50 {
1057                 payment_paths.truncate(50);
1058         }
1059
1060         // Draw multiple sufficient routes by randomly combining the selected paths.
1061         let mut drawn_routes = Vec::new();
1062         for i in 0..payment_paths.len() {
1063                 let mut cur_route = Vec::<PaymentPath>::new();
1064                 let mut aggregate_route_value_msat = 0;
1065
1066                 // Step (5).
1067                 // TODO: real random shuffle
1068                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1069                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1070
1071                 // Step (6).
1072                 for payment_path in cur_payment_paths {
1073                         cur_route.push(payment_path.clone());
1074                         aggregate_route_value_msat += payment_path.get_value_msat();
1075                         if aggregate_route_value_msat > final_value_msat {
1076                                 // Last path likely overpaid. Substract it from the most expensive
1077                                 // (in terms of proportional fee) path in this route and recompute fees.
1078                                 // This might be not the most economically efficient way, but fewer paths
1079                                 // also makes routing more reliable.
1080                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1081
1082                                 // First, drop some expensive low-value paths entirely if possible.
1083                                 // Sort by value so that we drop many really-low values first, since
1084                                 // fewer paths is better: the payment is less likely to fail.
1085                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1086                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1087                                 cur_route.sort_by_key(|path| path.get_value_msat());
1088                                 // We should make sure that at least 1 path left.
1089                                 let mut paths_left = cur_route.len();
1090                                 cur_route.retain(|path| {
1091                                         if paths_left == 1 {
1092                                                 return true
1093                                         }
1094                                         let mut keep = true;
1095                                         let path_value_msat = path.get_value_msat();
1096                                         if path_value_msat <= overpaid_value_msat {
1097                                                 keep = false;
1098                                                 overpaid_value_msat -= path_value_msat;
1099                                                 paths_left -= 1;
1100                                         }
1101                                         keep
1102                                 });
1103
1104                                 if overpaid_value_msat == 0 {
1105                                         break;
1106                                 }
1107
1108                                 assert!(cur_route.len() > 0);
1109
1110                                 // Step (7).
1111                                 // Now, substract the overpaid value from the most-expensive path.
1112                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1113                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1114                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1115                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1116                                 // We already dropped all the small channels above, meaning all the
1117                                 // remaining channels are larger than remaining overpaid_value_msat.
1118                                 // Thus, this can't be negative.
1119                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1120                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1121                                 break;
1122                         }
1123                 }
1124                 drawn_routes.push(cur_route);
1125         }
1126
1127         // Step (8).
1128         // Select the best route by lowest total fee.
1129         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1130         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1131         for payment_path in drawn_routes.first().unwrap() {
1132                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1133                         RouteHop {
1134                                 pubkey: payment_hop.pubkey,
1135                                 node_features: node_features.clone(),
1136                                 short_channel_id: payment_hop.short_channel_id,
1137                                 channel_features: payment_hop.channel_features.clone(),
1138                                 fee_msat: payment_hop.fee_msat,
1139                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1140                         }
1141                 }).collect());
1142         }
1143
1144         if let Some(features) = &payee_features {
1145                 for path in selected_paths.iter_mut() {
1146                         path.last_mut().unwrap().node_features = features.to_context();
1147                 }
1148         }
1149
1150         let route = Route { paths: selected_paths };
1151         log_trace!(logger, "Got route: {}", log_route!(route));
1152         Ok(route)
1153 }
1154
1155 #[cfg(test)]
1156 mod tests {
1157         use routing::router::{get_route, RouteHintHop, RoutingFees};
1158         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1159         use chain::transaction::OutPoint;
1160         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1161         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1162            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1163         use ln::channelmanager;
1164         use util::test_utils;
1165         use util::ser::Writeable;
1166
1167         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1168         use bitcoin::hashes::Hash;
1169         use bitcoin::network::constants::Network;
1170         use bitcoin::blockdata::constants::genesis_block;
1171         use bitcoin::blockdata::script::Builder;
1172         use bitcoin::blockdata::opcodes;
1173         use bitcoin::blockdata::transaction::TxOut;
1174
1175         use hex;
1176
1177         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1178         use bitcoin::secp256k1::{Secp256k1, All};
1179
1180         use prelude::*;
1181         use std::sync::Arc;
1182
1183         // Using the same keys for LN and BTC ids
1184         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1185            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1186                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1187                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1188
1189                 let unsigned_announcement = UnsignedChannelAnnouncement {
1190                         features,
1191                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1192                         short_channel_id,
1193                         node_id_1,
1194                         node_id_2,
1195                         bitcoin_key_1: node_id_1,
1196                         bitcoin_key_2: node_id_2,
1197                         excess_data: Vec::new(),
1198                 };
1199
1200                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1201                 let valid_announcement = ChannelAnnouncement {
1202                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1203                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1204                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1205                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1206                         contents: unsigned_announcement.clone(),
1207                 };
1208                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1209                         Ok(res) => assert!(res),
1210                         _ => panic!()
1211                 };
1212         }
1213
1214         fn update_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate) {
1215                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1216                 let valid_channel_update = ChannelUpdate {
1217                         signature: secp_ctx.sign(&msghash, node_privkey),
1218                         contents: update.clone()
1219                 };
1220
1221                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1222                         Ok(res) => assert!(res),
1223                         Err(_) => panic!()
1224                 };
1225         }
1226
1227         fn add_or_update_node(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey,
1228            features: NodeFeatures, timestamp: u32) {
1229                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1230                 let unsigned_announcement = UnsignedNodeAnnouncement {
1231                         features,
1232                         timestamp,
1233                         node_id,
1234                         rgb: [0; 3],
1235                         alias: [0; 32],
1236                         addresses: Vec::new(),
1237                         excess_address_data: Vec::new(),
1238                         excess_data: Vec::new(),
1239                 };
1240                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1241                 let valid_announcement = NodeAnnouncement {
1242                         signature: secp_ctx.sign(&msghash, node_privkey),
1243                         contents: unsigned_announcement.clone()
1244                 };
1245
1246                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1247                         Ok(_) => (),
1248                         Err(_) => panic!()
1249                 };
1250         }
1251
1252         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1253                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1254                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1255                 }).collect();
1256
1257                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1258
1259                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1260                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1261
1262                 (our_privkey, our_id, privkeys, pubkeys)
1263         }
1264
1265         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1266                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1267                 // test for it later.
1268                 let idx = (id - 1) * 2 + 1;
1269                 if idx > 8*3 {
1270                         vec![1 << (idx - 8*3), 0, 0, 0]
1271                 } else if idx > 8*2 {
1272                         vec![1 << (idx - 8*2), 0, 0]
1273                 } else if idx > 8*1 {
1274                         vec![1 << (idx - 8*1), 0]
1275                 } else {
1276                         vec![1 << idx]
1277                 }
1278         }
1279
1280         fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<crate::util::test_utils::TestLogger>>, std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<test_utils::TestLogger>) {
1281                 let secp_ctx = Secp256k1::new();
1282                 let logger = Arc::new(test_utils::TestLogger::new());
1283                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1284                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1285                 // Build network from our_id to node7:
1286                 //
1287                 //        -1(1)2-  node0  -1(3)2-
1288                 //       /                       \
1289                 // our_id -1(12)2- node7 -1(13)2--- node2
1290                 //       \                       /
1291                 //        -1(2)2-  node1  -1(4)2-
1292                 //
1293                 //
1294                 // chan1  1-to-2: disabled
1295                 // chan1  2-to-1: enabled, 0 fee
1296                 //
1297                 // chan2  1-to-2: enabled, ignored fee
1298                 // chan2  2-to-1: enabled, 0 fee
1299                 //
1300                 // chan3  1-to-2: enabled, 0 fee
1301                 // chan3  2-to-1: enabled, 100 msat fee
1302                 //
1303                 // chan4  1-to-2: enabled, 100% fee
1304                 // chan4  2-to-1: enabled, 0 fee
1305                 //
1306                 // chan12 1-to-2: enabled, ignored fee
1307                 // chan12 2-to-1: enabled, 0 fee
1308                 //
1309                 // chan13 1-to-2: enabled, 200% fee
1310                 // chan13 2-to-1: enabled, 0 fee
1311                 //
1312                 //
1313                 //       -1(5)2- node3 -1(8)2--
1314                 //       |         2          |
1315                 //       |       (11)         |
1316                 //      /          1           \
1317                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1318                 //      \                      /
1319                 //       -1(7)2- node5 -1(10)2-
1320                 //
1321                 // chan5  1-to-2: enabled, 100 msat fee
1322                 // chan5  2-to-1: enabled, 0 fee
1323                 //
1324                 // chan6  1-to-2: enabled, 0 fee
1325                 // chan6  2-to-1: enabled, 0 fee
1326                 //
1327                 // chan7  1-to-2: enabled, 100% fee
1328                 // chan7  2-to-1: enabled, 0 fee
1329                 //
1330                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1331                 // chan8  2-to-1: enabled, 0 fee
1332                 //
1333                 // chan9  1-to-2: enabled, 1001 msat fee
1334                 // chan9  2-to-1: enabled, 0 fee
1335                 //
1336                 // chan10 1-to-2: enabled, 0 fee
1337                 // chan10 2-to-1: enabled, 0 fee
1338                 //
1339                 // chan11 1-to-2: enabled, 0 fee
1340                 // chan11 2-to-1: enabled, 0 fee
1341
1342                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1343
1344                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1345                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1346                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1347                         short_channel_id: 1,
1348                         timestamp: 1,
1349                         flags: 1,
1350                         cltv_expiry_delta: 0,
1351                         htlc_minimum_msat: 0,
1352                         htlc_maximum_msat: OptionalField::Absent,
1353                         fee_base_msat: 0,
1354                         fee_proportional_millionths: 0,
1355                         excess_data: Vec::new()
1356                 });
1357
1358                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1359
1360                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1361                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1362                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1363                         short_channel_id: 2,
1364                         timestamp: 1,
1365                         flags: 0,
1366                         cltv_expiry_delta: u16::max_value(),
1367                         htlc_minimum_msat: 0,
1368                         htlc_maximum_msat: OptionalField::Absent,
1369                         fee_base_msat: u32::max_value(),
1370                         fee_proportional_millionths: u32::max_value(),
1371                         excess_data: Vec::new()
1372                 });
1373                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1374                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1375                         short_channel_id: 2,
1376                         timestamp: 1,
1377                         flags: 1,
1378                         cltv_expiry_delta: 0,
1379                         htlc_minimum_msat: 0,
1380                         htlc_maximum_msat: OptionalField::Absent,
1381                         fee_base_msat: 0,
1382                         fee_proportional_millionths: 0,
1383                         excess_data: Vec::new()
1384                 });
1385
1386                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1387
1388                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1389                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1390                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1391                         short_channel_id: 12,
1392                         timestamp: 1,
1393                         flags: 0,
1394                         cltv_expiry_delta: u16::max_value(),
1395                         htlc_minimum_msat: 0,
1396                         htlc_maximum_msat: OptionalField::Absent,
1397                         fee_base_msat: u32::max_value(),
1398                         fee_proportional_millionths: u32::max_value(),
1399                         excess_data: Vec::new()
1400                 });
1401                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1402                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1403                         short_channel_id: 12,
1404                         timestamp: 1,
1405                         flags: 1,
1406                         cltv_expiry_delta: 0,
1407                         htlc_minimum_msat: 0,
1408                         htlc_maximum_msat: OptionalField::Absent,
1409                         fee_base_msat: 0,
1410                         fee_proportional_millionths: 0,
1411                         excess_data: Vec::new()
1412                 });
1413
1414                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1415
1416                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1417                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1418                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1419                         short_channel_id: 3,
1420                         timestamp: 1,
1421                         flags: 0,
1422                         cltv_expiry_delta: (3 << 8) | 1,
1423                         htlc_minimum_msat: 0,
1424                         htlc_maximum_msat: OptionalField::Absent,
1425                         fee_base_msat: 0,
1426                         fee_proportional_millionths: 0,
1427                         excess_data: Vec::new()
1428                 });
1429                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1430                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1431                         short_channel_id: 3,
1432                         timestamp: 1,
1433                         flags: 1,
1434                         cltv_expiry_delta: (3 << 8) | 2,
1435                         htlc_minimum_msat: 0,
1436                         htlc_maximum_msat: OptionalField::Absent,
1437                         fee_base_msat: 100,
1438                         fee_proportional_millionths: 0,
1439                         excess_data: Vec::new()
1440                 });
1441
1442                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1443                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1444                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1445                         short_channel_id: 4,
1446                         timestamp: 1,
1447                         flags: 0,
1448                         cltv_expiry_delta: (4 << 8) | 1,
1449                         htlc_minimum_msat: 0,
1450                         htlc_maximum_msat: OptionalField::Absent,
1451                         fee_base_msat: 0,
1452                         fee_proportional_millionths: 1000000,
1453                         excess_data: Vec::new()
1454                 });
1455                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1456                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1457                         short_channel_id: 4,
1458                         timestamp: 1,
1459                         flags: 1,
1460                         cltv_expiry_delta: (4 << 8) | 2,
1461                         htlc_minimum_msat: 0,
1462                         htlc_maximum_msat: OptionalField::Absent,
1463                         fee_base_msat: 0,
1464                         fee_proportional_millionths: 0,
1465                         excess_data: Vec::new()
1466                 });
1467
1468                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1469                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1470                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1471                         short_channel_id: 13,
1472                         timestamp: 1,
1473                         flags: 0,
1474                         cltv_expiry_delta: (13 << 8) | 1,
1475                         htlc_minimum_msat: 0,
1476                         htlc_maximum_msat: OptionalField::Absent,
1477                         fee_base_msat: 0,
1478                         fee_proportional_millionths: 2000000,
1479                         excess_data: Vec::new()
1480                 });
1481                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1482                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1483                         short_channel_id: 13,
1484                         timestamp: 1,
1485                         flags: 1,
1486                         cltv_expiry_delta: (13 << 8) | 2,
1487                         htlc_minimum_msat: 0,
1488                         htlc_maximum_msat: OptionalField::Absent,
1489                         fee_base_msat: 0,
1490                         fee_proportional_millionths: 0,
1491                         excess_data: Vec::new()
1492                 });
1493
1494                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1495
1496                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1497                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1498                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1499                         short_channel_id: 6,
1500                         timestamp: 1,
1501                         flags: 0,
1502                         cltv_expiry_delta: (6 << 8) | 1,
1503                         htlc_minimum_msat: 0,
1504                         htlc_maximum_msat: OptionalField::Absent,
1505                         fee_base_msat: 0,
1506                         fee_proportional_millionths: 0,
1507                         excess_data: Vec::new()
1508                 });
1509                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1510                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1511                         short_channel_id: 6,
1512                         timestamp: 1,
1513                         flags: 1,
1514                         cltv_expiry_delta: (6 << 8) | 2,
1515                         htlc_minimum_msat: 0,
1516                         htlc_maximum_msat: OptionalField::Absent,
1517                         fee_base_msat: 0,
1518                         fee_proportional_millionths: 0,
1519                         excess_data: Vec::new(),
1520                 });
1521
1522                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1523                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1524                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1525                         short_channel_id: 11,
1526                         timestamp: 1,
1527                         flags: 0,
1528                         cltv_expiry_delta: (11 << 8) | 1,
1529                         htlc_minimum_msat: 0,
1530                         htlc_maximum_msat: OptionalField::Absent,
1531                         fee_base_msat: 0,
1532                         fee_proportional_millionths: 0,
1533                         excess_data: Vec::new()
1534                 });
1535                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1536                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1537                         short_channel_id: 11,
1538                         timestamp: 1,
1539                         flags: 1,
1540                         cltv_expiry_delta: (11 << 8) | 2,
1541                         htlc_minimum_msat: 0,
1542                         htlc_maximum_msat: OptionalField::Absent,
1543                         fee_base_msat: 0,
1544                         fee_proportional_millionths: 0,
1545                         excess_data: Vec::new()
1546                 });
1547
1548                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1549
1550                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1551
1552                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1553                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1554                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1555                         short_channel_id: 7,
1556                         timestamp: 1,
1557                         flags: 0,
1558                         cltv_expiry_delta: (7 << 8) | 1,
1559                         htlc_minimum_msat: 0,
1560                         htlc_maximum_msat: OptionalField::Absent,
1561                         fee_base_msat: 0,
1562                         fee_proportional_millionths: 1000000,
1563                         excess_data: Vec::new()
1564                 });
1565                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1566                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1567                         short_channel_id: 7,
1568                         timestamp: 1,
1569                         flags: 1,
1570                         cltv_expiry_delta: (7 << 8) | 2,
1571                         htlc_minimum_msat: 0,
1572                         htlc_maximum_msat: OptionalField::Absent,
1573                         fee_base_msat: 0,
1574                         fee_proportional_millionths: 0,
1575                         excess_data: Vec::new()
1576                 });
1577
1578                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1579
1580                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1581         }
1582
1583         #[test]
1584         fn simple_route_test() {
1585                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1586                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1587
1588                 // Simple route to 2 via 1
1589
1590                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger)) {
1591                         assert_eq!(err, "Cannot send a payment of 0 msat");
1592                 } else { panic!(); }
1593
1594                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1595                 assert_eq!(route.paths[0].len(), 2);
1596
1597                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1598                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1599                 assert_eq!(route.paths[0][0].fee_msat, 100);
1600                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1601                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1602                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1603
1604                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1605                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1606                 assert_eq!(route.paths[0][1].fee_msat, 100);
1607                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1608                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1609                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1610         }
1611
1612         #[test]
1613         fn invalid_first_hop_test() {
1614                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1615                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1616
1617                 // Simple route to 2 via 1
1618
1619                 let our_chans = vec![channelmanager::ChannelDetails {
1620                         channel_id: [0; 32],
1621                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1622                         short_channel_id: Some(2),
1623                         remote_network_id: our_id,
1624                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1625                         channel_value_satoshis: 100000,
1626                         user_id: 0,
1627                         outbound_capacity_msat: 100000,
1628                         inbound_capacity_msat: 100000,
1629                         is_outbound: true, is_funding_locked: true,
1630                         is_usable: true, is_public: true,
1631                         counterparty_forwarding_info: None,
1632                 }];
1633
1634                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
1635                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1636                 } else { panic!(); }
1637
1638                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1639                 assert_eq!(route.paths[0].len(), 2);
1640         }
1641
1642         #[test]
1643         fn htlc_minimum_test() {
1644                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1645                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1646
1647                 // Simple route to 2 via 1
1648
1649                 // Disable other paths
1650                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1651                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1652                         short_channel_id: 12,
1653                         timestamp: 2,
1654                         flags: 2, // to disable
1655                         cltv_expiry_delta: 0,
1656                         htlc_minimum_msat: 0,
1657                         htlc_maximum_msat: OptionalField::Absent,
1658                         fee_base_msat: 0,
1659                         fee_proportional_millionths: 0,
1660                         excess_data: Vec::new()
1661                 });
1662                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1663                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1664                         short_channel_id: 3,
1665                         timestamp: 2,
1666                         flags: 2, // to disable
1667                         cltv_expiry_delta: 0,
1668                         htlc_minimum_msat: 0,
1669                         htlc_maximum_msat: OptionalField::Absent,
1670                         fee_base_msat: 0,
1671                         fee_proportional_millionths: 0,
1672                         excess_data: Vec::new()
1673                 });
1674                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1675                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1676                         short_channel_id: 13,
1677                         timestamp: 2,
1678                         flags: 2, // to disable
1679                         cltv_expiry_delta: 0,
1680                         htlc_minimum_msat: 0,
1681                         htlc_maximum_msat: OptionalField::Absent,
1682                         fee_base_msat: 0,
1683                         fee_proportional_millionths: 0,
1684                         excess_data: Vec::new()
1685                 });
1686                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1687                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1688                         short_channel_id: 6,
1689                         timestamp: 2,
1690                         flags: 2, // to disable
1691                         cltv_expiry_delta: 0,
1692                         htlc_minimum_msat: 0,
1693                         htlc_maximum_msat: OptionalField::Absent,
1694                         fee_base_msat: 0,
1695                         fee_proportional_millionths: 0,
1696                         excess_data: Vec::new()
1697                 });
1698                 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: 2,
1702                         flags: 2, // to disable
1703                         cltv_expiry_delta: 0,
1704                         htlc_minimum_msat: 0,
1705                         htlc_maximum_msat: OptionalField::Absent,
1706                         fee_base_msat: 0,
1707                         fee_proportional_millionths: 0,
1708                         excess_data: Vec::new()
1709                 });
1710
1711                 // Check against amount_to_transfer_over_msat.
1712                 // Set minimal HTLC of 200_000_000 msat.
1713                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1714                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1715                         short_channel_id: 2,
1716                         timestamp: 3,
1717                         flags: 0,
1718                         cltv_expiry_delta: 0,
1719                         htlc_minimum_msat: 200_000_000,
1720                         htlc_maximum_msat: OptionalField::Absent,
1721                         fee_base_msat: 0,
1722                         fee_proportional_millionths: 0,
1723                         excess_data: Vec::new()
1724                 });
1725
1726                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1727                 // be used.
1728                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1729                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1730                         short_channel_id: 4,
1731                         timestamp: 3,
1732                         flags: 0,
1733                         cltv_expiry_delta: 0,
1734                         htlc_minimum_msat: 0,
1735                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1736                         fee_base_msat: 0,
1737                         fee_proportional_millionths: 0,
1738                         excess_data: Vec::new()
1739                 });
1740
1741                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1742                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)) {
1743                         assert_eq!(err, "Failed to find a path to the given destination");
1744                 } else { panic!(); }
1745
1746                 // Lift the restriction on the first hop.
1747                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1748                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1749                         short_channel_id: 2,
1750                         timestamp: 4,
1751                         flags: 0,
1752                         cltv_expiry_delta: 0,
1753                         htlc_minimum_msat: 0,
1754                         htlc_maximum_msat: OptionalField::Absent,
1755                         fee_base_msat: 0,
1756                         fee_proportional_millionths: 0,
1757                         excess_data: Vec::new()
1758                 });
1759
1760                 // A payment above the minimum should pass
1761                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)).unwrap();
1762                 assert_eq!(route.paths[0].len(), 2);
1763         }
1764
1765         #[test]
1766         fn htlc_minimum_overpay_test() {
1767                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1768                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1769
1770                 // A route to node#2 via two paths.
1771                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1772                 // Thus, they can't send 60 without overpaying.
1773                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1774                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1775                         short_channel_id: 2,
1776                         timestamp: 2,
1777                         flags: 0,
1778                         cltv_expiry_delta: 0,
1779                         htlc_minimum_msat: 35_000,
1780                         htlc_maximum_msat: OptionalField::Present(40_000),
1781                         fee_base_msat: 0,
1782                         fee_proportional_millionths: 0,
1783                         excess_data: Vec::new()
1784                 });
1785                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1786                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1787                         short_channel_id: 12,
1788                         timestamp: 3,
1789                         flags: 0,
1790                         cltv_expiry_delta: 0,
1791                         htlc_minimum_msat: 35_000,
1792                         htlc_maximum_msat: OptionalField::Present(40_000),
1793                         fee_base_msat: 0,
1794                         fee_proportional_millionths: 0,
1795                         excess_data: Vec::new()
1796                 });
1797
1798                 // Make 0 fee.
1799                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1800                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1801                         short_channel_id: 13,
1802                         timestamp: 2,
1803                         flags: 0,
1804                         cltv_expiry_delta: 0,
1805                         htlc_minimum_msat: 0,
1806                         htlc_maximum_msat: OptionalField::Absent,
1807                         fee_base_msat: 0,
1808                         fee_proportional_millionths: 0,
1809                         excess_data: Vec::new()
1810                 });
1811                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1812                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1813                         short_channel_id: 4,
1814                         timestamp: 2,
1815                         flags: 0,
1816                         cltv_expiry_delta: 0,
1817                         htlc_minimum_msat: 0,
1818                         htlc_maximum_msat: OptionalField::Absent,
1819                         fee_base_msat: 0,
1820                         fee_proportional_millionths: 0,
1821                         excess_data: Vec::new()
1822                 });
1823
1824                 // Disable other paths
1825                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1826                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1827                         short_channel_id: 1,
1828                         timestamp: 3,
1829                         flags: 2, // to disable
1830                         cltv_expiry_delta: 0,
1831                         htlc_minimum_msat: 0,
1832                         htlc_maximum_msat: OptionalField::Absent,
1833                         fee_base_msat: 0,
1834                         fee_proportional_millionths: 0,
1835                         excess_data: Vec::new()
1836                 });
1837
1838                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1839                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1840                 // Overpay fees to hit htlc_minimum_msat.
1841                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1842                 // TODO: this could be better balanced to overpay 10k and not 15k.
1843                 assert_eq!(overpaid_fees, 15_000);
1844
1845                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1846                 // while taking even more fee to match htlc_minimum_msat.
1847                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1848                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1849                         short_channel_id: 12,
1850                         timestamp: 4,
1851                         flags: 0,
1852                         cltv_expiry_delta: 0,
1853                         htlc_minimum_msat: 65_000,
1854                         htlc_maximum_msat: OptionalField::Present(80_000),
1855                         fee_base_msat: 0,
1856                         fee_proportional_millionths: 0,
1857                         excess_data: Vec::new()
1858                 });
1859                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1860                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1861                         short_channel_id: 2,
1862                         timestamp: 3,
1863                         flags: 0,
1864                         cltv_expiry_delta: 0,
1865                         htlc_minimum_msat: 0,
1866                         htlc_maximum_msat: OptionalField::Absent,
1867                         fee_base_msat: 0,
1868                         fee_proportional_millionths: 0,
1869                         excess_data: Vec::new()
1870                 });
1871                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1872                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1873                         short_channel_id: 4,
1874                         timestamp: 4,
1875                         flags: 0,
1876                         cltv_expiry_delta: 0,
1877                         htlc_minimum_msat: 0,
1878                         htlc_maximum_msat: OptionalField::Absent,
1879                         fee_base_msat: 0,
1880                         fee_proportional_millionths: 100_000,
1881                         excess_data: Vec::new()
1882                 });
1883
1884                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1885                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1886                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1887                 assert_eq!(route.paths.len(), 1);
1888                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1889                 let fees = route.paths[0][0].fee_msat;
1890                 assert_eq!(fees, 5_000);
1891
1892                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1893                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1894                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1895                 // the other channel.
1896                 assert_eq!(route.paths.len(), 1);
1897                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1898                 let fees = route.paths[0][0].fee_msat;
1899                 assert_eq!(fees, 5_000);
1900         }
1901
1902         #[test]
1903         fn disable_channels_test() {
1904                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1905                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1906
1907                 // // Disable channels 4 and 12 by flags=2
1908                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1909                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1910                         short_channel_id: 4,
1911                         timestamp: 2,
1912                         flags: 2, // to disable
1913                         cltv_expiry_delta: 0,
1914                         htlc_minimum_msat: 0,
1915                         htlc_maximum_msat: OptionalField::Absent,
1916                         fee_base_msat: 0,
1917                         fee_proportional_millionths: 0,
1918                         excess_data: Vec::new()
1919                 });
1920                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1921                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1922                         short_channel_id: 12,
1923                         timestamp: 2,
1924                         flags: 2, // to disable
1925                         cltv_expiry_delta: 0,
1926                         htlc_minimum_msat: 0,
1927                         htlc_maximum_msat: OptionalField::Absent,
1928                         fee_base_msat: 0,
1929                         fee_proportional_millionths: 0,
1930                         excess_data: Vec::new()
1931                 });
1932
1933                 // If all the channels require some features we don't understand, route should fail
1934                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1935                         assert_eq!(err, "Failed to find a path to the given destination");
1936                 } else { panic!(); }
1937
1938                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1939                 let our_chans = vec![channelmanager::ChannelDetails {
1940                         channel_id: [0; 32],
1941                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1942                         short_channel_id: Some(42),
1943                         remote_network_id: nodes[7].clone(),
1944                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1945                         channel_value_satoshis: 0,
1946                         user_id: 0,
1947                         outbound_capacity_msat: 250_000_000,
1948                         inbound_capacity_msat: 0,
1949                         is_outbound: true, is_funding_locked: true,
1950                         is_usable: true, is_public: true,
1951                         counterparty_forwarding_info: None,
1952                 }];
1953                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1954                 assert_eq!(route.paths[0].len(), 2);
1955
1956                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1957                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1958                 assert_eq!(route.paths[0][0].fee_msat, 200);
1959                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1960                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1961                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1962
1963                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1964                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1965                 assert_eq!(route.paths[0][1].fee_msat, 100);
1966                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1967                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1968                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1969         }
1970
1971         #[test]
1972         fn disable_node_test() {
1973                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1974                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1975
1976                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1977                 let mut unknown_features = NodeFeatures::known();
1978                 unknown_features.set_required_unknown_bits();
1979                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1980                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1981                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1982
1983                 // If all nodes require some features we don't understand, route should fail
1984                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1985                         assert_eq!(err, "Failed to find a path to the given destination");
1986                 } else { panic!(); }
1987
1988                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1989                 let our_chans = vec![channelmanager::ChannelDetails {
1990                         channel_id: [0; 32],
1991                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1992                         short_channel_id: Some(42),
1993                         remote_network_id: nodes[7].clone(),
1994                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1995                         channel_value_satoshis: 0,
1996                         user_id: 0,
1997                         outbound_capacity_msat: 250_000_000,
1998                         inbound_capacity_msat: 0,
1999                         is_outbound: true, is_funding_locked: true,
2000                         is_usable: true, is_public: true,
2001                         counterparty_forwarding_info: None,
2002                 }];
2003                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2004                 assert_eq!(route.paths[0].len(), 2);
2005
2006                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2007                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2008                 assert_eq!(route.paths[0][0].fee_msat, 200);
2009                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2010                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2011                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2012
2013                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2014                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2015                 assert_eq!(route.paths[0][1].fee_msat, 100);
2016                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2017                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2018                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2019
2020                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2021                 // naively) assume that the user checked the feature bits on the invoice, which override
2022                 // the node_announcement.
2023         }
2024
2025         #[test]
2026         fn our_chans_test() {
2027                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2028                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2029
2030                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2031                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2032                 assert_eq!(route.paths[0].len(), 3);
2033
2034                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2035                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2036                 assert_eq!(route.paths[0][0].fee_msat, 200);
2037                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2038                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2039                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2040
2041                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2042                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2043                 assert_eq!(route.paths[0][1].fee_msat, 100);
2044                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2045                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2046                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2047
2048                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2049                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2050                 assert_eq!(route.paths[0][2].fee_msat, 100);
2051                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2052                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2053                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2054
2055                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2056                 let our_chans = vec![channelmanager::ChannelDetails {
2057                         channel_id: [0; 32],
2058                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2059                         short_channel_id: Some(42),
2060                         remote_network_id: nodes[7].clone(),
2061                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2062                         channel_value_satoshis: 0,
2063                         user_id: 0,
2064                         outbound_capacity_msat: 250_000_000,
2065                         inbound_capacity_msat: 0,
2066                         is_outbound: true, is_funding_locked: true,
2067                         is_usable: true, is_public: true,
2068                         counterparty_forwarding_info: None,
2069                 }];
2070                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2071                 assert_eq!(route.paths[0].len(), 2);
2072
2073                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2074                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2075                 assert_eq!(route.paths[0][0].fee_msat, 200);
2076                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2077                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2078                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2079
2080                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2081                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2082                 assert_eq!(route.paths[0][1].fee_msat, 100);
2083                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2084                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2085                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2086         }
2087
2088         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHintHop> {
2089                 let zero_fees = RoutingFees {
2090                         base_msat: 0,
2091                         proportional_millionths: 0,
2092                 };
2093                 vec!(RouteHintHop {
2094                         src_node_id: nodes[3].clone(),
2095                         short_channel_id: 8,
2096                         fees: zero_fees,
2097                         cltv_expiry_delta: (8 << 8) | 1,
2098                         htlc_minimum_msat: None,
2099                         htlc_maximum_msat: None,
2100                 }, RouteHintHop {
2101                         src_node_id: nodes[4].clone(),
2102                         short_channel_id: 9,
2103                         fees: RoutingFees {
2104                                 base_msat: 1001,
2105                                 proportional_millionths: 0,
2106                         },
2107                         cltv_expiry_delta: (9 << 8) | 1,
2108                         htlc_minimum_msat: None,
2109                         htlc_maximum_msat: None,
2110                 }, RouteHintHop {
2111                         src_node_id: nodes[5].clone(),
2112                         short_channel_id: 10,
2113                         fees: zero_fees,
2114                         cltv_expiry_delta: (10 << 8) | 1,
2115                         htlc_minimum_msat: None,
2116                         htlc_maximum_msat: None,
2117                 })
2118         }
2119
2120         #[test]
2121         fn last_hops_test() {
2122                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2123                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2124
2125                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2126
2127                 // First check that lst hop can't have its source as the payee.
2128                 let invalid_last_hop = RouteHintHop {
2129                         src_node_id: nodes[6],
2130                         short_channel_id: 8,
2131                         fees: RoutingFees {
2132                                 base_msat: 1000,
2133                                 proportional_millionths: 0,
2134                         },
2135                         cltv_expiry_delta: (8 << 8) | 1,
2136                         htlc_minimum_msat: None,
2137                         htlc_maximum_msat: None,
2138                 };
2139
2140                 let mut invalid_last_hops = last_hops(&nodes);
2141                 invalid_last_hops.push(invalid_last_hop);
2142                 {
2143                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)) {
2144                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2145                         } else { panic!(); }
2146                 }
2147
2148                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2149                 assert_eq!(route.paths[0].len(), 5);
2150
2151                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2152                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2153                 assert_eq!(route.paths[0][0].fee_msat, 100);
2154                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2155                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2156                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2157
2158                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2159                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2160                 assert_eq!(route.paths[0][1].fee_msat, 0);
2161                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2162                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2163                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2164
2165                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2166                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2167                 assert_eq!(route.paths[0][2].fee_msat, 0);
2168                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2169                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2170                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2171
2172                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2173                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2174                 assert_eq!(route.paths[0][3].fee_msat, 0);
2175                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2176                 // If we have a peer in the node map, we'll use their features here since we don't have
2177                 // a way of figuring out their features from the invoice:
2178                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2179                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2180
2181                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2182                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2183                 assert_eq!(route.paths[0][4].fee_msat, 100);
2184                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2185                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2186                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2187         }
2188
2189         #[test]
2190         fn our_chans_last_hop_connect_test() {
2191                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2192                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2193
2194                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2195                 let our_chans = vec![channelmanager::ChannelDetails {
2196                         channel_id: [0; 32],
2197                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2198                         short_channel_id: Some(42),
2199                         remote_network_id: nodes[3].clone(),
2200                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2201                         channel_value_satoshis: 0,
2202                         user_id: 0,
2203                         outbound_capacity_msat: 250_000_000,
2204                         inbound_capacity_msat: 0,
2205                         is_outbound: true, is_funding_locked: true,
2206                         is_usable: true, is_public: true,
2207                         counterparty_forwarding_info: None,
2208                 }];
2209                 let mut last_hops = last_hops(&nodes);
2210                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2211                 assert_eq!(route.paths[0].len(), 2);
2212
2213                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2214                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2215                 assert_eq!(route.paths[0][0].fee_msat, 0);
2216                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2217                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2218                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2219
2220                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2221                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2222                 assert_eq!(route.paths[0][1].fee_msat, 100);
2223                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2224                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2225                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2226
2227                 last_hops[0].fees.base_msat = 1000;
2228
2229                 // Revert to via 6 as the fee on 8 goes up
2230                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2231                 assert_eq!(route.paths[0].len(), 4);
2232
2233                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2234                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2235                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2236                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2237                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2238                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2239
2240                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2241                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2242                 assert_eq!(route.paths[0][1].fee_msat, 100);
2243                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2244                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2245                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2246
2247                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2248                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2249                 assert_eq!(route.paths[0][2].fee_msat, 0);
2250                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2251                 // If we have a peer in the node map, we'll use their features here since we don't have
2252                 // a way of figuring out their features from the invoice:
2253                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2254                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2255
2256                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2257                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2258                 assert_eq!(route.paths[0][3].fee_msat, 100);
2259                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2260                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2261                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2262
2263                 // ...but still use 8 for larger payments as 6 has a variable feerate
2264                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger)).unwrap();
2265                 assert_eq!(route.paths[0].len(), 5);
2266
2267                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2268                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2269                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2270                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2271                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2272                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2273
2274                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2275                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2276                 assert_eq!(route.paths[0][1].fee_msat, 0);
2277                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2278                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2279                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2280
2281                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2282                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2283                 assert_eq!(route.paths[0][2].fee_msat, 0);
2284                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2285                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2286                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2287
2288                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2289                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2290                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2291                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2292                 // If we have a peer in the node map, we'll use their features here since we don't have
2293                 // a way of figuring out their features from the invoice:
2294                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2295                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2296
2297                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2298                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2299                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2300                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2301                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2302                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2303         }
2304
2305         #[test]
2306         fn unannounced_path_test() {
2307                 // We should be able to send a payment to a destination without any help of a routing graph
2308                 // if we have a channel with a common counterparty that appears in the first and last hop
2309                 // hints.
2310                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2311                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2312                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2313
2314                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2315                 let last_hops = vec![RouteHintHop {
2316                         src_node_id: middle_node_id,
2317                         short_channel_id: 8,
2318                         fees: RoutingFees {
2319                                 base_msat: 1000,
2320                                 proportional_millionths: 0,
2321                         },
2322                         cltv_expiry_delta: (8 << 8) | 1,
2323                         htlc_minimum_msat: None,
2324                         htlc_maximum_msat: None,
2325                 }];
2326                 let our_chans = vec![channelmanager::ChannelDetails {
2327                         channel_id: [0; 32],
2328                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2329                         short_channel_id: Some(42),
2330                         remote_network_id: middle_node_id,
2331                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2332                         channel_value_satoshis: 100000,
2333                         user_id: 0,
2334                         outbound_capacity_msat: 100000,
2335                         inbound_capacity_msat: 100000,
2336                         is_outbound: true, is_funding_locked: true,
2337                         is_usable: true, is_public: true,
2338                         counterparty_forwarding_info: None,
2339                 }];
2340                 let route = get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::new(test_utils::TestLogger::new())).unwrap();
2341
2342                 assert_eq!(route.paths[0].len(), 2);
2343
2344                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2345                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2346                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2347                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2348                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2349                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2350
2351                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2352                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2353                 assert_eq!(route.paths[0][1].fee_msat, 100);
2354                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2355                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2356                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2357         }
2358
2359         #[test]
2360         fn available_amount_while_routing_test() {
2361                 // Tests whether we choose the correct available channel amount while routing.
2362
2363                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2364                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2365
2366                 // We will use a simple single-path route from
2367                 // our node to node2 via node0: channels {1, 3}.
2368
2369                 // First disable all other paths.
2370                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2371                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2372                         short_channel_id: 2,
2373                         timestamp: 2,
2374                         flags: 2,
2375                         cltv_expiry_delta: 0,
2376                         htlc_minimum_msat: 0,
2377                         htlc_maximum_msat: OptionalField::Present(100_000),
2378                         fee_base_msat: 0,
2379                         fee_proportional_millionths: 0,
2380                         excess_data: Vec::new()
2381                 });
2382                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2383                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2384                         short_channel_id: 12,
2385                         timestamp: 2,
2386                         flags: 2,
2387                         cltv_expiry_delta: 0,
2388                         htlc_minimum_msat: 0,
2389                         htlc_maximum_msat: OptionalField::Present(100_000),
2390                         fee_base_msat: 0,
2391                         fee_proportional_millionths: 0,
2392                         excess_data: Vec::new()
2393                 });
2394
2395                 // Make the first channel (#1) very permissive,
2396                 // and we will be testing all limits on the second channel.
2397                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2398                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2399                         short_channel_id: 1,
2400                         timestamp: 2,
2401                         flags: 0,
2402                         cltv_expiry_delta: 0,
2403                         htlc_minimum_msat: 0,
2404                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2405                         fee_base_msat: 0,
2406                         fee_proportional_millionths: 0,
2407                         excess_data: Vec::new()
2408                 });
2409
2410                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2411                 // In this case, it should be set to 250_000 sats.
2412                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2413                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2414                         short_channel_id: 3,
2415                         timestamp: 2,
2416                         flags: 0,
2417                         cltv_expiry_delta: 0,
2418                         htlc_minimum_msat: 0,
2419                         htlc_maximum_msat: OptionalField::Absent,
2420                         fee_base_msat: 0,
2421                         fee_proportional_millionths: 0,
2422                         excess_data: Vec::new()
2423                 });
2424
2425                 {
2426                         // Attempt to route more than available results in a failure.
2427                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2428                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2429                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2430                         } else { panic!(); }
2431                 }
2432
2433                 {
2434                         // Now, attempt to route an exact amount we have should be fine.
2435                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2436                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2437                         assert_eq!(route.paths.len(), 1);
2438                         let path = route.paths.last().unwrap();
2439                         assert_eq!(path.len(), 2);
2440                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2441                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2442                 }
2443
2444                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2445                 // Disable channel #1 and use another first hop.
2446                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2447                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2448                         short_channel_id: 1,
2449                         timestamp: 3,
2450                         flags: 2,
2451                         cltv_expiry_delta: 0,
2452                         htlc_minimum_msat: 0,
2453                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2454                         fee_base_msat: 0,
2455                         fee_proportional_millionths: 0,
2456                         excess_data: Vec::new()
2457                 });
2458
2459                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2460                 let our_chans = vec![channelmanager::ChannelDetails {
2461                         channel_id: [0; 32],
2462                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2463                         short_channel_id: Some(42),
2464                         remote_network_id: nodes[0].clone(),
2465                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2466                         channel_value_satoshis: 0,
2467                         user_id: 0,
2468                         outbound_capacity_msat: 200_000_000,
2469                         inbound_capacity_msat: 0,
2470                         is_outbound: true, is_funding_locked: true,
2471                         is_usable: true, is_public: true,
2472                         counterparty_forwarding_info: None,
2473                 }];
2474
2475                 {
2476                         // Attempt to route more than available results in a failure.
2477                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2478                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2479                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2480                         } else { panic!(); }
2481                 }
2482
2483                 {
2484                         // Now, attempt to route an exact amount we have should be fine.
2485                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2486                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2487                         assert_eq!(route.paths.len(), 1);
2488                         let path = route.paths.last().unwrap();
2489                         assert_eq!(path.len(), 2);
2490                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2491                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2492                 }
2493
2494                 // Enable channel #1 back.
2495                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2496                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2497                         short_channel_id: 1,
2498                         timestamp: 4,
2499                         flags: 0,
2500                         cltv_expiry_delta: 0,
2501                         htlc_minimum_msat: 0,
2502                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2503                         fee_base_msat: 0,
2504                         fee_proportional_millionths: 0,
2505                         excess_data: Vec::new()
2506                 });
2507
2508
2509                 // Now let's see if routing works if we know only htlc_maximum_msat.
2510                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2511                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2512                         short_channel_id: 3,
2513                         timestamp: 3,
2514                         flags: 0,
2515                         cltv_expiry_delta: 0,
2516                         htlc_minimum_msat: 0,
2517                         htlc_maximum_msat: OptionalField::Present(15_000),
2518                         fee_base_msat: 0,
2519                         fee_proportional_millionths: 0,
2520                         excess_data: Vec::new()
2521                 });
2522
2523                 {
2524                         // Attempt to route more than available results in a failure.
2525                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2526                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2527                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2528                         } else { panic!(); }
2529                 }
2530
2531                 {
2532                         // Now, attempt to route an exact amount we have should be fine.
2533                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2534                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2535                         assert_eq!(route.paths.len(), 1);
2536                         let path = route.paths.last().unwrap();
2537                         assert_eq!(path.len(), 2);
2538                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2539                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2540                 }
2541
2542                 // Now let's see if routing works if we know only capacity from the UTXO.
2543
2544                 // We can't change UTXO capacity on the fly, so we'll disable
2545                 // the existing channel and add another one with the capacity we need.
2546                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2547                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2548                         short_channel_id: 3,
2549                         timestamp: 4,
2550                         flags: 2,
2551                         cltv_expiry_delta: 0,
2552                         htlc_minimum_msat: 0,
2553                         htlc_maximum_msat: OptionalField::Absent,
2554                         fee_base_msat: 0,
2555                         fee_proportional_millionths: 0,
2556                         excess_data: Vec::new()
2557                 });
2558
2559                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2560                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2561                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2562                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2563                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2564
2565                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2566                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2567
2568                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2569                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2570                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2571                         short_channel_id: 333,
2572                         timestamp: 1,
2573                         flags: 0,
2574                         cltv_expiry_delta: (3 << 8) | 1,
2575                         htlc_minimum_msat: 0,
2576                         htlc_maximum_msat: OptionalField::Absent,
2577                         fee_base_msat: 0,
2578                         fee_proportional_millionths: 0,
2579                         excess_data: Vec::new()
2580                 });
2581                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2582                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2583                         short_channel_id: 333,
2584                         timestamp: 1,
2585                         flags: 1,
2586                         cltv_expiry_delta: (3 << 8) | 2,
2587                         htlc_minimum_msat: 0,
2588                         htlc_maximum_msat: OptionalField::Absent,
2589                         fee_base_msat: 100,
2590                         fee_proportional_millionths: 0,
2591                         excess_data: Vec::new()
2592                 });
2593
2594                 {
2595                         // Attempt to route more than available results in a failure.
2596                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2597                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2598                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2599                         } else { panic!(); }
2600                 }
2601
2602                 {
2603                         // Now, attempt to route an exact amount we have should be fine.
2604                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2605                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2606                         assert_eq!(route.paths.len(), 1);
2607                         let path = route.paths.last().unwrap();
2608                         assert_eq!(path.len(), 2);
2609                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2610                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2611                 }
2612
2613                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2614                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2615                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2616                         short_channel_id: 333,
2617                         timestamp: 6,
2618                         flags: 0,
2619                         cltv_expiry_delta: 0,
2620                         htlc_minimum_msat: 0,
2621                         htlc_maximum_msat: OptionalField::Present(10_000),
2622                         fee_base_msat: 0,
2623                         fee_proportional_millionths: 0,
2624                         excess_data: Vec::new()
2625                 });
2626
2627                 {
2628                         // Attempt to route more than available results in a failure.
2629                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2630                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2631                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2632                         } else { panic!(); }
2633                 }
2634
2635                 {
2636                         // Now, attempt to route an exact amount we have should be fine.
2637                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2638                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2639                         assert_eq!(route.paths.len(), 1);
2640                         let path = route.paths.last().unwrap();
2641                         assert_eq!(path.len(), 2);
2642                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2643                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2644                 }
2645         }
2646
2647         #[test]
2648         fn available_liquidity_last_hop_test() {
2649                 // Check that available liquidity properly limits the path even when only
2650                 // one of the latter hops is limited.
2651                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2652                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2653
2654                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2655                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2656                 // Total capacity: 50 sats.
2657
2658                 // Disable other potential paths.
2659                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2660                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2661                         short_channel_id: 2,
2662                         timestamp: 2,
2663                         flags: 2,
2664                         cltv_expiry_delta: 0,
2665                         htlc_minimum_msat: 0,
2666                         htlc_maximum_msat: OptionalField::Present(100_000),
2667                         fee_base_msat: 0,
2668                         fee_proportional_millionths: 0,
2669                         excess_data: Vec::new()
2670                 });
2671                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2672                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2673                         short_channel_id: 7,
2674                         timestamp: 2,
2675                         flags: 2,
2676                         cltv_expiry_delta: 0,
2677                         htlc_minimum_msat: 0,
2678                         htlc_maximum_msat: OptionalField::Present(100_000),
2679                         fee_base_msat: 0,
2680                         fee_proportional_millionths: 0,
2681                         excess_data: Vec::new()
2682                 });
2683
2684                 // Limit capacities
2685
2686                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2687                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2688                         short_channel_id: 12,
2689                         timestamp: 2,
2690                         flags: 0,
2691                         cltv_expiry_delta: 0,
2692                         htlc_minimum_msat: 0,
2693                         htlc_maximum_msat: OptionalField::Present(100_000),
2694                         fee_base_msat: 0,
2695                         fee_proportional_millionths: 0,
2696                         excess_data: Vec::new()
2697                 });
2698                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2699                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2700                         short_channel_id: 13,
2701                         timestamp: 2,
2702                         flags: 0,
2703                         cltv_expiry_delta: 0,
2704                         htlc_minimum_msat: 0,
2705                         htlc_maximum_msat: OptionalField::Present(100_000),
2706                         fee_base_msat: 0,
2707                         fee_proportional_millionths: 0,
2708                         excess_data: Vec::new()
2709                 });
2710
2711                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2712                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2713                         short_channel_id: 6,
2714                         timestamp: 2,
2715                         flags: 0,
2716                         cltv_expiry_delta: 0,
2717                         htlc_minimum_msat: 0,
2718                         htlc_maximum_msat: OptionalField::Present(50_000),
2719                         fee_base_msat: 0,
2720                         fee_proportional_millionths: 0,
2721                         excess_data: Vec::new()
2722                 });
2723                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2724                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2725                         short_channel_id: 11,
2726                         timestamp: 2,
2727                         flags: 0,
2728                         cltv_expiry_delta: 0,
2729                         htlc_minimum_msat: 0,
2730                         htlc_maximum_msat: OptionalField::Present(100_000),
2731                         fee_base_msat: 0,
2732                         fee_proportional_millionths: 0,
2733                         excess_data: Vec::new()
2734                 });
2735                 {
2736                         // Attempt to route more than available results in a failure.
2737                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2738                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2739                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2740                         } else { panic!(); }
2741                 }
2742
2743                 {
2744                         // Now, attempt to route 49 sats (just a bit below the capacity).
2745                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2746                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2747                         assert_eq!(route.paths.len(), 1);
2748                         let mut total_amount_paid_msat = 0;
2749                         for path in &route.paths {
2750                                 assert_eq!(path.len(), 4);
2751                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2752                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2753                         }
2754                         assert_eq!(total_amount_paid_msat, 49_000);
2755                 }
2756
2757                 {
2758                         // Attempt to route an exact amount is also fine
2759                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2760                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2761                         assert_eq!(route.paths.len(), 1);
2762                         let mut total_amount_paid_msat = 0;
2763                         for path in &route.paths {
2764                                 assert_eq!(path.len(), 4);
2765                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2766                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2767                         }
2768                         assert_eq!(total_amount_paid_msat, 50_000);
2769                 }
2770         }
2771
2772         #[test]
2773         fn ignore_fee_first_hop_test() {
2774                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2775                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2776
2777                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2778                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2779                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2780                         short_channel_id: 1,
2781                         timestamp: 2,
2782                         flags: 0,
2783                         cltv_expiry_delta: 0,
2784                         htlc_minimum_msat: 0,
2785                         htlc_maximum_msat: OptionalField::Present(100_000),
2786                         fee_base_msat: 1_000_000,
2787                         fee_proportional_millionths: 0,
2788                         excess_data: Vec::new()
2789                 });
2790                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2791                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2792                         short_channel_id: 3,
2793                         timestamp: 2,
2794                         flags: 0,
2795                         cltv_expiry_delta: 0,
2796                         htlc_minimum_msat: 0,
2797                         htlc_maximum_msat: OptionalField::Present(50_000),
2798                         fee_base_msat: 0,
2799                         fee_proportional_millionths: 0,
2800                         excess_data: Vec::new()
2801                 });
2802
2803                 {
2804                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2805                         assert_eq!(route.paths.len(), 1);
2806                         let mut total_amount_paid_msat = 0;
2807                         for path in &route.paths {
2808                                 assert_eq!(path.len(), 2);
2809                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2810                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2811                         }
2812                         assert_eq!(total_amount_paid_msat, 50_000);
2813                 }
2814         }
2815
2816         #[test]
2817         fn simple_mpp_route_test() {
2818                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2819                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2820
2821                 // We need a route consisting of 3 paths:
2822                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2823                 // To achieve this, the amount being transferred should be around
2824                 // the total capacity of these 3 paths.
2825
2826                 // First, we set limits on these (previously unlimited) channels.
2827                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2828
2829                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2830                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2831                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2832                         short_channel_id: 1,
2833                         timestamp: 2,
2834                         flags: 0,
2835                         cltv_expiry_delta: 0,
2836                         htlc_minimum_msat: 0,
2837                         htlc_maximum_msat: OptionalField::Present(100_000),
2838                         fee_base_msat: 0,
2839                         fee_proportional_millionths: 0,
2840                         excess_data: Vec::new()
2841                 });
2842                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2843                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2844                         short_channel_id: 3,
2845                         timestamp: 2,
2846                         flags: 0,
2847                         cltv_expiry_delta: 0,
2848                         htlc_minimum_msat: 0,
2849                         htlc_maximum_msat: OptionalField::Present(50_000),
2850                         fee_base_msat: 0,
2851                         fee_proportional_millionths: 0,
2852                         excess_data: Vec::new()
2853                 });
2854
2855                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2856                 // (total limit 60).
2857                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2858                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2859                         short_channel_id: 12,
2860                         timestamp: 2,
2861                         flags: 0,
2862                         cltv_expiry_delta: 0,
2863                         htlc_minimum_msat: 0,
2864                         htlc_maximum_msat: OptionalField::Present(60_000),
2865                         fee_base_msat: 0,
2866                         fee_proportional_millionths: 0,
2867                         excess_data: Vec::new()
2868                 });
2869                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2870                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2871                         short_channel_id: 13,
2872                         timestamp: 2,
2873                         flags: 0,
2874                         cltv_expiry_delta: 0,
2875                         htlc_minimum_msat: 0,
2876                         htlc_maximum_msat: OptionalField::Present(60_000),
2877                         fee_base_msat: 0,
2878                         fee_proportional_millionths: 0,
2879                         excess_data: Vec::new()
2880                 });
2881
2882                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2883                 // (total capacity 180 sats).
2884                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2885                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2886                         short_channel_id: 2,
2887                         timestamp: 2,
2888                         flags: 0,
2889                         cltv_expiry_delta: 0,
2890                         htlc_minimum_msat: 0,
2891                         htlc_maximum_msat: OptionalField::Present(200_000),
2892                         fee_base_msat: 0,
2893                         fee_proportional_millionths: 0,
2894                         excess_data: Vec::new()
2895                 });
2896                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2897                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2898                         short_channel_id: 4,
2899                         timestamp: 2,
2900                         flags: 0,
2901                         cltv_expiry_delta: 0,
2902                         htlc_minimum_msat: 0,
2903                         htlc_maximum_msat: OptionalField::Present(180_000),
2904                         fee_base_msat: 0,
2905                         fee_proportional_millionths: 0,
2906                         excess_data: Vec::new()
2907                 });
2908
2909                 {
2910                         // Attempt to route more than available results in a failure.
2911                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2912                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2913                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2914                         } else { panic!(); }
2915                 }
2916
2917                 {
2918                         // Now, attempt to route 250 sats (just a bit below the capacity).
2919                         // Our algorithm should provide us with these 3 paths.
2920                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2921                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2922                         assert_eq!(route.paths.len(), 3);
2923                         let mut total_amount_paid_msat = 0;
2924                         for path in &route.paths {
2925                                 assert_eq!(path.len(), 2);
2926                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2927                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2928                         }
2929                         assert_eq!(total_amount_paid_msat, 250_000);
2930                 }
2931
2932                 {
2933                         // Attempt to route an exact amount is also fine
2934                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2935                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2936                         assert_eq!(route.paths.len(), 3);
2937                         let mut total_amount_paid_msat = 0;
2938                         for path in &route.paths {
2939                                 assert_eq!(path.len(), 2);
2940                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2941                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2942                         }
2943                         assert_eq!(total_amount_paid_msat, 290_000);
2944                 }
2945         }
2946
2947         #[test]
2948         fn long_mpp_route_test() {
2949                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2950                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2951
2952                 // We need a route consisting of 3 paths:
2953                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2954                 // Note that these paths overlap (channels 5, 12, 13).
2955                 // We will route 300 sats.
2956                 // Each path will have 100 sats capacity, those channels which
2957                 // are used twice will have 200 sats capacity.
2958
2959                 // Disable other potential paths.
2960                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2961                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2962                         short_channel_id: 2,
2963                         timestamp: 2,
2964                         flags: 2,
2965                         cltv_expiry_delta: 0,
2966                         htlc_minimum_msat: 0,
2967                         htlc_maximum_msat: OptionalField::Present(100_000),
2968                         fee_base_msat: 0,
2969                         fee_proportional_millionths: 0,
2970                         excess_data: Vec::new()
2971                 });
2972                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2973                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2974                         short_channel_id: 7,
2975                         timestamp: 2,
2976                         flags: 2,
2977                         cltv_expiry_delta: 0,
2978                         htlc_minimum_msat: 0,
2979                         htlc_maximum_msat: OptionalField::Present(100_000),
2980                         fee_base_msat: 0,
2981                         fee_proportional_millionths: 0,
2982                         excess_data: Vec::new()
2983                 });
2984
2985                 // Path via {node0, node2} is channels {1, 3, 5}.
2986                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2987                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2988                         short_channel_id: 1,
2989                         timestamp: 2,
2990                         flags: 0,
2991                         cltv_expiry_delta: 0,
2992                         htlc_minimum_msat: 0,
2993                         htlc_maximum_msat: OptionalField::Present(100_000),
2994                         fee_base_msat: 0,
2995                         fee_proportional_millionths: 0,
2996                         excess_data: Vec::new()
2997                 });
2998                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2999                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3000                         short_channel_id: 3,
3001                         timestamp: 2,
3002                         flags: 0,
3003                         cltv_expiry_delta: 0,
3004                         htlc_minimum_msat: 0,
3005                         htlc_maximum_msat: OptionalField::Present(100_000),
3006                         fee_base_msat: 0,
3007                         fee_proportional_millionths: 0,
3008                         excess_data: Vec::new()
3009                 });
3010
3011                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3012                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3013                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3014                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3015                         short_channel_id: 5,
3016                         timestamp: 2,
3017                         flags: 0,
3018                         cltv_expiry_delta: 0,
3019                         htlc_minimum_msat: 0,
3020                         htlc_maximum_msat: OptionalField::Present(200_000),
3021                         fee_base_msat: 0,
3022                         fee_proportional_millionths: 0,
3023                         excess_data: Vec::new()
3024                 });
3025
3026                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3027                 // Add 100 sats to the capacities of {12, 13}, because these channels
3028                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3029                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3030                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3031                         short_channel_id: 12,
3032                         timestamp: 2,
3033                         flags: 0,
3034                         cltv_expiry_delta: 0,
3035                         htlc_minimum_msat: 0,
3036                         htlc_maximum_msat: OptionalField::Present(200_000),
3037                         fee_base_msat: 0,
3038                         fee_proportional_millionths: 0,
3039                         excess_data: Vec::new()
3040                 });
3041                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3042                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3043                         short_channel_id: 13,
3044                         timestamp: 2,
3045                         flags: 0,
3046                         cltv_expiry_delta: 0,
3047                         htlc_minimum_msat: 0,
3048                         htlc_maximum_msat: OptionalField::Present(200_000),
3049                         fee_base_msat: 0,
3050                         fee_proportional_millionths: 0,
3051                         excess_data: Vec::new()
3052                 });
3053
3054                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3055                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3056                         short_channel_id: 6,
3057                         timestamp: 2,
3058                         flags: 0,
3059                         cltv_expiry_delta: 0,
3060                         htlc_minimum_msat: 0,
3061                         htlc_maximum_msat: OptionalField::Present(100_000),
3062                         fee_base_msat: 0,
3063                         fee_proportional_millionths: 0,
3064                         excess_data: Vec::new()
3065                 });
3066                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3067                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3068                         short_channel_id: 11,
3069                         timestamp: 2,
3070                         flags: 0,
3071                         cltv_expiry_delta: 0,
3072                         htlc_minimum_msat: 0,
3073                         htlc_maximum_msat: OptionalField::Present(100_000),
3074                         fee_base_msat: 0,
3075                         fee_proportional_millionths: 0,
3076                         excess_data: Vec::new()
3077                 });
3078
3079                 // Path via {node7, node2} is channels {12, 13, 5}.
3080                 // We already limited them to 200 sats (they are used twice for 100 sats).
3081                 // Nothing to do here.
3082
3083                 {
3084                         // Attempt to route more than available results in a failure.
3085                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3086                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3087                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3088                         } else { panic!(); }
3089                 }
3090
3091                 {
3092                         // Now, attempt to route 300 sats (exact amount we can route).
3093                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3094                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3095                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3096                         assert_eq!(route.paths.len(), 3);
3097
3098                         let mut total_amount_paid_msat = 0;
3099                         for path in &route.paths {
3100                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3101                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3102                         }
3103                         assert_eq!(total_amount_paid_msat, 300_000);
3104                 }
3105
3106         }
3107
3108         #[test]
3109         fn mpp_cheaper_route_test() {
3110                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3111                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3112
3113                 // This test checks that if we have two cheaper paths and one more expensive path,
3114                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3115                 // two cheaper paths will be taken.
3116                 // These paths have equal available liquidity.
3117
3118                 // We need a combination of 3 paths:
3119                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3120                 // Note that these paths overlap (channels 5, 12, 13).
3121                 // Each path will have 100 sats capacity, those channels which
3122                 // are used twice will have 200 sats capacity.
3123
3124                 // Disable other potential paths.
3125                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3126                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3127                         short_channel_id: 2,
3128                         timestamp: 2,
3129                         flags: 2,
3130                         cltv_expiry_delta: 0,
3131                         htlc_minimum_msat: 0,
3132                         htlc_maximum_msat: OptionalField::Present(100_000),
3133                         fee_base_msat: 0,
3134                         fee_proportional_millionths: 0,
3135                         excess_data: Vec::new()
3136                 });
3137                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3138                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3139                         short_channel_id: 7,
3140                         timestamp: 2,
3141                         flags: 2,
3142                         cltv_expiry_delta: 0,
3143                         htlc_minimum_msat: 0,
3144                         htlc_maximum_msat: OptionalField::Present(100_000),
3145                         fee_base_msat: 0,
3146                         fee_proportional_millionths: 0,
3147                         excess_data: Vec::new()
3148                 });
3149
3150                 // Path via {node0, node2} is channels {1, 3, 5}.
3151                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3152                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3153                         short_channel_id: 1,
3154                         timestamp: 2,
3155                         flags: 0,
3156                         cltv_expiry_delta: 0,
3157                         htlc_minimum_msat: 0,
3158                         htlc_maximum_msat: OptionalField::Present(100_000),
3159                         fee_base_msat: 0,
3160                         fee_proportional_millionths: 0,
3161                         excess_data: Vec::new()
3162                 });
3163                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3164                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3165                         short_channel_id: 3,
3166                         timestamp: 2,
3167                         flags: 0,
3168                         cltv_expiry_delta: 0,
3169                         htlc_minimum_msat: 0,
3170                         htlc_maximum_msat: OptionalField::Present(100_000),
3171                         fee_base_msat: 0,
3172                         fee_proportional_millionths: 0,
3173                         excess_data: Vec::new()
3174                 });
3175
3176                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3177                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3178                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3179                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3180                         short_channel_id: 5,
3181                         timestamp: 2,
3182                         flags: 0,
3183                         cltv_expiry_delta: 0,
3184                         htlc_minimum_msat: 0,
3185                         htlc_maximum_msat: OptionalField::Present(200_000),
3186                         fee_base_msat: 0,
3187                         fee_proportional_millionths: 0,
3188                         excess_data: Vec::new()
3189                 });
3190
3191                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3192                 // Add 100 sats to the capacities of {12, 13}, because these channels
3193                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3194                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3195                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3196                         short_channel_id: 12,
3197                         timestamp: 2,
3198                         flags: 0,
3199                         cltv_expiry_delta: 0,
3200                         htlc_minimum_msat: 0,
3201                         htlc_maximum_msat: OptionalField::Present(200_000),
3202                         fee_base_msat: 0,
3203                         fee_proportional_millionths: 0,
3204                         excess_data: Vec::new()
3205                 });
3206                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3207                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3208                         short_channel_id: 13,
3209                         timestamp: 2,
3210                         flags: 0,
3211                         cltv_expiry_delta: 0,
3212                         htlc_minimum_msat: 0,
3213                         htlc_maximum_msat: OptionalField::Present(200_000),
3214                         fee_base_msat: 0,
3215                         fee_proportional_millionths: 0,
3216                         excess_data: Vec::new()
3217                 });
3218
3219                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3220                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3221                         short_channel_id: 6,
3222                         timestamp: 2,
3223                         flags: 0,
3224                         cltv_expiry_delta: 0,
3225                         htlc_minimum_msat: 0,
3226                         htlc_maximum_msat: OptionalField::Present(100_000),
3227                         fee_base_msat: 1_000,
3228                         fee_proportional_millionths: 0,
3229                         excess_data: Vec::new()
3230                 });
3231                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3232                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3233                         short_channel_id: 11,
3234                         timestamp: 2,
3235                         flags: 0,
3236                         cltv_expiry_delta: 0,
3237                         htlc_minimum_msat: 0,
3238                         htlc_maximum_msat: OptionalField::Present(100_000),
3239                         fee_base_msat: 0,
3240                         fee_proportional_millionths: 0,
3241                         excess_data: Vec::new()
3242                 });
3243
3244                 // Path via {node7, node2} is channels {12, 13, 5}.
3245                 // We already limited them to 200 sats (they are used twice for 100 sats).
3246                 // Nothing to do here.
3247
3248                 {
3249                         // Now, attempt to route 180 sats.
3250                         // Our algorithm should provide us with these 2 paths.
3251                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3252                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3253                         assert_eq!(route.paths.len(), 2);
3254
3255                         let mut total_value_transferred_msat = 0;
3256                         let mut total_paid_msat = 0;
3257                         for path in &route.paths {
3258                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3259                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3260                                 for hop in path {
3261                                         total_paid_msat += hop.fee_msat;
3262                                 }
3263                         }
3264                         // If we paid fee, this would be higher.
3265                         assert_eq!(total_value_transferred_msat, 180_000);
3266                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3267                         assert_eq!(total_fees_paid, 0);
3268                 }
3269         }
3270
3271         #[test]
3272         fn fees_on_mpp_route_test() {
3273                 // This test makes sure that MPP algorithm properly takes into account
3274                 // fees charged on the channels, by making the fees impactful:
3275                 // if the fee is not properly accounted for, the behavior is different.
3276                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3277                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3278
3279                 // We need a route consisting of 2 paths:
3280                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3281                 // We will route 200 sats, Each path will have 100 sats capacity.
3282
3283                 // This test is not particularly stable: e.g.,
3284                 // there's a way to route via {node0, node2, node4}.
3285                 // It works while pathfinding is deterministic, but can be broken otherwise.
3286                 // It's fine to ignore this concern for now.
3287
3288                 // Disable other potential paths.
3289                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3290                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3291                         short_channel_id: 2,
3292                         timestamp: 2,
3293                         flags: 2,
3294                         cltv_expiry_delta: 0,
3295                         htlc_minimum_msat: 0,
3296                         htlc_maximum_msat: OptionalField::Present(100_000),
3297                         fee_base_msat: 0,
3298                         fee_proportional_millionths: 0,
3299                         excess_data: Vec::new()
3300                 });
3301
3302                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3303                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3304                         short_channel_id: 7,
3305                         timestamp: 2,
3306                         flags: 2,
3307                         cltv_expiry_delta: 0,
3308                         htlc_minimum_msat: 0,
3309                         htlc_maximum_msat: OptionalField::Present(100_000),
3310                         fee_base_msat: 0,
3311                         fee_proportional_millionths: 0,
3312                         excess_data: Vec::new()
3313                 });
3314
3315                 // Path via {node0, node2} is channels {1, 3, 5}.
3316                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3317                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3318                         short_channel_id: 1,
3319                         timestamp: 2,
3320                         flags: 0,
3321                         cltv_expiry_delta: 0,
3322                         htlc_minimum_msat: 0,
3323                         htlc_maximum_msat: OptionalField::Present(100_000),
3324                         fee_base_msat: 0,
3325                         fee_proportional_millionths: 0,
3326                         excess_data: Vec::new()
3327                 });
3328                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3329                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3330                         short_channel_id: 3,
3331                         timestamp: 2,
3332                         flags: 0,
3333                         cltv_expiry_delta: 0,
3334                         htlc_minimum_msat: 0,
3335                         htlc_maximum_msat: OptionalField::Present(100_000),
3336                         fee_base_msat: 0,
3337                         fee_proportional_millionths: 0,
3338                         excess_data: Vec::new()
3339                 });
3340
3341                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3342                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3343                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3344                         short_channel_id: 5,
3345                         timestamp: 2,
3346                         flags: 0,
3347                         cltv_expiry_delta: 0,
3348                         htlc_minimum_msat: 0,
3349                         htlc_maximum_msat: OptionalField::Present(100_000),
3350                         fee_base_msat: 0,
3351                         fee_proportional_millionths: 0,
3352                         excess_data: Vec::new()
3353                 });
3354
3355                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3356                 // All channels should be 100 sats capacity. But for the fee experiment,
3357                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3358                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3359                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3360                 // so no matter how large are other channels,
3361                 // the whole path will be limited by 100 sats with just these 2 conditions:
3362                 // - channel 12 capacity is 250 sats
3363                 // - fee for channel 6 is 150 sats
3364                 // Let's test this by enforcing these 2 conditions and removing other limits.
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: 12,
3368                         timestamp: 2,
3369                         flags: 0,
3370                         cltv_expiry_delta: 0,
3371                         htlc_minimum_msat: 0,
3372                         htlc_maximum_msat: OptionalField::Present(250_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[7], UnsignedChannelUpdate {
3378                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3379                         short_channel_id: 13,
3380                         timestamp: 2,
3381                         flags: 0,
3382                         cltv_expiry_delta: 0,
3383                         htlc_minimum_msat: 0,
3384                         htlc_maximum_msat: OptionalField::Absent,
3385                         fee_base_msat: 0,
3386                         fee_proportional_millionths: 0,
3387                         excess_data: Vec::new()
3388                 });
3389
3390                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3391                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3392                         short_channel_id: 6,
3393                         timestamp: 2,
3394                         flags: 0,
3395                         cltv_expiry_delta: 0,
3396                         htlc_minimum_msat: 0,
3397                         htlc_maximum_msat: OptionalField::Absent,
3398                         fee_base_msat: 150_000,
3399                         fee_proportional_millionths: 0,
3400                         excess_data: Vec::new()
3401                 });
3402                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3403                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3404                         short_channel_id: 11,
3405                         timestamp: 2,
3406                         flags: 0,
3407                         cltv_expiry_delta: 0,
3408                         htlc_minimum_msat: 0,
3409                         htlc_maximum_msat: OptionalField::Absent,
3410                         fee_base_msat: 0,
3411                         fee_proportional_millionths: 0,
3412                         excess_data: Vec::new()
3413                 });
3414
3415                 {
3416                         // Attempt to route more than available results in a failure.
3417                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3418                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3419                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3420                         } else { panic!(); }
3421                 }
3422
3423                 {
3424                         // Now, attempt to route 200 sats (exact amount we can route).
3425                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3426                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3427                         assert_eq!(route.paths.len(), 2);
3428
3429                         let mut total_amount_paid_msat = 0;
3430                         for path in &route.paths {
3431                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3432                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3433                         }
3434                         assert_eq!(total_amount_paid_msat, 200_000);
3435                 }
3436
3437         }
3438
3439         #[test]
3440         fn drop_lowest_channel_mpp_route_test() {
3441                 // This test checks that low-capacity channel is dropped when after
3442                 // path finding we realize that we found more capacity than we need.
3443                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3444                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3445
3446                 // We need a route consisting of 3 paths:
3447                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3448
3449                 // The first and the second paths should be sufficient, but the third should be
3450                 // cheaper, so that we select it but drop later.
3451
3452                 // First, we set limits on these (previously unlimited) channels.
3453                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3454
3455                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3456                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3457                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3458                         short_channel_id: 1,
3459                         timestamp: 2,
3460                         flags: 0,
3461                         cltv_expiry_delta: 0,
3462                         htlc_minimum_msat: 0,
3463                         htlc_maximum_msat: OptionalField::Present(100_000),
3464                         fee_base_msat: 0,
3465                         fee_proportional_millionths: 0,
3466                         excess_data: Vec::new()
3467                 });
3468                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3469                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3470                         short_channel_id: 3,
3471                         timestamp: 2,
3472                         flags: 0,
3473                         cltv_expiry_delta: 0,
3474                         htlc_minimum_msat: 0,
3475                         htlc_maximum_msat: OptionalField::Present(50_000),
3476                         fee_base_msat: 100,
3477                         fee_proportional_millionths: 0,
3478                         excess_data: Vec::new()
3479                 });
3480
3481                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3482                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3483                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3484                         short_channel_id: 12,
3485                         timestamp: 2,
3486                         flags: 0,
3487                         cltv_expiry_delta: 0,
3488                         htlc_minimum_msat: 0,
3489                         htlc_maximum_msat: OptionalField::Present(60_000),
3490                         fee_base_msat: 100,
3491                         fee_proportional_millionths: 0,
3492                         excess_data: Vec::new()
3493                 });
3494                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3495                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3496                         short_channel_id: 13,
3497                         timestamp: 2,
3498                         flags: 0,
3499                         cltv_expiry_delta: 0,
3500                         htlc_minimum_msat: 0,
3501                         htlc_maximum_msat: OptionalField::Present(60_000),
3502                         fee_base_msat: 0,
3503                         fee_proportional_millionths: 0,
3504                         excess_data: Vec::new()
3505                 });
3506
3507                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3508                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3509                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3510                         short_channel_id: 2,
3511                         timestamp: 2,
3512                         flags: 0,
3513                         cltv_expiry_delta: 0,
3514                         htlc_minimum_msat: 0,
3515                         htlc_maximum_msat: OptionalField::Present(20_000),
3516                         fee_base_msat: 0,
3517                         fee_proportional_millionths: 0,
3518                         excess_data: Vec::new()
3519                 });
3520                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3521                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3522                         short_channel_id: 4,
3523                         timestamp: 2,
3524                         flags: 0,
3525                         cltv_expiry_delta: 0,
3526                         htlc_minimum_msat: 0,
3527                         htlc_maximum_msat: OptionalField::Present(20_000),
3528                         fee_base_msat: 0,
3529                         fee_proportional_millionths: 0,
3530                         excess_data: Vec::new()
3531                 });
3532
3533                 {
3534                         // Attempt to route more than available results in a failure.
3535                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3536                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3537                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3538                         } else { panic!(); }
3539                 }
3540
3541                 {
3542                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3543                         // Our algorithm should provide us with these 3 paths.
3544                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3545                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3546                         assert_eq!(route.paths.len(), 3);
3547                         let mut total_amount_paid_msat = 0;
3548                         for path in &route.paths {
3549                                 assert_eq!(path.len(), 2);
3550                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3551                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3552                         }
3553                         assert_eq!(total_amount_paid_msat, 125_000);
3554                 }
3555
3556                 {
3557                         // Attempt to route without the last small cheap channel
3558                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3559                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3560                         assert_eq!(route.paths.len(), 2);
3561                         let mut total_amount_paid_msat = 0;
3562                         for path in &route.paths {
3563                                 assert_eq!(path.len(), 2);
3564                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3565                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3566                         }
3567                         assert_eq!(total_amount_paid_msat, 90_000);
3568                 }
3569         }
3570
3571         #[test]
3572         fn min_criteria_consistency() {
3573                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3574                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3575                 // was updated with a different criterion from the heap sorting, resulting in loops in
3576                 // calculated paths. We test for that specific case here.
3577
3578                 // We construct a network that looks like this:
3579                 //
3580                 //            node2 -1(3)2- node3
3581                 //              2          2
3582                 //               (2)     (4)
3583                 //                  1   1
3584                 //    node1 -1(5)2- node4 -1(1)2- node6
3585                 //    2
3586                 //   (6)
3587                 //        1
3588                 // our_node
3589                 //
3590                 // We create a loop on the side of our real path - our destination is node 6, with a
3591                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3592                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3593                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3594                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3595                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3596                 // "previous hop" being set to node 3, creating a loop in the path.
3597                 let secp_ctx = Secp256k1::new();
3598                 let logger = Arc::new(test_utils::TestLogger::new());
3599                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3600                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3601
3602                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3603                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3604                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3605                         short_channel_id: 6,
3606                         timestamp: 1,
3607                         flags: 0,
3608                         cltv_expiry_delta: (6 << 8) | 0,
3609                         htlc_minimum_msat: 0,
3610                         htlc_maximum_msat: OptionalField::Absent,
3611                         fee_base_msat: 0,
3612                         fee_proportional_millionths: 0,
3613                         excess_data: Vec::new()
3614                 });
3615                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3616
3617                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3618                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3619                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3620                         short_channel_id: 5,
3621                         timestamp: 1,
3622                         flags: 0,
3623                         cltv_expiry_delta: (5 << 8) | 0,
3624                         htlc_minimum_msat: 0,
3625                         htlc_maximum_msat: OptionalField::Absent,
3626                         fee_base_msat: 100,
3627                         fee_proportional_millionths: 0,
3628                         excess_data: Vec::new()
3629                 });
3630                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3631
3632                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3633                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3634                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3635                         short_channel_id: 4,
3636                         timestamp: 1,
3637                         flags: 0,
3638                         cltv_expiry_delta: (4 << 8) | 0,
3639                         htlc_minimum_msat: 0,
3640                         htlc_maximum_msat: OptionalField::Absent,
3641                         fee_base_msat: 0,
3642                         fee_proportional_millionths: 0,
3643                         excess_data: Vec::new()
3644                 });
3645                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3646
3647                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3648                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3649                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3650                         short_channel_id: 3,
3651                         timestamp: 1,
3652                         flags: 0,
3653                         cltv_expiry_delta: (3 << 8) | 0,
3654                         htlc_minimum_msat: 0,
3655                         htlc_maximum_msat: OptionalField::Absent,
3656                         fee_base_msat: 0,
3657                         fee_proportional_millionths: 0,
3658                         excess_data: Vec::new()
3659                 });
3660                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
3661
3662                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
3663                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3664                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3665                         short_channel_id: 2,
3666                         timestamp: 1,
3667                         flags: 0,
3668                         cltv_expiry_delta: (2 << 8) | 0,
3669                         htlc_minimum_msat: 0,
3670                         htlc_maximum_msat: OptionalField::Absent,
3671                         fee_base_msat: 0,
3672                         fee_proportional_millionths: 0,
3673                         excess_data: Vec::new()
3674                 });
3675
3676                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
3677                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3678                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3679                         short_channel_id: 1,
3680                         timestamp: 1,
3681                         flags: 0,
3682                         cltv_expiry_delta: (1 << 8) | 0,
3683                         htlc_minimum_msat: 100,
3684                         htlc_maximum_msat: OptionalField::Absent,
3685                         fee_base_msat: 0,
3686                         fee_proportional_millionths: 0,
3687                         excess_data: Vec::new()
3688                 });
3689                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
3690
3691                 {
3692                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
3693                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
3694                         assert_eq!(route.paths.len(), 1);
3695                         assert_eq!(route.paths[0].len(), 3);
3696
3697                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
3698                         assert_eq!(route.paths[0][0].short_channel_id, 6);
3699                         assert_eq!(route.paths[0][0].fee_msat, 100);
3700                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
3701                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
3702                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
3703
3704                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
3705                         assert_eq!(route.paths[0][1].short_channel_id, 5);
3706                         assert_eq!(route.paths[0][1].fee_msat, 0);
3707                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
3708                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
3709                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
3710
3711                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
3712                         assert_eq!(route.paths[0][2].short_channel_id, 1);
3713                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
3714                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
3715                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
3716                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
3717                 }
3718         }
3719
3720
3721         #[test]
3722         fn exact_fee_liquidity_limit() {
3723                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
3724                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
3725                 // we calculated fees on a higher value, resulting in us ignoring such paths.
3726                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3727                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
3728
3729                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
3730                 // send.
3731                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3732                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3733                         short_channel_id: 2,
3734                         timestamp: 2,
3735                         flags: 0,
3736                         cltv_expiry_delta: 0,
3737                         htlc_minimum_msat: 0,
3738                         htlc_maximum_msat: OptionalField::Present(85_000),
3739                         fee_base_msat: 0,
3740                         fee_proportional_millionths: 0,
3741                         excess_data: Vec::new()
3742                 });
3743
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: (4 << 8) | 1,
3750                         htlc_minimum_msat: 0,
3751                         htlc_maximum_msat: OptionalField::Present(270_000),
3752                         fee_base_msat: 0,
3753                         fee_proportional_millionths: 1000000,
3754                         excess_data: Vec::new()
3755                 });
3756
3757                 {
3758                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
3759                         // 200% fee charged channel 13 in the 1-to-2 direction.
3760                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3761                         assert_eq!(route.paths.len(), 1);
3762                         assert_eq!(route.paths[0].len(), 2);
3763
3764                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3765                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3766                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3767                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3768                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3769                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3770
3771                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3772                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3773                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3774                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3775                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
3776                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3777                 }
3778         }
3779
3780         #[test]
3781         fn htlc_max_reduction_below_min() {
3782                 // Test that if, while walking the graph, we reduce the value being sent to meet an
3783                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
3784                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
3785                 // resulting in us thinking there is no possible path, even if other paths exist.
3786                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3787                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3788
3789                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
3790                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
3791                 // then try to send 90_000.
3792                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3793                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3794                         short_channel_id: 2,
3795                         timestamp: 2,
3796                         flags: 0,
3797                         cltv_expiry_delta: 0,
3798                         htlc_minimum_msat: 0,
3799                         htlc_maximum_msat: OptionalField::Present(80_000),
3800                         fee_base_msat: 0,
3801                         fee_proportional_millionths: 0,
3802                         excess_data: Vec::new()
3803                 });
3804                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3805                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3806                         short_channel_id: 4,
3807                         timestamp: 2,
3808                         flags: 0,
3809                         cltv_expiry_delta: (4 << 8) | 1,
3810                         htlc_minimum_msat: 90_000,
3811                         htlc_maximum_msat: OptionalField::Absent,
3812                         fee_base_msat: 0,
3813                         fee_proportional_millionths: 0,
3814                         excess_data: Vec::new()
3815                 });
3816
3817                 {
3818                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
3819                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
3820                         // expensive) channels 12-13 path.
3821                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3822                         assert_eq!(route.paths.len(), 1);
3823                         assert_eq!(route.paths[0].len(), 2);
3824
3825                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3826                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3827                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3828                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3829                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3830                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3831
3832                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3833                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3834                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3835                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3836                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
3837                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3838                 }
3839         }
3840
3841         pub(super) fn random_init_seed() -> u64 {
3842                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
3843                 use core::hash::{BuildHasher, Hasher};
3844                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
3845                 println!("Using seed of {}", seed);
3846                 seed
3847         }
3848         use util::ser::Readable;
3849
3850         #[test]
3851         fn generate_routes() {
3852                 let mut d = match super::test_utils::get_route_file() {
3853                         Ok(f) => f,
3854                         Err(e) => {
3855                                 eprintln!("{}", e);
3856                                 return;
3857                         },
3858                 };
3859                 let graph = NetworkGraph::read(&mut d).unwrap();
3860
3861                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3862                 let mut seed = random_init_seed() as usize;
3863                 'load_endpoints: for _ in 0..10 {
3864                         loop {
3865                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3866                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3867                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3868                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3869                                 let amt = seed as u64 % 200_000_000;
3870                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3871                                         continue 'load_endpoints;
3872                                 }
3873                         }
3874                 }
3875         }
3876
3877         #[test]
3878         fn generate_routes_mpp() {
3879                 let mut d = match super::test_utils::get_route_file() {
3880                         Ok(f) => f,
3881                         Err(e) => {
3882                                 eprintln!("{}", e);
3883                                 return;
3884                         },
3885                 };
3886                 let graph = NetworkGraph::read(&mut d).unwrap();
3887
3888                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3889                 let mut seed = random_init_seed() as usize;
3890                 'load_endpoints: for _ in 0..10 {
3891                         loop {
3892                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3893                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3894                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3895                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3896                                 let amt = seed as u64 % 200_000_000;
3897                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3898                                         continue 'load_endpoints;
3899                                 }
3900                         }
3901                 }
3902         }
3903 }
3904
3905 #[cfg(test)]
3906 pub(crate) mod test_utils {
3907         use std::fs::File;
3908         /// Tries to open a network graph file, or panics with a URL to fetch it.
3909         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
3910                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
3911                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
3912                         .or_else(|_| { // Fall back to guessing based on the binary location
3913                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
3914                                 let mut path = std::env::current_exe().unwrap();
3915                                 path.pop(); // lightning-...
3916                                 path.pop(); // deps
3917                                 path.pop(); // debug
3918                                 path.pop(); // target
3919                                 path.push("lightning");
3920                                 path.push("net_graph-2021-05-31.bin");
3921                                 eprintln!("{}", path.to_str().unwrap());
3922                                 File::open(path)
3923                         })
3924                 .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");
3925                 #[cfg(require_route_graph_test)]
3926                 return Ok(res.unwrap());
3927                 #[cfg(not(require_route_graph_test))]
3928                 return res;
3929         }
3930 }
3931
3932 #[cfg(all(test, feature = "unstable"))]
3933 mod benches {
3934         use super::*;
3935         use util::logger::{Logger, Record};
3936
3937         use test::Bencher;
3938
3939         struct DummyLogger {}
3940         impl Logger for DummyLogger {
3941                 fn log(&self, _record: &Record) {}
3942         }
3943
3944         #[bench]
3945         fn generate_routes(bench: &mut Bencher) {
3946                 let mut d = test_utils::get_route_file().unwrap();
3947                 let graph = NetworkGraph::read(&mut d).unwrap();
3948
3949                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3950                 let mut path_endpoints = Vec::new();
3951                 let mut seed: usize = 0xdeadbeef;
3952                 'load_endpoints: for _ in 0..100 {
3953                         loop {
3954                                 seed *= 0xdeadbeef;
3955                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3956                                 seed *= 0xdeadbeef;
3957                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3958                                 let amt = seed as u64 % 1_000_000;
3959                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3960                                         path_endpoints.push((src, dst, amt));
3961                                         continue 'load_endpoints;
3962                                 }
3963                         }
3964                 }
3965
3966                 // ...then benchmark finding paths between the nodes we learned.
3967                 let mut idx = 0;
3968                 bench.iter(|| {
3969                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3970                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3971                         idx += 1;
3972                 });
3973         }
3974
3975         #[bench]
3976         fn generate_mpp_routes(bench: &mut Bencher) {
3977                 let mut d = test_utils::get_route_file().unwrap();
3978                 let graph = NetworkGraph::read(&mut d).unwrap();
3979
3980                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3981                 let mut path_endpoints = Vec::new();
3982                 let mut seed: usize = 0xdeadbeef;
3983                 'load_endpoints: for _ in 0..100 {
3984                         loop {
3985                                 seed *= 0xdeadbeef;
3986                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3987                                 seed *= 0xdeadbeef;
3988                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3989                                 let amt = seed as u64 % 1_000_000;
3990                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3991                                         path_endpoints.push((src, dst, amt));
3992                                         continue 'load_endpoints;
3993                                 }
3994                         }
3995                 }
3996
3997                 // ...then benchmark finding paths between the nodes we learned.
3998                 let mut idx = 0;
3999                 bench.iter(|| {
4000                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4001                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
4002                         idx += 1;
4003                 });
4004         }
4005 }