_ Git - rust-lightning/blob - lightning/src/routing/router.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! The top-level routing/network map tracking logic lives here.
  11 //!
  12 //! You probably want to create a NetGraphMsgHandler and use that as your RoutingMessageHandler and then
  13 //! interrogate it to get routes for your own payments.
  14
  15 use bitcoin::secp256k1::key::PublicKey;
  16
  17 use ln::channelmanager::ChannelDetails;
  18 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
  19 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
  20 use routing::network_graph::{NetworkGraph, RoutingFees};
  21 use util::ser::{Writeable, Readable};
  22 use util::logger::Logger;
  23
  24 use std::cmp;
  25 use std::collections::{HashMap, BinaryHeap};
  26 use std::ops::Deref;
  27
  28 /// A hop in a route
  29 #[derive(Clone, PartialEq)]
  30 pub struct RouteHop {
  31         /// The node_id of the node at this hop.
  32         pub pubkey: PublicKey,
  33         /// The node_announcement features of the node at this hop. For the last hop, these may be
  34         /// amended to match the features present in the invoice this node generated.
  35         pub node_features: NodeFeatures,
  36         /// The channel that should be used from the previous hop to reach this node.
  37         pub short_channel_id: u64,
  38         /// The channel_announcement features of the channel that should be used from the previous hop
  39         /// to reach this node.
  40         pub channel_features: ChannelFeatures,
  41         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  42         /// For the last hop, this should be the full value of the payment (might be more than
  43         /// requested if we had to match htlc_minimum_msat).
  44         pub fee_msat: u64,
  45         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  46         /// expected at the destination, in excess of the current block height.
  47         pub cltv_expiry_delta: u32,
  48 }
  49
  50 /// (C-not exported)
  51 impl Writeable for Vec<RouteHop> {
  52         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
  53                 (self.len() as u8).write(writer)?;
  54                 for hop in self.iter() {
  55                         hop.pubkey.write(writer)?;
  56                         hop.node_features.write(writer)?;
  57                         hop.short_channel_id.write(writer)?;
  58                         hop.channel_features.write(writer)?;
  59                         hop.fee_msat.write(writer)?;
  60                         hop.cltv_expiry_delta.write(writer)?;
  61                 }
  62                 Ok(())
  63         }
  64 }
  65
  66 /// (C-not exported)
  67 impl Readable for Vec<RouteHop> {
  68         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Vec<RouteHop>, DecodeError> {
  69                 let hops_count: u8 = Readable::read(reader)?;
  70                 let mut hops = Vec::with_capacity(hops_count as usize);
  71                 for _ in 0..hops_count {
  72                         hops.push(RouteHop {
  73                                 pubkey: Readable::read(reader)?,
  74                                 node_features: Readable::read(reader)?,
  75                                 short_channel_id: Readable::read(reader)?,
  76                                 channel_features: Readable::read(reader)?,
  77                                 fee_msat: Readable::read(reader)?,
  78                                 cltv_expiry_delta: Readable::read(reader)?,
  79                         });
  80                 }
  81                 Ok(hops)
  82         }
  83 }
  84
  85 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  86 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  87 #[derive(Clone, PartialEq)]
  88 pub struct Route {
  89         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  90         /// last RouteHop in each path must be the same.
  91         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  92         /// destination. Thus, this must always be at least length one. While the maximum length of any
  93         /// given path is variable, keeping the length of any path to less than 20 should currently
  94         /// ensure it is viable.
  95         pub paths: Vec<Vec<RouteHop>>,
  96 }
  97
  98 impl Writeable for Route {
  99         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 100                 (self.paths.len() as u64).write(writer)?;
 101                 for hops in self.paths.iter() {
 102                         hops.write(writer)?;
 103                 }
 104                 Ok(())
 105         }
 106 }
 107
 108 impl Readable for Route {
 109         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 110                 let path_count: u64 = Readable::read(reader)?;
 111                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 112                 for _ in 0..path_count {
 113                         paths.push(Readable::read(reader)?);
 114                 }
 115                 Ok(Route { paths })
 116         }
 117 }
 118
 119 /// A channel descriptor which provides a last-hop route to get_route
 120 #[derive(Eq, PartialEq, Debug, Clone)]
 121 pub struct RouteHintHop {
 122         /// The node_id of the non-target end of the route
 123         pub src_node_id: PublicKey,
 124         /// The short_channel_id of this channel
 125         pub short_channel_id: u64,
 126         /// The fees which must be paid to use this channel
 127         pub fees: RoutingFees,
 128         /// The difference in CLTV values between this node and the next node.
 129         pub cltv_expiry_delta: u16,
 130         /// The minimum value, in msat, which must be relayed to the next hop.
 131         pub htlc_minimum_msat: Option<u64>,
 132         /// The maximum value in msat available for routing with a single HTLC.
 133         pub htlc_maximum_msat: Option<u64>,
 134 }
 135
 136 #[derive(Eq, PartialEq)]
 137 struct RouteGraphNode {
 138         pubkey: PublicKey,
 139         lowest_fee_to_peer_through_node: u64,
 140         lowest_fee_to_node: u64,
 141         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 142         // This value is upper-bounded by us by:
 143         // - how much is needed for a path being constructed
 144         // - how much value can channels following this node (up to the destination) can contribute,
 145         //   considering their capacity and fees
 146         value_contribution_msat: u64,
 147         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 148         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 149         path_htlc_minimum_msat: u64,
 150 }
 151
 152 impl cmp::Ord for RouteGraphNode {
 153         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 154                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 155                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 156                 other_score.cmp(&self_score).then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 157         }
 158 }
 159
 160 impl cmp::PartialOrd for RouteGraphNode {
 161         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 162                 Some(self.cmp(other))
 163         }
 164 }
 165
 166 struct DummyDirectionalChannelInfo {
 167         cltv_expiry_delta: u32,
 168         htlc_minimum_msat: u64,
 169         htlc_maximum_msat: Option<u64>,
 170         fees: RoutingFees,
 171 }
 172
 173 /// It's useful to keep track of the hops associated with the fees required to use them,
 174 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 175 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 176 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 177 #[derive(Clone)]
 178 struct PathBuildingHop<'a> {
 179         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 180         // Note that node_features is calculated separately after our initial graph walk.
 181         pubkey: PublicKey,
 182         short_channel_id: u64,
 183         channel_features: &'a ChannelFeatures,
 184         fee_msat: u64,
 185         cltv_expiry_delta: u32,
 186
 187         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 188         src_lowest_inbound_fees: RoutingFees,
 189         /// Fees of the channel used in this hop.
 190         channel_fees: RoutingFees,
 191         /// All the fees paid *after* this channel on the way to the destination
 192         next_hops_fee_msat: u64,
 193         /// Fee paid for the use of the current channel (see channel_fees).
 194         /// The value will be actually deducted from the counterparty balance on the previous link.
 195         hop_use_fee_msat: u64,
 196         /// Used to compare channels when choosing the for routing.
 197         /// Includes paying for the use of a hop and the following hops, as well as
 198         /// an estimated cost of reaching this hop.
 199         /// Might get stale when fees are recomputed. Primarily for internal use.
 200         total_fee_msat: u64,
 201         /// This is useful for update_value_and_recompute_fees to make sure
 202         /// we don't fall below the minimum. Should not be updated manually and
 203         /// generally should not be accessed.
 204         htlc_minimum_msat: u64,
 205         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 206         /// walk and may be invalid thereafter.
 207         path_htlc_minimum_msat: u64,
 208         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 209         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 210         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 211         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 212         /// avoid processing them again.
 213         was_processed: bool,
 214         #[cfg(any(test, feature = "fuzztarget"))]
 215         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 216         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 217         // value_contribution_msat, which requires tracking it here. See comments below where it is
 218         // used for more info.
 219         value_contribution_msat: u64,
 220 }
 221
 222 // Instantiated with a list of hops with correct data in them collected during path finding,
 223 // an instance of this struct should be further modified only via given methods.
 224 #[derive(Clone)]
 225 struct PaymentPath<'a> {
 226         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 227 }
 228
 229 impl<'a> PaymentPath<'a> {
 230         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 231         fn get_value_msat(&self) -> u64 {
 232                 self.hops.last().unwrap().0.fee_msat
 233         }
 234
 235         fn get_total_fee_paid_msat(&self) -> u64 {
 236                 if self.hops.len() < 1 {
 237                         return 0;
 238                 }
 239                 let mut result = 0;
 240                 // Can't use next_hops_fee_msat because it gets outdated.
 241                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 242                         if i != self.hops.len() - 1 {
 243                                 result += hop.fee_msat;
 244                         }
 245                 }
 246                 return result;
 247         }
 248
 249         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 250         // to change fees may result in an inconsistency.
 251         //
 252         // Sometimes we call this function right after constructing a path which is inconsistent in
 253         // that it the value being transferred has decreased while we were doing path finding, leading
 254         // to the fees being paid not lining up with the actual limits.
 255         //
 256         // Note that this function is not aware of the available_liquidity limit, and thus does not
 257         // support increasing the value being transferred.
 258         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 259                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 260
 261                 let mut total_fee_paid_msat = 0 as u64;
 262                 for i in (0..self.hops.len()).rev() {
 263                         let last_hop = i == self.hops.len() - 1;
 264
 265                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 266                         // will consist of the fees for the use of the next hop, and extra fees to match
 267                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 268                         let mut cur_hop_fees_msat = 0;
 269                         if !last_hop {
 270                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 271                         }
 272
 273                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 274                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 275                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 276                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 277                         // set it too high just to maliciously take more fees by exploiting this
 278                         // match htlc_minimum_msat logic.
 279                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 280                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 281                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 282                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 283                                 //
 284                                 // This might make us end up with a broken route, although this should be super-rare
 285                                 // in practice, both because of how healthy channels look like, and how we pick
 286                                 // channels in add_entry.
 287                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 288                                 // all payments*.
 289                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 290                                 total_fee_paid_msat += extra_fees_msat;
 291                                 cur_hop_fees_msat += extra_fees_msat;
 292                         }
 293
 294                         if last_hop {
 295                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 296                                 // it still could overpay for the htlc_minimum_msat.
 297                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 298                         } else {
 299                                 // Propagate updated fees for the use of the channels to one hop back, where they
 300                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 301                                 cur_hop.fee_msat = cur_hop_fees_msat;
 302                         }
 303
 304                         // Fee for the use of the current hop which will be deducted on the previous hop.
 305                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 306                         // this channel is free for us.
 307                         if i != 0 {
 308                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 309                                         cur_hop.hop_use_fee_msat = new_fee;
 310                                         total_fee_paid_msat += new_fee;
 311                                 } else {
 312                                         // It should not be possible because this function is called only to reduce the
 313                                         // value. In that case, compute_fee was already called with the same fees for
 314                                         // larger amount and there was no overflow.
 315                                         unreachable!();
 316                                 }
 317                         }
 318                 }
 319         }
 320 }
 321
 322 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 323         let proportional_fee_millions =
 324                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 325         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 326                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 327
 328                 Some(new_fee)
 329         } else {
 330                 // This function may be (indirectly) called without any verification,
 331                 // with channel_fees provided by a caller. We should handle it gracefully.
 332                 None
 333         }
 334 }
 335
 336 /// Gets a route from us (payer) to the given target node (payee).
 337 ///
 338 /// If the payee provided features in their invoice, they should be provided via payee_features.
 339 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 340 ///
 341 /// Extra routing hops between known nodes and the target will be used if they are included in
 342 /// last_hops.
 343 ///
 344 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 345 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 346 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 347 /// in first_hops will be used.
 348 ///
 349 /// Panics if first_hops contains channels without short_channel_ids
 350 /// (ChannelManager::list_usable_channels will never include such channels).
 351 ///
 352 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 353 /// equal), however the enabled/disabled bit on such channels as well as the
 354 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 355 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 356         last_hops: &[&RouteHintHop], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 357         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 358         // uptime/success in using a node in the past.
 359         if *payee == *our_node_id {
 360                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 361         }
 362
 363         if final_value_msat > MAX_VALUE_MSAT {
 364                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 365         }
 366
 367         if final_value_msat == 0 {
 368                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 369         }
 370
 371         for last_hop in last_hops {
 372                 if last_hop.src_node_id == *payee {
 373                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 374                 }
 375         }
 376
 377         // The general routing idea is the following:
 378         // 1. Fill first/last hops communicated by the caller.
 379         // 2. Attempt to construct a path from payer to payee for transferring
 380         //    any ~sufficient (described later) value.
 381         //    If succeed, remember which channels were used and how much liquidity they have available,
 382         //    so that future paths don't rely on the same liquidity.
 383         // 3. Prooceed to the next step if:
 384         //    - we hit the recommended target value;
 385         //    - OR if we could not construct a new path. Any next attempt will fail too.
 386         //    Otherwise, repeat step 2.
 387         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 388         //    (not recommended value). If yes, proceed. If not, fail routing.
 389         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 390         // 6. Of all the found paths, select only those with the lowest total fee.
 391         // 7. The last path in every selected route is likely to be more than we need.
 392         //    Reduce its value-to-transfer and recompute fees.
 393         // 8. Choose the best route by the lowest total fee.
 394
 395         // As for the actual search algorithm,
 396         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 397         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 398         //
 399         // We are not a faithful Dijkstra's implementation because we can change values which impact
 400         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 401         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 402         // the value we are currently attempting to send over a path, we simply reduce the value being
 403         // sent along the path for any hops after that channel. This may imply that later fees (which
 404         // we've already tabulated) are lower because a smaller value is passing through the channels
 405         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 406         // channels which were selected earlier (and which may still be used for other paths without a
 407         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 408         // de-preferenced.
 409         //
 410         // One potentially problematic case for this algorithm would be if there are many
 411         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 412         // graph walking), we may never find a path which is not liquidity-limited and has lower
 413         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 414         // Because we only consider paths with at least 5% of the total value being sent, the damage
 415         // from such a case should be limited, however this could be further reduced in the future by
 416         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 417         // limits for the purposes of fee calculation.
 418         //
 419         // Alternatively, we could store more detailed path information in the heap (targets, below)
 420         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 421         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 422         // and practically (as we would need to store dynamically-allocated path information in heap
 423         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 424         // results of such an algorithm would likely be biased towards lower-value paths.
 425         //
 426         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 427         // outside of our current search value, running a path search more times to gather candidate
 428         // paths at different values. While this may be acceptable, further path searches may increase
 429         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 430         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 431         // the same time, remaining generic across different payment values.
 432         //
 433         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 434         // to use as the A* heuristic beyond just the cost to get one node further than the current
 435         // one.
 436
 437         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 438                 cltv_expiry_delta: 0,
 439                 htlc_minimum_msat: 0,
 440                 htlc_maximum_msat: None,
 441                 fees: RoutingFees {
 442                         base_msat: 0,
 443                         proportional_millionths: 0,
 444                 }
 445         };
 446
 447         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 448         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 449         // work reliably.
 450         let allow_mpp = if let Some(features) = &payee_features {
 451                 features.supports_basic_mpp()
 452         } else if let Some(node) = network.get_nodes().get(&payee) {
 453                 if let Some(node_info) = node.announcement_info.as_ref() {
 454                         node_info.features.supports_basic_mpp()
 455                 } else { false }
 456         } else { false };
 457
 458         // Step (1).
 459         // Prepare the data we'll use for payee-to-payer search by
 460         // inserting first hops suggested by the caller as targets.
 461         // Our search will then attempt to reach them while traversing from the payee node.
 462         let mut first_hop_targets: HashMap<_, (_, ChannelFeatures, _, NodeFeatures)> =
 463                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 464         if let Some(hops) = first_hops {
 465                 for chan in hops {
 466                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 467                         if chan.remote_network_id == *our_node_id {
 468                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 469                         }
 470                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.to_context(), chan.outbound_capacity_msat, chan.counterparty_features.to_context()));
 471                 }
 472                 if first_hop_targets.is_empty() {
 473                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 474                 }
 475         }
 476
 477         let empty_channel_features = ChannelFeatures::empty();
 478
 479         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 480         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 481         // adding duplicate entries when we find a better path to a given node.
 482         let mut targets = BinaryHeap::new();
 483
 484         // Map from node_id to information about the best current path to that node, including feerate
 485         // information.
 486         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 487
 488         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 489         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 490         // htlc_minimum with extra fees while still finding a cheaper path.
 491         let mut hit_minimum_limit;
 492
 493         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 494         // We start with a path_value of the exact amount we want, and if that generates a route we may
 495         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 496         // amount we want in total across paths, selecting the best subset at the end.
 497         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 498         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 499         let mut path_value_msat = final_value_msat;
 500
 501         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 502         // This map allows paths to be aware of the channel use by other paths in the same call.
 503         // This would help to make a better path finding decisions and not "overbook" channels.
 504         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 505         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network.get_nodes().len());
 506
 507         // Keeping track of how much value we already collected across other paths. Helps to decide:
 508         // - how much a new path should be transferring (upper bound);
 509         // - whether a channel should be disregarded because
 510         //   it's available liquidity is too small comparing to how much more we need to collect;
 511         // - when we want to stop looking for new paths.
 512         let mut already_collected_value_msat = 0;
 513
 514         macro_rules! add_entry {
 515                 // Adds entry which goes from $src_node_id to $dest_node_id
 516                 // over the channel with id $chan_id with fees described in
 517                 // $directional_info.
 518                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 519                 // since that value has to be transferred over this channel.
 520                 ( $chan_id: expr, $src_node_id: expr, $dest_node_id: expr, $directional_info: expr, $capacity_sats: expr, $chan_features: expr, $next_hops_fee_msat: expr,
 521                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 522                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 523                         // practice these cases should be caught earlier:
 524                         // - for regular channels at channel announcement (TODO)
 525                         // - for first and last hops early in get_route
 526                         if $src_node_id != $dest_node_id.clone() {
 527                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 528                                         let mut initial_liquidity_available_msat = None;
 529                                         if let Some(capacity_sats) = $capacity_sats {
 530                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 531                                         }
 532
 533                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 534                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 535                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 536                                                 } else {
 537                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 538                                                 }
 539                                         }
 540
 541                                         match initial_liquidity_available_msat {
 542                                                 Some(available_msat) => available_msat,
 543                                                 // We assume channels with unknown balance have
 544                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 545                                                 None => 250_000 * 1000
 546                                         }
 547                                 });
 548
 549                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 550                                 // It may be misleading because we might later choose to reduce the value transferred
 551                                 // over these channels, and the channel which was insufficient might become sufficient.
 552                                 // Worst case: we drop a good channel here because it can't cover the high following
 553                                 // fees caused by one expensive channel, but then this channel could have been used
 554                                 // if the amount being transferred over this path is lower.
 555                                 // We do this for now, but this is a subject for removal.
 556                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 557
 558                                         // Routing Fragmentation Mitigation heuristic:
 559                                         //
 560                                         // Routing fragmentation across many payment paths increases the overall routing
 561                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 562                                         // Taking too many smaller paths also increases the chance of payment failure.
 563                                         // Thus to avoid this effect, we require from our collected links to provide
 564                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 565                                         //
 566                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 567                                         // This means as we successfully advance in our collection,
 568                                         // the absolute liquidity contribution is lowered,
 569                                         // thus increasing the number of potential channels to be selected.
 570
 571                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 572                                         // or 100% if we're not allowed to do multipath payments.
 573                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 574                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 575                                         } else {
 576                                                 final_value_msat
 577                                         };
 578                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 579                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 580
 581                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 582                                         // Includes paying fees for the use of the following channels.
 583                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 584                                                 Some(result) => result,
 585                                                 // Can't overflow due to how the values were computed right above.
 586                                                 None => unreachable!(),
 587                                         };
 588                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 589                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 590                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 591
 592                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 593                                         // bother considering this channel.
 594                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 595                                         // be only reduced later (not increased), so this channel should just be skipped
 596                                         // as not sufficient.
 597                                         if !over_path_minimum_msat {
 598                                                 hit_minimum_limit = true;
 599                                         } else if contributes_sufficient_value {
 600                                                 // Note that low contribution here (limited by available_liquidity_msat)
 601                                                 // might violate htlc_minimum_msat on the hops which are next along the
 602                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 603                                                 // path fees knowing the final path contribution after constructing it.
 604                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 605                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 606                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 607                                                         _ => u64::max_value()
 608                                                 };
 609                                                 let hm_entry = dist.entry(&$src_node_id);
 610                                                 let old_entry = hm_entry.or_insert_with(|| {
 611                                                         // If there was previously no known way to access
 612                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 613                                                         // a semi-dummy record just to compute the fees to reach the source node.
 614                                                         // This will affect our decision on selecting $chan_id
 615                                                         // as a way to reach the $dest_node_id.
 616                                                         let mut fee_base_msat = u32::max_value();
 617                                                         let mut fee_proportional_millionths = u32::max_value();
 618                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 619                                                                 fee_base_msat = fees.base_msat;
 620                                                                 fee_proportional_millionths = fees.proportional_millionths;
 621                                                         }
 622                                                         PathBuildingHop {
 623                                                                 pubkey: $dest_node_id.clone(),
 624                                                                 short_channel_id: 0,
 625                                                                 channel_features: $chan_features,
 626                                                                 fee_msat: 0,
 627                                                                 cltv_expiry_delta: 0,
 628                                                                 src_lowest_inbound_fees: RoutingFees {
 629                                                                         base_msat: fee_base_msat,
 630                                                                         proportional_millionths: fee_proportional_millionths,
 631                                                                 },
 632                                                                 channel_fees: $directional_info.fees,
 633                                                                 next_hops_fee_msat: u64::max_value(),
 634                                                                 hop_use_fee_msat: u64::max_value(),
 635                                                                 total_fee_msat: u64::max_value(),
 636                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 637                                                                 path_htlc_minimum_msat,
 638                                                                 was_processed: false,
 639                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 640                                                                 value_contribution_msat,
 641                                                         }
 642                                                 });
 643
 644                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 645                                                 let mut should_process = !old_entry.was_processed;
 646                                                 #[cfg(any(test, feature = "fuzztarget"))]
 647                                                 {
 648                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 649                                                         // of already-seen nodes only happens in cases we expect (see below).
 650                                                         if !should_process { should_process = true; }
 651                                                 }
 652
 653                                                 if should_process {
 654                                                         let mut hop_use_fee_msat = 0;
 655                                                         let mut total_fee_msat = $next_hops_fee_msat;
 656
 657                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 658                                                         // will have the same effective-fee
 659                                                         if $src_node_id != *our_node_id {
 660                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 661                                                                         // max_value means we'll always fail
 662                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 663                                                                         None => total_fee_msat = u64::max_value(),
 664                                                                         Some(fee_msat) => {
 665                                                                                 hop_use_fee_msat = fee_msat;
 666                                                                                 total_fee_msat += hop_use_fee_msat;
 667                                                                                 // When calculating the lowest inbound fees to a node, we
 668                                                                                 // calculate fees here not based on the actual value we think
 669                                                                                 // will flow over this channel, but on the minimum value that
 670                                                                                 // we'll accept flowing over it. The minimum accepted value
 671                                                                                 // is a constant through each path collection run, ensuring
 672                                                                                 // consistent basis. Otherwise we may later find a
 673                                                                                 // different path to the source node that is more expensive,
 674                                                                                 // but which we consider to be cheaper because we are capacity
 675                                                                                 // constrained and the relative fee becomes lower.
 676                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 677                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 678                                                                                         Some(Some(v)) => {
 679                                                                                                 total_fee_msat = v;
 680                                                                                         },
 681                                                                                         _ => {
 682                                                                                                 total_fee_msat = u64::max_value();
 683                                                                                         }
 684                                                                                 };
 685                                                                         }
 686                                                                 }
 687                                                         }
 688
 689                                                         let new_graph_node = RouteGraphNode {
 690                                                                 pubkey: $src_node_id,
 691                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 692                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 693                                                                 value_contribution_msat: value_contribution_msat,
 694                                                                 path_htlc_minimum_msat,
 695                                                         };
 696
 697                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 698                                                         // if this way is cheaper than the already known
 699                                                         // (considering the cost to "reach" this channel from the route destination,
 700                                                         // the cost of using this channel,
 701                                                         // and the cost of routing to the source node of this channel).
 702                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 703                                                         // paying it. Consider the following exploit:
 704                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 705                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 706                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 707                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 708                                                         // to this channel.
 709                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 710                                                         // but it may require additional tracking - we don't want to double-count
 711                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 712                                                         // can't use something that may decrease on future hops.
 713                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 714                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 715
 716                                                         if !old_entry.was_processed && new_cost < old_cost {
 717                                                                 targets.push(new_graph_node);
 718                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 719                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 720                                                                 old_entry.total_fee_msat = total_fee_msat;
 721                                                                 old_entry.pubkey = $dest_node_id.clone();
 722                                                                 old_entry.short_channel_id = $chan_id.clone();
 723                                                                 old_entry.channel_features = $chan_features;
 724                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 725                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 726                                                                 old_entry.channel_fees = $directional_info.fees;
 727                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 728                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 729                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 730                                                                 {
 731                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 732                                                                 }
 733                                                         } else if old_entry.was_processed && new_cost < old_cost {
 734                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 735                                                                 {
 736                                                                         // If we're skipping processing a node which was previously
 737                                                                         // processed even though we found another path to it with a
 738                                                                         // cheaper fee, check that it was because the second path we
 739                                                                         // found (which we are processing now) has a lower value
 740                                                                         // contribution due to an HTLC minimum limit.
 741                                                                         //
 742                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 743                                                                         // through channel A, and one through channel B. Channel A and
 744                                                                         // B are both in the to-process heap, with their scores set by
 745                                                                         // a higher htlc_minimum than fee.
 746                                                                         // Channel A is processed first, and the channels onwards from
 747                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 748                                                                         // Channel B off of the heap, note that it has a much more
 749                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 750                                                                         // all of node 1's channels using the new, reduced, amount.
 751                                                                         //
 752                                                                         // This would be bogus - we'd be selecting a higher-fee path
 753                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 754                                                                         // already decided to use.
 755                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 756                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 757                                                                 }
 758                                                         }
 759                                                 }
 760                                         }
 761                                 }
 762                         }
 763                 };
 764         }
 765
 766         let empty_node_features = NodeFeatures::empty();
 767         // Find ways (channels with destination) to reach a given node and store them
 768         // in the corresponding data structures (routing graph etc).
 769         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 770         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 771         // This data can later be helpful to optimize routing (pay lower fees).
 772         macro_rules! add_entries_to_cheapest_to_target_node {
 773                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 774                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 775                                 let was_processed = elem.was_processed;
 776                                 elem.was_processed = true;
 777                                 was_processed
 778                         } else {
 779                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 780                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 781                                 // If we're processing any other node, it is always be the result of a channel from it.
 782                                 assert_eq!($node_id, payee);
 783                                 false
 784                         };
 785
 786                         if !skip_node {
 787                                 if first_hops.is_some() {
 788                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&$node_id) {
 789                                                 add_entry!(first_hop, *our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 790                                         }
 791                                 }
 792
 793                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 794                                         &node_info.features
 795                                 } else {
 796                                         &empty_node_features
 797                                 };
 798
 799                                 if !features.requires_unknown_bits() {
 800                                         for chan_id in $node.channels.iter() {
 801                                                 let chan = network.get_channels().get(chan_id).unwrap();
 802                                                 if !chan.features.requires_unknown_bits() {
 803                                                         if chan.node_one == *$node_id {
 804                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 805                                                                 if first_hops.is_none() || chan.node_two != *our_node_id {
 806                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 807                                                                                 if two_to_one.enabled {
 808                                                                                         add_entry!(chan_id, chan.node_two, chan.node_one, two_to_one, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 809                                                                                 }
 810                                                                         }
 811                                                                 }
 812                                                         } else {
 813                                                                 if first_hops.is_none() || chan.node_one != *our_node_id {
 814                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 815                                                                                 if one_to_two.enabled {
 816                                                                                         add_entry!(chan_id, chan.node_one, chan.node_two, one_to_two, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 817                                                                                 }
 818                                                                         }
 819                                                                 }
 820                                                         }
 821                                                 }
 822                                         }
 823                                 }
 824                         }
 825                 };
 826         }
 827
 828         let mut payment_paths = Vec::<PaymentPath>::new();
 829
 830         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 831         'paths_collection: loop {
 832                 // For every new path, start from scratch, except
 833                 // bookkeeped_channels_liquidity_available_msat, which will improve
 834                 // the further iterations of path finding. Also don't erase first_hop_targets.
 835                 targets.clear();
 836                 dist.clear();
 837                 hit_minimum_limit = false;
 838
 839                 // If first hop is a private channel and the only way to reach the payee, this is the only
 840                 // place where it could be added.
 841                 if first_hops.is_some() {
 842                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&payee) {
 843                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 844                         }
 845                 }
 846
 847                 // Add the payee as a target, so that the payee-to-payer
 848                 // search algorithm knows what to start with.
 849                 match network.get_nodes().get(payee) {
 850                         // The payee is not in our network graph, so nothing to add here.
 851                         // There is still a chance of reaching them via last_hops though,
 852                         // so don't yet fail the payment here.
 853                         // If not, targets.pop() will not even let us enter the loop in step 2.
 854                         None => {},
 855                         Some(node) => {
 856                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 857                         },
 858                 }
 859
 860                 // Step (1).
 861                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 862                 // earlier than general path finding, they will be somewhat prioritized, although currently
 863                 // it matters only if the fees are exactly the same.
 864                 for hop in last_hops.iter() {
 865                         let have_hop_src_in_graph =
 866                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
 867                                         // If this hop connects to a node with which we have a direct channel, ignore
 868                                         // the network graph and add both the hop and our direct channel to
 869                                         // the candidate set.
 870                                         //
 871                                         // Currently there are no channel-context features defined, so we are a
 872                                         // bit lazy here. In the future, we should pull them out via our
 873                                         // ChannelManager, but there's no reason to waste the space until we
 874                                         // need them.
 875                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 876                                         true
 877                                 } else {
 878                                         // In any other case, only add the hop if the source is in the regular network
 879                                         // graph:
 880                                         network.get_nodes().get(&hop.src_node_id).is_some()
 881                                 };
 882                         if have_hop_src_in_graph {
 883                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 884                                 // really sucks, cause we're gonna need that eventually.
 885                                 let last_hop_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 886                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 887                                         None => 0
 888                                 };
 889                                 let directional_info = DummyDirectionalChannelInfo {
 890                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 891                                         htlc_minimum_msat: last_hop_htlc_minimum_msat,
 892                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 893                                         fees: hop.fees,
 894                                 };
 895                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, &empty_channel_features, 0, path_value_msat, 0);
 896                         }
 897                 }
 898
 899                 // At this point, targets are filled with the data from first and
 900                 // last hops communicated by the caller, and the payment receiver.
 901                 let mut found_new_path = false;
 902
 903                 // Step (2).
 904                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 905                 // - not enough outgoing liquidity:
 906                 //   0 < already_collected_value_msat < final_value_msat
 907                 // - enough outgoing liquidity:
 908                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 909                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 910                 // paths_collection will be stopped because found_new_path==false.
 911                 // This is not necessarily a routing failure.
 912                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 913
 914                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 915                         // traversing the graph and arrange the path out of what we found.
 916                         if pubkey == *our_node_id {
 917                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 918                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
 919
 920                                 'path_walk: loop {
 921                                         if let Some(&(_, _, _, ref features)) = first_hop_targets.get(&ordered_hops.last().unwrap().0.pubkey) {
 922                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
 923                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().0.pubkey) {
 924                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 925                                                         ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
 926                                                 } else {
 927                                                         ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
 928                                                 }
 929                                         } else {
 930                                                 // We should be able to fill in features for everything except the last
 931                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 932                                                 // should be able to extend it further as BOLT 11 does have feature
 933                                                 // flags for the last hop node itself).
 934                                                 assert!(ordered_hops.last().unwrap().0.pubkey == *payee);
 935                                         }
 936
 937                                         // Means we succesfully traversed from the payer to the payee, now
 938                                         // save this path for the payment route. Also, update the liquidity
 939                                         // remaining on the used hops, so that we take them into account
 940                                         // while looking for more paths.
 941                                         if ordered_hops.last().unwrap().0.pubkey == *payee {
 942                                                 break 'path_walk;
 943                                         }
 944
 945                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.pubkey) {
 946                                                 Some(payment_hop) => payment_hop,
 947                                                 // We can't arrive at None because, if we ever add an entry to targets,
 948                                                 // we also fill in the entry in dist (see add_entry!).
 949                                                 None => unreachable!(),
 950                                         };
 951                                         // We "propagate" the fees one hop backward (topologically) here,
 952                                         // so that fees paid for a HTLC forwarding on the current channel are
 953                                         // associated with the previous channel (where they will be subtracted).
 954                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
 955                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
 956                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
 957                                 }
 958                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
 959                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
 960                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
 961
 962                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 963
 964                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 965                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 966                                 // on some channels we already passed (assuming dest->source direction). Here, we
 967                                 // recompute the fees again, so that if that's the case, we match the currently
 968                                 // underpaid htlc_minimum_msat with fees.
 969                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
 970
 971                                 // Since a path allows to transfer as much value as
 972                                 // the smallest channel it has ("bottleneck"), we should recompute
 973                                 // the fees so sender HTLC don't overpay fees when traversing
 974                                 // larger channels than the bottleneck. This may happen because
 975                                 // when we were selecting those channels we were not aware how much value
 976                                 // this path will transfer, and the relative fee for them
 977                                 // might have been computed considering a larger value.
 978                                 // Remember that we used these channels so that we don't rely
 979                                 // on the same liquidity in future paths.
 980                                 let mut prevented_redundant_path_selection = false;
 981                                 for (payment_hop, _) in payment_path.hops.iter() {
 982                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
 983                                         let mut spent_on_hop_msat = value_contribution_msat;
 984                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 985                                         spent_on_hop_msat += next_hops_fee_msat;
 986                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
 987                                                 // If this path used all of this channel's available liquidity, we know
 988                                                 // this path will not be selected again in the next loop iteration.
 989                                                 prevented_redundant_path_selection = true;
 990                                         }
 991                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 992                                 }
 993                                 if !prevented_redundant_path_selection {
 994                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
 995                                         // we'll probably end up picking the same path again on the next iteration.
 996                                         // Decrease the available liquidity of a hop in the middle of the path.
 997                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(
 998                                                 &payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id).unwrap();
 999                                         *victim_liquidity = 0;
1000                                 }
1001
1002                                 // Track the total amount all our collected paths allow to send so that we:
1003                                 // - know when to stop looking for more paths
1004                                 // - know which of the hops are useless considering how much more sats we need
1005                                 //   (contributes_sufficient_value)
1006                                 already_collected_value_msat += value_contribution_msat;
1007
1008                                 payment_paths.push(payment_path);
1009                                 found_new_path = true;
1010                                 break 'path_construction;
1011                         }
1012
1013                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1014                         // the equivalent of the `elem.was_processed` check in
1015                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1016                         if pubkey == *payee { continue 'path_construction; }
1017
1018                         // Otherwise, since the current target node is not us,
1019                         // keep "unrolling" the payment graph from payee to payer by
1020                         // finding a way to reach the current target from the payer side.
1021                         match network.get_nodes().get(&pubkey) {
1022                                 None => {},
1023                                 Some(node) => {
1024                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1025                                 },
1026                         }
1027                 }
1028
1029                 if !allow_mpp {
1030                         // If we don't support MPP, no use trying to gather more value ever.
1031                         break 'paths_collection;
1032                 }
1033
1034                 // Step (3).
1035                 // Stop either when the recommended value is reached or if no new path was found in this
1036                 // iteration.
1037                 // In the latter case, making another path finding attempt won't help,
1038                 // because we deterministically terminated the search due to low liquidity.
1039                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1040                         break 'paths_collection;
1041                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1042                         // Further, if this was our first walk of the graph, and we weren't limited by an
1043                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1044                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1045                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1046                         // still keeping a lower total fee than this path.
1047                         if !hit_minimum_limit {
1048                                 break 'paths_collection;
1049                         }
1050                         path_value_msat = recommended_value_msat;
1051                 }
1052         }
1053
1054         // Step (4).
1055         if payment_paths.len() == 0 {
1056                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1057         }
1058
1059         if already_collected_value_msat < final_value_msat {
1060                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1061         }
1062
1063         // Sort by total fees and take the best paths.
1064         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1065         if payment_paths.len() > 50 {
1066                 payment_paths.truncate(50);
1067         }
1068
1069         // Draw multiple sufficient routes by randomly combining the selected paths.
1070         let mut drawn_routes = Vec::new();
1071         for i in 0..payment_paths.len() {
1072                 let mut cur_route = Vec::<PaymentPath>::new();
1073                 let mut aggregate_route_value_msat = 0;
1074
1075                 // Step (5).
1076                 // TODO: real random shuffle
1077                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1078                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1079
1080                 // Step (6).
1081                 for payment_path in cur_payment_paths {
1082                         cur_route.push(payment_path.clone());
1083                         aggregate_route_value_msat += payment_path.get_value_msat();
1084                         if aggregate_route_value_msat > final_value_msat {
1085                                 // Last path likely overpaid. Substract it from the most expensive
1086                                 // (in terms of proportional fee) path in this route and recompute fees.
1087                                 // This might be not the most economically efficient way, but fewer paths
1088                                 // also makes routing more reliable.
1089                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1090
1091                                 // First, drop some expensive low-value paths entirely if possible.
1092                                 // Sort by value so that we drop many really-low values first, since
1093                                 // fewer paths is better: the payment is less likely to fail.
1094                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1095                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1096                                 cur_route.sort_by_key(|path| path.get_value_msat());
1097                                 // We should make sure that at least 1 path left.
1098                                 let mut paths_left = cur_route.len();
1099                                 cur_route.retain(|path| {
1100                                         if paths_left == 1 {
1101                                                 return true
1102                                         }
1103                                         let mut keep = true;
1104                                         let path_value_msat = path.get_value_msat();
1105                                         if path_value_msat <= overpaid_value_msat {
1106                                                 keep = false;
1107                                                 overpaid_value_msat -= path_value_msat;
1108                                                 paths_left -= 1;
1109                                         }
1110                                         keep
1111                                 });
1112
1113                                 if overpaid_value_msat == 0 {
1114                                         break;
1115                                 }
1116
1117                                 assert!(cur_route.len() > 0);
1118
1119                                 // Step (7).
1120                                 // Now, substract the overpaid value from the most-expensive path.
1121                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1122                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1123                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1124                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1125                                 // We already dropped all the small channels above, meaning all the
1126                                 // remaining channels are larger than remaining overpaid_value_msat.
1127                                 // Thus, this can't be negative.
1128                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1129                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1130                                 break;
1131                         }
1132                 }
1133                 drawn_routes.push(cur_route);
1134         }
1135
1136         // Step (8).
1137         // Select the best route by lowest total fee.
1138         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1139         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1140         for payment_path in drawn_routes.first().unwrap() {
1141                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1142                         RouteHop {
1143                                 pubkey: payment_hop.pubkey,
1144                                 node_features: node_features.clone(),
1145                                 short_channel_id: payment_hop.short_channel_id,
1146                                 channel_features: payment_hop.channel_features.clone(),
1147                                 fee_msat: payment_hop.fee_msat,
1148                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1149                         }
1150                 }).collect());
1151         }
1152
1153         if let Some(features) = &payee_features {
1154                 for path in selected_paths.iter_mut() {
1155                         path.last_mut().unwrap().node_features = features.to_context();
1156                 }
1157         }
1158
1159         let route = Route { paths: selected_paths };
1160         log_trace!(logger, "Got route: {}", log_route!(route));
1161         Ok(route)
1162 }
1163
1164 #[cfg(test)]
1165 mod tests {
1166         use routing::router::{get_route, RouteHintHop, RoutingFees};
1167         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1168         use chain::transaction::OutPoint;
1169         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1170         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1171            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1172         use ln::channelmanager;
1173         use util::test_utils;
1174         use util::ser::Writeable;
1175
1176         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1177         use bitcoin::hashes::Hash;
1178         use bitcoin::network::constants::Network;
1179         use bitcoin::blockdata::constants::genesis_block;
1180         use bitcoin::blockdata::script::Builder;
1181         use bitcoin::blockdata::opcodes;
1182         use bitcoin::blockdata::transaction::TxOut;
1183
1184         use hex;
1185
1186         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1187         use bitcoin::secp256k1::{Secp256k1, All};
1188
1189         use std::sync::Arc;
1190
1191         // Using the same keys for LN and BTC ids
1192         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1193            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1194                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1195                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1196
1197                 let unsigned_announcement = UnsignedChannelAnnouncement {
1198                         features,
1199                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1200                         short_channel_id,
1201                         node_id_1,
1202                         node_id_2,
1203                         bitcoin_key_1: node_id_1,
1204                         bitcoin_key_2: node_id_2,
1205                         excess_data: Vec::new(),
1206                 };
1207
1208                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1209                 let valid_announcement = ChannelAnnouncement {
1210                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1211                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1212                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1213                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1214                         contents: unsigned_announcement.clone(),
1215                 };
1216                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1217                         Ok(res) => assert!(res),
1218                         _ => panic!()
1219                 };
1220         }
1221
1222         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) {
1223                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1224                 let valid_channel_update = ChannelUpdate {
1225                         signature: secp_ctx.sign(&msghash, node_privkey),
1226                         contents: update.clone()
1227                 };
1228
1229                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1230                         Ok(res) => assert!(res),
1231                         Err(_) => panic!()
1232                 };
1233         }
1234
1235         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,
1236            features: NodeFeatures, timestamp: u32) {
1237                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1238                 let unsigned_announcement = UnsignedNodeAnnouncement {
1239                         features,
1240                         timestamp,
1241                         node_id,
1242                         rgb: [0; 3],
1243                         alias: [0; 32],
1244                         addresses: Vec::new(),
1245                         excess_address_data: Vec::new(),
1246                         excess_data: Vec::new(),
1247                 };
1248                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1249                 let valid_announcement = NodeAnnouncement {
1250                         signature: secp_ctx.sign(&msghash, node_privkey),
1251                         contents: unsigned_announcement.clone()
1252                 };
1253
1254                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1255                         Ok(_) => (),
1256                         Err(_) => panic!()
1257                 };
1258         }
1259
1260         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1261                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1262                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1263                 }).collect();
1264
1265                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1266
1267                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1268                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1269
1270                 (our_privkey, our_id, privkeys, pubkeys)
1271         }
1272
1273         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1274                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1275                 // test for it later.
1276                 let idx = (id - 1) * 2 + 1;
1277                 if idx > 8*3 {
1278                         vec![1 << (idx - 8*3), 0, 0, 0]
1279                 } else if idx > 8*2 {
1280                         vec![1 << (idx - 8*2), 0, 0]
1281                 } else if idx > 8*1 {
1282                         vec![1 << (idx - 8*1), 0]
1283                 } else {
1284                         vec![1 << idx]
1285                 }
1286         }
1287
1288         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>) {
1289                 let secp_ctx = Secp256k1::new();
1290                 let logger = Arc::new(test_utils::TestLogger::new());
1291                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1292                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1293                 // Build network from our_id to node7:
1294                 //
1295                 //        -1(1)2-  node0  -1(3)2-
1296                 //       /                       \
1297                 // our_id -1(12)2- node7 -1(13)2--- node2
1298                 //       \                       /
1299                 //        -1(2)2-  node1  -1(4)2-
1300                 //
1301                 //
1302                 // chan1  1-to-2: disabled
1303                 // chan1  2-to-1: enabled, 0 fee
1304                 //
1305                 // chan2  1-to-2: enabled, ignored fee
1306                 // chan2  2-to-1: enabled, 0 fee
1307                 //
1308                 // chan3  1-to-2: enabled, 0 fee
1309                 // chan3  2-to-1: enabled, 100 msat fee
1310                 //
1311                 // chan4  1-to-2: enabled, 100% fee
1312                 // chan4  2-to-1: enabled, 0 fee
1313                 //
1314                 // chan12 1-to-2: enabled, ignored fee
1315                 // chan12 2-to-1: enabled, 0 fee
1316                 //
1317                 // chan13 1-to-2: enabled, 200% fee
1318                 // chan13 2-to-1: enabled, 0 fee
1319                 //
1320                 //
1321                 //       -1(5)2- node3 -1(8)2--
1322                 //       |         2          |
1323                 //       |       (11)         |
1324                 //      /          1           \
1325                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1326                 //      \                      /
1327                 //       -1(7)2- node5 -1(10)2-
1328                 //
1329                 // chan5  1-to-2: enabled, 100 msat fee
1330                 // chan5  2-to-1: enabled, 0 fee
1331                 //
1332                 // chan6  1-to-2: enabled, 0 fee
1333                 // chan6  2-to-1: enabled, 0 fee
1334                 //
1335                 // chan7  1-to-2: enabled, 100% fee
1336                 // chan7  2-to-1: enabled, 0 fee
1337                 //
1338                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1339                 // chan8  2-to-1: enabled, 0 fee
1340                 //
1341                 // chan9  1-to-2: enabled, 1001 msat fee
1342                 // chan9  2-to-1: enabled, 0 fee
1343                 //
1344                 // chan10 1-to-2: enabled, 0 fee
1345                 // chan10 2-to-1: enabled, 0 fee
1346                 //
1347                 // chan11 1-to-2: enabled, 0 fee
1348                 // chan11 2-to-1: enabled, 0 fee
1349
1350                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1351
1352                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1353                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1354                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1355                         short_channel_id: 1,
1356                         timestamp: 1,
1357                         flags: 1,
1358                         cltv_expiry_delta: 0,
1359                         htlc_minimum_msat: 0,
1360                         htlc_maximum_msat: OptionalField::Absent,
1361                         fee_base_msat: 0,
1362                         fee_proportional_millionths: 0,
1363                         excess_data: Vec::new()
1364                 });
1365
1366                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1367
1368                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1369                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1370                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1371                         short_channel_id: 2,
1372                         timestamp: 1,
1373                         flags: 0,
1374                         cltv_expiry_delta: u16::max_value(),
1375                         htlc_minimum_msat: 0,
1376                         htlc_maximum_msat: OptionalField::Absent,
1377                         fee_base_msat: u32::max_value(),
1378                         fee_proportional_millionths: u32::max_value(),
1379                         excess_data: Vec::new()
1380                 });
1381                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1382                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1383                         short_channel_id: 2,
1384                         timestamp: 1,
1385                         flags: 1,
1386                         cltv_expiry_delta: 0,
1387                         htlc_minimum_msat: 0,
1388                         htlc_maximum_msat: OptionalField::Absent,
1389                         fee_base_msat: 0,
1390                         fee_proportional_millionths: 0,
1391                         excess_data: Vec::new()
1392                 });
1393
1394                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1395
1396                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1397                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1398                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1399                         short_channel_id: 12,
1400                         timestamp: 1,
1401                         flags: 0,
1402                         cltv_expiry_delta: u16::max_value(),
1403                         htlc_minimum_msat: 0,
1404                         htlc_maximum_msat: OptionalField::Absent,
1405                         fee_base_msat: u32::max_value(),
1406                         fee_proportional_millionths: u32::max_value(),
1407                         excess_data: Vec::new()
1408                 });
1409                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1410                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1411                         short_channel_id: 12,
1412                         timestamp: 1,
1413                         flags: 1,
1414                         cltv_expiry_delta: 0,
1415                         htlc_minimum_msat: 0,
1416                         htlc_maximum_msat: OptionalField::Absent,
1417                         fee_base_msat: 0,
1418                         fee_proportional_millionths: 0,
1419                         excess_data: Vec::new()
1420                 });
1421
1422                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1423
1424                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1425                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1426                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1427                         short_channel_id: 3,
1428                         timestamp: 1,
1429                         flags: 0,
1430                         cltv_expiry_delta: (3 << 8) | 1,
1431                         htlc_minimum_msat: 0,
1432                         htlc_maximum_msat: OptionalField::Absent,
1433                         fee_base_msat: 0,
1434                         fee_proportional_millionths: 0,
1435                         excess_data: Vec::new()
1436                 });
1437                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1438                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1439                         short_channel_id: 3,
1440                         timestamp: 1,
1441                         flags: 1,
1442                         cltv_expiry_delta: (3 << 8) | 2,
1443                         htlc_minimum_msat: 0,
1444                         htlc_maximum_msat: OptionalField::Absent,
1445                         fee_base_msat: 100,
1446                         fee_proportional_millionths: 0,
1447                         excess_data: Vec::new()
1448                 });
1449
1450                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1451                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1452                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1453                         short_channel_id: 4,
1454                         timestamp: 1,
1455                         flags: 0,
1456                         cltv_expiry_delta: (4 << 8) | 1,
1457                         htlc_minimum_msat: 0,
1458                         htlc_maximum_msat: OptionalField::Absent,
1459                         fee_base_msat: 0,
1460                         fee_proportional_millionths: 1000000,
1461                         excess_data: Vec::new()
1462                 });
1463                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1464                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1465                         short_channel_id: 4,
1466                         timestamp: 1,
1467                         flags: 1,
1468                         cltv_expiry_delta: (4 << 8) | 2,
1469                         htlc_minimum_msat: 0,
1470                         htlc_maximum_msat: OptionalField::Absent,
1471                         fee_base_msat: 0,
1472                         fee_proportional_millionths: 0,
1473                         excess_data: Vec::new()
1474                 });
1475
1476                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1477                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1478                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1479                         short_channel_id: 13,
1480                         timestamp: 1,
1481                         flags: 0,
1482                         cltv_expiry_delta: (13 << 8) | 1,
1483                         htlc_minimum_msat: 0,
1484                         htlc_maximum_msat: OptionalField::Absent,
1485                         fee_base_msat: 0,
1486                         fee_proportional_millionths: 2000000,
1487                         excess_data: Vec::new()
1488                 });
1489                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1490                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1491                         short_channel_id: 13,
1492                         timestamp: 1,
1493                         flags: 1,
1494                         cltv_expiry_delta: (13 << 8) | 2,
1495                         htlc_minimum_msat: 0,
1496                         htlc_maximum_msat: OptionalField::Absent,
1497                         fee_base_msat: 0,
1498                         fee_proportional_millionths: 0,
1499                         excess_data: Vec::new()
1500                 });
1501
1502                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1503
1504                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1505                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1506                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1507                         short_channel_id: 6,
1508                         timestamp: 1,
1509                         flags: 0,
1510                         cltv_expiry_delta: (6 << 8) | 1,
1511                         htlc_minimum_msat: 0,
1512                         htlc_maximum_msat: OptionalField::Absent,
1513                         fee_base_msat: 0,
1514                         fee_proportional_millionths: 0,
1515                         excess_data: Vec::new()
1516                 });
1517                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1518                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1519                         short_channel_id: 6,
1520                         timestamp: 1,
1521                         flags: 1,
1522                         cltv_expiry_delta: (6 << 8) | 2,
1523                         htlc_minimum_msat: 0,
1524                         htlc_maximum_msat: OptionalField::Absent,
1525                         fee_base_msat: 0,
1526                         fee_proportional_millionths: 0,
1527                         excess_data: Vec::new(),
1528                 });
1529
1530                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1531                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1532                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1533                         short_channel_id: 11,
1534                         timestamp: 1,
1535                         flags: 0,
1536                         cltv_expiry_delta: (11 << 8) | 1,
1537                         htlc_minimum_msat: 0,
1538                         htlc_maximum_msat: OptionalField::Absent,
1539                         fee_base_msat: 0,
1540                         fee_proportional_millionths: 0,
1541                         excess_data: Vec::new()
1542                 });
1543                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1544                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1545                         short_channel_id: 11,
1546                         timestamp: 1,
1547                         flags: 1,
1548                         cltv_expiry_delta: (11 << 8) | 2,
1549                         htlc_minimum_msat: 0,
1550                         htlc_maximum_msat: OptionalField::Absent,
1551                         fee_base_msat: 0,
1552                         fee_proportional_millionths: 0,
1553                         excess_data: Vec::new()
1554                 });
1555
1556                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1557
1558                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1559
1560                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1561                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1562                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1563                         short_channel_id: 7,
1564                         timestamp: 1,
1565                         flags: 0,
1566                         cltv_expiry_delta: (7 << 8) | 1,
1567                         htlc_minimum_msat: 0,
1568                         htlc_maximum_msat: OptionalField::Absent,
1569                         fee_base_msat: 0,
1570                         fee_proportional_millionths: 1000000,
1571                         excess_data: Vec::new()
1572                 });
1573                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1574                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1575                         short_channel_id: 7,
1576                         timestamp: 1,
1577                         flags: 1,
1578                         cltv_expiry_delta: (7 << 8) | 2,
1579                         htlc_minimum_msat: 0,
1580                         htlc_maximum_msat: OptionalField::Absent,
1581                         fee_base_msat: 0,
1582                         fee_proportional_millionths: 0,
1583                         excess_data: Vec::new()
1584                 });
1585
1586                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1587
1588                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1589         }
1590
1591         #[test]
1592         fn simple_route_test() {
1593                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1594                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1595
1596                 // Simple route to 2 via 1
1597
1598                 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)) {
1599                         assert_eq!(err, "Cannot send a payment of 0 msat");
1600                 } else { panic!(); }
1601
1602                 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();
1603                 assert_eq!(route.paths[0].len(), 2);
1604
1605                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1606                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1607                 assert_eq!(route.paths[0][0].fee_msat, 100);
1608                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1609                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1610                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1611
1612                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1613                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1614                 assert_eq!(route.paths[0][1].fee_msat, 100);
1615                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1616                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1617                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1618         }
1619
1620         #[test]
1621         fn invalid_first_hop_test() {
1622                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1623                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1624
1625                 // Simple route to 2 via 1
1626
1627                 let our_chans = vec![channelmanager::ChannelDetails {
1628                         channel_id: [0; 32],
1629                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1630                         short_channel_id: Some(2),
1631                         remote_network_id: our_id,
1632                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1633                         channel_value_satoshis: 100000,
1634                         user_id: 0,
1635                         outbound_capacity_msat: 100000,
1636                         inbound_capacity_msat: 100000,
1637                         is_live: true, is_public: true,
1638                         counterparty_forwarding_info: None,
1639                 }];
1640
1641                 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)) {
1642                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1643                 } else { panic!(); }
1644
1645                 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();
1646                 assert_eq!(route.paths[0].len(), 2);
1647         }
1648
1649         #[test]
1650         fn htlc_minimum_test() {
1651                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1652                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1653
1654                 // Simple route to 2 via 1
1655
1656                 // Disable other paths
1657                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1658                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1659                         short_channel_id: 12,
1660                         timestamp: 2,
1661                         flags: 2, // to disable
1662                         cltv_expiry_delta: 0,
1663                         htlc_minimum_msat: 0,
1664                         htlc_maximum_msat: OptionalField::Absent,
1665                         fee_base_msat: 0,
1666                         fee_proportional_millionths: 0,
1667                         excess_data: Vec::new()
1668                 });
1669                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1670                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1671                         short_channel_id: 3,
1672                         timestamp: 2,
1673                         flags: 2, // to disable
1674                         cltv_expiry_delta: 0,
1675                         htlc_minimum_msat: 0,
1676                         htlc_maximum_msat: OptionalField::Absent,
1677                         fee_base_msat: 0,
1678                         fee_proportional_millionths: 0,
1679                         excess_data: Vec::new()
1680                 });
1681                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1682                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1683                         short_channel_id: 13,
1684                         timestamp: 2,
1685                         flags: 2, // to disable
1686                         cltv_expiry_delta: 0,
1687                         htlc_minimum_msat: 0,
1688                         htlc_maximum_msat: OptionalField::Absent,
1689                         fee_base_msat: 0,
1690                         fee_proportional_millionths: 0,
1691                         excess_data: Vec::new()
1692                 });
1693                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1694                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1695                         short_channel_id: 6,
1696                         timestamp: 2,
1697                         flags: 2, // to disable
1698                         cltv_expiry_delta: 0,
1699                         htlc_minimum_msat: 0,
1700                         htlc_maximum_msat: OptionalField::Absent,
1701                         fee_base_msat: 0,
1702                         fee_proportional_millionths: 0,
1703                         excess_data: Vec::new()
1704                 });
1705                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1706                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1707                         short_channel_id: 7,
1708                         timestamp: 2,
1709                         flags: 2, // to disable
1710                         cltv_expiry_delta: 0,
1711                         htlc_minimum_msat: 0,
1712                         htlc_maximum_msat: OptionalField::Absent,
1713                         fee_base_msat: 0,
1714                         fee_proportional_millionths: 0,
1715                         excess_data: Vec::new()
1716                 });
1717
1718                 // Check against amount_to_transfer_over_msat.
1719                 // Set minimal HTLC of 200_000_000 msat.
1720                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1721                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1722                         short_channel_id: 2,
1723                         timestamp: 3,
1724                         flags: 0,
1725                         cltv_expiry_delta: 0,
1726                         htlc_minimum_msat: 200_000_000,
1727                         htlc_maximum_msat: OptionalField::Absent,
1728                         fee_base_msat: 0,
1729                         fee_proportional_millionths: 0,
1730                         excess_data: Vec::new()
1731                 });
1732
1733                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1734                 // be used.
1735                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1736                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1737                         short_channel_id: 4,
1738                         timestamp: 3,
1739                         flags: 0,
1740                         cltv_expiry_delta: 0,
1741                         htlc_minimum_msat: 0,
1742                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1743                         fee_base_msat: 0,
1744                         fee_proportional_millionths: 0,
1745                         excess_data: Vec::new()
1746                 });
1747
1748                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1749                 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)) {
1750                         assert_eq!(err, "Failed to find a path to the given destination");
1751                 } else { panic!(); }
1752
1753                 // Lift the restriction on the first hop.
1754                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1755                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1756                         short_channel_id: 2,
1757                         timestamp: 4,
1758                         flags: 0,
1759                         cltv_expiry_delta: 0,
1760                         htlc_minimum_msat: 0,
1761                         htlc_maximum_msat: OptionalField::Absent,
1762                         fee_base_msat: 0,
1763                         fee_proportional_millionths: 0,
1764                         excess_data: Vec::new()
1765                 });
1766
1767                 // A payment above the minimum should pass
1768                 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();
1769                 assert_eq!(route.paths[0].len(), 2);
1770         }
1771
1772         #[test]
1773         fn htlc_minimum_overpay_test() {
1774                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1775                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1776
1777                 // A route to node#2 via two paths.
1778                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1779                 // Thus, they can't send 60 without overpaying.
1780                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1781                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1782                         short_channel_id: 2,
1783                         timestamp: 2,
1784                         flags: 0,
1785                         cltv_expiry_delta: 0,
1786                         htlc_minimum_msat: 35_000,
1787                         htlc_maximum_msat: OptionalField::Present(40_000),
1788                         fee_base_msat: 0,
1789                         fee_proportional_millionths: 0,
1790                         excess_data: Vec::new()
1791                 });
1792                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1793                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1794                         short_channel_id: 12,
1795                         timestamp: 3,
1796                         flags: 0,
1797                         cltv_expiry_delta: 0,
1798                         htlc_minimum_msat: 35_000,
1799                         htlc_maximum_msat: OptionalField::Present(40_000),
1800                         fee_base_msat: 0,
1801                         fee_proportional_millionths: 0,
1802                         excess_data: Vec::new()
1803                 });
1804
1805                 // Make 0 fee.
1806                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1807                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1808                         short_channel_id: 13,
1809                         timestamp: 2,
1810                         flags: 0,
1811                         cltv_expiry_delta: 0,
1812                         htlc_minimum_msat: 0,
1813                         htlc_maximum_msat: OptionalField::Absent,
1814                         fee_base_msat: 0,
1815                         fee_proportional_millionths: 0,
1816                         excess_data: Vec::new()
1817                 });
1818                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1819                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1820                         short_channel_id: 4,
1821                         timestamp: 2,
1822                         flags: 0,
1823                         cltv_expiry_delta: 0,
1824                         htlc_minimum_msat: 0,
1825                         htlc_maximum_msat: OptionalField::Absent,
1826                         fee_base_msat: 0,
1827                         fee_proportional_millionths: 0,
1828                         excess_data: Vec::new()
1829                 });
1830
1831                 // Disable other paths
1832                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1833                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1834                         short_channel_id: 1,
1835                         timestamp: 3,
1836                         flags: 2, // to disable
1837                         cltv_expiry_delta: 0,
1838                         htlc_minimum_msat: 0,
1839                         htlc_maximum_msat: OptionalField::Absent,
1840                         fee_base_msat: 0,
1841                         fee_proportional_millionths: 0,
1842                         excess_data: Vec::new()
1843                 });
1844
1845                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1846                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1847                 // Overpay fees to hit htlc_minimum_msat.
1848                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1849                 // TODO: this could be better balanced to overpay 10k and not 15k.
1850                 assert_eq!(overpaid_fees, 15_000);
1851
1852                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1853                 // while taking even more fee to match htlc_minimum_msat.
1854                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1855                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1856                         short_channel_id: 12,
1857                         timestamp: 4,
1858                         flags: 0,
1859                         cltv_expiry_delta: 0,
1860                         htlc_minimum_msat: 65_000,
1861                         htlc_maximum_msat: OptionalField::Present(80_000),
1862                         fee_base_msat: 0,
1863                         fee_proportional_millionths: 0,
1864                         excess_data: Vec::new()
1865                 });
1866                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1867                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1868                         short_channel_id: 2,
1869                         timestamp: 3,
1870                         flags: 0,
1871                         cltv_expiry_delta: 0,
1872                         htlc_minimum_msat: 0,
1873                         htlc_maximum_msat: OptionalField::Absent,
1874                         fee_base_msat: 0,
1875                         fee_proportional_millionths: 0,
1876                         excess_data: Vec::new()
1877                 });
1878                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1879                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1880                         short_channel_id: 4,
1881                         timestamp: 4,
1882                         flags: 0,
1883                         cltv_expiry_delta: 0,
1884                         htlc_minimum_msat: 0,
1885                         htlc_maximum_msat: OptionalField::Absent,
1886                         fee_base_msat: 0,
1887                         fee_proportional_millionths: 100_000,
1888                         excess_data: Vec::new()
1889                 });
1890
1891                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1892                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1893                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1894                 assert_eq!(route.paths.len(), 1);
1895                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1896                 let fees = route.paths[0][0].fee_msat;
1897                 assert_eq!(fees, 5_000);
1898
1899                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1900                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1901                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1902                 // the other channel.
1903                 assert_eq!(route.paths.len(), 1);
1904                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1905                 let fees = route.paths[0][0].fee_msat;
1906                 assert_eq!(fees, 5_000);
1907         }
1908
1909         #[test]
1910         fn disable_channels_test() {
1911                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1912                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1913
1914                 // // Disable channels 4 and 12 by flags=2
1915                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1916                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1917                         short_channel_id: 4,
1918                         timestamp: 2,
1919                         flags: 2, // to disable
1920                         cltv_expiry_delta: 0,
1921                         htlc_minimum_msat: 0,
1922                         htlc_maximum_msat: OptionalField::Absent,
1923                         fee_base_msat: 0,
1924                         fee_proportional_millionths: 0,
1925                         excess_data: Vec::new()
1926                 });
1927                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1928                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1929                         short_channel_id: 12,
1930                         timestamp: 2,
1931                         flags: 2, // to disable
1932                         cltv_expiry_delta: 0,
1933                         htlc_minimum_msat: 0,
1934                         htlc_maximum_msat: OptionalField::Absent,
1935                         fee_base_msat: 0,
1936                         fee_proportional_millionths: 0,
1937                         excess_data: Vec::new()
1938                 });
1939
1940                 // If all the channels require some features we don't understand, route should fail
1941                 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)) {
1942                         assert_eq!(err, "Failed to find a path to the given destination");
1943                 } else { panic!(); }
1944
1945                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1946                 let our_chans = vec![channelmanager::ChannelDetails {
1947                         channel_id: [0; 32],
1948                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1949                         short_channel_id: Some(42),
1950                         remote_network_id: nodes[7].clone(),
1951                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1952                         channel_value_satoshis: 0,
1953                         user_id: 0,
1954                         outbound_capacity_msat: 250_000_000,
1955                         inbound_capacity_msat: 0,
1956                         is_live: true, is_public: true,
1957                         counterparty_forwarding_info: None,
1958                 }];
1959                 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();
1960                 assert_eq!(route.paths[0].len(), 2);
1961
1962                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1963                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1964                 assert_eq!(route.paths[0][0].fee_msat, 200);
1965                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1966                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1967                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1968
1969                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1970                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1971                 assert_eq!(route.paths[0][1].fee_msat, 100);
1972                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1973                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1974                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1975         }
1976
1977         #[test]
1978         fn disable_node_test() {
1979                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1980                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1981
1982                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1983                 let mut unknown_features = NodeFeatures::known();
1984                 unknown_features.set_required_unknown_bits();
1985                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1986                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1987                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1988
1989                 // If all nodes require some features we don't understand, route should fail
1990                 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)) {
1991                         assert_eq!(err, "Failed to find a path to the given destination");
1992                 } else { panic!(); }
1993
1994                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1995                 let our_chans = vec![channelmanager::ChannelDetails {
1996                         channel_id: [0; 32],
1997                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1998                         short_channel_id: Some(42),
1999                         remote_network_id: nodes[7].clone(),
2000                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2001                         channel_value_satoshis: 0,
2002                         user_id: 0,
2003                         outbound_capacity_msat: 250_000_000,
2004                         inbound_capacity_msat: 0,
2005                         is_live: true, is_public: true,
2006                         counterparty_forwarding_info: None,
2007                 }];
2008                 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();
2009                 assert_eq!(route.paths[0].len(), 2);
2010
2011                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2012                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2013                 assert_eq!(route.paths[0][0].fee_msat, 200);
2014                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2015                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2016                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2017
2018                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2019                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2020                 assert_eq!(route.paths[0][1].fee_msat, 100);
2021                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2022                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2023                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2024
2025                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2026                 // naively) assume that the user checked the feature bits on the invoice, which override
2027                 // the node_announcement.
2028         }
2029
2030         #[test]
2031         fn our_chans_test() {
2032                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2033                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2034
2035                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2036                 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();
2037                 assert_eq!(route.paths[0].len(), 3);
2038
2039                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2040                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2041                 assert_eq!(route.paths[0][0].fee_msat, 200);
2042                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2043                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2044                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2045
2046                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2047                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2048                 assert_eq!(route.paths[0][1].fee_msat, 100);
2049                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2050                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2051                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2052
2053                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2054                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2055                 assert_eq!(route.paths[0][2].fee_msat, 100);
2056                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2057                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2058                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2059
2060                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2061                 let our_chans = vec![channelmanager::ChannelDetails {
2062                         channel_id: [0; 32],
2063                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2064                         short_channel_id: Some(42),
2065                         remote_network_id: nodes[7].clone(),
2066                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2067                         channel_value_satoshis: 0,
2068                         user_id: 0,
2069                         outbound_capacity_msat: 250_000_000,
2070                         inbound_capacity_msat: 0,
2071                         is_live: true, is_public: true,
2072                         counterparty_forwarding_info: None,
2073                 }];
2074                 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();
2075                 assert_eq!(route.paths[0].len(), 2);
2076
2077                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2078                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2079                 assert_eq!(route.paths[0][0].fee_msat, 200);
2080                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2081                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2082                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2083
2084                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2085                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2086                 assert_eq!(route.paths[0][1].fee_msat, 100);
2087                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2088                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2089                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2090         }
2091
2092         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHintHop> {
2093                 let zero_fees = RoutingFees {
2094                         base_msat: 0,
2095                         proportional_millionths: 0,
2096                 };
2097                 vec!(RouteHintHop {
2098                         src_node_id: nodes[3].clone(),
2099                         short_channel_id: 8,
2100                         fees: zero_fees,
2101                         cltv_expiry_delta: (8 << 8) | 1,
2102                         htlc_minimum_msat: None,
2103                         htlc_maximum_msat: None,
2104                 }, RouteHintHop {
2105                         src_node_id: nodes[4].clone(),
2106                         short_channel_id: 9,
2107                         fees: RoutingFees {
2108                                 base_msat: 1001,
2109                                 proportional_millionths: 0,
2110                         },
2111                         cltv_expiry_delta: (9 << 8) | 1,
2112                         htlc_minimum_msat: None,
2113                         htlc_maximum_msat: None,
2114                 }, RouteHintHop {
2115                         src_node_id: nodes[5].clone(),
2116                         short_channel_id: 10,
2117                         fees: zero_fees,
2118                         cltv_expiry_delta: (10 << 8) | 1,
2119                         htlc_minimum_msat: None,
2120                         htlc_maximum_msat: None,
2121                 })
2122         }
2123
2124         #[test]
2125         fn last_hops_test() {
2126                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2127                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2128
2129                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2130
2131                 // First check that lst hop can't have its source as the payee.
2132                 let invalid_last_hop = RouteHintHop {
2133                         src_node_id: nodes[6],
2134                         short_channel_id: 8,
2135                         fees: RoutingFees {
2136                                 base_msat: 1000,
2137                                 proportional_millionths: 0,
2138                         },
2139                         cltv_expiry_delta: (8 << 8) | 1,
2140                         htlc_minimum_msat: None,
2141                         htlc_maximum_msat: None,
2142                 };
2143
2144                 let mut invalid_last_hops = last_hops(&nodes);
2145                 invalid_last_hops.push(invalid_last_hop);
2146                 {
2147                         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)) {
2148                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2149                         } else { panic!(); }
2150                 }
2151
2152                 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();
2153                 assert_eq!(route.paths[0].len(), 5);
2154
2155                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2156                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2157                 assert_eq!(route.paths[0][0].fee_msat, 100);
2158                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2159                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2160                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2161
2162                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2163                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2164                 assert_eq!(route.paths[0][1].fee_msat, 0);
2165                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2166                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2167                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2168
2169                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2170                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2171                 assert_eq!(route.paths[0][2].fee_msat, 0);
2172                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2173                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2174                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2175
2176                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2177                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2178                 assert_eq!(route.paths[0][3].fee_msat, 0);
2179                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2180                 // If we have a peer in the node map, we'll use their features here since we don't have
2181                 // a way of figuring out their features from the invoice:
2182                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2183                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2184
2185                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2186                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2187                 assert_eq!(route.paths[0][4].fee_msat, 100);
2188                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2189                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2190                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2191         }
2192
2193         #[test]
2194         fn our_chans_last_hop_connect_test() {
2195                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2196                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2197
2198                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2199                 let our_chans = vec![channelmanager::ChannelDetails {
2200                         channel_id: [0; 32],
2201                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2202                         short_channel_id: Some(42),
2203                         remote_network_id: nodes[3].clone(),
2204                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2205                         channel_value_satoshis: 0,
2206                         user_id: 0,
2207                         outbound_capacity_msat: 250_000_000,
2208                         inbound_capacity_msat: 0,
2209                         is_live: true, is_public: true,
2210                         counterparty_forwarding_info: None,
2211                 }];
2212                 let mut last_hops = last_hops(&nodes);
2213                 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();
2214                 assert_eq!(route.paths[0].len(), 2);
2215
2216                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2217                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2218                 assert_eq!(route.paths[0][0].fee_msat, 0);
2219                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2220                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2221                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2222
2223                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2224                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2225                 assert_eq!(route.paths[0][1].fee_msat, 100);
2226                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2227                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2228                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2229
2230                 last_hops[0].fees.base_msat = 1000;
2231
2232                 // Revert to via 6 as the fee on 8 goes up
2233                 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();
2234                 assert_eq!(route.paths[0].len(), 4);
2235
2236                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2237                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2238                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2239                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2240                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2241                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2242
2243                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2244                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2245                 assert_eq!(route.paths[0][1].fee_msat, 100);
2246                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2247                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2248                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2249
2250                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2251                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2252                 assert_eq!(route.paths[0][2].fee_msat, 0);
2253                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2254                 // If we have a peer in the node map, we'll use their features here since we don't have
2255                 // a way of figuring out their features from the invoice:
2256                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2257                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2258
2259                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2260                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2261                 assert_eq!(route.paths[0][3].fee_msat, 100);
2262                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2263                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2264                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2265
2266                 // ...but still use 8 for larger payments as 6 has a variable feerate
2267                 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();
2268                 assert_eq!(route.paths[0].len(), 5);
2269
2270                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2271                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2272                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2273                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2274                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2275                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2276
2277                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2278                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2279                 assert_eq!(route.paths[0][1].fee_msat, 0);
2280                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2281                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2282                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2283
2284                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2285                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2286                 assert_eq!(route.paths[0][2].fee_msat, 0);
2287                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2288                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2289                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2290
2291                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2292                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2293                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2294                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2295                 // If we have a peer in the node map, we'll use their features here since we don't have
2296                 // a way of figuring out their features from the invoice:
2297                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2298                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2299
2300                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2301                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2302                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2303                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2304                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2305                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2306         }
2307
2308         #[test]
2309         fn unannounced_path_test() {
2310                 // We should be able to send a payment to a destination without any help of a routing graph
2311                 // if we have a channel with a common counterparty that appears in the first and last hop
2312                 // hints.
2313                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2314                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2315                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2316
2317                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2318                 let last_hops = vec![RouteHintHop {
2319                         src_node_id: middle_node_id,
2320                         short_channel_id: 8,
2321                         fees: RoutingFees {
2322                                 base_msat: 1000,
2323                                 proportional_millionths: 0,
2324                         },
2325                         cltv_expiry_delta: (8 << 8) | 1,
2326                         htlc_minimum_msat: None,
2327                         htlc_maximum_msat: None,
2328                 }];
2329                 let our_chans = vec![channelmanager::ChannelDetails {
2330                         channel_id: [0; 32],
2331                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2332                         short_channel_id: Some(42),
2333                         remote_network_id: middle_node_id,
2334                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2335                         channel_value_satoshis: 100000,
2336                         user_id: 0,
2337                         outbound_capacity_msat: 100000,
2338                         inbound_capacity_msat: 100000,
2339                         is_live: true, is_public: true,
2340                         counterparty_forwarding_info: None,
2341                 }];
2342                 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();
2343
2344                 assert_eq!(route.paths[0].len(), 2);
2345
2346                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2347                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2348                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2349                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2350                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2351                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2352
2353                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2354                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2355                 assert_eq!(route.paths[0][1].fee_msat, 100);
2356                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2357                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2358                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2359         }
2360
2361         #[test]
2362         fn available_amount_while_routing_test() {
2363                 // Tests whether we choose the correct available channel amount while routing.
2364
2365                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2366                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2367
2368                 // We will use a simple single-path route from
2369                 // our node to node2 via node0: channels {1, 3}.
2370
2371                 // First disable all other paths.
2372                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2373                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2374                         short_channel_id: 2,
2375                         timestamp: 2,
2376                         flags: 2,
2377                         cltv_expiry_delta: 0,
2378                         htlc_minimum_msat: 0,
2379                         htlc_maximum_msat: OptionalField::Present(100_000),
2380                         fee_base_msat: 0,
2381                         fee_proportional_millionths: 0,
2382                         excess_data: Vec::new()
2383                 });
2384                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2385                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2386                         short_channel_id: 12,
2387                         timestamp: 2,
2388                         flags: 2,
2389                         cltv_expiry_delta: 0,
2390                         htlc_minimum_msat: 0,
2391                         htlc_maximum_msat: OptionalField::Present(100_000),
2392                         fee_base_msat: 0,
2393                         fee_proportional_millionths: 0,
2394                         excess_data: Vec::new()
2395                 });
2396
2397                 // Make the first channel (#1) very permissive,
2398                 // and we will be testing all limits on the second channel.
2399                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2400                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2401                         short_channel_id: 1,
2402                         timestamp: 2,
2403                         flags: 0,
2404                         cltv_expiry_delta: 0,
2405                         htlc_minimum_msat: 0,
2406                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2407                         fee_base_msat: 0,
2408                         fee_proportional_millionths: 0,
2409                         excess_data: Vec::new()
2410                 });
2411
2412                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2413                 // In this case, it should be set to 250_000 sats.
2414                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2415                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2416                         short_channel_id: 3,
2417                         timestamp: 2,
2418                         flags: 0,
2419                         cltv_expiry_delta: 0,
2420                         htlc_minimum_msat: 0,
2421                         htlc_maximum_msat: OptionalField::Absent,
2422                         fee_base_msat: 0,
2423                         fee_proportional_millionths: 0,
2424                         excess_data: Vec::new()
2425                 });
2426
2427                 {
2428                         // Attempt to route more than available results in a failure.
2429                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2430                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2431                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2432                         } else { panic!(); }
2433                 }
2434
2435                 {
2436                         // Now, attempt to route an exact amount we have should be fine.
2437                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2438                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2439                         assert_eq!(route.paths.len(), 1);
2440                         let path = route.paths.last().unwrap();
2441                         assert_eq!(path.len(), 2);
2442                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2443                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2444                 }
2445
2446                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2447                 // Disable channel #1 and use another first hop.
2448                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2449                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2450                         short_channel_id: 1,
2451                         timestamp: 3,
2452                         flags: 2,
2453                         cltv_expiry_delta: 0,
2454                         htlc_minimum_msat: 0,
2455                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2456                         fee_base_msat: 0,
2457                         fee_proportional_millionths: 0,
2458                         excess_data: Vec::new()
2459                 });
2460
2461                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2462                 let our_chans = vec![channelmanager::ChannelDetails {
2463                         channel_id: [0; 32],
2464                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2465                         short_channel_id: Some(42),
2466                         remote_network_id: nodes[0].clone(),
2467                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2468                         channel_value_satoshis: 0,
2469                         user_id: 0,
2470                         outbound_capacity_msat: 200_000_000,
2471                         inbound_capacity_msat: 0,
2472                         is_live: true, is_public: true,
2473                         counterparty_forwarding_info: None,
2474                 }];
2475
2476                 {
2477                         // Attempt to route more than available results in a failure.
2478                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2479                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2480                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2481                         } else { panic!(); }
2482                 }
2483
2484                 {
2485                         // Now, attempt to route an exact amount we have should be fine.
2486                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2487                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2488                         assert_eq!(route.paths.len(), 1);
2489                         let path = route.paths.last().unwrap();
2490                         assert_eq!(path.len(), 2);
2491                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2492                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2493                 }
2494
2495                 // Enable channel #1 back.
2496                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2497                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2498                         short_channel_id: 1,
2499                         timestamp: 4,
2500                         flags: 0,
2501                         cltv_expiry_delta: 0,
2502                         htlc_minimum_msat: 0,
2503                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2504                         fee_base_msat: 0,
2505                         fee_proportional_millionths: 0,
2506                         excess_data: Vec::new()
2507                 });
2508
2509
2510                 // Now let's see if routing works if we know only htlc_maximum_msat.
2511                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2512                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2513                         short_channel_id: 3,
2514                         timestamp: 3,
2515                         flags: 0,
2516                         cltv_expiry_delta: 0,
2517                         htlc_minimum_msat: 0,
2518                         htlc_maximum_msat: OptionalField::Present(15_000),
2519                         fee_base_msat: 0,
2520                         fee_proportional_millionths: 0,
2521                         excess_data: Vec::new()
2522                 });
2523
2524                 {
2525                         // Attempt to route more than available results in a failure.
2526                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2527                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2528                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2529                         } else { panic!(); }
2530                 }
2531
2532                 {
2533                         // Now, attempt to route an exact amount we have should be fine.
2534                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2535                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2536                         assert_eq!(route.paths.len(), 1);
2537                         let path = route.paths.last().unwrap();
2538                         assert_eq!(path.len(), 2);
2539                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2540                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2541                 }
2542
2543                 // Now let's see if routing works if we know only capacity from the UTXO.
2544
2545                 // We can't change UTXO capacity on the fly, so we'll disable
2546                 // the existing channel and add another one with the capacity we need.
2547                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2548                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2549                         short_channel_id: 3,
2550                         timestamp: 4,
2551                         flags: 2,
2552                         cltv_expiry_delta: 0,
2553                         htlc_minimum_msat: 0,
2554                         htlc_maximum_msat: OptionalField::Absent,
2555                         fee_base_msat: 0,
2556                         fee_proportional_millionths: 0,
2557                         excess_data: Vec::new()
2558                 });
2559
2560                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2561                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2562                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2563                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2564                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2565
2566                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2567                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2568
2569                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2570                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2571                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2572                         short_channel_id: 333,
2573                         timestamp: 1,
2574                         flags: 0,
2575                         cltv_expiry_delta: (3 << 8) | 1,
2576                         htlc_minimum_msat: 0,
2577                         htlc_maximum_msat: OptionalField::Absent,
2578                         fee_base_msat: 0,
2579                         fee_proportional_millionths: 0,
2580                         excess_data: Vec::new()
2581                 });
2582                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2583                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2584                         short_channel_id: 333,
2585                         timestamp: 1,
2586                         flags: 1,
2587                         cltv_expiry_delta: (3 << 8) | 2,
2588                         htlc_minimum_msat: 0,
2589                         htlc_maximum_msat: OptionalField::Absent,
2590                         fee_base_msat: 100,
2591                         fee_proportional_millionths: 0,
2592                         excess_data: Vec::new()
2593                 });
2594
2595                 {
2596                         // Attempt to route more than available results in a failure.
2597                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2598                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2599                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2600                         } else { panic!(); }
2601                 }
2602
2603                 {
2604                         // Now, attempt to route an exact amount we have should be fine.
2605                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2606                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2607                         assert_eq!(route.paths.len(), 1);
2608                         let path = route.paths.last().unwrap();
2609                         assert_eq!(path.len(), 2);
2610                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2611                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2612                 }
2613
2614                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2615                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2616                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2617                         short_channel_id: 333,
2618                         timestamp: 6,
2619                         flags: 0,
2620                         cltv_expiry_delta: 0,
2621                         htlc_minimum_msat: 0,
2622                         htlc_maximum_msat: OptionalField::Present(10_000),
2623                         fee_base_msat: 0,
2624                         fee_proportional_millionths: 0,
2625                         excess_data: Vec::new()
2626                 });
2627
2628                 {
2629                         // Attempt to route more than available results in a failure.
2630                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2631                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2632                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2633                         } else { panic!(); }
2634                 }
2635
2636                 {
2637                         // Now, attempt to route an exact amount we have should be fine.
2638                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2639                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2640                         assert_eq!(route.paths.len(), 1);
2641                         let path = route.paths.last().unwrap();
2642                         assert_eq!(path.len(), 2);
2643                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2644                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2645                 }
2646         }
2647
2648         #[test]
2649         fn available_liquidity_last_hop_test() {
2650                 // Check that available liquidity properly limits the path even when only
2651                 // one of the latter hops is limited.
2652                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2653                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2654
2655                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2656                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2657                 // Total capacity: 50 sats.
2658
2659                 // Disable other potential paths.
2660                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2661                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2662                         short_channel_id: 2,
2663                         timestamp: 2,
2664                         flags: 2,
2665                         cltv_expiry_delta: 0,
2666                         htlc_minimum_msat: 0,
2667                         htlc_maximum_msat: OptionalField::Present(100_000),
2668                         fee_base_msat: 0,
2669                         fee_proportional_millionths: 0,
2670                         excess_data: Vec::new()
2671                 });
2672                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2673                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2674                         short_channel_id: 7,
2675                         timestamp: 2,
2676                         flags: 2,
2677                         cltv_expiry_delta: 0,
2678                         htlc_minimum_msat: 0,
2679                         htlc_maximum_msat: OptionalField::Present(100_000),
2680                         fee_base_msat: 0,
2681                         fee_proportional_millionths: 0,
2682                         excess_data: Vec::new()
2683                 });
2684
2685                 // Limit capacities
2686
2687                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2688                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2689                         short_channel_id: 12,
2690                         timestamp: 2,
2691                         flags: 0,
2692                         cltv_expiry_delta: 0,
2693                         htlc_minimum_msat: 0,
2694                         htlc_maximum_msat: OptionalField::Present(100_000),
2695                         fee_base_msat: 0,
2696                         fee_proportional_millionths: 0,
2697                         excess_data: Vec::new()
2698                 });
2699                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2700                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2701                         short_channel_id: 13,
2702                         timestamp: 2,
2703                         flags: 0,
2704                         cltv_expiry_delta: 0,
2705                         htlc_minimum_msat: 0,
2706                         htlc_maximum_msat: OptionalField::Present(100_000),
2707                         fee_base_msat: 0,
2708                         fee_proportional_millionths: 0,
2709                         excess_data: Vec::new()
2710                 });
2711
2712                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2713                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2714                         short_channel_id: 6,
2715                         timestamp: 2,
2716                         flags: 0,
2717                         cltv_expiry_delta: 0,
2718                         htlc_minimum_msat: 0,
2719                         htlc_maximum_msat: OptionalField::Present(50_000),
2720                         fee_base_msat: 0,
2721                         fee_proportional_millionths: 0,
2722                         excess_data: Vec::new()
2723                 });
2724                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2725                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2726                         short_channel_id: 11,
2727                         timestamp: 2,
2728                         flags: 0,
2729                         cltv_expiry_delta: 0,
2730                         htlc_minimum_msat: 0,
2731                         htlc_maximum_msat: OptionalField::Present(100_000),
2732                         fee_base_msat: 0,
2733                         fee_proportional_millionths: 0,
2734                         excess_data: Vec::new()
2735                 });
2736                 {
2737                         // Attempt to route more than available results in a failure.
2738                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2739                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2740                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2741                         } else { panic!(); }
2742                 }
2743
2744                 {
2745                         // Now, attempt to route 49 sats (just a bit below the capacity).
2746                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2747                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2748                         assert_eq!(route.paths.len(), 1);
2749                         let mut total_amount_paid_msat = 0;
2750                         for path in &route.paths {
2751                                 assert_eq!(path.len(), 4);
2752                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2753                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2754                         }
2755                         assert_eq!(total_amount_paid_msat, 49_000);
2756                 }
2757
2758                 {
2759                         // Attempt to route an exact amount is also fine
2760                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2761                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2762                         assert_eq!(route.paths.len(), 1);
2763                         let mut total_amount_paid_msat = 0;
2764                         for path in &route.paths {
2765                                 assert_eq!(path.len(), 4);
2766                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2767                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2768                         }
2769                         assert_eq!(total_amount_paid_msat, 50_000);
2770                 }
2771         }
2772
2773         #[test]
2774         fn ignore_fee_first_hop_test() {
2775                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2776                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2777
2778                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2779                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2780                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2781                         short_channel_id: 1,
2782                         timestamp: 2,
2783                         flags: 0,
2784                         cltv_expiry_delta: 0,
2785                         htlc_minimum_msat: 0,
2786                         htlc_maximum_msat: OptionalField::Present(100_000),
2787                         fee_base_msat: 1_000_000,
2788                         fee_proportional_millionths: 0,
2789                         excess_data: Vec::new()
2790                 });
2791                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2792                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2793                         short_channel_id: 3,
2794                         timestamp: 2,
2795                         flags: 0,
2796                         cltv_expiry_delta: 0,
2797                         htlc_minimum_msat: 0,
2798                         htlc_maximum_msat: OptionalField::Present(50_000),
2799                         fee_base_msat: 0,
2800                         fee_proportional_millionths: 0,
2801                         excess_data: Vec::new()
2802                 });
2803
2804                 {
2805                         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();
2806                         assert_eq!(route.paths.len(), 1);
2807                         let mut total_amount_paid_msat = 0;
2808                         for path in &route.paths {
2809                                 assert_eq!(path.len(), 2);
2810                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2811                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2812                         }
2813                         assert_eq!(total_amount_paid_msat, 50_000);
2814                 }
2815         }
2816
2817         #[test]
2818         fn simple_mpp_route_test() {
2819                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2820                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2821
2822                 // We need a route consisting of 3 paths:
2823                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2824                 // To achieve this, the amount being transferred should be around
2825                 // the total capacity of these 3 paths.
2826
2827                 // First, we set limits on these (previously unlimited) channels.
2828                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2829
2830                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2831                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2832                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2833                         short_channel_id: 1,
2834                         timestamp: 2,
2835                         flags: 0,
2836                         cltv_expiry_delta: 0,
2837                         htlc_minimum_msat: 0,
2838                         htlc_maximum_msat: OptionalField::Present(100_000),
2839                         fee_base_msat: 0,
2840                         fee_proportional_millionths: 0,
2841                         excess_data: Vec::new()
2842                 });
2843                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2844                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2845                         short_channel_id: 3,
2846                         timestamp: 2,
2847                         flags: 0,
2848                         cltv_expiry_delta: 0,
2849                         htlc_minimum_msat: 0,
2850                         htlc_maximum_msat: OptionalField::Present(50_000),
2851                         fee_base_msat: 0,
2852                         fee_proportional_millionths: 0,
2853                         excess_data: Vec::new()
2854                 });
2855
2856                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2857                 // (total limit 60).
2858                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2859                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2860                         short_channel_id: 12,
2861                         timestamp: 2,
2862                         flags: 0,
2863                         cltv_expiry_delta: 0,
2864                         htlc_minimum_msat: 0,
2865                         htlc_maximum_msat: OptionalField::Present(60_000),
2866                         fee_base_msat: 0,
2867                         fee_proportional_millionths: 0,
2868                         excess_data: Vec::new()
2869                 });
2870                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2871                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2872                         short_channel_id: 13,
2873                         timestamp: 2,
2874                         flags: 0,
2875                         cltv_expiry_delta: 0,
2876                         htlc_minimum_msat: 0,
2877                         htlc_maximum_msat: OptionalField::Present(60_000),
2878                         fee_base_msat: 0,
2879                         fee_proportional_millionths: 0,
2880                         excess_data: Vec::new()
2881                 });
2882
2883                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2884                 // (total capacity 180 sats).
2885                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2886                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2887                         short_channel_id: 2,
2888                         timestamp: 2,
2889                         flags: 0,
2890                         cltv_expiry_delta: 0,
2891                         htlc_minimum_msat: 0,
2892                         htlc_maximum_msat: OptionalField::Present(200_000),
2893                         fee_base_msat: 0,
2894                         fee_proportional_millionths: 0,
2895                         excess_data: Vec::new()
2896                 });
2897                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2898                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2899                         short_channel_id: 4,
2900                         timestamp: 2,
2901                         flags: 0,
2902                         cltv_expiry_delta: 0,
2903                         htlc_minimum_msat: 0,
2904                         htlc_maximum_msat: OptionalField::Present(180_000),
2905                         fee_base_msat: 0,
2906                         fee_proportional_millionths: 0,
2907                         excess_data: Vec::new()
2908                 });
2909
2910                 {
2911                         // Attempt to route more than available results in a failure.
2912                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2913                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2914                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2915                         } else { panic!(); }
2916                 }
2917
2918                 {
2919                         // Now, attempt to route 250 sats (just a bit below the capacity).
2920                         // Our algorithm should provide us with these 3 paths.
2921                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2922                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2923                         assert_eq!(route.paths.len(), 3);
2924                         let mut total_amount_paid_msat = 0;
2925                         for path in &route.paths {
2926                                 assert_eq!(path.len(), 2);
2927                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2928                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2929                         }
2930                         assert_eq!(total_amount_paid_msat, 250_000);
2931                 }
2932
2933                 {
2934                         // Attempt to route an exact amount is also fine
2935                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2936                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2937                         assert_eq!(route.paths.len(), 3);
2938                         let mut total_amount_paid_msat = 0;
2939                         for path in &route.paths {
2940                                 assert_eq!(path.len(), 2);
2941                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2942                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2943                         }
2944                         assert_eq!(total_amount_paid_msat, 290_000);
2945                 }
2946         }
2947
2948         #[test]
2949         fn long_mpp_route_test() {
2950                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2951                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2952
2953                 // We need a route consisting of 3 paths:
2954                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2955                 // Note that these paths overlap (channels 5, 12, 13).
2956                 // We will route 300 sats.
2957                 // Each path will have 100 sats capacity, those channels which
2958                 // are used twice will have 200 sats capacity.
2959
2960                 // Disable other potential paths.
2961                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2962                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2963                         short_channel_id: 2,
2964                         timestamp: 2,
2965                         flags: 2,
2966                         cltv_expiry_delta: 0,
2967                         htlc_minimum_msat: 0,
2968                         htlc_maximum_msat: OptionalField::Present(100_000),
2969                         fee_base_msat: 0,
2970                         fee_proportional_millionths: 0,
2971                         excess_data: Vec::new()
2972                 });
2973                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2974                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2975                         short_channel_id: 7,
2976                         timestamp: 2,
2977                         flags: 2,
2978                         cltv_expiry_delta: 0,
2979                         htlc_minimum_msat: 0,
2980                         htlc_maximum_msat: OptionalField::Present(100_000),
2981                         fee_base_msat: 0,
2982                         fee_proportional_millionths: 0,
2983                         excess_data: Vec::new()
2984                 });
2985
2986                 // Path via {node0, node2} is channels {1, 3, 5}.
2987                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2988                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2989                         short_channel_id: 1,
2990                         timestamp: 2,
2991                         flags: 0,
2992                         cltv_expiry_delta: 0,
2993                         htlc_minimum_msat: 0,
2994                         htlc_maximum_msat: OptionalField::Present(100_000),
2995                         fee_base_msat: 0,
2996                         fee_proportional_millionths: 0,
2997                         excess_data: Vec::new()
2998                 });
2999                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3000                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3001                         short_channel_id: 3,
3002                         timestamp: 2,
3003                         flags: 0,
3004                         cltv_expiry_delta: 0,
3005                         htlc_minimum_msat: 0,
3006                         htlc_maximum_msat: OptionalField::Present(100_000),
3007                         fee_base_msat: 0,
3008                         fee_proportional_millionths: 0,
3009                         excess_data: Vec::new()
3010                 });
3011
3012                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3013                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3014                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3015                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3016                         short_channel_id: 5,
3017                         timestamp: 2,
3018                         flags: 0,
3019                         cltv_expiry_delta: 0,
3020                         htlc_minimum_msat: 0,
3021                         htlc_maximum_msat: OptionalField::Present(200_000),
3022                         fee_base_msat: 0,
3023                         fee_proportional_millionths: 0,
3024                         excess_data: Vec::new()
3025                 });
3026
3027                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3028                 // Add 100 sats to the capacities of {12, 13}, because these channels
3029                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3030                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3031                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3032                         short_channel_id: 12,
3033                         timestamp: 2,
3034                         flags: 0,
3035                         cltv_expiry_delta: 0,
3036                         htlc_minimum_msat: 0,
3037                         htlc_maximum_msat: OptionalField::Present(200_000),
3038                         fee_base_msat: 0,
3039                         fee_proportional_millionths: 0,
3040                         excess_data: Vec::new()
3041                 });
3042                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3043                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3044                         short_channel_id: 13,
3045                         timestamp: 2,
3046                         flags: 0,
3047                         cltv_expiry_delta: 0,
3048                         htlc_minimum_msat: 0,
3049                         htlc_maximum_msat: OptionalField::Present(200_000),
3050                         fee_base_msat: 0,
3051                         fee_proportional_millionths: 0,
3052                         excess_data: Vec::new()
3053                 });
3054
3055                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3056                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3057                         short_channel_id: 6,
3058                         timestamp: 2,
3059                         flags: 0,
3060                         cltv_expiry_delta: 0,
3061                         htlc_minimum_msat: 0,
3062                         htlc_maximum_msat: OptionalField::Present(100_000),
3063                         fee_base_msat: 0,
3064                         fee_proportional_millionths: 0,
3065                         excess_data: Vec::new()
3066                 });
3067                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3068                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3069                         short_channel_id: 11,
3070                         timestamp: 2,
3071                         flags: 0,
3072                         cltv_expiry_delta: 0,
3073                         htlc_minimum_msat: 0,
3074                         htlc_maximum_msat: OptionalField::Present(100_000),
3075                         fee_base_msat: 0,
3076                         fee_proportional_millionths: 0,
3077                         excess_data: Vec::new()
3078                 });
3079
3080                 // Path via {node7, node2} is channels {12, 13, 5}.
3081                 // We already limited them to 200 sats (they are used twice for 100 sats).
3082                 // Nothing to do here.
3083
3084                 {
3085                         // Attempt to route more than available results in a failure.
3086                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3087                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3088                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3089                         } else { panic!(); }
3090                 }
3091
3092                 {
3093                         // Now, attempt to route 300 sats (exact amount we can route).
3094                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3095                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3096                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3097                         assert_eq!(route.paths.len(), 3);
3098
3099                         let mut total_amount_paid_msat = 0;
3100                         for path in &route.paths {
3101                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3102                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3103                         }
3104                         assert_eq!(total_amount_paid_msat, 300_000);
3105                 }
3106
3107         }
3108
3109         #[test]
3110         fn mpp_cheaper_route_test() {
3111                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3112                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3113
3114                 // This test checks that if we have two cheaper paths and one more expensive path,
3115                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3116                 // two cheaper paths will be taken.
3117                 // These paths have equal available liquidity.
3118
3119                 // We need a combination of 3 paths:
3120                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3121                 // Note that these paths overlap (channels 5, 12, 13).
3122                 // Each path will have 100 sats capacity, those channels which
3123                 // are used twice will have 200 sats capacity.
3124
3125                 // Disable other potential paths.
3126                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3127                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3128                         short_channel_id: 2,
3129                         timestamp: 2,
3130                         flags: 2,
3131                         cltv_expiry_delta: 0,
3132                         htlc_minimum_msat: 0,
3133                         htlc_maximum_msat: OptionalField::Present(100_000),
3134                         fee_base_msat: 0,
3135                         fee_proportional_millionths: 0,
3136                         excess_data: Vec::new()
3137                 });
3138                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3139                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3140                         short_channel_id: 7,
3141                         timestamp: 2,
3142                         flags: 2,
3143                         cltv_expiry_delta: 0,
3144                         htlc_minimum_msat: 0,
3145                         htlc_maximum_msat: OptionalField::Present(100_000),
3146                         fee_base_msat: 0,
3147                         fee_proportional_millionths: 0,
3148                         excess_data: Vec::new()
3149                 });
3150
3151                 // Path via {node0, node2} is channels {1, 3, 5}.
3152                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3153                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3154                         short_channel_id: 1,
3155                         timestamp: 2,
3156                         flags: 0,
3157                         cltv_expiry_delta: 0,
3158                         htlc_minimum_msat: 0,
3159                         htlc_maximum_msat: OptionalField::Present(100_000),
3160                         fee_base_msat: 0,
3161                         fee_proportional_millionths: 0,
3162                         excess_data: Vec::new()
3163                 });
3164                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3165                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3166                         short_channel_id: 3,
3167                         timestamp: 2,
3168                         flags: 0,
3169                         cltv_expiry_delta: 0,
3170                         htlc_minimum_msat: 0,
3171                         htlc_maximum_msat: OptionalField::Present(100_000),
3172                         fee_base_msat: 0,
3173                         fee_proportional_millionths: 0,
3174                         excess_data: Vec::new()
3175                 });
3176
3177                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3178                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3179                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3180                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3181                         short_channel_id: 5,
3182                         timestamp: 2,
3183                         flags: 0,
3184                         cltv_expiry_delta: 0,
3185                         htlc_minimum_msat: 0,
3186                         htlc_maximum_msat: OptionalField::Present(200_000),
3187                         fee_base_msat: 0,
3188                         fee_proportional_millionths: 0,
3189                         excess_data: Vec::new()
3190                 });
3191
3192                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3193                 // Add 100 sats to the capacities of {12, 13}, because these channels
3194                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3195                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3196                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3197                         short_channel_id: 12,
3198                         timestamp: 2,
3199                         flags: 0,
3200                         cltv_expiry_delta: 0,
3201                         htlc_minimum_msat: 0,
3202                         htlc_maximum_msat: OptionalField::Present(200_000),
3203                         fee_base_msat: 0,
3204                         fee_proportional_millionths: 0,
3205                         excess_data: Vec::new()
3206                 });
3207                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3208                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3209                         short_channel_id: 13,
3210                         timestamp: 2,
3211                         flags: 0,
3212                         cltv_expiry_delta: 0,
3213                         htlc_minimum_msat: 0,
3214                         htlc_maximum_msat: OptionalField::Present(200_000),
3215                         fee_base_msat: 0,
3216                         fee_proportional_millionths: 0,
3217                         excess_data: Vec::new()
3218                 });
3219
3220                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3221                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3222                         short_channel_id: 6,
3223                         timestamp: 2,
3224                         flags: 0,
3225                         cltv_expiry_delta: 0,
3226                         htlc_minimum_msat: 0,
3227                         htlc_maximum_msat: OptionalField::Present(100_000),
3228                         fee_base_msat: 1_000,
3229                         fee_proportional_millionths: 0,
3230                         excess_data: Vec::new()
3231                 });
3232                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3233                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3234                         short_channel_id: 11,
3235                         timestamp: 2,
3236                         flags: 0,
3237                         cltv_expiry_delta: 0,
3238                         htlc_minimum_msat: 0,
3239                         htlc_maximum_msat: OptionalField::Present(100_000),
3240                         fee_base_msat: 0,
3241                         fee_proportional_millionths: 0,
3242                         excess_data: Vec::new()
3243                 });
3244
3245                 // Path via {node7, node2} is channels {12, 13, 5}.
3246                 // We already limited them to 200 sats (they are used twice for 100 sats).
3247                 // Nothing to do here.
3248
3249                 {
3250                         // Now, attempt to route 180 sats.
3251                         // Our algorithm should provide us with these 2 paths.
3252                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3253                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3254                         assert_eq!(route.paths.len(), 2);
3255
3256                         let mut total_value_transferred_msat = 0;
3257                         let mut total_paid_msat = 0;
3258                         for path in &route.paths {
3259                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3260                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3261                                 for hop in path {
3262                                         total_paid_msat += hop.fee_msat;
3263                                 }
3264                         }
3265                         // If we paid fee, this would be higher.
3266                         assert_eq!(total_value_transferred_msat, 180_000);
3267                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3268                         assert_eq!(total_fees_paid, 0);
3269                 }
3270         }
3271
3272         #[test]
3273         fn fees_on_mpp_route_test() {
3274                 // This test makes sure that MPP algorithm properly takes into account
3275                 // fees charged on the channels, by making the fees impactful:
3276                 // if the fee is not properly accounted for, the behavior is different.
3277                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3278                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3279
3280                 // We need a route consisting of 2 paths:
3281                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3282                 // We will route 200 sats, Each path will have 100 sats capacity.
3283
3284                 // This test is not particularly stable: e.g.,
3285                 // there's a way to route via {node0, node2, node4}.
3286                 // It works while pathfinding is deterministic, but can be broken otherwise.
3287                 // It's fine to ignore this concern for now.
3288
3289                 // Disable other potential paths.
3290                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3291                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3292                         short_channel_id: 2,
3293                         timestamp: 2,
3294                         flags: 2,
3295                         cltv_expiry_delta: 0,
3296                         htlc_minimum_msat: 0,
3297                         htlc_maximum_msat: OptionalField::Present(100_000),
3298                         fee_base_msat: 0,
3299                         fee_proportional_millionths: 0,
3300                         excess_data: Vec::new()
3301                 });
3302
3303                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3304                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3305                         short_channel_id: 7,
3306                         timestamp: 2,
3307                         flags: 2,
3308                         cltv_expiry_delta: 0,
3309                         htlc_minimum_msat: 0,
3310                         htlc_maximum_msat: OptionalField::Present(100_000),
3311                         fee_base_msat: 0,
3312                         fee_proportional_millionths: 0,
3313                         excess_data: Vec::new()
3314                 });
3315
3316                 // Path via {node0, node2} is channels {1, 3, 5}.
3317                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3318                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3319                         short_channel_id: 1,
3320                         timestamp: 2,
3321                         flags: 0,
3322                         cltv_expiry_delta: 0,
3323                         htlc_minimum_msat: 0,
3324                         htlc_maximum_msat: OptionalField::Present(100_000),
3325                         fee_base_msat: 0,
3326                         fee_proportional_millionths: 0,
3327                         excess_data: Vec::new()
3328                 });
3329                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3330                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3331                         short_channel_id: 3,
3332                         timestamp: 2,
3333                         flags: 0,
3334                         cltv_expiry_delta: 0,
3335                         htlc_minimum_msat: 0,
3336                         htlc_maximum_msat: OptionalField::Present(100_000),
3337                         fee_base_msat: 0,
3338                         fee_proportional_millionths: 0,
3339                         excess_data: Vec::new()
3340                 });
3341
3342                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3343                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3344                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3345                         short_channel_id: 5,
3346                         timestamp: 2,
3347                         flags: 0,
3348                         cltv_expiry_delta: 0,
3349                         htlc_minimum_msat: 0,
3350                         htlc_maximum_msat: OptionalField::Present(100_000),
3351                         fee_base_msat: 0,
3352                         fee_proportional_millionths: 0,
3353                         excess_data: Vec::new()
3354                 });
3355
3356                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3357                 // All channels should be 100 sats capacity. But for the fee experiment,
3358                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3359                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3360                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3361                 // so no matter how large are other channels,
3362                 // the whole path will be limited by 100 sats with just these 2 conditions:
3363                 // - channel 12 capacity is 250 sats
3364                 // - fee for channel 6 is 150 sats
3365                 // Let's test this by enforcing these 2 conditions and removing other limits.
3366                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3367                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3368                         short_channel_id: 12,
3369                         timestamp: 2,
3370                         flags: 0,
3371                         cltv_expiry_delta: 0,
3372                         htlc_minimum_msat: 0,
3373                         htlc_maximum_msat: OptionalField::Present(250_000),
3374                         fee_base_msat: 0,
3375                         fee_proportional_millionths: 0,
3376                         excess_data: Vec::new()
3377                 });
3378                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3379                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3380                         short_channel_id: 13,
3381                         timestamp: 2,
3382                         flags: 0,
3383                         cltv_expiry_delta: 0,
3384                         htlc_minimum_msat: 0,
3385                         htlc_maximum_msat: OptionalField::Absent,
3386                         fee_base_msat: 0,
3387                         fee_proportional_millionths: 0,
3388                         excess_data: Vec::new()
3389                 });
3390
3391                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3392                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3393                         short_channel_id: 6,
3394                         timestamp: 2,
3395                         flags: 0,
3396                         cltv_expiry_delta: 0,
3397                         htlc_minimum_msat: 0,
3398                         htlc_maximum_msat: OptionalField::Absent,
3399                         fee_base_msat: 150_000,
3400                         fee_proportional_millionths: 0,
3401                         excess_data: Vec::new()
3402                 });
3403                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3404                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3405                         short_channel_id: 11,
3406                         timestamp: 2,
3407                         flags: 0,
3408                         cltv_expiry_delta: 0,
3409                         htlc_minimum_msat: 0,
3410                         htlc_maximum_msat: OptionalField::Absent,
3411                         fee_base_msat: 0,
3412                         fee_proportional_millionths: 0,
3413                         excess_data: Vec::new()
3414                 });
3415
3416                 {
3417                         // Attempt to route more than available results in a failure.
3418                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3419                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3420                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3421                         } else { panic!(); }
3422                 }
3423
3424                 {
3425                         // Now, attempt to route 200 sats (exact amount we can route).
3426                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3427                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3428                         assert_eq!(route.paths.len(), 2);
3429
3430                         let mut total_amount_paid_msat = 0;
3431                         for path in &route.paths {
3432                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3433                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3434                         }
3435                         assert_eq!(total_amount_paid_msat, 200_000);
3436                 }
3437
3438         }
3439
3440         #[test]
3441         fn drop_lowest_channel_mpp_route_test() {
3442                 // This test checks that low-capacity channel is dropped when after
3443                 // path finding we realize that we found more capacity than we need.
3444                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3445                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3446
3447                 // We need a route consisting of 3 paths:
3448                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3449
3450                 // The first and the second paths should be sufficient, but the third should be
3451                 // cheaper, so that we select it but drop later.
3452
3453                 // First, we set limits on these (previously unlimited) channels.
3454                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3455
3456                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3457                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3458                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3459                         short_channel_id: 1,
3460                         timestamp: 2,
3461                         flags: 0,
3462                         cltv_expiry_delta: 0,
3463                         htlc_minimum_msat: 0,
3464                         htlc_maximum_msat: OptionalField::Present(100_000),
3465                         fee_base_msat: 0,
3466                         fee_proportional_millionths: 0,
3467                         excess_data: Vec::new()
3468                 });
3469                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3470                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3471                         short_channel_id: 3,
3472                         timestamp: 2,
3473                         flags: 0,
3474                         cltv_expiry_delta: 0,
3475                         htlc_minimum_msat: 0,
3476                         htlc_maximum_msat: OptionalField::Present(50_000),
3477                         fee_base_msat: 100,
3478                         fee_proportional_millionths: 0,
3479                         excess_data: Vec::new()
3480                 });
3481
3482                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3483                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3484                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3485                         short_channel_id: 12,
3486                         timestamp: 2,
3487                         flags: 0,
3488                         cltv_expiry_delta: 0,
3489                         htlc_minimum_msat: 0,
3490                         htlc_maximum_msat: OptionalField::Present(60_000),
3491                         fee_base_msat: 100,
3492                         fee_proportional_millionths: 0,
3493                         excess_data: Vec::new()
3494                 });
3495                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3496                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3497                         short_channel_id: 13,
3498                         timestamp: 2,
3499                         flags: 0,
3500                         cltv_expiry_delta: 0,
3501                         htlc_minimum_msat: 0,
3502                         htlc_maximum_msat: OptionalField::Present(60_000),
3503                         fee_base_msat: 0,
3504                         fee_proportional_millionths: 0,
3505                         excess_data: Vec::new()
3506                 });
3507
3508                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3509                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3510                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3511                         short_channel_id: 2,
3512                         timestamp: 2,
3513                         flags: 0,
3514                         cltv_expiry_delta: 0,
3515                         htlc_minimum_msat: 0,
3516                         htlc_maximum_msat: OptionalField::Present(20_000),
3517                         fee_base_msat: 0,
3518                         fee_proportional_millionths: 0,
3519                         excess_data: Vec::new()
3520                 });
3521                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3522                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3523                         short_channel_id: 4,
3524                         timestamp: 2,
3525                         flags: 0,
3526                         cltv_expiry_delta: 0,
3527                         htlc_minimum_msat: 0,
3528                         htlc_maximum_msat: OptionalField::Present(20_000),
3529                         fee_base_msat: 0,
3530                         fee_proportional_millionths: 0,
3531                         excess_data: Vec::new()
3532                 });
3533
3534                 {
3535                         // Attempt to route more than available results in a failure.
3536                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3537                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3538                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3539                         } else { panic!(); }
3540                 }
3541
3542                 {
3543                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3544                         // Our algorithm should provide us with these 3 paths.
3545                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3546                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3547                         assert_eq!(route.paths.len(), 3);
3548                         let mut total_amount_paid_msat = 0;
3549                         for path in &route.paths {
3550                                 assert_eq!(path.len(), 2);
3551                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3552                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3553                         }
3554                         assert_eq!(total_amount_paid_msat, 125_000);
3555                 }
3556
3557                 {
3558                         // Attempt to route without the last small cheap channel
3559                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3560                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3561                         assert_eq!(route.paths.len(), 2);
3562                         let mut total_amount_paid_msat = 0;
3563                         for path in &route.paths {
3564                                 assert_eq!(path.len(), 2);
3565                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3566                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3567                         }
3568                         assert_eq!(total_amount_paid_msat, 90_000);
3569                 }
3570         }
3571
3572         #[test]
3573         fn min_criteria_consistency() {
3574                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3575                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3576                 // was updated with a different criterion from the heap sorting, resulting in loops in
3577                 // calculated paths. We test for that specific case here.
3578
3579                 // We construct a network that looks like this:
3580                 //
3581                 //            node2 -1(3)2- node3
3582                 //              2          2
3583                 //               (2)     (4)
3584                 //                  1   1
3585                 //    node1 -1(5)2- node4 -1(1)2- node6
3586                 //    2
3587                 //   (6)
3588                 //        1
3589                 // our_node
3590                 //
3591                 // We create a loop on the side of our real path - our destination is node 6, with a
3592                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3593                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3594                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3595                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3596                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3597                 // "previous hop" being set to node 3, creating a loop in the path.
3598                 let secp_ctx = Secp256k1::new();
3599                 let logger = Arc::new(test_utils::TestLogger::new());
3600                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3601                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3602
3603                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3604                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3605                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3606                         short_channel_id: 6,
3607                         timestamp: 1,
3608                         flags: 0,
3609                         cltv_expiry_delta: (6 << 8) | 0,
3610                         htlc_minimum_msat: 0,
3611                         htlc_maximum_msat: OptionalField::Absent,
3612                         fee_base_msat: 0,
3613                         fee_proportional_millionths: 0,
3614                         excess_data: Vec::new()
3615                 });
3616                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3617
3618                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3619                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3620                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3621                         short_channel_id: 5,
3622                         timestamp: 1,
3623                         flags: 0,
3624                         cltv_expiry_delta: (5 << 8) | 0,
3625                         htlc_minimum_msat: 0,
3626                         htlc_maximum_msat: OptionalField::Absent,
3627                         fee_base_msat: 100,
3628                         fee_proportional_millionths: 0,
3629                         excess_data: Vec::new()
3630                 });
3631                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3632
3633                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3634                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3635                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3636                         short_channel_id: 4,
3637                         timestamp: 1,
3638                         flags: 0,
3639                         cltv_expiry_delta: (4 << 8) | 0,
3640                         htlc_minimum_msat: 0,
3641                         htlc_maximum_msat: OptionalField::Absent,
3642                         fee_base_msat: 0,
3643                         fee_proportional_millionths: 0,
3644                         excess_data: Vec::new()
3645                 });
3646                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3647
3648                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3649                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3650                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3651                         short_channel_id: 3,
3652                         timestamp: 1,
3653                         flags: 0,
3654                         cltv_expiry_delta: (3 << 8) | 0,
3655                         htlc_minimum_msat: 0,
3656                         htlc_maximum_msat: OptionalField::Absent,
3657                         fee_base_msat: 0,
3658                         fee_proportional_millionths: 0,
3659                         excess_data: Vec::new()
3660                 });
3661                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
3662
3663                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
3664                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3665                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3666                         short_channel_id: 2,
3667                         timestamp: 1,
3668                         flags: 0,
3669                         cltv_expiry_delta: (2 << 8) | 0,
3670                         htlc_minimum_msat: 0,
3671                         htlc_maximum_msat: OptionalField::Absent,
3672                         fee_base_msat: 0,
3673                         fee_proportional_millionths: 0,
3674                         excess_data: Vec::new()
3675                 });
3676
3677                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
3678                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3679                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3680                         short_channel_id: 1,
3681                         timestamp: 1,
3682                         flags: 0,
3683                         cltv_expiry_delta: (1 << 8) | 0,
3684                         htlc_minimum_msat: 100,
3685                         htlc_maximum_msat: OptionalField::Absent,
3686                         fee_base_msat: 0,
3687                         fee_proportional_millionths: 0,
3688                         excess_data: Vec::new()
3689                 });
3690                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
3691
3692                 {
3693                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
3694                         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();
3695                         assert_eq!(route.paths.len(), 1);
3696                         assert_eq!(route.paths[0].len(), 3);
3697
3698                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
3699                         assert_eq!(route.paths[0][0].short_channel_id, 6);
3700                         assert_eq!(route.paths[0][0].fee_msat, 100);
3701                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
3702                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
3703                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
3704
3705                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
3706                         assert_eq!(route.paths[0][1].short_channel_id, 5);
3707                         assert_eq!(route.paths[0][1].fee_msat, 0);
3708                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
3709                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
3710                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
3711
3712                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
3713                         assert_eq!(route.paths[0][2].short_channel_id, 1);
3714                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
3715                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
3716                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
3717                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
3718                 }
3719         }
3720
3721
3722         #[test]
3723         fn exact_fee_liquidity_limit() {
3724                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
3725                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
3726                 // we calculated fees on a higher value, resulting in us ignoring such paths.
3727                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3728                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
3729
3730                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
3731                 // send.
3732                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3733                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3734                         short_channel_id: 2,
3735                         timestamp: 2,
3736                         flags: 0,
3737                         cltv_expiry_delta: 0,
3738                         htlc_minimum_msat: 0,
3739                         htlc_maximum_msat: OptionalField::Present(85_000),
3740                         fee_base_msat: 0,
3741                         fee_proportional_millionths: 0,
3742                         excess_data: Vec::new()
3743                 });
3744
3745                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3746                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3747                         short_channel_id: 12,
3748                         timestamp: 2,
3749                         flags: 0,
3750                         cltv_expiry_delta: (4 << 8) | 1,
3751                         htlc_minimum_msat: 0,
3752                         htlc_maximum_msat: OptionalField::Present(270_000),
3753                         fee_base_msat: 0,
3754                         fee_proportional_millionths: 1000000,
3755                         excess_data: Vec::new()
3756                 });
3757
3758                 {
3759                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
3760                         // 200% fee charged channel 13 in the 1-to-2 direction.
3761                         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();
3762                         assert_eq!(route.paths.len(), 1);
3763                         assert_eq!(route.paths[0].len(), 2);
3764
3765                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3766                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3767                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3768                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3769                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3770                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3771
3772                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3773                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3774                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3775                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3776                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
3777                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3778                 }
3779         }
3780
3781         #[test]
3782         fn htlc_max_reduction_below_min() {
3783                 // Test that if, while walking the graph, we reduce the value being sent to meet an
3784                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
3785                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
3786                 // resulting in us thinking there is no possible path, even if other paths exist.
3787                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3788                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3789
3790                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
3791                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
3792                 // then try to send 90_000.
3793                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3794                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3795                         short_channel_id: 2,
3796                         timestamp: 2,
3797                         flags: 0,
3798                         cltv_expiry_delta: 0,
3799                         htlc_minimum_msat: 0,
3800                         htlc_maximum_msat: OptionalField::Present(80_000),
3801                         fee_base_msat: 0,
3802                         fee_proportional_millionths: 0,
3803                         excess_data: Vec::new()
3804                 });
3805                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3806                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3807                         short_channel_id: 4,
3808                         timestamp: 2,
3809                         flags: 0,
3810                         cltv_expiry_delta: (4 << 8) | 1,
3811                         htlc_minimum_msat: 90_000,
3812                         htlc_maximum_msat: OptionalField::Absent,
3813                         fee_base_msat: 0,
3814                         fee_proportional_millionths: 0,
3815                         excess_data: Vec::new()
3816                 });
3817
3818                 {
3819                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
3820                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
3821                         // expensive) channels 12-13 path.
3822                         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();
3823                         assert_eq!(route.paths.len(), 1);
3824                         assert_eq!(route.paths[0].len(), 2);
3825
3826                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3827                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3828                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3829                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3830                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3831                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3832
3833                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3834                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3835                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3836                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3837                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
3838                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3839                 }
3840         }
3841
3842         use std::fs::File;
3843         use util::ser::Readable;
3844         /// Tries to open a network graph file, or panics with a URL to fetch it.
3845         pub(super) fn get_route_file() -> Result<std::fs::File, std::io::Error> {
3846                 let res = File::open("net_graph-2021-02-12.bin") // By default we're run in RL/lightning
3847                         .or_else(|_| File::open("lightning/net_graph-2021-02-12.bin")) // We may be run manually in RL/
3848                         .or_else(|_| { // Fall back to guessing based on the binary location
3849                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
3850                                 let mut path = std::env::current_exe().unwrap();
3851                                 path.pop(); // lightning-...
3852                                 path.pop(); // deps
3853                                 path.pop(); // debug
3854                                 path.pop(); // target
3855                                 path.push("lightning");
3856                                 path.push("net_graph-2021-02-12.bin");
3857                                 eprintln!("{}", path.to_str().unwrap());
3858                                 File::open(path)
3859                         });
3860                 #[cfg(require_route_graph_test)]
3861                 return Ok(res.expect("Didn't have route graph and was configured to require it"));
3862                 #[cfg(not(require_route_graph_test))]
3863                 return res;
3864         }
3865
3866         pub(super) fn random_init_seed() -> u64 {
3867                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
3868                 use std::hash::{BuildHasher, Hasher};
3869                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
3870                 println!("Using seed of {}", seed);
3871                 seed
3872         }
3873
3874         #[test]
3875         fn generate_routes() {
3876                 let mut d = match get_route_file() {
3877                         Ok(f) => f,
3878                         Err(_) => {
3879                                 eprintln!("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3880                                 return;
3881                         },
3882                 };
3883                 let graph = NetworkGraph::read(&mut d).unwrap();
3884
3885                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3886                 let mut seed = random_init_seed() as usize;
3887                 'load_endpoints: for _ in 0..10 {
3888                         loop {
3889                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3890                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3891                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3892                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3893                                 let amt = seed as u64 % 200_000_000;
3894                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3895                                         continue 'load_endpoints;
3896                                 }
3897                         }
3898                 }
3899         }
3900
3901         #[test]
3902         fn generate_routes_mpp() {
3903                 let mut d = match get_route_file() {
3904                         Ok(f) => f,
3905                         Err(_) => {
3906                                 eprintln!("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3907                                 return;
3908                         },
3909                 };
3910                 let graph = NetworkGraph::read(&mut d).unwrap();
3911
3912                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3913                 let mut seed = random_init_seed() as usize;
3914                 'load_endpoints: for _ in 0..10 {
3915                         loop {
3916                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3917                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3918                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3919                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3920                                 let amt = seed as u64 % 200_000_000;
3921                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3922                                         continue 'load_endpoints;
3923                                 }
3924                         }
3925                 }
3926         }
3927 }
3928
3929 #[cfg(all(test, feature = "unstable"))]
3930 mod benches {
3931         use super::*;
3932         use util::logger::{Logger, Record};
3933
3934         use test::Bencher;
3935
3936         struct DummyLogger {}
3937         impl Logger for DummyLogger {
3938                 fn log(&self, _record: &Record) {}
3939         }
3940
3941         #[bench]
3942         fn generate_routes(bench: &mut Bencher) {
3943                 let mut d = tests::get_route_file()
3944                         .expect("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3945                 let graph = NetworkGraph::read(&mut d).unwrap();
3946
3947                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3948                 let mut path_endpoints = Vec::new();
3949                 let mut seed: usize = 0xdeadbeef;
3950                 'load_endpoints: for _ in 0..100 {
3951                         loop {
3952                                 seed *= 0xdeadbeef;
3953                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3954                                 seed *= 0xdeadbeef;
3955                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3956                                 let amt = seed as u64 % 1_000_000;
3957                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3958                                         path_endpoints.push((src, dst, amt));
3959                                         continue 'load_endpoints;
3960                                 }
3961                         }
3962                 }
3963
3964                 // ...then benchmark finding paths between the nodes we learned.
3965                 let mut idx = 0;
3966                 bench.iter(|| {
3967                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3968                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3969                         idx += 1;
3970                 });
3971         }
3972
3973         #[bench]
3974         fn generate_mpp_routes(bench: &mut Bencher) {
3975                 let mut d = tests::get_route_file()
3976                         .expect("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3977                 let graph = NetworkGraph::read(&mut d).unwrap();
3978
3979                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3980                 let mut path_endpoints = Vec::new();
3981                 let mut seed: usize = 0xdeadbeef;
3982                 'load_endpoints: for _ in 0..100 {
3983                         loop {
3984                                 seed *= 0xdeadbeef;
3985                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3986                                 seed *= 0xdeadbeef;
3987                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3988                                 let amt = seed as u64 % 1_000_000;
3989                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3990                                         path_endpoints.push((src, dst, amt));
3991                                         continue 'load_endpoints;
3992                                 }
3993                         }
3994                 }
3995
3996                 // ...then benchmark finding paths between the nodes we learned.
3997                 let mut idx = 0;
3998                 bench.iter(|| {
3999                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4000                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
4001                         idx += 1;
4002                 });
4003         }
4004 }