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