_ 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         /// The maximum htlc_minimum_msat along the path, taking into consideration the fees required
 146         /// to meet the minimum over the hops required to get there.
 147         path_htlc_minimum_msat: u64,
 148 }
 149
 150 impl cmp::Ord for RouteGraphNode {
 151         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 152                 other.lowest_fee_to_peer_through_node.cmp(&self.lowest_fee_to_peer_through_node)
 153                         .then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 154         }
 155 }
 156
 157 impl cmp::PartialOrd for RouteGraphNode {
 158         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 159                 Some(self.cmp(other))
 160         }
 161 }
 162
 163 struct DummyDirectionalChannelInfo {
 164         cltv_expiry_delta: u32,
 165         htlc_minimum_msat: u64,
 166         htlc_maximum_msat: Option<u64>,
 167         fees: RoutingFees,
 168 }
 169
 170 /// It's useful to keep track of the hops associated with the fees required to use them,
 171 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 172 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 173 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 174 #[derive(Clone)]
 175 struct PathBuildingHop {
 176         /// Hop-specific details unrelated to the path during the routing phase,
 177         /// but rather relevant to the LN graph.
 178         route_hop: RouteHop,
 179         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 180         src_lowest_inbound_fees: RoutingFees,
 181         /// Fees of the channel used in this hop.
 182         channel_fees: RoutingFees,
 183         /// All the fees paid *after* this channel on the way to the destination
 184         next_hops_fee_msat: u64,
 185         /// Fee paid for the use of the current channel (see channel_fees).
 186         /// The value will be actually deducted from the counterparty balance on the previous link.
 187         hop_use_fee_msat: u64,
 188         /// Used to compare channels when choosing the for routing.
 189         /// Includes paying for the use of a hop and the following hops, as well as
 190         /// an estimated cost of reaching this hop.
 191         /// Might get stale when fees are recomputed. Primarily for internal use.
 192         total_fee_msat: u64,
 193         /// This is useful for update_value_and_recompute_fees to make sure
 194         /// we don't fall below the minimum. Should not be updated manually and
 195         /// generally should not be accessed.
 196         htlc_minimum_msat: u64,
 197 }
 198
 199 impl PathBuildingHop {
 200         // What we are paying for the use of this channels and the following channels.
 201         fn get_fee_paid_msat(&self) -> u64 {
 202                 if let Some(fee_paid_msat) =
 203                    self.next_hops_fee_msat.checked_add(self.hop_use_fee_msat) {
 204                         return fee_paid_msat;
 205                 } else {
 206                         return u64::max_value();
 207                 }
 208         }
 209 }
 210
 211 // Instantiated with a list of hops with correct data in them collected during path finding,
 212 // an instance of this struct should be further modified only via given methods.
 213 #[derive(Clone)]
 214 struct PaymentPath {
 215         hops: Vec<PathBuildingHop>,
 216 }
 217
 218 impl PaymentPath {
 219
 220         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 221         fn get_value_msat(&self) -> u64 {
 222                 self.hops.last().unwrap().route_hop.fee_msat
 223         }
 224
 225         fn get_total_fee_paid_msat(&self) -> u64 {
 226                 if self.hops.len() < 1 {
 227                         return 0;
 228                 }
 229                 let mut result = 0;
 230                 // Can't use next_hops_fee_msat because it gets outdated.
 231                 for (i, hop) in self.hops.iter().enumerate() {
 232                         if i != self.hops.len() - 1 {
 233                                 result += hop.route_hop.fee_msat;
 234                         }
 235                 }
 236                 return result;
 237         }
 238
 239         // If an amount transferred by the path is updated, the fees should be adjusted.
 240         // Any other way to change fees may result in an inconsistency.
 241         // Also, it's only safe to reduce the value, to not violate limits like
 242         // htlc_minimum_msat.
 243         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 244                 if value_msat == self.hops.last().unwrap().route_hop.fee_msat {
 245                         // Nothing to change.
 246                         return;
 247                 }
 248                 assert!(value_msat < self.hops.last().unwrap().route_hop.fee_msat);
 249
 250                 let mut total_fee_paid_msat = 0 as u64;
 251                 for i in (0..self.hops.len()).rev() {
 252                         let last_hop = i == self.hops.len() - 1;
 253
 254                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 255                         // will consist of the fees for the use of the next hop, and extra fees to match
 256                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 257                         let mut cur_hop_fees_msat = 0;
 258                         if !last_hop {
 259                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().hop_use_fee_msat;
 260                         }
 261
 262                         let mut cur_hop = self.hops.get_mut(i).unwrap();
 263                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 264                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 265                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 266                         // set it too high just to maliciously take more fees by exploiting this
 267                         // match htlc_minimum_msat logic.
 268                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 269                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 270                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 271                                 total_fee_paid_msat += extra_fees_msat;
 272                                 cur_hop_fees_msat += extra_fees_msat;
 273                         }
 274
 275                         if last_hop {
 276                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 277                                 // it still could overpay for the htlc_minimum_msat.
 278                                 cur_hop.route_hop.fee_msat = cur_hop_transferred_amount_msat;
 279                         } else {
 280                                 // Propagate updated fees for the use of the channels to one hop back, where they
 281                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 282                                 cur_hop.route_hop.fee_msat = cur_hop_fees_msat;
 283                         }
 284
 285                         // Fee for the use of the current hop which will be deducted on the previous hop.
 286                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 287                         // this channel is free for us.
 288                         if i != 0 {
 289                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 290                                         cur_hop.hop_use_fee_msat = new_fee;
 291                                         total_fee_paid_msat += new_fee;
 292                                 } else {
 293                                         // It should not be possible because this function is called only to reduce the
 294                                         // value. In that case, compute_fee was already called with the same fees for
 295                                         // larger amount and there was no overflow.
 296                                         unreachable!();
 297                                 }
 298                         }
 299                 }
 300         }
 301 }
 302
 303 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 304         let proportional_fee_millions =
 305                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 306         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 307                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 308
 309                 Some(new_fee)
 310         } else {
 311                 // This function may be (indirectly) called without any verification,
 312                 // with channel_fees provided by a caller. We should handle it gracefully.
 313                 None
 314         }
 315 }
 316
 317 /// Gets a route from us (payer) to the given target node (payee).
 318 ///
 319 /// Extra routing hops between known nodes and the target will be used if they are included in
 320 /// last_hops.
 321 ///
 322 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 323 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 324 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 325 /// in first_hops will be used.
 326 ///
 327 /// Panics if first_hops contains channels without short_channel_ids
 328 /// (ChannelManager::list_usable_channels will never include such channels).
 329 ///
 330 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 331 /// equal), however the enabled/disabled bit on such channels as well as the
 332 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 333 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, first_hops: Option<&[&ChannelDetails]>,
 334         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 335         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 336         // uptime/success in using a node in the past.
 337         if *payee == *our_node_id {
 338                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 339         }
 340
 341         if final_value_msat > MAX_VALUE_MSAT {
 342                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 343         }
 344
 345         if final_value_msat == 0 {
 346                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 347         }
 348
 349         for last_hop in last_hops {
 350                 if last_hop.src_node_id == *payee {
 351                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 352                 }
 353         }
 354
 355         // The general routing idea is the following:
 356         // 1. Fill first/last hops communicated by the caller.
 357         // 2. Attempt to construct a path from payer to payee for transferring
 358         //    any ~sufficient (described later) value.
 359         //    If succeed, remember which channels were used and how much liquidity they have available,
 360         //    so that future paths don't rely on the same liquidity.
 361         // 3. Prooceed to the next step if:
 362         //    - we hit the recommended target value;
 363         //    - OR if we could not construct a new path. Any next attempt will fail too.
 364         //    Otherwise, repeat step 2.
 365         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 366         //    (not recommended value). If yes, proceed. If not, fail routing.
 367         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 368         // 6. Of all the found paths, select only those with the lowest total fee.
 369         // 7. The last path in every selected route is likely to be more than we need.
 370         //    Reduce its value-to-transfer and recompute fees.
 371         // 8. Choose the best route by the lowest total fee.
 372
 373         // As for the actual search algorithm,
 374         // we do a payee-to-payer Dijkstra's sorting by each node's distance from the payee
 375         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty A*").
 376         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 377         // to use as the A* heuristic beyond just the cost to get one node further than the current
 378         // one.
 379
 380         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 381                 cltv_expiry_delta: 0,
 382                 htlc_minimum_msat: 0,
 383                 htlc_maximum_msat: None,
 384                 fees: RoutingFees {
 385                         base_msat: 0,
 386                         proportional_millionths: 0,
 387                 }
 388         };
 389
 390         let mut targets = BinaryHeap::new(); //TODO: Do we care about switching to eg Fibbonaci heap?
 391         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 392
 393         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 394         // Don't stop searching for paths when we think they're
 395         // sufficient to transfer a given value aggregately.
 396         // Search for higher value, so that we collect many more paths,
 397         // and then select the best combination among them.
 398         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 399         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 400
 401         // Step (1).
 402         // Prepare the data we'll use for payee-to-payer search by
 403         // inserting first hops suggested by the caller as targets.
 404         // Our search will then attempt to reach them while traversing from the payee node.
 405         let mut first_hop_targets = HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 406         if let Some(hops) = first_hops {
 407                 for chan in hops {
 408                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 409                         if chan.remote_network_id == *our_node_id {
 410                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 411                         }
 412                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.clone(), chan.outbound_capacity_msat));
 413                 }
 414                 if first_hop_targets.is_empty() {
 415                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 416                 }
 417         }
 418
 419         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 420         // This map allows paths to be aware of the channel use by other paths in the same call.
 421         // This would help to make a better path finding decisions and not "overbook" channels.
 422         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 423         let mut bookkeeped_channels_liquidity_available_msat = HashMap::new();
 424
 425         // Keeping track of how much value we already collected across other paths. Helps to decide:
 426         // - how much a new path should be transferring (upper bound);
 427         // - whether a channel should be disregarded because
 428         //   it's available liquidity is too small comparing to how much more we need to collect;
 429         // - when we want to stop looking for new paths.
 430         let mut already_collected_value_msat = 0;
 431
 432         macro_rules! add_entry {
 433                 // Adds entry which goes from $src_node_id to $dest_node_id
 434                 // over the channel with id $chan_id with fees described in
 435                 // $directional_info.
 436                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 437                 // since that value has to be transferred over this channel.
 438                 ( $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,
 439                    $next_hops_value_contribution: expr, $incl_fee_next_hops_htlc_minimum_msat: expr ) => {
 440                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 441                         // practice these cases should be caught earlier:
 442                         // - for regular channels at channel announcement (TODO)
 443                         // - for first and last hops early in get_route
 444                         if $src_node_id != $dest_node_id.clone() {
 445                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 446                                         let mut initial_liquidity_available_msat = None;
 447                                         if let Some(capacity_sats) = $capacity_sats {
 448                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 449                                         }
 450
 451                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 452                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 453                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 454                                                 } else {
 455                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 456                                                 }
 457                                         }
 458
 459                                         match initial_liquidity_available_msat {
 460                                                 Some(available_msat) => available_msat,
 461                                                 // We assume channels with unknown balance have
 462                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 463                                                 None => 250_000 * 1000
 464                                         }
 465                                 });
 466
 467                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 468                                 // It may be misleading because we might later choose to reduce the value transferred
 469                                 // over these channels, and the channel which was insufficient might become sufficient.
 470                                 // Worst case: we drop a good channel here because it can't cover the high following
 471                                 // fees caused by one expensive channel, but then this channel could have been used
 472                                 // if the amount being transferred over this path is lower.
 473                                 // We do this for now, but this is a subject for removal.
 474                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 475
 476                                         // Routing Fragmentation Mitigation heuristic:
 477                                         //
 478                                         // Routing fragmentation across many payment paths increases the overall routing
 479                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 480                                         // Taking too many smaller paths also increases the chance of payment failure.
 481                                         // Thus to avoid this effect, we require from our collected links to provide
 482                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 483                                         //
 484                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 485                                         // This means as we successfully advance in our collection,
 486                                         // the absolute liquidity contribution is lowered,
 487                                         // thus increasing the number of potential channels to be selected.
 488
 489                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up).
 490                                         let minimal_value_contribution_msat: u64 = (recommended_value_msat - already_collected_value_msat + 19) / 20;
 491                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 492                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 493
 494                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 495                                         // Includes paying fees for the use of the following channels.
 496                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 497                                                 Some(result) => result,
 498                                                 // Can't overflow due to how the values were computed right above.
 499                                                 None => unreachable!(),
 500                                         };
 501                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 502                                                 amount_to_transfer_over_msat >= $incl_fee_next_hops_htlc_minimum_msat;
 503
 504                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 505                                         // bother considering this channel.
 506                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 507                                         // be only reduced later (not increased), so this channel should just be skipped
 508                                         // as not sufficient.
 509                                         // TODO: Explore simply adding fee to hit htlc_minimum_msat
 510                                         if contributes_sufficient_value && over_path_minimum_msat {
 511                                                 let hm_entry = dist.entry(&$src_node_id);
 512                                                 let old_entry = hm_entry.or_insert_with(|| {
 513                                                         // If there was previously no known way to access
 514                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 515                                                         // a semi-dummy record just to compute the fees to reach the source node.
 516                                                         // This will affect our decision on selecting $chan_id
 517                                                         // as a way to reach the $dest_node_id.
 518                                                         let mut fee_base_msat = u32::max_value();
 519                                                         let mut fee_proportional_millionths = u32::max_value();
 520                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 521                                                                 fee_base_msat = fees.base_msat;
 522                                                                 fee_proportional_millionths = fees.proportional_millionths;
 523                                                         }
 524                                                         PathBuildingHop {
 525                                                                 route_hop: RouteHop {
 526                                                                         pubkey: $dest_node_id.clone(),
 527                                                                         node_features: NodeFeatures::empty(),
 528                                                                         short_channel_id: 0,
 529                                                                         channel_features: $chan_features.clone(),
 530                                                                         fee_msat: 0,
 531                                                                         cltv_expiry_delta: 0,
 532                                                                 },
 533                                                                 src_lowest_inbound_fees: RoutingFees {
 534                                                                         base_msat: fee_base_msat,
 535                                                                         proportional_millionths: fee_proportional_millionths,
 536                                                                 },
 537                                                                 channel_fees: $directional_info.fees,
 538                                                                 next_hops_fee_msat: u64::max_value(),
 539                                                                 hop_use_fee_msat: u64::max_value(),
 540                                                                 total_fee_msat: u64::max_value(),
 541                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 542                                                         }
 543                                                 });
 544
 545                                                 let mut hop_use_fee_msat = 0;
 546                                                 let mut total_fee_msat = $next_hops_fee_msat;
 547
 548                                                 // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 549                                                 // will have the same effective-fee
 550                                                 if $src_node_id != *our_node_id {
 551                                                         match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 552                                                                 // max_value means we'll always fail
 553                                                                 // the old_entry.total_fee_msat > total_fee_msat check
 554                                                                 None => total_fee_msat = u64::max_value(),
 555                                                                 Some(fee_msat) => {
 556                                                                         hop_use_fee_msat = fee_msat;
 557                                                                         total_fee_msat += hop_use_fee_msat;
 558                                                                         if let Some(prev_hop_fee_msat) = compute_fees(total_fee_msat + amount_to_transfer_over_msat,
 559                                                                                                                                                                 old_entry.src_lowest_inbound_fees) {
 560                                                                                 if let Some(incremented_total_fee_msat) = total_fee_msat.checked_add(prev_hop_fee_msat) {
 561                                                                                         total_fee_msat = incremented_total_fee_msat;
 562                                                                                 }
 563                                                                                 else {
 564                                                                                         // max_value means we'll always fail
 565                                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 566                                                                                         total_fee_msat = u64::max_value();
 567                                                                                 }
 568                                                                         } else {
 569                                                                                 // max_value means we'll always fail
 570                                                                                 // the old_entry.total_fee_msat > total_fee_msat check
 571                                                                                 total_fee_msat = u64::max_value();
 572                                                                         }
 573                                                                 }
 574                                                         }
 575                                                 }
 576
 577                                                 let new_graph_node = RouteGraphNode {
 578                                                         pubkey: $src_node_id,
 579                                                         lowest_fee_to_peer_through_node: total_fee_msat,
 580                                                         lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 581                                                         value_contribution_msat: value_contribution_msat,
 582                                                         path_htlc_minimum_msat: match compute_fees($incl_fee_next_hops_htlc_minimum_msat, $directional_info.fees) {
 583                                                                 Some(fee_msat) => cmp::max(fee_msat, $directional_info.htlc_minimum_msat),
 584                                                                 None => u64::max_value(),
 585                                                         },
 586                                                 };
 587
 588                                                 // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 589                                                 // if this way is cheaper than the already known
 590                                                 // (considering the cost to "reach" this channel from the route destination,
 591                                                 // the cost of using this channel,
 592                                                 // and the cost of routing to the source node of this channel).
 593                                                 // Also, consider that htlc_minimum_msat_difference, because we might end up
 594                                                 // paying it. Consider the following exploit:
 595                                                 // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 596                                                 // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 597                                                 // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 598                                                 // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 599                                                 // to this channel.
 600                                                 // TODO: this scoring could be smarter (e.g. 0.5*htlc_minimum_msat here).
 601                                                 let mut old_cost = old_entry.total_fee_msat;
 602                                                 if let Some(increased_old_cost) = old_cost.checked_add(old_entry.htlc_minimum_msat) {
 603                                                         old_cost = increased_old_cost;
 604                                                 } else {
 605                                                         old_cost = u64::max_value();
 606                                                 }
 607
 608                                                 let mut new_cost = total_fee_msat;
 609                                                 if let Some(increased_new_cost) = new_cost.checked_add($directional_info.htlc_minimum_msat) {
 610                                                         new_cost = increased_new_cost;
 611                                                 } else {
 612                                                         new_cost = u64::max_value();
 613                                                 }
 614
 615                                                 if new_cost < old_cost {
 616                                                         targets.push(new_graph_node);
 617                                                         old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 618                                                         old_entry.hop_use_fee_msat = hop_use_fee_msat;
 619                                                         old_entry.total_fee_msat = total_fee_msat;
 620                                                         old_entry.route_hop = RouteHop {
 621                                                                 pubkey: $dest_node_id.clone(),
 622                                                                 node_features: NodeFeatures::empty(),
 623                                                                 short_channel_id: $chan_id.clone(),
 624                                                                 channel_features: $chan_features.clone(),
 625                                                                 fee_msat: 0, // This value will be later filled with hop_use_fee_msat of the following channel
 626                                                                 cltv_expiry_delta: $directional_info.cltv_expiry_delta as u32,
 627                                                         };
 628                                                         old_entry.channel_fees = $directional_info.fees;
 629                                                         // It's probably fine to replace the old entry, because the new one
 630                                                         // passed the htlc_minimum-related checks above.
 631                                                         old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 632                                                 }
 633                                         }
 634                                 }
 635                         }
 636                 };
 637         }
 638
 639         // Find ways (channels with destination) to reach a given node and store them
 640         // in the corresponding data structures (routing graph etc).
 641         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 642         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 643         // This data can later be helpful to optimize routing (pay lower fees).
 644         macro_rules! add_entries_to_cheapest_to_target_node {
 645                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $incl_fee_next_hops_htlc_minimum_msat: expr ) => {
 646                         if first_hops.is_some() {
 647                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&$node_id) {
 648                                         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, $incl_fee_next_hops_htlc_minimum_msat);
 649                                 }
 650                         }
 651
 652                         let features;
 653                         if let Some(node_info) = $node.announcement_info.as_ref() {
 654                                 features = node_info.features.clone();
 655                         } else {
 656                                 features = NodeFeatures::empty();
 657                         }
 658
 659                         if !features.requires_unknown_bits() {
 660                                 for chan_id in $node.channels.iter() {
 661                                         let chan = network.get_channels().get(chan_id).unwrap();
 662                                         if !chan.features.requires_unknown_bits() {
 663                                                 if chan.node_one == *$node_id {
 664                                                         // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 665                                                         if first_hops.is_none() || chan.node_two != *our_node_id {
 666                                                                 if let Some(two_to_one) = chan.two_to_one.as_ref() {
 667                                                                         if two_to_one.enabled {
 668                                                                                 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, $incl_fee_next_hops_htlc_minimum_msat);
 669                                                                         }
 670                                                                 }
 671                                                         }
 672                                                 } else {
 673                                                         if first_hops.is_none() || chan.node_one != *our_node_id {
 674                                                                 if let Some(one_to_two) = chan.one_to_two.as_ref() {
 675                                                                         if one_to_two.enabled {
 676                                                                                 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, $incl_fee_next_hops_htlc_minimum_msat);
 677                                                                         }
 678                                                                 }
 679
 680                                                         }
 681                                                 }
 682                                         }
 683                                 }
 684                         }
 685                 };
 686         }
 687
 688         let mut payment_paths = Vec::<PaymentPath>::new();
 689
 690         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 691         'paths_collection: loop {
 692                 // For every new path, start from scratch, except
 693                 // bookkeeped_channels_liquidity_available_msat, which will improve
 694                 // the further iterations of path finding. Also don't erase first_hop_targets.
 695                 targets.clear();
 696                 dist.clear();
 697
 698                 // If first hop is a private channel and the only way to reach the payee, this is the only
 699                 // place where it could be added.
 700                 if first_hops.is_some() {
 701                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&payee) {
 702                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, recommended_value_msat, 0);
 703                         }
 704                 }
 705
 706                 // Add the payee as a target, so that the payee-to-payer
 707                 // search algorithm knows what to start with.
 708                 match network.get_nodes().get(payee) {
 709                         // The payee is not in our network graph, so nothing to add here.
 710                         // There is still a chance of reaching them via last_hops though,
 711                         // so don't yet fail the payment here.
 712                         // If not, targets.pop() will not even let us enter the loop in step 2.
 713                         None => {},
 714                         Some(node) => {
 715                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, recommended_value_msat, 0);
 716                         },
 717                 }
 718
 719                 // Step (1).
 720                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 721                 // earlier than general path finding, they will be somewhat prioritized, although currently
 722                 // it matters only if the fees are exactly the same.
 723                 for hop in last_hops.iter() {
 724                         let have_hop_src_in_graph =
 725                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&hop.src_node_id) {
 726                                         // If this hop connects to a node with which we have a direct channel, ignore
 727                                         // the network graph and add both the hop and our direct channel to
 728                                         // the candidate set.
 729                                         //
 730                                         // Currently there are no channel-context features defined, so we are a
 731                                         // bit lazy here. In the future, we should pull them out via our
 732                                         // ChannelManager, but there's no reason to waste the space until we
 733                                         // need them.
 734                                         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, 0);
 735                                         true
 736                                 } else {
 737                                         // In any other case, only add the hop if the source is in the regular network
 738                                         // graph:
 739                                         network.get_nodes().get(&hop.src_node_id).is_some()
 740                                 };
 741                         if have_hop_src_in_graph {
 742                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 743                                 // really sucks, cause we're gonna need that eventually.
 744                                 let last_path_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 745                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 746                                         None => 0
 747                                 };
 748                                 let directional_info = DummyDirectionalChannelInfo {
 749                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 750                                         htlc_minimum_msat: last_path_htlc_minimum_msat,
 751                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 752                                         fees: hop.fees,
 753                                 };
 754                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, ChannelFeatures::empty(), 0, recommended_value_msat, 0);
 755                         }
 756                 }
 757
 758                 // At this point, targets are filled with the data from first and
 759                 // last hops communicated by the caller, and the payment receiver.
 760                 let mut found_new_path = false;
 761
 762                 // Step (2).
 763                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 764                 // - not enough outgoing liquidity:
 765                 //   0 < already_collected_value_msat < final_value_msat
 766                 // - enough outgoing liquidity:
 767                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 768                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 769                 // paths_collection will be stopped because found_new_path==false.
 770                 // This is not necessarily a routing failure.
 771                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 772
 773                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 774                         // traversing the graph and arrange the path out of what we found.
 775                         if pubkey == *our_node_id {
 776                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 777                                 let mut ordered_hops = vec!(new_entry.clone());
 778
 779                                 'path_walk: loop {
 780                                         if let Some(&(_, ref features, _)) = first_hop_targets.get(&ordered_hops.last().unwrap().route_hop.pubkey) {
 781                                                 ordered_hops.last_mut().unwrap().route_hop.node_features = features.to_context();
 782                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().route_hop.pubkey) {
 783                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 784                                                         ordered_hops.last_mut().unwrap().route_hop.node_features = node_info.features.clone();
 785                                                 } else {
 786                                                         ordered_hops.last_mut().unwrap().route_hop.node_features = NodeFeatures::empty();
 787                                                 }
 788                                         } else {
 789                                                 // We should be able to fill in features for everything except the last
 790                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 791                                                 // should be able to extend it further as BOLT 11 does have feature
 792                                                 // flags for the last hop node itself).
 793                                                 assert!(ordered_hops.last().unwrap().route_hop.pubkey == *payee);
 794                                         }
 795
 796                                         // Means we succesfully traversed from the payer to the payee, now
 797                                         // save this path for the payment route. Also, update the liquidity
 798                                         // remaining on the used hops, so that we take them into account
 799                                         // while looking for more paths.
 800                                         if ordered_hops.last().unwrap().route_hop.pubkey == *payee {
 801                                                 break 'path_walk;
 802                                         }
 803
 804                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().route_hop.pubkey) {
 805                                                 Some(payment_hop) => payment_hop,
 806                                                 None => {
 807                                                         // If we can't reach a given node, something went wrong
 808                                                         // during path traverse.
 809                                                         // Stop looking for more paths here because next iterations
 810                                                         // will face the exact same issue.
 811                                                         break 'paths_collection;
 812                                                 }
 813                                         };
 814                                         // We "propagate" the fees one hop backward (topologically) here,
 815                                         // so that fees paid for a HTLC forwarding on the current channel are
 816                                         // associated with the previous channel (where they will be subtracted).
 817                                         ordered_hops.last_mut().unwrap().route_hop.fee_msat = new_entry.hop_use_fee_msat;
 818                                         ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = new_entry.route_hop.cltv_expiry_delta;
 819                                         ordered_hops.push(new_entry.clone());
 820                                 }
 821                                 ordered_hops.last_mut().unwrap().route_hop.fee_msat = value_contribution_msat;
 822                                 ordered_hops.last_mut().unwrap().hop_use_fee_msat = 0;
 823                                 ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = final_cltv;
 824
 825                                 let payment_path = PaymentPath {hops: ordered_hops};
 826                                 // Since a path allows to transfer as much value as
 827                                 // the smallest channel it has ("bottleneck"), we should recompute
 828                                 // the fees so sender HTLC don't overpay fees when traversing
 829                                 // larger channels than the bottleneck. This may happen because
 830                                 // when we were selecting those channels we were not aware how much value
 831                                 // this path will transfer, and the relative fee for them
 832                                 // might have been computed considering a larger value.
 833                                 // Remember that we used these channels so that we don't rely
 834                                 // on the same liquidity in future paths.
 835                                 for (i, payment_hop) in payment_path.hops.iter().enumerate() {
 836                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.route_hop.short_channel_id).unwrap();
 837                                         let mut spent_on_hop_msat = value_contribution_msat;
 838                                         let hop_and_after_fee = payment_hop.get_fee_paid_msat();
 839                                         if i == payment_path.hops.len() - 1 {
 840                                                 // For the last hop the fee should always be 0.
 841                                                 assert_eq!(hop_and_after_fee, 0);
 842                                         }
 843                                         spent_on_hop_msat += hop_and_after_fee;
 844                                         if *channel_liquidity_available_msat < spent_on_hop_msat {
 845                                                 // This should not happen because we do recompute fees right before,
 846                                                 // trying to avoid cases when a hop is not usable due to the fee situation.
 847                                                 break 'path_construction;
 848                                         }
 849                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 850                                 }
 851                                 // Track the total amount all our collected paths allow to send so that we:
 852                                 // - know when to stop looking for more paths
 853                                 // - know which of the hops are useless considering how much more sats we need
 854                                 //   (contributes_sufficient_value)
 855                                 already_collected_value_msat += value_contribution_msat;
 856
 857                                 payment_paths.push(payment_path);
 858                                 found_new_path = true;
 859                                 break 'path_construction;
 860                         }
 861
 862                         // Otherwise, since the current target node is not us,
 863                         // keep "unrolling" the payment graph from payee to payer by
 864                         // finding a way to reach the current target from the payer side.
 865                         match network.get_nodes().get(&pubkey) {
 866                                 None => {},
 867                                 Some(node) => {
 868                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
 869                                 },
 870                         }
 871                 }
 872
 873                 // Step (3).
 874                 // Stop either when recommended value is reached,
 875                 // or if during last iteration no new path was found.
 876                 // In the latter case, making another path finding attempt could not help,
 877                 // because we deterministically terminate the search due to low liquidity.
 878                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
 879                         break 'paths_collection;
 880                 }
 881         }
 882
 883         // Step (4).
 884         if payment_paths.len() == 0 {
 885                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
 886         }
 887
 888         if already_collected_value_msat < final_value_msat {
 889                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
 890         }
 891
 892         // Sort by total fees and take the best paths.
 893         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
 894         if payment_paths.len() > 50 {
 895                 payment_paths.truncate(50);
 896         }
 897
 898         // Draw multiple sufficient routes by randomly combining the selected paths.
 899         let mut drawn_routes = Vec::new();
 900         for i in 0..payment_paths.len() {
 901                 let mut cur_route = Vec::<PaymentPath>::new();
 902                 let mut aggregate_route_value_msat = 0;
 903
 904                 // Step (5).
 905                 // TODO: real random shuffle
 906                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
 907                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
 908
 909                 // Step (6).
 910                 for payment_path in cur_payment_paths {
 911                         cur_route.push(payment_path.clone());
 912                         aggregate_route_value_msat += payment_path.get_value_msat();
 913                         if aggregate_route_value_msat > final_value_msat {
 914                                 // Last path likely overpaid. Substract it from the most expensive
 915                                 // (in terms of proportional fee) path in this route and recompute fees.
 916                                 // This might be not the most economically efficient way, but fewer paths
 917                                 // also makes routing more reliable.
 918                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
 919
 920                                 // First, drop some expensive low-value paths entirely if possible.
 921                                 // Sort by value so that we drop many really-low values first, since
 922                                 // fewer paths is better: the payment is less likely to fail.
 923                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
 924                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
 925                                 cur_route.sort_by_key(|path| path.get_value_msat());
 926                                 // We should make sure that at least 1 path left.
 927                                 let mut paths_left = cur_route.len();
 928                                 cur_route.retain(|path| {
 929                                         if paths_left == 1 {
 930                                                 return true
 931                                         }
 932                                         let mut keep = true;
 933                                         let path_value_msat = path.get_value_msat();
 934                                         if path_value_msat <= overpaid_value_msat {
 935                                                 keep = false;
 936                                                 overpaid_value_msat -= path_value_msat;
 937                                                 paths_left -= 1;
 938                                         }
 939                                         keep
 940                                 });
 941
 942                                 if overpaid_value_msat == 0 {
 943                                         break;
 944                                 }
 945
 946                                 assert!(cur_route.len() > 0);
 947
 948                                 // Step (7).
 949                                 // Now, substract the overpaid value from the most-expensive path.
 950                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
 951                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
 952                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.channel_fees.proportional_millionths as u64).sum::<u64>() });
 953                                 for expensive_payment_path in &mut cur_route {
 954                                         if let Some(expensive_path_new_value_msat) = expensive_payment_path.get_value_msat().checked_sub(overpaid_value_msat) {
 955                                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
 956                                                 break;
 957                                         } else {
 958                                                 // We already dropped all the small channels above, meaning all the
 959                                                 // remaining channels are larger than remaining overpaid_value_msat.
 960                                                 // Thus, this can't be negative.
 961                                                 unreachable!();
 962                                         }
 963                                 }
 964                                 break;
 965                         }
 966                 }
 967                 drawn_routes.push(cur_route);
 968         }
 969
 970         // Step (8).
 971         // Select the best route by lowest total fee.
 972         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
 973         let mut selected_paths = Vec::<Vec::<RouteHop>>::new();
 974         for payment_path in drawn_routes.first().unwrap() {
 975                 selected_paths.push(payment_path.hops.iter().map(|payment_hop| payment_hop.route_hop.clone()).collect());
 976         }
 977
 978         let route = Route { paths: selected_paths };
 979         log_trace!(logger, "Got route: {}", log_route!(route));
 980         return Ok(route);
 981 }
 982
 983 #[cfg(test)]
 984 mod tests {
 985         use routing::router::{get_route, RouteHint, RoutingFees};
 986         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
 987         use ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
 988         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
 989            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
 990         use ln::channelmanager;
 991         use util::test_utils;
 992         use util::ser::Writeable;
 993
 994         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
 995         use bitcoin::hashes::Hash;
 996         use bitcoin::network::constants::Network;
 997         use bitcoin::blockdata::constants::genesis_block;
 998         use bitcoin::blockdata::script::Builder;
 999         use bitcoin::blockdata::opcodes;
1000         use bitcoin::blockdata::transaction::TxOut;
1001
1002         use hex;
1003
1004         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1005         use bitcoin::secp256k1::{Secp256k1, All};
1006
1007         use std::sync::Arc;
1008
1009         // Using the same keys for LN and BTC ids
1010         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1011            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1012                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1013                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1014
1015                 let unsigned_announcement = UnsignedChannelAnnouncement {
1016                         features,
1017                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1018                         short_channel_id,
1019                         node_id_1,
1020                         node_id_2,
1021                         bitcoin_key_1: node_id_1,
1022                         bitcoin_key_2: node_id_2,
1023                         excess_data: Vec::new(),
1024                 };
1025
1026                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1027                 let valid_announcement = ChannelAnnouncement {
1028                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1029                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1030                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1031                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1032                         contents: unsigned_announcement.clone(),
1033                 };
1034                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1035                         Ok(res) => assert!(res),
1036                         _ => panic!()
1037                 };
1038         }
1039
1040         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) {
1041                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1042                 let valid_channel_update = ChannelUpdate {
1043                         signature: secp_ctx.sign(&msghash, node_privkey),
1044                         contents: update.clone()
1045                 };
1046
1047                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1048                         Ok(res) => assert!(res),
1049                         Err(_) => panic!()
1050                 };
1051         }
1052
1053         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,
1054            features: NodeFeatures, timestamp: u32) {
1055                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1056                 let unsigned_announcement = UnsignedNodeAnnouncement {
1057                         features,
1058                         timestamp,
1059                         node_id,
1060                         rgb: [0; 3],
1061                         alias: [0; 32],
1062                         addresses: Vec::new(),
1063                         excess_address_data: Vec::new(),
1064                         excess_data: Vec::new(),
1065                 };
1066                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1067                 let valid_announcement = NodeAnnouncement {
1068                         signature: secp_ctx.sign(&msghash, node_privkey),
1069                         contents: unsigned_announcement.clone()
1070                 };
1071
1072                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1073                         Ok(_) => (),
1074                         Err(_) => panic!()
1075                 };
1076         }
1077
1078         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1079                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1080                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1081                 }).collect();
1082
1083                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1084
1085                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1086                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1087
1088                 (our_privkey, our_id, privkeys, pubkeys)
1089         }
1090
1091         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1092                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1093                 // test for it later.
1094                 let idx = (id - 1) * 2 + 1;
1095                 if idx > 8*3 {
1096                         vec![1 << (idx - 8*3), 0, 0, 0]
1097                 } else if idx > 8*2 {
1098                         vec![1 << (idx - 8*2), 0, 0]
1099                 } else if idx > 8*1 {
1100                         vec![1 << (idx - 8*1), 0]
1101                 } else {
1102                         vec![1 << idx]
1103                 }
1104         }
1105
1106         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>) {
1107                 let secp_ctx = Secp256k1::new();
1108                 let logger = Arc::new(test_utils::TestLogger::new());
1109                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1110                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1111                 // Build network from our_id to node7:
1112                 //
1113                 //        -1(1)2-  node0  -1(3)2-
1114                 //       /                       \
1115                 // our_id -1(12)2- node7 -1(13)2--- node2
1116                 //       \                       /
1117                 //        -1(2)2-  node1  -1(4)2-
1118                 //
1119                 //
1120                 // chan1  1-to-2: disabled
1121                 // chan1  2-to-1: enabled, 0 fee
1122                 //
1123                 // chan2  1-to-2: enabled, ignored fee
1124                 // chan2  2-to-1: enabled, 0 fee
1125                 //
1126                 // chan3  1-to-2: enabled, 0 fee
1127                 // chan3  2-to-1: enabled, 100 msat fee
1128                 //
1129                 // chan4  1-to-2: enabled, 100% fee
1130                 // chan4  2-to-1: enabled, 0 fee
1131                 //
1132                 // chan12 1-to-2: enabled, ignored fee
1133                 // chan12 2-to-1: enabled, 0 fee
1134                 //
1135                 // chan13 1-to-2: enabled, 200% fee
1136                 // chan13 2-to-1: enabled, 0 fee
1137                 //
1138                 //
1139                 //       -1(5)2- node3 -1(8)2--
1140                 //       |         2          |
1141                 //       |       (11)         |
1142                 //      /          1           \
1143                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1144                 //      \                      /
1145                 //       -1(7)2- node5 -1(10)2-
1146                 //
1147                 // chan5  1-to-2: enabled, 100 msat fee
1148                 // chan5  2-to-1: enabled, 0 fee
1149                 //
1150                 // chan6  1-to-2: enabled, 0 fee
1151                 // chan6  2-to-1: enabled, 0 fee
1152                 //
1153                 // chan7  1-to-2: enabled, 100% fee
1154                 // chan7  2-to-1: enabled, 0 fee
1155                 //
1156                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1157                 // chan8  2-to-1: enabled, 0 fee
1158                 //
1159                 // chan9  1-to-2: enabled, 1001 msat fee
1160                 // chan9  2-to-1: enabled, 0 fee
1161                 //
1162                 // chan10 1-to-2: enabled, 0 fee
1163                 // chan10 2-to-1: enabled, 0 fee
1164                 //
1165                 // chan11 1-to-2: enabled, 0 fee
1166                 // chan11 2-to-1: enabled, 0 fee
1167
1168                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1169
1170                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1171                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1172                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1173                         short_channel_id: 1,
1174                         timestamp: 1,
1175                         flags: 1,
1176                         cltv_expiry_delta: 0,
1177                         htlc_minimum_msat: 0,
1178                         htlc_maximum_msat: OptionalField::Absent,
1179                         fee_base_msat: 0,
1180                         fee_proportional_millionths: 0,
1181                         excess_data: Vec::new()
1182                 });
1183
1184                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1185
1186                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1187                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1188                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1189                         short_channel_id: 2,
1190                         timestamp: 1,
1191                         flags: 0,
1192                         cltv_expiry_delta: u16::max_value(),
1193                         htlc_minimum_msat: 0,
1194                         htlc_maximum_msat: OptionalField::Absent,
1195                         fee_base_msat: u32::max_value(),
1196                         fee_proportional_millionths: u32::max_value(),
1197                         excess_data: Vec::new()
1198                 });
1199                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1200                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1201                         short_channel_id: 2,
1202                         timestamp: 1,
1203                         flags: 1,
1204                         cltv_expiry_delta: 0,
1205                         htlc_minimum_msat: 0,
1206                         htlc_maximum_msat: OptionalField::Absent,
1207                         fee_base_msat: 0,
1208                         fee_proportional_millionths: 0,
1209                         excess_data: Vec::new()
1210                 });
1211
1212                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1213
1214                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1215                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1216                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1217                         short_channel_id: 12,
1218                         timestamp: 1,
1219                         flags: 0,
1220                         cltv_expiry_delta: u16::max_value(),
1221                         htlc_minimum_msat: 0,
1222                         htlc_maximum_msat: OptionalField::Absent,
1223                         fee_base_msat: u32::max_value(),
1224                         fee_proportional_millionths: u32::max_value(),
1225                         excess_data: Vec::new()
1226                 });
1227                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1228                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1229                         short_channel_id: 12,
1230                         timestamp: 1,
1231                         flags: 1,
1232                         cltv_expiry_delta: 0,
1233                         htlc_minimum_msat: 0,
1234                         htlc_maximum_msat: OptionalField::Absent,
1235                         fee_base_msat: 0,
1236                         fee_proportional_millionths: 0,
1237                         excess_data: Vec::new()
1238                 });
1239
1240                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1241
1242                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1243                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1244                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1245                         short_channel_id: 3,
1246                         timestamp: 1,
1247                         flags: 0,
1248                         cltv_expiry_delta: (3 << 8) | 1,
1249                         htlc_minimum_msat: 0,
1250                         htlc_maximum_msat: OptionalField::Absent,
1251                         fee_base_msat: 0,
1252                         fee_proportional_millionths: 0,
1253                         excess_data: Vec::new()
1254                 });
1255                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1256                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1257                         short_channel_id: 3,
1258                         timestamp: 1,
1259                         flags: 1,
1260                         cltv_expiry_delta: (3 << 8) | 2,
1261                         htlc_minimum_msat: 0,
1262                         htlc_maximum_msat: OptionalField::Absent,
1263                         fee_base_msat: 100,
1264                         fee_proportional_millionths: 0,
1265                         excess_data: Vec::new()
1266                 });
1267
1268                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1269                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1270                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1271                         short_channel_id: 4,
1272                         timestamp: 1,
1273                         flags: 0,
1274                         cltv_expiry_delta: (4 << 8) | 1,
1275                         htlc_minimum_msat: 0,
1276                         htlc_maximum_msat: OptionalField::Absent,
1277                         fee_base_msat: 0,
1278                         fee_proportional_millionths: 1000000,
1279                         excess_data: Vec::new()
1280                 });
1281                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1282                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1283                         short_channel_id: 4,
1284                         timestamp: 1,
1285                         flags: 1,
1286                         cltv_expiry_delta: (4 << 8) | 2,
1287                         htlc_minimum_msat: 0,
1288                         htlc_maximum_msat: OptionalField::Absent,
1289                         fee_base_msat: 0,
1290                         fee_proportional_millionths: 0,
1291                         excess_data: Vec::new()
1292                 });
1293
1294                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1295                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1296                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1297                         short_channel_id: 13,
1298                         timestamp: 1,
1299                         flags: 0,
1300                         cltv_expiry_delta: (13 << 8) | 1,
1301                         htlc_minimum_msat: 0,
1302                         htlc_maximum_msat: OptionalField::Absent,
1303                         fee_base_msat: 0,
1304                         fee_proportional_millionths: 2000000,
1305                         excess_data: Vec::new()
1306                 });
1307                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1308                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1309                         short_channel_id: 13,
1310                         timestamp: 1,
1311                         flags: 1,
1312                         cltv_expiry_delta: (13 << 8) | 2,
1313                         htlc_minimum_msat: 0,
1314                         htlc_maximum_msat: OptionalField::Absent,
1315                         fee_base_msat: 0,
1316                         fee_proportional_millionths: 0,
1317                         excess_data: Vec::new()
1318                 });
1319
1320                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1321
1322                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1323                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1324                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1325                         short_channel_id: 6,
1326                         timestamp: 1,
1327                         flags: 0,
1328                         cltv_expiry_delta: (6 << 8) | 1,
1329                         htlc_minimum_msat: 0,
1330                         htlc_maximum_msat: OptionalField::Absent,
1331                         fee_base_msat: 0,
1332                         fee_proportional_millionths: 0,
1333                         excess_data: Vec::new()
1334                 });
1335                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1336                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1337                         short_channel_id: 6,
1338                         timestamp: 1,
1339                         flags: 1,
1340                         cltv_expiry_delta: (6 << 8) | 2,
1341                         htlc_minimum_msat: 0,
1342                         htlc_maximum_msat: OptionalField::Absent,
1343                         fee_base_msat: 0,
1344                         fee_proportional_millionths: 0,
1345                         excess_data: Vec::new(),
1346                 });
1347
1348                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1349                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1350                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1351                         short_channel_id: 11,
1352                         timestamp: 1,
1353                         flags: 0,
1354                         cltv_expiry_delta: (11 << 8) | 1,
1355                         htlc_minimum_msat: 0,
1356                         htlc_maximum_msat: OptionalField::Absent,
1357                         fee_base_msat: 0,
1358                         fee_proportional_millionths: 0,
1359                         excess_data: Vec::new()
1360                 });
1361                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1362                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1363                         short_channel_id: 11,
1364                         timestamp: 1,
1365                         flags: 1,
1366                         cltv_expiry_delta: (11 << 8) | 2,
1367                         htlc_minimum_msat: 0,
1368                         htlc_maximum_msat: OptionalField::Absent,
1369                         fee_base_msat: 0,
1370                         fee_proportional_millionths: 0,
1371                         excess_data: Vec::new()
1372                 });
1373
1374                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1375
1376                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1377
1378                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1379                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1380                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1381                         short_channel_id: 7,
1382                         timestamp: 1,
1383                         flags: 0,
1384                         cltv_expiry_delta: (7 << 8) | 1,
1385                         htlc_minimum_msat: 0,
1386                         htlc_maximum_msat: OptionalField::Absent,
1387                         fee_base_msat: 0,
1388                         fee_proportional_millionths: 1000000,
1389                         excess_data: Vec::new()
1390                 });
1391                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1392                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1393                         short_channel_id: 7,
1394                         timestamp: 1,
1395                         flags: 1,
1396                         cltv_expiry_delta: (7 << 8) | 2,
1397                         htlc_minimum_msat: 0,
1398                         htlc_maximum_msat: OptionalField::Absent,
1399                         fee_base_msat: 0,
1400                         fee_proportional_millionths: 0,
1401                         excess_data: Vec::new()
1402                 });
1403
1404                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1405
1406                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1407         }
1408
1409         #[test]
1410         fn simple_route_test() {
1411                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1412                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1413
1414                 // Simple route to 2 via 1
1415
1416                 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)) {
1417                         assert_eq!(err, "Cannot send a payment of 0 msat");
1418                 } else { panic!(); }
1419
1420                 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();
1421                 assert_eq!(route.paths[0].len(), 2);
1422
1423                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1424                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1425                 assert_eq!(route.paths[0][0].fee_msat, 100);
1426                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1427                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1428                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1429
1430                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1431                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1432                 assert_eq!(route.paths[0][1].fee_msat, 100);
1433                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1434                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1435                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1436         }
1437
1438         #[test]
1439         fn invalid_first_hop_test() {
1440                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1441                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1442
1443                 // Simple route to 2 via 1
1444
1445                 let our_chans = vec![channelmanager::ChannelDetails {
1446                         channel_id: [0; 32],
1447                         short_channel_id: Some(2),
1448                         remote_network_id: our_id,
1449                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1450                         channel_value_satoshis: 100000,
1451                         user_id: 0,
1452                         outbound_capacity_msat: 100000,
1453                         inbound_capacity_msat: 100000,
1454                         is_live: true,
1455                 }];
1456
1457                 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)) {
1458                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1459                 } else { panic!(); }
1460
1461                 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();
1462                 assert_eq!(route.paths[0].len(), 2);
1463         }
1464
1465         #[test]
1466         fn htlc_minimum_test() {
1467                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1468                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1469
1470                 // Simple route to 2 via 1
1471
1472                 // Disable other paths
1473                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1474                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1475                         short_channel_id: 12,
1476                         timestamp: 2,
1477                         flags: 2, // to disable
1478                         cltv_expiry_delta: 0,
1479                         htlc_minimum_msat: 0,
1480                         htlc_maximum_msat: OptionalField::Absent,
1481                         fee_base_msat: 0,
1482                         fee_proportional_millionths: 0,
1483                         excess_data: Vec::new()
1484                 });
1485                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1486                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1487                         short_channel_id: 3,
1488                         timestamp: 2,
1489                         flags: 2, // to disable
1490                         cltv_expiry_delta: 0,
1491                         htlc_minimum_msat: 0,
1492                         htlc_maximum_msat: OptionalField::Absent,
1493                         fee_base_msat: 0,
1494                         fee_proportional_millionths: 0,
1495                         excess_data: Vec::new()
1496                 });
1497                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1498                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1499                         short_channel_id: 13,
1500                         timestamp: 2,
1501                         flags: 2, // to disable
1502                         cltv_expiry_delta: 0,
1503                         htlc_minimum_msat: 0,
1504                         htlc_maximum_msat: OptionalField::Absent,
1505                         fee_base_msat: 0,
1506                         fee_proportional_millionths: 0,
1507                         excess_data: Vec::new()
1508                 });
1509                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1510                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1511                         short_channel_id: 6,
1512                         timestamp: 2,
1513                         flags: 2, // to disable
1514                         cltv_expiry_delta: 0,
1515                         htlc_minimum_msat: 0,
1516                         htlc_maximum_msat: OptionalField::Absent,
1517                         fee_base_msat: 0,
1518                         fee_proportional_millionths: 0,
1519                         excess_data: Vec::new()
1520                 });
1521                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1522                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1523                         short_channel_id: 7,
1524                         timestamp: 2,
1525                         flags: 2, // to disable
1526                         cltv_expiry_delta: 0,
1527                         htlc_minimum_msat: 0,
1528                         htlc_maximum_msat: OptionalField::Absent,
1529                         fee_base_msat: 0,
1530                         fee_proportional_millionths: 0,
1531                         excess_data: Vec::new()
1532                 });
1533
1534                 // Check against amount_to_transfer_over_msat.
1535                 // We will be transferring 300_000_000 msat.
1536                 // Set minimal HTLC of 200_000_000 msat.
1537                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1538                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1539                         short_channel_id: 2,
1540                         timestamp: 3,
1541                         flags: 0,
1542                         cltv_expiry_delta: 0,
1543                         htlc_minimum_msat: 200_000_000,
1544                         htlc_maximum_msat: OptionalField::Absent,
1545                         fee_base_msat: 0,
1546                         fee_proportional_millionths: 0,
1547                         excess_data: Vec::new()
1548                 });
1549
1550                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1551                 // be used.
1552                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1553                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1554                         short_channel_id: 4,
1555                         timestamp: 3,
1556                         flags: 0,
1557                         cltv_expiry_delta: 0,
1558                         htlc_minimum_msat: 0,
1559                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1560                         fee_base_msat: 0,
1561                         fee_proportional_millionths: 0,
1562                         excess_data: Vec::new()
1563                 });
1564
1565                 // Not possible to send 299_999_999: we first allocate 200_000_000 for the channel#12,
1566                 // and then the amount_to_transfer_over_msat over channel#2 is less than our limit.
1567                 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)) {
1568                         assert_eq!(err, "Failed to find a path to the given destination");
1569                 } else { panic!(); }
1570
1571                 // Lift the restriction on the first hop.
1572                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1573                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1574                         short_channel_id: 2,
1575                         timestamp: 4,
1576                         flags: 0,
1577                         cltv_expiry_delta: 0,
1578                         htlc_minimum_msat: 0,
1579                         htlc_maximum_msat: OptionalField::Absent,
1580                         fee_base_msat: 0,
1581                         fee_proportional_millionths: 0,
1582                         excess_data: Vec::new()
1583                 });
1584
1585                 // A payment above the minimum should pass
1586                 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();
1587                 assert_eq!(route.paths[0].len(), 2);
1588         }
1589
1590         #[test]
1591         fn htlc_minimum_overpay_test() {
1592                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1593                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1594
1595                 // A route to node#2 via two paths.
1596                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1597                 // Thus, they can't send 60 without overpaying.
1598                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1599                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1600                         short_channel_id: 2,
1601                         timestamp: 2,
1602                         flags: 0,
1603                         cltv_expiry_delta: 0,
1604                         htlc_minimum_msat: 35_000,
1605                         htlc_maximum_msat: OptionalField::Present(40_000),
1606                         fee_base_msat: 0,
1607                         fee_proportional_millionths: 0,
1608                         excess_data: Vec::new()
1609                 });
1610                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1611                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1612                         short_channel_id: 12,
1613                         timestamp: 3,
1614                         flags: 0,
1615                         cltv_expiry_delta: 0,
1616                         htlc_minimum_msat: 35_000,
1617                         htlc_maximum_msat: OptionalField::Present(40_000),
1618                         fee_base_msat: 0,
1619                         fee_proportional_millionths: 0,
1620                         excess_data: Vec::new()
1621                 });
1622
1623                 // Make 0 fee.
1624                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1625                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1626                         short_channel_id: 13,
1627                         timestamp: 2,
1628                         flags: 0,
1629                         cltv_expiry_delta: 0,
1630                         htlc_minimum_msat: 0,
1631                         htlc_maximum_msat: OptionalField::Absent,
1632                         fee_base_msat: 0,
1633                         fee_proportional_millionths: 0,
1634                         excess_data: Vec::new()
1635                 });
1636                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1637                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1638                         short_channel_id: 4,
1639                         timestamp: 2,
1640                         flags: 0,
1641                         cltv_expiry_delta: 0,
1642                         htlc_minimum_msat: 0,
1643                         htlc_maximum_msat: OptionalField::Absent,
1644                         fee_base_msat: 0,
1645                         fee_proportional_millionths: 0,
1646                         excess_data: Vec::new()
1647                 });
1648
1649                 // Disable other paths
1650                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1651                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1652                         short_channel_id: 1,
1653                         timestamp: 3,
1654                         flags: 2, // to disable
1655                         cltv_expiry_delta: 0,
1656                         htlc_minimum_msat: 0,
1657                         htlc_maximum_msat: OptionalField::Absent,
1658                         fee_base_msat: 0,
1659                         fee_proportional_millionths: 0,
1660                         excess_data: Vec::new()
1661                 });
1662
1663                 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();
1664                 // Overpay fees to hit htlc_minimum_msat.
1665                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1666                 // TODO: this could be better balanced to overpay 10k and not 15k.
1667                 assert_eq!(overpaid_fees, 15_000);
1668
1669                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1670                 // while taking even more fee to match htlc_minimum_msat.
1671                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1672                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1673                         short_channel_id: 12,
1674                         timestamp: 4,
1675                         flags: 0,
1676                         cltv_expiry_delta: 0,
1677                         htlc_minimum_msat: 65_000,
1678                         htlc_maximum_msat: OptionalField::Present(80_000),
1679                         fee_base_msat: 0,
1680                         fee_proportional_millionths: 0,
1681                         excess_data: Vec::new()
1682                 });
1683                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1684                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1685                         short_channel_id: 2,
1686                         timestamp: 3,
1687                         flags: 0,
1688                         cltv_expiry_delta: 0,
1689                         htlc_minimum_msat: 0,
1690                         htlc_maximum_msat: OptionalField::Absent,
1691                         fee_base_msat: 0,
1692                         fee_proportional_millionths: 0,
1693                         excess_data: Vec::new()
1694                 });
1695                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1696                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1697                         short_channel_id: 4,
1698                         timestamp: 4,
1699                         flags: 0,
1700                         cltv_expiry_delta: 0,
1701                         htlc_minimum_msat: 0,
1702                         htlc_maximum_msat: OptionalField::Absent,
1703                         fee_base_msat: 0,
1704                         fee_proportional_millionths: 100_000,
1705                         excess_data: Vec::new()
1706                 });
1707
1708                 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();
1709                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1710                 assert_eq!(route.paths.len(), 1);
1711                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1712                 let fees = route.paths[0][0].fee_msat;
1713                 assert_eq!(fees, 5_000);
1714
1715                 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();
1716                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1717                 // the other channel.
1718                 assert_eq!(route.paths.len(), 1);
1719                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1720                 let fees = route.paths[0][0].fee_msat;
1721                 assert_eq!(fees, 5_000);
1722         }
1723
1724         #[test]
1725         fn disable_channels_test() {
1726                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1727                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1728
1729                 // // Disable channels 4 and 12 by flags=2
1730                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1731                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1732                         short_channel_id: 4,
1733                         timestamp: 2,
1734                         flags: 2, // to disable
1735                         cltv_expiry_delta: 0,
1736                         htlc_minimum_msat: 0,
1737                         htlc_maximum_msat: OptionalField::Absent,
1738                         fee_base_msat: 0,
1739                         fee_proportional_millionths: 0,
1740                         excess_data: Vec::new()
1741                 });
1742                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1743                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1744                         short_channel_id: 12,
1745                         timestamp: 2,
1746                         flags: 2, // to disable
1747                         cltv_expiry_delta: 0,
1748                         htlc_minimum_msat: 0,
1749                         htlc_maximum_msat: OptionalField::Absent,
1750                         fee_base_msat: 0,
1751                         fee_proportional_millionths: 0,
1752                         excess_data: Vec::new()
1753                 });
1754
1755                 // If all the channels require some features we don't understand, route should fail
1756                 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)) {
1757                         assert_eq!(err, "Failed to find a path to the given destination");
1758                 } else { panic!(); }
1759
1760                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1761                 let our_chans = vec![channelmanager::ChannelDetails {
1762                         channel_id: [0; 32],
1763                         short_channel_id: Some(42),
1764                         remote_network_id: nodes[7].clone(),
1765                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1766                         channel_value_satoshis: 0,
1767                         user_id: 0,
1768                         outbound_capacity_msat: 250_000_000,
1769                         inbound_capacity_msat: 0,
1770                         is_live: true,
1771                 }];
1772                 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();
1773                 assert_eq!(route.paths[0].len(), 2);
1774
1775                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1776                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1777                 assert_eq!(route.paths[0][0].fee_msat, 200);
1778                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1779                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1780                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1781
1782                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1783                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1784                 assert_eq!(route.paths[0][1].fee_msat, 100);
1785                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1786                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1787                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1788         }
1789
1790         #[test]
1791         fn disable_node_test() {
1792                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1793                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1794
1795                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1796                 let mut unknown_features = NodeFeatures::known();
1797                 unknown_features.set_required_unknown_bits();
1798                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1799                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1800                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1801
1802                 // If all nodes require some features we don't understand, route should fail
1803                 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)) {
1804                         assert_eq!(err, "Failed to find a path to the given destination");
1805                 } else { panic!(); }
1806
1807                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1808                 let our_chans = vec![channelmanager::ChannelDetails {
1809                         channel_id: [0; 32],
1810                         short_channel_id: Some(42),
1811                         remote_network_id: nodes[7].clone(),
1812                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1813                         channel_value_satoshis: 0,
1814                         user_id: 0,
1815                         outbound_capacity_msat: 250_000_000,
1816                         inbound_capacity_msat: 0,
1817                         is_live: true,
1818                 }];
1819                 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();
1820                 assert_eq!(route.paths[0].len(), 2);
1821
1822                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1823                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1824                 assert_eq!(route.paths[0][0].fee_msat, 200);
1825                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1826                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1827                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1828
1829                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1830                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1831                 assert_eq!(route.paths[0][1].fee_msat, 100);
1832                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1833                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1834                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1835
1836                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
1837                 // naively) assume that the user checked the feature bits on the invoice, which override
1838                 // the node_announcement.
1839         }
1840
1841         #[test]
1842         fn our_chans_test() {
1843                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1844                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1845
1846                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
1847                 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();
1848                 assert_eq!(route.paths[0].len(), 3);
1849
1850                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1851                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1852                 assert_eq!(route.paths[0][0].fee_msat, 200);
1853                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1854                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1855                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1856
1857                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1858                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1859                 assert_eq!(route.paths[0][1].fee_msat, 100);
1860                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
1861                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1862                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1863
1864                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
1865                 assert_eq!(route.paths[0][2].short_channel_id, 3);
1866                 assert_eq!(route.paths[0][2].fee_msat, 100);
1867                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
1868                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
1869                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
1870
1871                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1872                 let our_chans = vec![channelmanager::ChannelDetails {
1873                         channel_id: [0; 32],
1874                         short_channel_id: Some(42),
1875                         remote_network_id: nodes[7].clone(),
1876                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1877                         channel_value_satoshis: 0,
1878                         user_id: 0,
1879                         outbound_capacity_msat: 250_000_000,
1880                         inbound_capacity_msat: 0,
1881                         is_live: true,
1882                 }];
1883                 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();
1884                 assert_eq!(route.paths[0].len(), 2);
1885
1886                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1887                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1888                 assert_eq!(route.paths[0][0].fee_msat, 200);
1889                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1890                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
1891                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1892
1893                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1894                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1895                 assert_eq!(route.paths[0][1].fee_msat, 100);
1896                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1897                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1898                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1899         }
1900
1901         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
1902                 let zero_fees = RoutingFees {
1903                         base_msat: 0,
1904                         proportional_millionths: 0,
1905                 };
1906                 vec!(RouteHint {
1907                         src_node_id: nodes[3].clone(),
1908                         short_channel_id: 8,
1909                         fees: zero_fees,
1910                         cltv_expiry_delta: (8 << 8) | 1,
1911                         htlc_minimum_msat: None,
1912                         htlc_maximum_msat: None,
1913                 }, RouteHint {
1914                         src_node_id: nodes[4].clone(),
1915                         short_channel_id: 9,
1916                         fees: RoutingFees {
1917                                 base_msat: 1001,
1918                                 proportional_millionths: 0,
1919                         },
1920                         cltv_expiry_delta: (9 << 8) | 1,
1921                         htlc_minimum_msat: None,
1922                         htlc_maximum_msat: None,
1923                 }, RouteHint {
1924                         src_node_id: nodes[5].clone(),
1925                         short_channel_id: 10,
1926                         fees: zero_fees,
1927                         cltv_expiry_delta: (10 << 8) | 1,
1928                         htlc_minimum_msat: None,
1929                         htlc_maximum_msat: None,
1930                 })
1931         }
1932
1933         #[test]
1934         fn last_hops_test() {
1935                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1936                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1937
1938                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
1939
1940                 // First check that lst hop can't have its source as the payee.
1941                 let invalid_last_hop = RouteHint {
1942                         src_node_id: nodes[6],
1943                         short_channel_id: 8,
1944                         fees: RoutingFees {
1945                                 base_msat: 1000,
1946                                 proportional_millionths: 0,
1947                         },
1948                         cltv_expiry_delta: (8 << 8) | 1,
1949                         htlc_minimum_msat: None,
1950                         htlc_maximum_msat: None,
1951                 };
1952
1953                 let mut invalid_last_hops = last_hops(&nodes);
1954                 invalid_last_hops.push(invalid_last_hop);
1955                 {
1956                         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)) {
1957                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
1958                         } else { panic!(); }
1959                 }
1960
1961                 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();
1962                 assert_eq!(route.paths[0].len(), 5);
1963
1964                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1965                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1966                 assert_eq!(route.paths[0][0].fee_msat, 100);
1967                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1968                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1969                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1970
1971                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1972                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1973                 assert_eq!(route.paths[0][1].fee_msat, 0);
1974                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
1975                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1976                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1977
1978                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
1979                 assert_eq!(route.paths[0][2].short_channel_id, 6);
1980                 assert_eq!(route.paths[0][2].fee_msat, 0);
1981                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
1982                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
1983                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
1984
1985                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
1986                 assert_eq!(route.paths[0][3].short_channel_id, 11);
1987                 assert_eq!(route.paths[0][3].fee_msat, 0);
1988                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
1989                 // If we have a peer in the node map, we'll use their features here since we don't have
1990                 // a way of figuring out their features from the invoice:
1991                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
1992                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
1993
1994                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
1995                 assert_eq!(route.paths[0][4].short_channel_id, 8);
1996                 assert_eq!(route.paths[0][4].fee_msat, 100);
1997                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
1998                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
1999                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2000         }
2001
2002         #[test]
2003         fn our_chans_last_hop_connect_test() {
2004                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2005                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2006
2007                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2008                 let our_chans = vec![channelmanager::ChannelDetails {
2009                         channel_id: [0; 32],
2010                         short_channel_id: Some(42),
2011                         remote_network_id: nodes[3].clone(),
2012                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2013                         channel_value_satoshis: 0,
2014                         user_id: 0,
2015                         outbound_capacity_msat: 250_000_000,
2016                         inbound_capacity_msat: 0,
2017                         is_live: true,
2018                 }];
2019                 let mut last_hops = last_hops(&nodes);
2020                 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();
2021                 assert_eq!(route.paths[0].len(), 2);
2022
2023                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2024                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2025                 assert_eq!(route.paths[0][0].fee_msat, 0);
2026                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2027                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2028                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2029
2030                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2031                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2032                 assert_eq!(route.paths[0][1].fee_msat, 100);
2033                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2034                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2035                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2036
2037                 last_hops[0].fees.base_msat = 1000;
2038
2039                 // Revert to via 6 as the fee on 8 goes up
2040                 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();
2041                 assert_eq!(route.paths[0].len(), 4);
2042
2043                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2044                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2045                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2046                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2047                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2048                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2049
2050                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2051                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2052                 assert_eq!(route.paths[0][1].fee_msat, 100);
2053                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2054                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2055                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2056
2057                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2058                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2059                 assert_eq!(route.paths[0][2].fee_msat, 0);
2060                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2061                 // If we have a peer in the node map, we'll use their features here since we don't have
2062                 // a way of figuring out their features from the invoice:
2063                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2064                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2065
2066                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2067                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2068                 assert_eq!(route.paths[0][3].fee_msat, 100);
2069                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2070                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2071                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2072
2073                 // ...but still use 8 for larger payments as 6 has a variable feerate
2074                 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();
2075                 assert_eq!(route.paths[0].len(), 5);
2076
2077                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2078                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2079                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2080                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2081                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2082                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2083
2084                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2085                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2086                 assert_eq!(route.paths[0][1].fee_msat, 0);
2087                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2088                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2089                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2090
2091                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2092                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2093                 assert_eq!(route.paths[0][2].fee_msat, 0);
2094                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2095                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2096                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2097
2098                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2099                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2100                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2101                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2102                 // If we have a peer in the node map, we'll use their features here since we don't have
2103                 // a way of figuring out their features from the invoice:
2104                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2105                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2106
2107                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2108                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2109                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2110                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2111                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2112                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2113         }
2114
2115         #[test]
2116         fn unannounced_path_test() {
2117                 // We should be able to send a payment to a destination without any help of a routing graph
2118                 // if we have a channel with a common counterparty that appears in the first and last hop
2119                 // hints.
2120                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2121                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2122                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2123
2124                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2125                 let last_hops = vec![RouteHint {
2126                         src_node_id: middle_node_id,
2127                         short_channel_id: 8,
2128                         fees: RoutingFees {
2129                                 base_msat: 1000,
2130                                 proportional_millionths: 0,
2131                         },
2132                         cltv_expiry_delta: (8 << 8) | 1,
2133                         htlc_minimum_msat: None,
2134                         htlc_maximum_msat: None,
2135                 }];
2136                 let our_chans = vec![channelmanager::ChannelDetails {
2137                         channel_id: [0; 32],
2138                         short_channel_id: Some(42),
2139                         remote_network_id: middle_node_id,
2140                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2141                         channel_value_satoshis: 100000,
2142                         user_id: 0,
2143                         outbound_capacity_msat: 100000,
2144                         inbound_capacity_msat: 100000,
2145                         is_live: true,
2146                 }];
2147                 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();
2148
2149                 assert_eq!(route.paths[0].len(), 2);
2150
2151                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2152                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2153                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2154                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2155                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2156                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2157
2158                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2159                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2160                 assert_eq!(route.paths[0][1].fee_msat, 100);
2161                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2162                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2163                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2164         }
2165
2166         #[test]
2167         fn available_amount_while_routing_test() {
2168                 // Tests whether we choose the correct available channel amount while routing.
2169
2170                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2171                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2172
2173                 // We will use a simple single-path route from
2174                 // our node to node2 via node0: channels {1, 3}.
2175
2176                 // First disable all other paths.
2177                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2178                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2179                         short_channel_id: 2,
2180                         timestamp: 2,
2181                         flags: 2,
2182                         cltv_expiry_delta: 0,
2183                         htlc_minimum_msat: 0,
2184                         htlc_maximum_msat: OptionalField::Present(100_000),
2185                         fee_base_msat: 0,
2186                         fee_proportional_millionths: 0,
2187                         excess_data: Vec::new()
2188                 });
2189                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2190                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2191                         short_channel_id: 12,
2192                         timestamp: 2,
2193                         flags: 2,
2194                         cltv_expiry_delta: 0,
2195                         htlc_minimum_msat: 0,
2196                         htlc_maximum_msat: OptionalField::Present(100_000),
2197                         fee_base_msat: 0,
2198                         fee_proportional_millionths: 0,
2199                         excess_data: Vec::new()
2200                 });
2201
2202                 // Make the first channel (#1) very permissive,
2203                 // and we will be testing all limits on the second channel.
2204                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2205                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2206                         short_channel_id: 1,
2207                         timestamp: 2,
2208                         flags: 0,
2209                         cltv_expiry_delta: 0,
2210                         htlc_minimum_msat: 0,
2211                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2212                         fee_base_msat: 0,
2213                         fee_proportional_millionths: 0,
2214                         excess_data: Vec::new()
2215                 });
2216
2217                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2218                 // In this case, it should be set to 250_000 sats.
2219                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2220                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2221                         short_channel_id: 3,
2222                         timestamp: 2,
2223                         flags: 0,
2224                         cltv_expiry_delta: 0,
2225                         htlc_minimum_msat: 0,
2226                         htlc_maximum_msat: OptionalField::Absent,
2227                         fee_base_msat: 0,
2228                         fee_proportional_millionths: 0,
2229                         excess_data: Vec::new()
2230                 });
2231
2232                 {
2233                         // Attempt to route more than available results in a failure.
2234                         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)) {
2235                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2236                         } else { panic!(); }
2237                 }
2238
2239                 {
2240                         // Now, attempt to route an exact amount we have should be fine.
2241                         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();
2242                         assert_eq!(route.paths.len(), 1);
2243                         let path = route.paths.last().unwrap();
2244                         assert_eq!(path.len(), 2);
2245                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2246                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2247                 }
2248
2249                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2250                 // Disable channel #1 and use another first hop.
2251                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2252                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2253                         short_channel_id: 1,
2254                         timestamp: 3,
2255                         flags: 2,
2256                         cltv_expiry_delta: 0,
2257                         htlc_minimum_msat: 0,
2258                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2259                         fee_base_msat: 0,
2260                         fee_proportional_millionths: 0,
2261                         excess_data: Vec::new()
2262                 });
2263
2264                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2265                 let our_chans = vec![channelmanager::ChannelDetails {
2266                         channel_id: [0; 32],
2267                         short_channel_id: Some(42),
2268                         remote_network_id: nodes[0].clone(),
2269                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2270                         channel_value_satoshis: 0,
2271                         user_id: 0,
2272                         outbound_capacity_msat: 200_000_000,
2273                         inbound_capacity_msat: 0,
2274                         is_live: true,
2275                 }];
2276
2277                 {
2278                         // Attempt to route more than available results in a failure.
2279                         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)) {
2280                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2281                         } else { panic!(); }
2282                 }
2283
2284                 {
2285                         // Now, attempt to route an exact amount we have should be fine.
2286                         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();
2287                         assert_eq!(route.paths.len(), 1);
2288                         let path = route.paths.last().unwrap();
2289                         assert_eq!(path.len(), 2);
2290                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2291                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2292                 }
2293
2294                 // Enable channel #1 back.
2295                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2296                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2297                         short_channel_id: 1,
2298                         timestamp: 4,
2299                         flags: 0,
2300                         cltv_expiry_delta: 0,
2301                         htlc_minimum_msat: 0,
2302                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2303                         fee_base_msat: 0,
2304                         fee_proportional_millionths: 0,
2305                         excess_data: Vec::new()
2306                 });
2307
2308
2309                 // Now let's see if routing works if we know only htlc_maximum_msat.
2310                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2311                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2312                         short_channel_id: 3,
2313                         timestamp: 3,
2314                         flags: 0,
2315                         cltv_expiry_delta: 0,
2316                         htlc_minimum_msat: 0,
2317                         htlc_maximum_msat: OptionalField::Present(15_000),
2318                         fee_base_msat: 0,
2319                         fee_proportional_millionths: 0,
2320                         excess_data: Vec::new()
2321                 });
2322
2323                 {
2324                         // Attempt to route more than available results in a failure.
2325                         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)) {
2326                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2327                         } else { panic!(); }
2328                 }
2329
2330                 {
2331                         // Now, attempt to route an exact amount we have should be fine.
2332                         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();
2333                         assert_eq!(route.paths.len(), 1);
2334                         let path = route.paths.last().unwrap();
2335                         assert_eq!(path.len(), 2);
2336                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2337                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2338                 }
2339
2340                 // Now let's see if routing works if we know only capacity from the UTXO.
2341
2342                 // We can't change UTXO capacity on the fly, so we'll disable
2343                 // the existing channel and add another one with the capacity we need.
2344                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2345                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2346                         short_channel_id: 3,
2347                         timestamp: 4,
2348                         flags: 2,
2349                         cltv_expiry_delta: 0,
2350                         htlc_minimum_msat: 0,
2351                         htlc_maximum_msat: OptionalField::Absent,
2352                         fee_base_msat: 0,
2353                         fee_proportional_millionths: 0,
2354                         excess_data: Vec::new()
2355                 });
2356
2357                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2358                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2359                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2360                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2361                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2362
2363                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2364                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2365
2366                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2367                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2368                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2369                         short_channel_id: 333,
2370                         timestamp: 1,
2371                         flags: 0,
2372                         cltv_expiry_delta: (3 << 8) | 1,
2373                         htlc_minimum_msat: 0,
2374                         htlc_maximum_msat: OptionalField::Absent,
2375                         fee_base_msat: 0,
2376                         fee_proportional_millionths: 0,
2377                         excess_data: Vec::new()
2378                 });
2379                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2380                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2381                         short_channel_id: 333,
2382                         timestamp: 1,
2383                         flags: 1,
2384                         cltv_expiry_delta: (3 << 8) | 2,
2385                         htlc_minimum_msat: 0,
2386                         htlc_maximum_msat: OptionalField::Absent,
2387                         fee_base_msat: 100,
2388                         fee_proportional_millionths: 0,
2389                         excess_data: Vec::new()
2390                 });
2391
2392                 {
2393                         // Attempt to route more than available results in a failure.
2394                         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)) {
2395                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2396                         } else { panic!(); }
2397                 }
2398
2399                 {
2400                         // Now, attempt to route an exact amount we have should be fine.
2401                         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();
2402                         assert_eq!(route.paths.len(), 1);
2403                         let path = route.paths.last().unwrap();
2404                         assert_eq!(path.len(), 2);
2405                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2406                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2407                 }
2408
2409                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2410                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2411                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2412                         short_channel_id: 333,
2413                         timestamp: 6,
2414                         flags: 0,
2415                         cltv_expiry_delta: 0,
2416                         htlc_minimum_msat: 0,
2417                         htlc_maximum_msat: OptionalField::Present(10_000),
2418                         fee_base_msat: 0,
2419                         fee_proportional_millionths: 0,
2420                         excess_data: Vec::new()
2421                 });
2422
2423                 {
2424                         // Attempt to route more than available results in a failure.
2425                         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)) {
2426                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2427                         } else { panic!(); }
2428                 }
2429
2430                 {
2431                         // Now, attempt to route an exact amount we have should be fine.
2432                         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();
2433                         assert_eq!(route.paths.len(), 1);
2434                         let path = route.paths.last().unwrap();
2435                         assert_eq!(path.len(), 2);
2436                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2437                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2438                 }
2439         }
2440
2441         #[test]
2442         fn available_liquidity_last_hop_test() {
2443                 // Check that available liquidity properly limits the path even when only
2444                 // one of the latter hops is limited.
2445                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2446                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2447
2448                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2449                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2450                 // Total capacity: 50 sats.
2451
2452                 // Disable other potential paths.
2453                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2454                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2455                         short_channel_id: 2,
2456                         timestamp: 2,
2457                         flags: 2,
2458                         cltv_expiry_delta: 0,
2459                         htlc_minimum_msat: 0,
2460                         htlc_maximum_msat: OptionalField::Present(100_000),
2461                         fee_base_msat: 0,
2462                         fee_proportional_millionths: 0,
2463                         excess_data: Vec::new()
2464                 });
2465                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2466                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2467                         short_channel_id: 7,
2468                         timestamp: 2,
2469                         flags: 2,
2470                         cltv_expiry_delta: 0,
2471                         htlc_minimum_msat: 0,
2472                         htlc_maximum_msat: OptionalField::Present(100_000),
2473                         fee_base_msat: 0,
2474                         fee_proportional_millionths: 0,
2475                         excess_data: Vec::new()
2476                 });
2477
2478                 // Limit capacities
2479
2480                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2481                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2482                         short_channel_id: 12,
2483                         timestamp: 2,
2484                         flags: 0,
2485                         cltv_expiry_delta: 0,
2486                         htlc_minimum_msat: 0,
2487                         htlc_maximum_msat: OptionalField::Present(100_000),
2488                         fee_base_msat: 0,
2489                         fee_proportional_millionths: 0,
2490                         excess_data: Vec::new()
2491                 });
2492                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2493                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2494                         short_channel_id: 13,
2495                         timestamp: 2,
2496                         flags: 0,
2497                         cltv_expiry_delta: 0,
2498                         htlc_minimum_msat: 0,
2499                         htlc_maximum_msat: OptionalField::Present(100_000),
2500                         fee_base_msat: 0,
2501                         fee_proportional_millionths: 0,
2502                         excess_data: Vec::new()
2503                 });
2504
2505                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2506                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2507                         short_channel_id: 6,
2508                         timestamp: 2,
2509                         flags: 0,
2510                         cltv_expiry_delta: 0,
2511                         htlc_minimum_msat: 0,
2512                         htlc_maximum_msat: OptionalField::Present(50_000),
2513                         fee_base_msat: 0,
2514                         fee_proportional_millionths: 0,
2515                         excess_data: Vec::new()
2516                 });
2517                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2518                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2519                         short_channel_id: 11,
2520                         timestamp: 2,
2521                         flags: 0,
2522                         cltv_expiry_delta: 0,
2523                         htlc_minimum_msat: 0,
2524                         htlc_maximum_msat: OptionalField::Present(100_000),
2525                         fee_base_msat: 0,
2526                         fee_proportional_millionths: 0,
2527                         excess_data: Vec::new()
2528                 });
2529                 {
2530                         // Attempt to route more than available results in a failure.
2531                         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)) {
2532                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2533                         } else { panic!(); }
2534                 }
2535
2536                 {
2537                         // Now, attempt to route 49 sats (just a bit below the capacity).
2538                         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();
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, 49_000);
2547                 }
2548
2549                 {
2550                         // Attempt to route an exact amount is also fine
2551                         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();
2552                         assert_eq!(route.paths.len(), 1);
2553                         let mut total_amount_paid_msat = 0;
2554                         for path in &route.paths {
2555                                 assert_eq!(path.len(), 4);
2556                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2557                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2558                         }
2559                         assert_eq!(total_amount_paid_msat, 50_000);
2560                 }
2561         }
2562
2563         #[test]
2564         fn ignore_fee_first_hop_test() {
2565                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2566                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2567
2568                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2569                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2570                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2571                         short_channel_id: 1,
2572                         timestamp: 2,
2573                         flags: 0,
2574                         cltv_expiry_delta: 0,
2575                         htlc_minimum_msat: 0,
2576                         htlc_maximum_msat: OptionalField::Present(100_000),
2577                         fee_base_msat: 1_000_000,
2578                         fee_proportional_millionths: 0,
2579                         excess_data: Vec::new()
2580                 });
2581                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2582                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2583                         short_channel_id: 3,
2584                         timestamp: 2,
2585                         flags: 0,
2586                         cltv_expiry_delta: 0,
2587                         htlc_minimum_msat: 0,
2588                         htlc_maximum_msat: OptionalField::Present(50_000),
2589                         fee_base_msat: 0,
2590                         fee_proportional_millionths: 0,
2591                         excess_data: Vec::new()
2592                 });
2593
2594                 {
2595                         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();
2596                         assert_eq!(route.paths.len(), 1);
2597                         let mut total_amount_paid_msat = 0;
2598                         for path in &route.paths {
2599                                 assert_eq!(path.len(), 2);
2600                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2601                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2602                         }
2603                         assert_eq!(total_amount_paid_msat, 50_000);
2604                 }
2605         }
2606
2607         #[test]
2608         fn simple_mpp_route_test() {
2609                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2610                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2611
2612                 // We need a route consisting of 3 paths:
2613                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2614                 // To achieve this, the amount being transferred should be around
2615                 // the total capacity of these 3 paths.
2616
2617                 // First, we set limits on these (previously unlimited) channels.
2618                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2619
2620                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2621                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2622                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2623                         short_channel_id: 1,
2624                         timestamp: 2,
2625                         flags: 0,
2626                         cltv_expiry_delta: 0,
2627                         htlc_minimum_msat: 0,
2628                         htlc_maximum_msat: OptionalField::Present(100_000),
2629                         fee_base_msat: 0,
2630                         fee_proportional_millionths: 0,
2631                         excess_data: Vec::new()
2632                 });
2633                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2634                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2635                         short_channel_id: 3,
2636                         timestamp: 2,
2637                         flags: 0,
2638                         cltv_expiry_delta: 0,
2639                         htlc_minimum_msat: 0,
2640                         htlc_maximum_msat: OptionalField::Present(50_000),
2641                         fee_base_msat: 0,
2642                         fee_proportional_millionths: 0,
2643                         excess_data: Vec::new()
2644                 });
2645
2646                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2647                 // (total limit 60).
2648                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2649                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2650                         short_channel_id: 12,
2651                         timestamp: 2,
2652                         flags: 0,
2653                         cltv_expiry_delta: 0,
2654                         htlc_minimum_msat: 0,
2655                         htlc_maximum_msat: OptionalField::Present(60_000),
2656                         fee_base_msat: 0,
2657                         fee_proportional_millionths: 0,
2658                         excess_data: Vec::new()
2659                 });
2660                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2661                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2662                         short_channel_id: 13,
2663                         timestamp: 2,
2664                         flags: 0,
2665                         cltv_expiry_delta: 0,
2666                         htlc_minimum_msat: 0,
2667                         htlc_maximum_msat: OptionalField::Present(60_000),
2668                         fee_base_msat: 0,
2669                         fee_proportional_millionths: 0,
2670                         excess_data: Vec::new()
2671                 });
2672
2673                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2674                 // (total capacity 180 sats).
2675                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2676                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2677                         short_channel_id: 2,
2678                         timestamp: 2,
2679                         flags: 0,
2680                         cltv_expiry_delta: 0,
2681                         htlc_minimum_msat: 0,
2682                         htlc_maximum_msat: OptionalField::Present(200_000),
2683                         fee_base_msat: 0,
2684                         fee_proportional_millionths: 0,
2685                         excess_data: Vec::new()
2686                 });
2687                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2688                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2689                         short_channel_id: 4,
2690                         timestamp: 2,
2691                         flags: 0,
2692                         cltv_expiry_delta: 0,
2693                         htlc_minimum_msat: 0,
2694                         htlc_maximum_msat: OptionalField::Present(180_000),
2695                         fee_base_msat: 0,
2696                         fee_proportional_millionths: 0,
2697                         excess_data: Vec::new()
2698                 });
2699
2700                 {
2701                         // Attempt to route more than available results in a failure.
2702                         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)) {
2703                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2704                         } else { panic!(); }
2705                 }
2706
2707                 {
2708                         // Now, attempt to route 250 sats (just a bit below the capacity).
2709                         // Our algorithm should provide us with these 3 paths.
2710                         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();
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, 250_000);
2719                 }
2720
2721                 {
2722                         // Attempt to route an exact amount is also fine
2723                         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();
2724                         assert_eq!(route.paths.len(), 3);
2725                         let mut total_amount_paid_msat = 0;
2726                         for path in &route.paths {
2727                                 assert_eq!(path.len(), 2);
2728                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2729                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2730                         }
2731                         assert_eq!(total_amount_paid_msat, 290_000);
2732                 }
2733         }
2734
2735         #[test]
2736         fn long_mpp_route_test() {
2737                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2738                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2739
2740                 // We need a route consisting of 3 paths:
2741                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2742                 // Note that these paths overlap (channels 5, 12, 13).
2743                 // We will route 300 sats.
2744                 // Each path will have 100 sats capacity, those channels which
2745                 // are used twice will have 200 sats capacity.
2746
2747                 // Disable other potential paths.
2748                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2749                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2750                         short_channel_id: 2,
2751                         timestamp: 2,
2752                         flags: 2,
2753                         cltv_expiry_delta: 0,
2754                         htlc_minimum_msat: 0,
2755                         htlc_maximum_msat: OptionalField::Present(100_000),
2756                         fee_base_msat: 0,
2757                         fee_proportional_millionths: 0,
2758                         excess_data: Vec::new()
2759                 });
2760                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2761                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2762                         short_channel_id: 7,
2763                         timestamp: 2,
2764                         flags: 2,
2765                         cltv_expiry_delta: 0,
2766                         htlc_minimum_msat: 0,
2767                         htlc_maximum_msat: OptionalField::Present(100_000),
2768                         fee_base_msat: 0,
2769                         fee_proportional_millionths: 0,
2770                         excess_data: Vec::new()
2771                 });
2772
2773                 // Path via {node0, node2} is channels {1, 3, 5}.
2774                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2775                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2776                         short_channel_id: 1,
2777                         timestamp: 2,
2778                         flags: 0,
2779                         cltv_expiry_delta: 0,
2780                         htlc_minimum_msat: 0,
2781                         htlc_maximum_msat: OptionalField::Present(100_000),
2782                         fee_base_msat: 0,
2783                         fee_proportional_millionths: 0,
2784                         excess_data: Vec::new()
2785                 });
2786                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2787                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2788                         short_channel_id: 3,
2789                         timestamp: 2,
2790                         flags: 0,
2791                         cltv_expiry_delta: 0,
2792                         htlc_minimum_msat: 0,
2793                         htlc_maximum_msat: OptionalField::Present(100_000),
2794                         fee_base_msat: 0,
2795                         fee_proportional_millionths: 0,
2796                         excess_data: Vec::new()
2797                 });
2798
2799                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
2800                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
2801                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2802                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2803                         short_channel_id: 5,
2804                         timestamp: 2,
2805                         flags: 0,
2806                         cltv_expiry_delta: 0,
2807                         htlc_minimum_msat: 0,
2808                         htlc_maximum_msat: OptionalField::Present(200_000),
2809                         fee_base_msat: 0,
2810                         fee_proportional_millionths: 0,
2811                         excess_data: Vec::new()
2812                 });
2813
2814                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2815                 // Add 100 sats to the capacities of {12, 13}, because these channels
2816                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
2817                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2818                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2819                         short_channel_id: 12,
2820                         timestamp: 2,
2821                         flags: 0,
2822                         cltv_expiry_delta: 0,
2823                         htlc_minimum_msat: 0,
2824                         htlc_maximum_msat: OptionalField::Present(200_000),
2825                         fee_base_msat: 0,
2826                         fee_proportional_millionths: 0,
2827                         excess_data: Vec::new()
2828                 });
2829                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2830                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2831                         short_channel_id: 13,
2832                         timestamp: 2,
2833                         flags: 0,
2834                         cltv_expiry_delta: 0,
2835                         htlc_minimum_msat: 0,
2836                         htlc_maximum_msat: OptionalField::Present(200_000),
2837                         fee_base_msat: 0,
2838                         fee_proportional_millionths: 0,
2839                         excess_data: Vec::new()
2840                 });
2841
2842                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2843                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2844                         short_channel_id: 6,
2845                         timestamp: 2,
2846                         flags: 0,
2847                         cltv_expiry_delta: 0,
2848                         htlc_minimum_msat: 0,
2849                         htlc_maximum_msat: OptionalField::Present(100_000),
2850                         fee_base_msat: 0,
2851                         fee_proportional_millionths: 0,
2852                         excess_data: Vec::new()
2853                 });
2854                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2855                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2856                         short_channel_id: 11,
2857                         timestamp: 2,
2858                         flags: 0,
2859                         cltv_expiry_delta: 0,
2860                         htlc_minimum_msat: 0,
2861                         htlc_maximum_msat: OptionalField::Present(100_000),
2862                         fee_base_msat: 0,
2863                         fee_proportional_millionths: 0,
2864                         excess_data: Vec::new()
2865                 });
2866
2867                 // Path via {node7, node2} is channels {12, 13, 5}.
2868                 // We already limited them to 200 sats (they are used twice for 100 sats).
2869                 // Nothing to do here.
2870
2871                 {
2872                         // Attempt to route more than available results in a failure.
2873                         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)) {
2874                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2875                         } else { panic!(); }
2876                 }
2877
2878                 {
2879                         // Now, attempt to route 300 sats (exact amount we can route).
2880                         // Our algorithm should provide us with these 3 paths, 100 sats each.
2881                         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();
2882                         assert_eq!(route.paths.len(), 3);
2883
2884                         let mut total_amount_paid_msat = 0;
2885                         for path in &route.paths {
2886                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2887                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2888                         }
2889                         assert_eq!(total_amount_paid_msat, 300_000);
2890                 }
2891
2892         }
2893
2894         #[test]
2895         fn mpp_cheaper_route_test() {
2896                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2897                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2898
2899                 // This test checks that if we have two cheaper paths and one more expensive path,
2900                 // so that liquidity-wise any 2 of 3 combination is sufficient,
2901                 // two cheaper paths will be taken.
2902                 // These paths have equal available liquidity.
2903
2904                 // We need a combination of 3 paths:
2905                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2906                 // Note that these paths overlap (channels 5, 12, 13).
2907                 // Each path will have 100 sats capacity, those channels which
2908                 // are used twice will have 200 sats capacity.
2909
2910                 // Disable other potential paths.
2911                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2912                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2913                         short_channel_id: 2,
2914                         timestamp: 2,
2915                         flags: 2,
2916                         cltv_expiry_delta: 0,
2917                         htlc_minimum_msat: 0,
2918                         htlc_maximum_msat: OptionalField::Present(100_000),
2919                         fee_base_msat: 0,
2920                         fee_proportional_millionths: 0,
2921                         excess_data: Vec::new()
2922                 });
2923                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2924                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2925                         short_channel_id: 7,
2926                         timestamp: 2,
2927                         flags: 2,
2928                         cltv_expiry_delta: 0,
2929                         htlc_minimum_msat: 0,
2930                         htlc_maximum_msat: OptionalField::Present(100_000),
2931                         fee_base_msat: 0,
2932                         fee_proportional_millionths: 0,
2933                         excess_data: Vec::new()
2934                 });
2935
2936                 // Path via {node0, node2} is channels {1, 3, 5}.
2937                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2938                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2939                         short_channel_id: 1,
2940                         timestamp: 2,
2941                         flags: 0,
2942                         cltv_expiry_delta: 0,
2943                         htlc_minimum_msat: 0,
2944                         htlc_maximum_msat: OptionalField::Present(100_000),
2945                         fee_base_msat: 0,
2946                         fee_proportional_millionths: 0,
2947                         excess_data: Vec::new()
2948                 });
2949                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2950                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2951                         short_channel_id: 3,
2952                         timestamp: 2,
2953                         flags: 0,
2954                         cltv_expiry_delta: 0,
2955                         htlc_minimum_msat: 0,
2956                         htlc_maximum_msat: OptionalField::Present(100_000),
2957                         fee_base_msat: 0,
2958                         fee_proportional_millionths: 0,
2959                         excess_data: Vec::new()
2960                 });
2961
2962                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
2963                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
2964                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2965                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2966                         short_channel_id: 5,
2967                         timestamp: 2,
2968                         flags: 0,
2969                         cltv_expiry_delta: 0,
2970                         htlc_minimum_msat: 0,
2971                         htlc_maximum_msat: OptionalField::Present(200_000),
2972                         fee_base_msat: 0,
2973                         fee_proportional_millionths: 0,
2974                         excess_data: Vec::new()
2975                 });
2976
2977                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2978                 // Add 100 sats to the capacities of {12, 13}, because these channels
2979                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
2980                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2981                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2982                         short_channel_id: 12,
2983                         timestamp: 2,
2984                         flags: 0,
2985                         cltv_expiry_delta: 0,
2986                         htlc_minimum_msat: 0,
2987                         htlc_maximum_msat: OptionalField::Present(200_000),
2988                         fee_base_msat: 0,
2989                         fee_proportional_millionths: 0,
2990                         excess_data: Vec::new()
2991                 });
2992                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2993                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2994                         short_channel_id: 13,
2995                         timestamp: 2,
2996                         flags: 0,
2997                         cltv_expiry_delta: 0,
2998                         htlc_minimum_msat: 0,
2999                         htlc_maximum_msat: OptionalField::Present(200_000),
3000                         fee_base_msat: 0,
3001                         fee_proportional_millionths: 0,
3002                         excess_data: Vec::new()
3003                 });
3004
3005                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3006                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3007                         short_channel_id: 6,
3008                         timestamp: 2,
3009                         flags: 0,
3010                         cltv_expiry_delta: 0,
3011                         htlc_minimum_msat: 0,
3012                         htlc_maximum_msat: OptionalField::Present(100_000),
3013                         fee_base_msat: 1_000,
3014                         fee_proportional_millionths: 0,
3015                         excess_data: Vec::new()
3016                 });
3017                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3018                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3019                         short_channel_id: 11,
3020                         timestamp: 2,
3021                         flags: 0,
3022                         cltv_expiry_delta: 0,
3023                         htlc_minimum_msat: 0,
3024                         htlc_maximum_msat: OptionalField::Present(100_000),
3025                         fee_base_msat: 0,
3026                         fee_proportional_millionths: 0,
3027                         excess_data: Vec::new()
3028                 });
3029
3030                 // Path via {node7, node2} is channels {12, 13, 5}.
3031                 // We already limited them to 200 sats (they are used twice for 100 sats).
3032                 // Nothing to do here.
3033
3034                 {
3035                         // Now, attempt to route 180 sats.
3036                         // Our algorithm should provide us with these 2 paths.
3037                         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();
3038                         assert_eq!(route.paths.len(), 2);
3039
3040                         let mut total_value_transferred_msat = 0;
3041                         let mut total_paid_msat = 0;
3042                         for path in &route.paths {
3043                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3044                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3045                                 for hop in path {
3046                                         total_paid_msat += hop.fee_msat;
3047                                 }
3048                         }
3049                         // If we paid fee, this would be higher.
3050                         assert_eq!(total_value_transferred_msat, 180_000);
3051                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3052                         assert_eq!(total_fees_paid, 0);
3053                 }
3054         }
3055
3056         #[test]
3057         fn fees_on_mpp_route_test() {
3058                 // This test makes sure that MPP algorithm properly takes into account
3059                 // fees charged on the channels, by making the fees impactful:
3060                 // if the fee is not properly accounted for, the behavior is different.
3061                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3062                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3063
3064                 // We need a route consisting of 2 paths:
3065                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3066                 // We will route 200 sats, Each path will have 100 sats capacity.
3067
3068                 // This test is not particularly stable: e.g.,
3069                 // there's a way to route via {node0, node2, node4}.
3070                 // It works while pathfinding is deterministic, but can be broken otherwise.
3071                 // It's fine to ignore this concern for now.
3072
3073                 // Disable other potential paths.
3074                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3075                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3076                         short_channel_id: 2,
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                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3088                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3089                         short_channel_id: 7,
3090                         timestamp: 2,
3091                         flags: 2,
3092                         cltv_expiry_delta: 0,
3093                         htlc_minimum_msat: 0,
3094                         htlc_maximum_msat: OptionalField::Present(100_000),
3095                         fee_base_msat: 0,
3096                         fee_proportional_millionths: 0,
3097                         excess_data: Vec::new()
3098                 });
3099
3100                 // Path via {node0, node2} is channels {1, 3, 5}.
3101                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3102                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3103                         short_channel_id: 1,
3104                         timestamp: 2,
3105                         flags: 0,
3106                         cltv_expiry_delta: 0,
3107                         htlc_minimum_msat: 0,
3108                         htlc_maximum_msat: OptionalField::Present(100_000),
3109                         fee_base_msat: 0,
3110                         fee_proportional_millionths: 0,
3111                         excess_data: Vec::new()
3112                 });
3113                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3114                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3115                         short_channel_id: 3,
3116                         timestamp: 2,
3117                         flags: 0,
3118                         cltv_expiry_delta: 0,
3119                         htlc_minimum_msat: 0,
3120                         htlc_maximum_msat: OptionalField::Present(100_000),
3121                         fee_base_msat: 0,
3122                         fee_proportional_millionths: 0,
3123                         excess_data: Vec::new()
3124                 });
3125
3126                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3127                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3128                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3129                         short_channel_id: 5,
3130                         timestamp: 2,
3131                         flags: 0,
3132                         cltv_expiry_delta: 0,
3133                         htlc_minimum_msat: 0,
3134                         htlc_maximum_msat: OptionalField::Present(100_000),
3135                         fee_base_msat: 0,
3136                         fee_proportional_millionths: 0,
3137                         excess_data: Vec::new()
3138                 });
3139
3140                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3141                 // All channels should be 100 sats capacity. But for the fee experiment,
3142                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3143                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3144                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3145                 // so no matter how large are other channels,
3146                 // the whole path will be limited by 100 sats with just these 2 conditions:
3147                 // - channel 12 capacity is 250 sats
3148                 // - fee for channel 6 is 150 sats
3149                 // Let's test this by enforcing these 2 conditions and removing other limits.
3150                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3151                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3152                         short_channel_id: 12,
3153                         timestamp: 2,
3154                         flags: 0,
3155                         cltv_expiry_delta: 0,
3156                         htlc_minimum_msat: 0,
3157                         htlc_maximum_msat: OptionalField::Present(250_000),
3158                         fee_base_msat: 0,
3159                         fee_proportional_millionths: 0,
3160                         excess_data: Vec::new()
3161                 });
3162                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3163                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3164                         short_channel_id: 13,
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: 0,
3171                         fee_proportional_millionths: 0,
3172                         excess_data: Vec::new()
3173                 });
3174
3175                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3176                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3177                         short_channel_id: 6,
3178                         timestamp: 2,
3179                         flags: 0,
3180                         cltv_expiry_delta: 0,
3181                         htlc_minimum_msat: 0,
3182                         htlc_maximum_msat: OptionalField::Absent,
3183                         fee_base_msat: 150_000,
3184                         fee_proportional_millionths: 0,
3185                         excess_data: Vec::new()
3186                 });
3187                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3188                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3189                         short_channel_id: 11,
3190                         timestamp: 2,
3191                         flags: 0,
3192                         cltv_expiry_delta: 0,
3193                         htlc_minimum_msat: 0,
3194                         htlc_maximum_msat: OptionalField::Absent,
3195                         fee_base_msat: 0,
3196                         fee_proportional_millionths: 0,
3197                         excess_data: Vec::new()
3198                 });
3199
3200                 {
3201                         // Attempt to route more than available results in a failure.
3202                         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)) {
3203                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3204                         } else { panic!(); }
3205                 }
3206
3207                 {
3208                         // Now, attempt to route 200 sats (exact amount we can route).
3209                         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();
3210                         assert_eq!(route.paths.len(), 2);
3211
3212                         let mut total_amount_paid_msat = 0;
3213                         for path in &route.paths {
3214                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3215                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3216                         }
3217                         assert_eq!(total_amount_paid_msat, 200_000);
3218                 }
3219
3220         }
3221
3222         #[test]
3223         fn drop_lowest_channel_mpp_route_test() {
3224                 // This test checks that low-capacity channel is dropped when after
3225                 // path finding we realize that we found more capacity than we need.
3226                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3227                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3228
3229                 // We need a route consisting of 3 paths:
3230                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3231
3232                 // The first and the second paths should be sufficient, but the third should be
3233                 // cheaper, so that we select it but drop later.
3234
3235                 // First, we set limits on these (previously unlimited) channels.
3236                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3237
3238                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3239                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3240                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3241                         short_channel_id: 1,
3242                         timestamp: 2,
3243                         flags: 0,
3244                         cltv_expiry_delta: 0,
3245                         htlc_minimum_msat: 0,
3246                         htlc_maximum_msat: OptionalField::Present(100_000),
3247                         fee_base_msat: 0,
3248                         fee_proportional_millionths: 0,
3249                         excess_data: Vec::new()
3250                 });
3251                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3252                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3253                         short_channel_id: 3,
3254                         timestamp: 2,
3255                         flags: 0,
3256                         cltv_expiry_delta: 0,
3257                         htlc_minimum_msat: 0,
3258                         htlc_maximum_msat: OptionalField::Present(50_000),
3259                         fee_base_msat: 100,
3260                         fee_proportional_millionths: 0,
3261                         excess_data: Vec::new()
3262                 });
3263
3264                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3265                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3266                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3267                         short_channel_id: 12,
3268                         timestamp: 2,
3269                         flags: 0,
3270                         cltv_expiry_delta: 0,
3271                         htlc_minimum_msat: 0,
3272                         htlc_maximum_msat: OptionalField::Present(60_000),
3273                         fee_base_msat: 100,
3274                         fee_proportional_millionths: 0,
3275                         excess_data: Vec::new()
3276                 });
3277                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3278                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3279                         short_channel_id: 13,
3280                         timestamp: 2,
3281                         flags: 0,
3282                         cltv_expiry_delta: 0,
3283                         htlc_minimum_msat: 0,
3284                         htlc_maximum_msat: OptionalField::Present(60_000),
3285                         fee_base_msat: 0,
3286                         fee_proportional_millionths: 0,
3287                         excess_data: Vec::new()
3288                 });
3289
3290                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3291                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3292                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3293                         short_channel_id: 2,
3294                         timestamp: 2,
3295                         flags: 0,
3296                         cltv_expiry_delta: 0,
3297                         htlc_minimum_msat: 0,
3298                         htlc_maximum_msat: OptionalField::Present(20_000),
3299                         fee_base_msat: 0,
3300                         fee_proportional_millionths: 0,
3301                         excess_data: Vec::new()
3302                 });
3303                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3304                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3305                         short_channel_id: 4,
3306                         timestamp: 2,
3307                         flags: 0,
3308                         cltv_expiry_delta: 0,
3309                         htlc_minimum_msat: 0,
3310                         htlc_maximum_msat: OptionalField::Present(20_000),
3311                         fee_base_msat: 0,
3312                         fee_proportional_millionths: 0,
3313                         excess_data: Vec::new()
3314                 });
3315
3316                 {
3317                         // Attempt to route more than available results in a failure.
3318                         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)) {
3319                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3320                         } else { panic!(); }
3321                 }
3322
3323                 {
3324                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3325                         // Our algorithm should provide us with these 3 paths.
3326                         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();
3327                         assert_eq!(route.paths.len(), 3);
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, 125_000);
3335                 }
3336
3337                 {
3338                         // Attempt to route without the last small cheap channel
3339                         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();
3340                         assert_eq!(route.paths.len(), 2);
3341                         let mut total_amount_paid_msat = 0;
3342                         for path in &route.paths {
3343                                 assert_eq!(path.len(), 2);
3344                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3345                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3346                         }
3347                         assert_eq!(total_amount_paid_msat, 90_000);
3348                 }
3349         }
3350
3351 }