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

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! The top-level routing/network map tracking logic lives here.
  11 //!
  12 //! You probably want to create a NetGraphMsgHandler and use that as your RoutingMessageHandler and then
  13 //! interrogate it to get routes for your own payments.
  14
  15 use bitcoin::secp256k1::key::PublicKey;
  16
  17 use ln::channelmanager::ChannelDetails;
  18 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
  19 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
  20 use routing::network_graph::{NetworkGraph, RoutingFees};
  21 use util::ser::{Writeable, Readable};
  22 use util::logger::Logger;
  23
  24 use prelude::*;
  25 use alloc::collections::BinaryHeap;
  26 use core::cmp;
  27 use std::collections::HashMap;
  28 use core::ops::Deref;
  29
  30 /// A hop in a route
  31 #[derive(Clone, PartialEq)]
  32 pub struct RouteHop {
  33         /// The node_id of the node at this hop.
  34         pub pubkey: PublicKey,
  35         /// The node_announcement features of the node at this hop. For the last hop, these may be
  36         /// amended to match the features present in the invoice this node generated.
  37         pub node_features: NodeFeatures,
  38         /// The channel that should be used from the previous hop to reach this node.
  39         pub short_channel_id: u64,
  40         /// The channel_announcement features of the channel that should be used from the previous hop
  41         /// to reach this node.
  42         pub channel_features: ChannelFeatures,
  43         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  44         /// For the last hop, this should be the full value of the payment (might be more than
  45         /// requested if we had to match htlc_minimum_msat).
  46         pub fee_msat: u64,
  47         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  48         /// expected at the destination, in excess of the current block height.
  49         pub cltv_expiry_delta: u32,
  50 }
  51
  52 impl_writeable_tlv_based!(RouteHop, {
  53         (0, pubkey),
  54         (2, node_features),
  55         (4, short_channel_id),
  56         (6, channel_features),
  57         (8, fee_msat),
  58         (10, cltv_expiry_delta),
  59 }, {}, {});
  60
  61 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  62 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  63 #[derive(Clone, PartialEq)]
  64 pub struct Route {
  65         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  66         /// last RouteHop in each path must be the same.
  67         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  68         /// destination. Thus, this must always be at least length one. While the maximum length of any
  69         /// given path is variable, keeping the length of any path to less than 20 should currently
  70         /// ensure it is viable.
  71         pub paths: Vec<Vec<RouteHop>>,
  72 }
  73
  74 const SERIALIZATION_VERSION: u8 = 1;
  75 const MIN_SERIALIZATION_VERSION: u8 = 1;
  76
  77 impl Writeable for Route {
  78         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
  79                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
  80                 (self.paths.len() as u64).write(writer)?;
  81                 for hops in self.paths.iter() {
  82                         (hops.len() as u8).write(writer)?;
  83                         for hop in hops.iter() {
  84                                 hop.write(writer)?;
  85                         }
  86                 }
  87                 write_tlv_fields!(writer, {}, {});
  88                 Ok(())
  89         }
  90 }
  91
  92 impl Readable for Route {
  93         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
  94                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
  95                 let path_count: u64 = Readable::read(reader)?;
  96                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
  97                 for _ in 0..path_count {
  98                         let hop_count: u8 = Readable::read(reader)?;
  99                         let mut hops = Vec::with_capacity(hop_count as usize);
 100                         for _ in 0..hop_count {
 101                                 hops.push(Readable::read(reader)?);
 102                         }
 103                         paths.push(hops);
 104                 }
 105                 read_tlv_fields!(reader, {}, {});
 106                 Ok(Route { paths })
 107         }
 108 }
 109
 110 /// A list of hops along a payment path terminating with a channel to the recipient.
 111 #[derive(Eq, PartialEq, Debug, Clone)]
 112 pub struct RouteHint(pub Vec<RouteHintHop>);
 113
 114 /// A channel descriptor for a hop along a payment path.
 115 #[derive(Eq, PartialEq, Debug, Clone)]
 116 pub struct RouteHintHop {
 117         /// The node_id of the non-target end of the route
 118         pub src_node_id: PublicKey,
 119         /// The short_channel_id of this channel
 120         pub short_channel_id: u64,
 121         /// The fees which must be paid to use this channel
 122         pub fees: RoutingFees,
 123         /// The difference in CLTV values between this node and the next node.
 124         pub cltv_expiry_delta: u16,
 125         /// The minimum value, in msat, which must be relayed to the next hop.
 126         pub htlc_minimum_msat: Option<u64>,
 127         /// The maximum value in msat available for routing with a single HTLC.
 128         pub htlc_maximum_msat: Option<u64>,
 129 }
 130
 131 #[derive(Eq, PartialEq)]
 132 struct RouteGraphNode {
 133         pubkey: PublicKey,
 134         lowest_fee_to_peer_through_node: u64,
 135         lowest_fee_to_node: u64,
 136         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 137         // This value is upper-bounded by us by:
 138         // - how much is needed for a path being constructed
 139         // - how much value can channels following this node (up to the destination) can contribute,
 140         //   considering their capacity and fees
 141         value_contribution_msat: u64,
 142         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 143         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 144         path_htlc_minimum_msat: u64,
 145 }
 146
 147 impl cmp::Ord for RouteGraphNode {
 148         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 149                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 150                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 151                 other_score.cmp(&self_score).then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 152         }
 153 }
 154
 155 impl cmp::PartialOrd for RouteGraphNode {
 156         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 157                 Some(self.cmp(other))
 158         }
 159 }
 160
 161 struct DummyDirectionalChannelInfo {
 162         cltv_expiry_delta: u32,
 163         htlc_minimum_msat: u64,
 164         htlc_maximum_msat: Option<u64>,
 165         fees: RoutingFees,
 166 }
 167
 168 /// It's useful to keep track of the hops associated with the fees required to use them,
 169 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 170 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 171 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 172 #[derive(Clone)]
 173 struct PathBuildingHop<'a> {
 174         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 175         // Note that node_features is calculated separately after our initial graph walk.
 176         pubkey: PublicKey,
 177         short_channel_id: u64,
 178         channel_features: &'a ChannelFeatures,
 179         fee_msat: u64,
 180         cltv_expiry_delta: u32,
 181
 182         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 183         src_lowest_inbound_fees: RoutingFees,
 184         /// Fees of the channel used in this hop.
 185         channel_fees: RoutingFees,
 186         /// All the fees paid *after* this channel on the way to the destination
 187         next_hops_fee_msat: u64,
 188         /// Fee paid for the use of the current channel (see channel_fees).
 189         /// The value will be actually deducted from the counterparty balance on the previous link.
 190         hop_use_fee_msat: u64,
 191         /// Used to compare channels when choosing the for routing.
 192         /// Includes paying for the use of a hop and the following hops, as well as
 193         /// an estimated cost of reaching this hop.
 194         /// Might get stale when fees are recomputed. Primarily for internal use.
 195         total_fee_msat: u64,
 196         /// This is useful for update_value_and_recompute_fees to make sure
 197         /// we don't fall below the minimum. Should not be updated manually and
 198         /// generally should not be accessed.
 199         htlc_minimum_msat: u64,
 200         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 201         /// walk and may be invalid thereafter.
 202         path_htlc_minimum_msat: u64,
 203         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 204         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 205         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 206         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 207         /// avoid processing them again.
 208         was_processed: bool,
 209         #[cfg(any(test, feature = "fuzztarget"))]
 210         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 211         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 212         // value_contribution_msat, which requires tracking it here. See comments below where it is
 213         // used for more info.
 214         value_contribution_msat: u64,
 215 }
 216
 217 // Instantiated with a list of hops with correct data in them collected during path finding,
 218 // an instance of this struct should be further modified only via given methods.
 219 #[derive(Clone)]
 220 struct PaymentPath<'a> {
 221         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 222 }
 223
 224 impl<'a> PaymentPath<'a> {
 225         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 226         fn get_value_msat(&self) -> u64 {
 227                 self.hops.last().unwrap().0.fee_msat
 228         }
 229
 230         fn get_total_fee_paid_msat(&self) -> u64 {
 231                 if self.hops.len() < 1 {
 232                         return 0;
 233                 }
 234                 let mut result = 0;
 235                 // Can't use next_hops_fee_msat because it gets outdated.
 236                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 237                         if i != self.hops.len() - 1 {
 238                                 result += hop.fee_msat;
 239                         }
 240                 }
 241                 return result;
 242         }
 243
 244         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 245         // to change fees may result in an inconsistency.
 246         //
 247         // Sometimes we call this function right after constructing a path which is inconsistent in
 248         // that it the value being transferred has decreased while we were doing path finding, leading
 249         // to the fees being paid not lining up with the actual limits.
 250         //
 251         // Note that this function is not aware of the available_liquidity limit, and thus does not
 252         // support increasing the value being transferred.
 253         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 254                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 255
 256                 let mut total_fee_paid_msat = 0 as u64;
 257                 for i in (0..self.hops.len()).rev() {
 258                         let last_hop = i == self.hops.len() - 1;
 259
 260                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 261                         // will consist of the fees for the use of the next hop, and extra fees to match
 262                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 263                         let mut cur_hop_fees_msat = 0;
 264                         if !last_hop {
 265                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 266                         }
 267
 268                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 269                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 270                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 271                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 272                         // set it too high just to maliciously take more fees by exploiting this
 273                         // match htlc_minimum_msat logic.
 274                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 275                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 276                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 277                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 278                                 //
 279                                 // This might make us end up with a broken route, although this should be super-rare
 280                                 // in practice, both because of how healthy channels look like, and how we pick
 281                                 // channels in add_entry.
 282                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 283                                 // all payments*.
 284                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 285                                 total_fee_paid_msat += extra_fees_msat;
 286                                 cur_hop_fees_msat += extra_fees_msat;
 287                         }
 288
 289                         if last_hop {
 290                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 291                                 // it still could overpay for the htlc_minimum_msat.
 292                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 293                         } else {
 294                                 // Propagate updated fees for the use of the channels to one hop back, where they
 295                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 296                                 cur_hop.fee_msat = cur_hop_fees_msat;
 297                         }
 298
 299                         // Fee for the use of the current hop which will be deducted on the previous hop.
 300                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 301                         // this channel is free for us.
 302                         if i != 0 {
 303                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 304                                         cur_hop.hop_use_fee_msat = new_fee;
 305                                         total_fee_paid_msat += new_fee;
 306                                 } else {
 307                                         // It should not be possible because this function is called only to reduce the
 308                                         // value. In that case, compute_fee was already called with the same fees for
 309                                         // larger amount and there was no overflow.
 310                                         unreachable!();
 311                                 }
 312                         }
 313                 }
 314         }
 315 }
 316
 317 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 318         let proportional_fee_millions =
 319                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 320         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 321                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 322
 323                 Some(new_fee)
 324         } else {
 325                 // This function may be (indirectly) called without any verification,
 326                 // with channel_fees provided by a caller. We should handle it gracefully.
 327                 None
 328         }
 329 }
 330
 331 /// Gets a route from us (payer) to the given target node (payee).
 332 ///
 333 /// If the payee provided features in their invoice, they should be provided via payee_features.
 334 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 335 ///
 336 /// Private routing paths between a public node and the target may be included in `last_hops`.
 337 /// Currently, only the last hop in each path is considered.
 338 ///
 339 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 340 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 341 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 342 /// in first_hops will be used.
 343 ///
 344 /// Panics if first_hops contains channels without short_channel_ids
 345 /// (ChannelManager::list_usable_channels will never include such channels).
 346 ///
 347 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 348 /// equal), however the enabled/disabled bit on such channels as well as the
 349 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 350 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 351         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 352         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 353         // uptime/success in using a node in the past.
 354         if *payee == *our_node_id {
 355                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 356         }
 357
 358         if final_value_msat > MAX_VALUE_MSAT {
 359                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 360         }
 361
 362         if final_value_msat == 0 {
 363                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 364         }
 365
 366         let last_hops = last_hops.iter().filter_map(|hops| hops.0.last()).collect::<Vec<_>>();
 367         for last_hop in last_hops.iter() {
 368                 if last_hop.src_node_id == *payee {
 369                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 370                 }
 371         }
 372
 373         // The general routing idea is the following:
 374         // 1. Fill first/last hops communicated by the caller.
 375         // 2. Attempt to construct a path from payer to payee for transferring
 376         //    any ~sufficient (described later) value.
 377         //    If succeed, remember which channels were used and how much liquidity they have available,
 378         //    so that future paths don't rely on the same liquidity.
 379         // 3. Prooceed to the next step if:
 380         //    - we hit the recommended target value;
 381         //    - OR if we could not construct a new path. Any next attempt will fail too.
 382         //    Otherwise, repeat step 2.
 383         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 384         //    (not recommended value). If yes, proceed. If not, fail routing.
 385         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 386         // 6. Of all the found paths, select only those with the lowest total fee.
 387         // 7. The last path in every selected route is likely to be more than we need.
 388         //    Reduce its value-to-transfer and recompute fees.
 389         // 8. Choose the best route by the lowest total fee.
 390
 391         // As for the actual search algorithm,
 392         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 393         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 394         //
 395         // We are not a faithful Dijkstra's implementation because we can change values which impact
 396         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 397         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 398         // the value we are currently attempting to send over a path, we simply reduce the value being
 399         // sent along the path for any hops after that channel. This may imply that later fees (which
 400         // we've already tabulated) are lower because a smaller value is passing through the channels
 401         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 402         // channels which were selected earlier (and which may still be used for other paths without a
 403         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 404         // de-preferenced.
 405         //
 406         // One potentially problematic case for this algorithm would be if there are many
 407         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 408         // graph walking), we may never find a path which is not liquidity-limited and has lower
 409         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 410         // Because we only consider paths with at least 5% of the total value being sent, the damage
 411         // from such a case should be limited, however this could be further reduced in the future by
 412         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 413         // limits for the purposes of fee calculation.
 414         //
 415         // Alternatively, we could store more detailed path information in the heap (targets, below)
 416         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 417         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 418         // and practically (as we would need to store dynamically-allocated path information in heap
 419         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 420         // results of such an algorithm would likely be biased towards lower-value paths.
 421         //
 422         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 423         // outside of our current search value, running a path search more times to gather candidate
 424         // paths at different values. While this may be acceptable, further path searches may increase
 425         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 426         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 427         // the same time, remaining generic across different payment values.
 428         //
 429         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 430         // to use as the A* heuristic beyond just the cost to get one node further than the current
 431         // one.
 432
 433         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 434                 cltv_expiry_delta: 0,
 435                 htlc_minimum_msat: 0,
 436                 htlc_maximum_msat: None,
 437                 fees: RoutingFees {
 438                         base_msat: 0,
 439                         proportional_millionths: 0,
 440                 }
 441         };
 442
 443         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 444         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 445         // work reliably.
 446         let allow_mpp = if let Some(features) = &payee_features {
 447                 features.supports_basic_mpp()
 448         } else if let Some(node) = network.get_nodes().get(&payee) {
 449                 if let Some(node_info) = node.announcement_info.as_ref() {
 450                         node_info.features.supports_basic_mpp()
 451                 } else { false }
 452         } else { false };
 453
 454         // Step (1).
 455         // Prepare the data we'll use for payee-to-payer search by
 456         // inserting first hops suggested by the caller as targets.
 457         // Our search will then attempt to reach them while traversing from the payee node.
 458         let mut first_hop_targets: HashMap<_, (_, ChannelFeatures, _, NodeFeatures)> =
 459                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 460         if let Some(hops) = first_hops {
 461                 for chan in hops {
 462                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 463                         if chan.remote_network_id == *our_node_id {
 464                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 465                         }
 466                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.to_context(), chan.outbound_capacity_msat, chan.counterparty_features.to_context()));
 467                 }
 468                 if first_hop_targets.is_empty() {
 469                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 470                 }
 471         }
 472
 473         let empty_channel_features = ChannelFeatures::empty();
 474
 475         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 476         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 477         // adding duplicate entries when we find a better path to a given node.
 478         let mut targets = BinaryHeap::new();
 479
 480         // Map from node_id to information about the best current path to that node, including feerate
 481         // information.
 482         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 483
 484         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 485         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 486         // htlc_minimum with extra fees while still finding a cheaper path.
 487         let mut hit_minimum_limit;
 488
 489         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 490         // We start with a path_value of the exact amount we want, and if that generates a route we may
 491         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 492         // amount we want in total across paths, selecting the best subset at the end.
 493         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 494         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 495         let mut path_value_msat = final_value_msat;
 496
 497         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 498         // This map allows paths to be aware of the channel use by other paths in the same call.
 499         // This would help to make a better path finding decisions and not "overbook" channels.
 500         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 501         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network.get_nodes().len());
 502
 503         // Keeping track of how much value we already collected across other paths. Helps to decide:
 504         // - how much a new path should be transferring (upper bound);
 505         // - whether a channel should be disregarded because
 506         //   it's available liquidity is too small comparing to how much more we need to collect;
 507         // - when we want to stop looking for new paths.
 508         let mut already_collected_value_msat = 0;
 509
 510         macro_rules! add_entry {
 511                 // Adds entry which goes from $src_node_id to $dest_node_id
 512                 // over the channel with id $chan_id with fees described in
 513                 // $directional_info.
 514                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 515                 // since that value has to be transferred over this channel.
 516                 ( $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,
 517                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 518                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 519                         // practice these cases should be caught earlier:
 520                         // - for regular channels at channel announcement (TODO)
 521                         // - for first and last hops early in get_route
 522                         if $src_node_id != $dest_node_id.clone() {
 523                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 524                                         let mut initial_liquidity_available_msat = None;
 525                                         if let Some(capacity_sats) = $capacity_sats {
 526                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 527                                         }
 528
 529                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 530                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 531                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 532                                                 } else {
 533                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 534                                                 }
 535                                         }
 536
 537                                         match initial_liquidity_available_msat {
 538                                                 Some(available_msat) => available_msat,
 539                                                 // We assume channels with unknown balance have
 540                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 541                                                 None => 250_000 * 1000
 542                                         }
 543                                 });
 544
 545                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 546                                 // It may be misleading because we might later choose to reduce the value transferred
 547                                 // over these channels, and the channel which was insufficient might become sufficient.
 548                                 // Worst case: we drop a good channel here because it can't cover the high following
 549                                 // fees caused by one expensive channel, but then this channel could have been used
 550                                 // if the amount being transferred over this path is lower.
 551                                 // We do this for now, but this is a subject for removal.
 552                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 553
 554                                         // Routing Fragmentation Mitigation heuristic:
 555                                         //
 556                                         // Routing fragmentation across many payment paths increases the overall routing
 557                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 558                                         // Taking too many smaller paths also increases the chance of payment failure.
 559                                         // Thus to avoid this effect, we require from our collected links to provide
 560                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 561                                         //
 562                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 563                                         // This means as we successfully advance in our collection,
 564                                         // the absolute liquidity contribution is lowered,
 565                                         // thus increasing the number of potential channels to be selected.
 566
 567                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 568                                         // or 100% if we're not allowed to do multipath payments.
 569                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 570                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 571                                         } else {
 572                                                 final_value_msat
 573                                         };
 574                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 575                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 576
 577                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 578                                         // Includes paying fees for the use of the following channels.
 579                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 580                                                 Some(result) => result,
 581                                                 // Can't overflow due to how the values were computed right above.
 582                                                 None => unreachable!(),
 583                                         };
 584                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 585                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 586                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 587
 588                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 589                                         // bother considering this channel.
 590                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 591                                         // be only reduced later (not increased), so this channel should just be skipped
 592                                         // as not sufficient.
 593                                         if !over_path_minimum_msat {
 594                                                 hit_minimum_limit = true;
 595                                         } else if contributes_sufficient_value {
 596                                                 // Note that low contribution here (limited by available_liquidity_msat)
 597                                                 // might violate htlc_minimum_msat on the hops which are next along the
 598                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 599                                                 // path fees knowing the final path contribution after constructing it.
 600                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 601                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 602                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 603                                                         _ => u64::max_value()
 604                                                 };
 605                                                 let hm_entry = dist.entry(&$src_node_id);
 606                                                 let old_entry = hm_entry.or_insert_with(|| {
 607                                                         // If there was previously no known way to access
 608                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 609                                                         // a semi-dummy record just to compute the fees to reach the source node.
 610                                                         // This will affect our decision on selecting $chan_id
 611                                                         // as a way to reach the $dest_node_id.
 612                                                         let mut fee_base_msat = u32::max_value();
 613                                                         let mut fee_proportional_millionths = u32::max_value();
 614                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 615                                                                 fee_base_msat = fees.base_msat;
 616                                                                 fee_proportional_millionths = fees.proportional_millionths;
 617                                                         }
 618                                                         PathBuildingHop {
 619                                                                 pubkey: $dest_node_id.clone(),
 620                                                                 short_channel_id: 0,
 621                                                                 channel_features: $chan_features,
 622                                                                 fee_msat: 0,
 623                                                                 cltv_expiry_delta: 0,
 624                                                                 src_lowest_inbound_fees: RoutingFees {
 625                                                                         base_msat: fee_base_msat,
 626                                                                         proportional_millionths: fee_proportional_millionths,
 627                                                                 },
 628                                                                 channel_fees: $directional_info.fees,
 629                                                                 next_hops_fee_msat: u64::max_value(),
 630                                                                 hop_use_fee_msat: u64::max_value(),
 631                                                                 total_fee_msat: u64::max_value(),
 632                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 633                                                                 path_htlc_minimum_msat,
 634                                                                 was_processed: false,
 635                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 636                                                                 value_contribution_msat,
 637                                                         }
 638                                                 });
 639
 640                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 641                                                 let mut should_process = !old_entry.was_processed;
 642                                                 #[cfg(any(test, feature = "fuzztarget"))]
 643                                                 {
 644                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 645                                                         // of already-seen nodes only happens in cases we expect (see below).
 646                                                         if !should_process { should_process = true; }
 647                                                 }
 648
 649                                                 if should_process {
 650                                                         let mut hop_use_fee_msat = 0;
 651                                                         let mut total_fee_msat = $next_hops_fee_msat;
 652
 653                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 654                                                         // will have the same effective-fee
 655                                                         if $src_node_id != *our_node_id {
 656                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 657                                                                         // max_value means we'll always fail
 658                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 659                                                                         None => total_fee_msat = u64::max_value(),
 660                                                                         Some(fee_msat) => {
 661                                                                                 hop_use_fee_msat = fee_msat;
 662                                                                                 total_fee_msat += hop_use_fee_msat;
 663                                                                                 // When calculating the lowest inbound fees to a node, we
 664                                                                                 // calculate fees here not based on the actual value we think
 665                                                                                 // will flow over this channel, but on the minimum value that
 666                                                                                 // we'll accept flowing over it. The minimum accepted value
 667                                                                                 // is a constant through each path collection run, ensuring
 668                                                                                 // consistent basis. Otherwise we may later find a
 669                                                                                 // different path to the source node that is more expensive,
 670                                                                                 // but which we consider to be cheaper because we are capacity
 671                                                                                 // constrained and the relative fee becomes lower.
 672                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 673                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 674                                                                                         Some(Some(v)) => {
 675                                                                                                 total_fee_msat = v;
 676                                                                                         },
 677                                                                                         _ => {
 678                                                                                                 total_fee_msat = u64::max_value();
 679                                                                                         }
 680                                                                                 };
 681                                                                         }
 682                                                                 }
 683                                                         }
 684
 685                                                         let new_graph_node = RouteGraphNode {
 686                                                                 pubkey: $src_node_id,
 687                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 688                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 689                                                                 value_contribution_msat: value_contribution_msat,
 690                                                                 path_htlc_minimum_msat,
 691                                                         };
 692
 693                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 694                                                         // if this way is cheaper than the already known
 695                                                         // (considering the cost to "reach" this channel from the route destination,
 696                                                         // the cost of using this channel,
 697                                                         // and the cost of routing to the source node of this channel).
 698                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 699                                                         // paying it. Consider the following exploit:
 700                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 701                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 702                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 703                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 704                                                         // to this channel.
 705                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 706                                                         // but it may require additional tracking - we don't want to double-count
 707                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 708                                                         // can't use something that may decrease on future hops.
 709                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 710                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 711
 712                                                         if !old_entry.was_processed && new_cost < old_cost {
 713                                                                 targets.push(new_graph_node);
 714                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 715                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 716                                                                 old_entry.total_fee_msat = total_fee_msat;
 717                                                                 old_entry.pubkey = $dest_node_id.clone();
 718                                                                 old_entry.short_channel_id = $chan_id.clone();
 719                                                                 old_entry.channel_features = $chan_features;
 720                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 721                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 722                                                                 old_entry.channel_fees = $directional_info.fees;
 723                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 724                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 725                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 726                                                                 {
 727                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 728                                                                 }
 729                                                         } else if old_entry.was_processed && new_cost < old_cost {
 730                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 731                                                                 {
 732                                                                         // If we're skipping processing a node which was previously
 733                                                                         // processed even though we found another path to it with a
 734                                                                         // cheaper fee, check that it was because the second path we
 735                                                                         // found (which we are processing now) has a lower value
 736                                                                         // contribution due to an HTLC minimum limit.
 737                                                                         //
 738                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 739                                                                         // through channel A, and one through channel B. Channel A and
 740                                                                         // B are both in the to-process heap, with their scores set by
 741                                                                         // a higher htlc_minimum than fee.
 742                                                                         // Channel A is processed first, and the channels onwards from
 743                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 744                                                                         // Channel B off of the heap, note that it has a much more
 745                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 746                                                                         // all of node 1's channels using the new, reduced, amount.
 747                                                                         //
 748                                                                         // This would be bogus - we'd be selecting a higher-fee path
 749                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 750                                                                         // already decided to use.
 751                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 752                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 753                                                                 }
 754                                                         }
 755                                                 }
 756                                         }
 757                                 }
 758                         }
 759                 };
 760         }
 761
 762         let empty_node_features = NodeFeatures::empty();
 763         // Find ways (channels with destination) to reach a given node and store them
 764         // in the corresponding data structures (routing graph etc).
 765         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 766         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 767         // This data can later be helpful to optimize routing (pay lower fees).
 768         macro_rules! add_entries_to_cheapest_to_target_node {
 769                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 770                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 771                                 let was_processed = elem.was_processed;
 772                                 elem.was_processed = true;
 773                                 was_processed
 774                         } else {
 775                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 776                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 777                                 // If we're processing any other node, it is always be the result of a channel from it.
 778                                 assert_eq!($node_id, payee);
 779                                 false
 780                         };
 781
 782                         if !skip_node {
 783                                 if first_hops.is_some() {
 784                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&$node_id) {
 785                                                 add_entry!(first_hop, *our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 786                                         }
 787                                 }
 788
 789                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 790                                         &node_info.features
 791                                 } else {
 792                                         &empty_node_features
 793                                 };
 794
 795                                 if !features.requires_unknown_bits() {
 796                                         for chan_id in $node.channels.iter() {
 797                                                 let chan = network.get_channels().get(chan_id).unwrap();
 798                                                 if !chan.features.requires_unknown_bits() {
 799                                                         if chan.node_one == *$node_id {
 800                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 801                                                                 if first_hops.is_none() || chan.node_two != *our_node_id {
 802                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 803                                                                                 if two_to_one.enabled {
 804                                                                                         add_entry!(chan_id, chan.node_two, chan.node_one, two_to_one, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 805                                                                                 }
 806                                                                         }
 807                                                                 }
 808                                                         } else {
 809                                                                 if first_hops.is_none() || chan.node_one != *our_node_id {
 810                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 811                                                                                 if one_to_two.enabled {
 812                                                                                         add_entry!(chan_id, chan.node_one, chan.node_two, one_to_two, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 813                                                                                 }
 814                                                                         }
 815                                                                 }
 816                                                         }
 817                                                 }
 818                                         }
 819                                 }
 820                         }
 821                 };
 822         }
 823
 824         let mut payment_paths = Vec::<PaymentPath>::new();
 825
 826         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 827         'paths_collection: loop {
 828                 // For every new path, start from scratch, except
 829                 // bookkeeped_channels_liquidity_available_msat, which will improve
 830                 // the further iterations of path finding. Also don't erase first_hop_targets.
 831                 targets.clear();
 832                 dist.clear();
 833                 hit_minimum_limit = false;
 834
 835                 // If first hop is a private channel and the only way to reach the payee, this is the only
 836                 // place where it could be added.
 837                 if first_hops.is_some() {
 838                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&payee) {
 839                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 840                         }
 841                 }
 842
 843                 // Add the payee as a target, so that the payee-to-payer
 844                 // search algorithm knows what to start with.
 845                 match network.get_nodes().get(payee) {
 846                         // The payee is not in our network graph, so nothing to add here.
 847                         // There is still a chance of reaching them via last_hops though,
 848                         // so don't yet fail the payment here.
 849                         // If not, targets.pop() will not even let us enter the loop in step 2.
 850                         None => {},
 851                         Some(node) => {
 852                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 853                         },
 854                 }
 855
 856                 // Step (1).
 857                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 858                 // earlier than general path finding, they will be somewhat prioritized, although currently
 859                 // it matters only if the fees are exactly the same.
 860                 for hop in last_hops.iter() {
 861                         let have_hop_src_in_graph =
 862                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
 863                                         // If this hop connects to a node with which we have a direct channel, ignore
 864                                         // the network graph and add both the hop and our direct channel to
 865                                         // the candidate set.
 866                                         //
 867                                         // Currently there are no channel-context features defined, so we are a
 868                                         // bit lazy here. In the future, we should pull them out via our
 869                                         // ChannelManager, but there's no reason to waste the space until we
 870                                         // need them.
 871                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 872                                         true
 873                                 } else {
 874                                         // In any other case, only add the hop if the source is in the regular network
 875                                         // graph:
 876                                         network.get_nodes().get(&hop.src_node_id).is_some()
 877                                 };
 878                         if have_hop_src_in_graph {
 879                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 880                                 // really sucks, cause we're gonna need that eventually.
 881                                 let last_hop_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 882                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 883                                         None => 0
 884                                 };
 885                                 let directional_info = DummyDirectionalChannelInfo {
 886                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 887                                         htlc_minimum_msat: last_hop_htlc_minimum_msat,
 888                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 889                                         fees: hop.fees,
 890                                 };
 891                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, &empty_channel_features, 0, path_value_msat, 0);
 892                         }
 893                 }
 894
 895                 // At this point, targets are filled with the data from first and
 896                 // last hops communicated by the caller, and the payment receiver.
 897                 let mut found_new_path = false;
 898
 899                 // Step (2).
 900                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 901                 // - not enough outgoing liquidity:
 902                 //   0 < already_collected_value_msat < final_value_msat
 903                 // - enough outgoing liquidity:
 904                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 905                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 906                 // paths_collection will be stopped because found_new_path==false.
 907                 // This is not necessarily a routing failure.
 908                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 909
 910                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 911                         // traversing the graph and arrange the path out of what we found.
 912                         if pubkey == *our_node_id {
 913                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 914                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
 915
 916                                 'path_walk: loop {
 917                                         if let Some(&(_, _, _, ref features)) = first_hop_targets.get(&ordered_hops.last().unwrap().0.pubkey) {
 918                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
 919                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().0.pubkey) {
 920                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 921                                                         ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
 922                                                 } else {
 923                                                         ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
 924                                                 }
 925                                         } else {
 926                                                 // We should be able to fill in features for everything except the last
 927                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 928                                                 // should be able to extend it further as BOLT 11 does have feature
 929                                                 // flags for the last hop node itself).
 930                                                 assert!(ordered_hops.last().unwrap().0.pubkey == *payee);
 931                                         }
 932
 933                                         // Means we succesfully traversed from the payer to the payee, now
 934                                         // save this path for the payment route. Also, update the liquidity
 935                                         // remaining on the used hops, so that we take them into account
 936                                         // while looking for more paths.
 937                                         if ordered_hops.last().unwrap().0.pubkey == *payee {
 938                                                 break 'path_walk;
 939                                         }
 940
 941                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.pubkey) {
 942                                                 Some(payment_hop) => payment_hop,
 943                                                 // We can't arrive at None because, if we ever add an entry to targets,
 944                                                 // we also fill in the entry in dist (see add_entry!).
 945                                                 None => unreachable!(),
 946                                         };
 947                                         // We "propagate" the fees one hop backward (topologically) here,
 948                                         // so that fees paid for a HTLC forwarding on the current channel are
 949                                         // associated with the previous channel (where they will be subtracted).
 950                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
 951                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
 952                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
 953                                 }
 954                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
 955                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
 956                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
 957
 958                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 959
 960                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 961                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 962                                 // on some channels we already passed (assuming dest->source direction). Here, we
 963                                 // recompute the fees again, so that if that's the case, we match the currently
 964                                 // underpaid htlc_minimum_msat with fees.
 965                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
 966
 967                                 // Since a path allows to transfer as much value as
 968                                 // the smallest channel it has ("bottleneck"), we should recompute
 969                                 // the fees so sender HTLC don't overpay fees when traversing
 970                                 // larger channels than the bottleneck. This may happen because
 971                                 // when we were selecting those channels we were not aware how much value
 972                                 // this path will transfer, and the relative fee for them
 973                                 // might have been computed considering a larger value.
 974                                 // Remember that we used these channels so that we don't rely
 975                                 // on the same liquidity in future paths.
 976                                 let mut prevented_redundant_path_selection = false;
 977                                 for (payment_hop, _) in payment_path.hops.iter() {
 978                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
 979                                         let mut spent_on_hop_msat = value_contribution_msat;
 980                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 981                                         spent_on_hop_msat += next_hops_fee_msat;
 982                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
 983                                                 // If this path used all of this channel's available liquidity, we know
 984                                                 // this path will not be selected again in the next loop iteration.
 985                                                 prevented_redundant_path_selection = true;
 986                                         }
 987                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 988                                 }
 989                                 if !prevented_redundant_path_selection {
 990                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
 991                                         // we'll probably end up picking the same path again on the next iteration.
 992                                         // Decrease the available liquidity of a hop in the middle of the path.
 993                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(
 994                                                 &payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id).unwrap();
 995                                         *victim_liquidity = 0;
 996                                 }
 997
 998                                 // Track the total amount all our collected paths allow to send so that we:
 999                                 // - know when to stop looking for more paths
1000                                 // - know which of the hops are useless considering how much more sats we need
1001                                 //   (contributes_sufficient_value)
1002                                 already_collected_value_msat += value_contribution_msat;
1003
1004                                 payment_paths.push(payment_path);
1005                                 found_new_path = true;
1006                                 break 'path_construction;
1007                         }
1008
1009                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1010                         // the equivalent of the `elem.was_processed` check in
1011                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1012                         if pubkey == *payee { continue 'path_construction; }
1013
1014                         // Otherwise, since the current target node is not us,
1015                         // keep "unrolling" the payment graph from payee to payer by
1016                         // finding a way to reach the current target from the payer side.
1017                         match network.get_nodes().get(&pubkey) {
1018                                 None => {},
1019                                 Some(node) => {
1020                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1021                                 },
1022                         }
1023                 }
1024
1025                 if !allow_mpp {
1026                         // If we don't support MPP, no use trying to gather more value ever.
1027                         break 'paths_collection;
1028                 }
1029
1030                 // Step (3).
1031                 // Stop either when the recommended value is reached or if no new path was found in this
1032                 // iteration.
1033                 // In the latter case, making another path finding attempt won't help,
1034                 // because we deterministically terminated the search due to low liquidity.
1035                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1036                         break 'paths_collection;
1037                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1038                         // Further, if this was our first walk of the graph, and we weren't limited by an
1039                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1040                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1041                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1042                         // still keeping a lower total fee than this path.
1043                         if !hit_minimum_limit {
1044                                 break 'paths_collection;
1045                         }
1046                         path_value_msat = recommended_value_msat;
1047                 }
1048         }
1049
1050         // Step (4).
1051         if payment_paths.len() == 0 {
1052                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1053         }
1054
1055         if already_collected_value_msat < final_value_msat {
1056                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1057         }
1058
1059         // Sort by total fees and take the best paths.
1060         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1061         if payment_paths.len() > 50 {
1062                 payment_paths.truncate(50);
1063         }
1064
1065         // Draw multiple sufficient routes by randomly combining the selected paths.
1066         let mut drawn_routes = Vec::new();
1067         for i in 0..payment_paths.len() {
1068                 let mut cur_route = Vec::<PaymentPath>::new();
1069                 let mut aggregate_route_value_msat = 0;
1070
1071                 // Step (5).
1072                 // TODO: real random shuffle
1073                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1074                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1075
1076                 // Step (6).
1077                 for payment_path in cur_payment_paths {
1078                         cur_route.push(payment_path.clone());
1079                         aggregate_route_value_msat += payment_path.get_value_msat();
1080                         if aggregate_route_value_msat > final_value_msat {
1081                                 // Last path likely overpaid. Substract it from the most expensive
1082                                 // (in terms of proportional fee) path in this route and recompute fees.
1083                                 // This might be not the most economically efficient way, but fewer paths
1084                                 // also makes routing more reliable.
1085                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1086
1087                                 // First, drop some expensive low-value paths entirely if possible.
1088                                 // Sort by value so that we drop many really-low values first, since
1089                                 // fewer paths is better: the payment is less likely to fail.
1090                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1091                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1092                                 cur_route.sort_by_key(|path| path.get_value_msat());
1093                                 // We should make sure that at least 1 path left.
1094                                 let mut paths_left = cur_route.len();
1095                                 cur_route.retain(|path| {
1096                                         if paths_left == 1 {
1097                                                 return true
1098                                         }
1099                                         let mut keep = true;
1100                                         let path_value_msat = path.get_value_msat();
1101                                         if path_value_msat <= overpaid_value_msat {
1102                                                 keep = false;
1103                                                 overpaid_value_msat -= path_value_msat;
1104                                                 paths_left -= 1;
1105                                         }
1106                                         keep
1107                                 });
1108
1109                                 if overpaid_value_msat == 0 {
1110                                         break;
1111                                 }
1112
1113                                 assert!(cur_route.len() > 0);
1114
1115                                 // Step (7).
1116                                 // Now, substract the overpaid value from the most-expensive path.
1117                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1118                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1119                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1120                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1121                                 // We already dropped all the small channels above, meaning all the
1122                                 // remaining channels are larger than remaining overpaid_value_msat.
1123                                 // Thus, this can't be negative.
1124                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1125                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1126                                 break;
1127                         }
1128                 }
1129                 drawn_routes.push(cur_route);
1130         }
1131
1132         // Step (8).
1133         // Select the best route by lowest total fee.
1134         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1135         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1136         for payment_path in drawn_routes.first().unwrap() {
1137                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1138                         RouteHop {
1139                                 pubkey: payment_hop.pubkey,
1140                                 node_features: node_features.clone(),
1141                                 short_channel_id: payment_hop.short_channel_id,
1142                                 channel_features: payment_hop.channel_features.clone(),
1143                                 fee_msat: payment_hop.fee_msat,
1144                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1145                         }
1146                 }).collect());
1147         }
1148
1149         if let Some(features) = &payee_features {
1150                 for path in selected_paths.iter_mut() {
1151                         path.last_mut().unwrap().node_features = features.to_context();
1152                 }
1153         }
1154
1155         let route = Route { paths: selected_paths };
1156         log_trace!(logger, "Got route: {}", log_route!(route));
1157         Ok(route)
1158 }
1159
1160 #[cfg(test)]
1161 mod tests {
1162         use routing::router::{get_route, RouteHint, RouteHintHop, RoutingFees};
1163         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1164         use chain::transaction::OutPoint;
1165         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1166         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1167            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1168         use ln::channelmanager;
1169         use util::test_utils;
1170         use util::ser::Writeable;
1171
1172         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1173         use bitcoin::hashes::Hash;
1174         use bitcoin::network::constants::Network;
1175         use bitcoin::blockdata::constants::genesis_block;
1176         use bitcoin::blockdata::script::Builder;
1177         use bitcoin::blockdata::opcodes;
1178         use bitcoin::blockdata::transaction::TxOut;
1179
1180         use hex;
1181
1182         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1183         use bitcoin::secp256k1::{Secp256k1, All};
1184
1185         use prelude::*;
1186         use std::sync::Arc;
1187
1188         // Using the same keys for LN and BTC ids
1189         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1190            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1191                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1192                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1193
1194                 let unsigned_announcement = UnsignedChannelAnnouncement {
1195                         features,
1196                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1197                         short_channel_id,
1198                         node_id_1,
1199                         node_id_2,
1200                         bitcoin_key_1: node_id_1,
1201                         bitcoin_key_2: node_id_2,
1202                         excess_data: Vec::new(),
1203                 };
1204
1205                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1206                 let valid_announcement = ChannelAnnouncement {
1207                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1208                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1209                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1210                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1211                         contents: unsigned_announcement.clone(),
1212                 };
1213                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1214                         Ok(res) => assert!(res),
1215                         _ => panic!()
1216                 };
1217         }
1218
1219         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) {
1220                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1221                 let valid_channel_update = ChannelUpdate {
1222                         signature: secp_ctx.sign(&msghash, node_privkey),
1223                         contents: update.clone()
1224                 };
1225
1226                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1227                         Ok(res) => assert!(res),
1228                         Err(_) => panic!()
1229                 };
1230         }
1231
1232         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,
1233            features: NodeFeatures, timestamp: u32) {
1234                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1235                 let unsigned_announcement = UnsignedNodeAnnouncement {
1236                         features,
1237                         timestamp,
1238                         node_id,
1239                         rgb: [0; 3],
1240                         alias: [0; 32],
1241                         addresses: Vec::new(),
1242                         excess_address_data: Vec::new(),
1243                         excess_data: Vec::new(),
1244                 };
1245                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1246                 let valid_announcement = NodeAnnouncement {
1247                         signature: secp_ctx.sign(&msghash, node_privkey),
1248                         contents: unsigned_announcement.clone()
1249                 };
1250
1251                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1252                         Ok(_) => (),
1253                         Err(_) => panic!()
1254                 };
1255         }
1256
1257         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1258                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1259                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1260                 }).collect();
1261
1262                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1263
1264                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1265                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1266
1267                 (our_privkey, our_id, privkeys, pubkeys)
1268         }
1269
1270         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1271                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1272                 // test for it later.
1273                 let idx = (id - 1) * 2 + 1;
1274                 if idx > 8*3 {
1275                         vec![1 << (idx - 8*3), 0, 0, 0]
1276                 } else if idx > 8*2 {
1277                         vec![1 << (idx - 8*2), 0, 0]
1278                 } else if idx > 8*1 {
1279                         vec![1 << (idx - 8*1), 0]
1280                 } else {
1281                         vec![1 << idx]
1282                 }
1283         }
1284
1285         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>) {
1286                 let secp_ctx = Secp256k1::new();
1287                 let logger = Arc::new(test_utils::TestLogger::new());
1288                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1289                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1290                 // Build network from our_id to node7:
1291                 //
1292                 //        -1(1)2-  node0  -1(3)2-
1293                 //       /                       \
1294                 // our_id -1(12)2- node7 -1(13)2--- node2
1295                 //       \                       /
1296                 //        -1(2)2-  node1  -1(4)2-
1297                 //
1298                 //
1299                 // chan1  1-to-2: disabled
1300                 // chan1  2-to-1: enabled, 0 fee
1301                 //
1302                 // chan2  1-to-2: enabled, ignored fee
1303                 // chan2  2-to-1: enabled, 0 fee
1304                 //
1305                 // chan3  1-to-2: enabled, 0 fee
1306                 // chan3  2-to-1: enabled, 100 msat fee
1307                 //
1308                 // chan4  1-to-2: enabled, 100% fee
1309                 // chan4  2-to-1: enabled, 0 fee
1310                 //
1311                 // chan12 1-to-2: enabled, ignored fee
1312                 // chan12 2-to-1: enabled, 0 fee
1313                 //
1314                 // chan13 1-to-2: enabled, 200% fee
1315                 // chan13 2-to-1: enabled, 0 fee
1316                 //
1317                 //
1318                 //       -1(5)2- node3 -1(8)2--
1319                 //       |         2          |
1320                 //       |       (11)         |
1321                 //      /          1           \
1322                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1323                 //      \                      /
1324                 //       -1(7)2- node5 -1(10)2-
1325                 //
1326                 // chan5  1-to-2: enabled, 100 msat fee
1327                 // chan5  2-to-1: enabled, 0 fee
1328                 //
1329                 // chan6  1-to-2: enabled, 0 fee
1330                 // chan6  2-to-1: enabled, 0 fee
1331                 //
1332                 // chan7  1-to-2: enabled, 100% fee
1333                 // chan7  2-to-1: enabled, 0 fee
1334                 //
1335                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1336                 // chan8  2-to-1: enabled, 0 fee
1337                 //
1338                 // chan9  1-to-2: enabled, 1001 msat fee
1339                 // chan9  2-to-1: enabled, 0 fee
1340                 //
1341                 // chan10 1-to-2: enabled, 0 fee
1342                 // chan10 2-to-1: enabled, 0 fee
1343                 //
1344                 // chan11 1-to-2: enabled, 0 fee
1345                 // chan11 2-to-1: enabled, 0 fee
1346
1347                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1348
1349                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1350                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1351                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1352                         short_channel_id: 1,
1353                         timestamp: 1,
1354                         flags: 1,
1355                         cltv_expiry_delta: 0,
1356                         htlc_minimum_msat: 0,
1357                         htlc_maximum_msat: OptionalField::Absent,
1358                         fee_base_msat: 0,
1359                         fee_proportional_millionths: 0,
1360                         excess_data: Vec::new()
1361                 });
1362
1363                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1364
1365                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1366                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1367                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1368                         short_channel_id: 2,
1369                         timestamp: 1,
1370                         flags: 0,
1371                         cltv_expiry_delta: u16::max_value(),
1372                         htlc_minimum_msat: 0,
1373                         htlc_maximum_msat: OptionalField::Absent,
1374                         fee_base_msat: u32::max_value(),
1375                         fee_proportional_millionths: u32::max_value(),
1376                         excess_data: Vec::new()
1377                 });
1378                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1379                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1380                         short_channel_id: 2,
1381                         timestamp: 1,
1382                         flags: 1,
1383                         cltv_expiry_delta: 0,
1384                         htlc_minimum_msat: 0,
1385                         htlc_maximum_msat: OptionalField::Absent,
1386                         fee_base_msat: 0,
1387                         fee_proportional_millionths: 0,
1388                         excess_data: Vec::new()
1389                 });
1390
1391                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1392
1393                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1394                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1395                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1396                         short_channel_id: 12,
1397                         timestamp: 1,
1398                         flags: 0,
1399                         cltv_expiry_delta: u16::max_value(),
1400                         htlc_minimum_msat: 0,
1401                         htlc_maximum_msat: OptionalField::Absent,
1402                         fee_base_msat: u32::max_value(),
1403                         fee_proportional_millionths: u32::max_value(),
1404                         excess_data: Vec::new()
1405                 });
1406                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1407                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1408                         short_channel_id: 12,
1409                         timestamp: 1,
1410                         flags: 1,
1411                         cltv_expiry_delta: 0,
1412                         htlc_minimum_msat: 0,
1413                         htlc_maximum_msat: OptionalField::Absent,
1414                         fee_base_msat: 0,
1415                         fee_proportional_millionths: 0,
1416                         excess_data: Vec::new()
1417                 });
1418
1419                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1420
1421                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1422                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1423                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1424                         short_channel_id: 3,
1425                         timestamp: 1,
1426                         flags: 0,
1427                         cltv_expiry_delta: (3 << 8) | 1,
1428                         htlc_minimum_msat: 0,
1429                         htlc_maximum_msat: OptionalField::Absent,
1430                         fee_base_msat: 0,
1431                         fee_proportional_millionths: 0,
1432                         excess_data: Vec::new()
1433                 });
1434                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1435                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1436                         short_channel_id: 3,
1437                         timestamp: 1,
1438                         flags: 1,
1439                         cltv_expiry_delta: (3 << 8) | 2,
1440                         htlc_minimum_msat: 0,
1441                         htlc_maximum_msat: OptionalField::Absent,
1442                         fee_base_msat: 100,
1443                         fee_proportional_millionths: 0,
1444                         excess_data: Vec::new()
1445                 });
1446
1447                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1448                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1449                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1450                         short_channel_id: 4,
1451                         timestamp: 1,
1452                         flags: 0,
1453                         cltv_expiry_delta: (4 << 8) | 1,
1454                         htlc_minimum_msat: 0,
1455                         htlc_maximum_msat: OptionalField::Absent,
1456                         fee_base_msat: 0,
1457                         fee_proportional_millionths: 1000000,
1458                         excess_data: Vec::new()
1459                 });
1460                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1461                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1462                         short_channel_id: 4,
1463                         timestamp: 1,
1464                         flags: 1,
1465                         cltv_expiry_delta: (4 << 8) | 2,
1466                         htlc_minimum_msat: 0,
1467                         htlc_maximum_msat: OptionalField::Absent,
1468                         fee_base_msat: 0,
1469                         fee_proportional_millionths: 0,
1470                         excess_data: Vec::new()
1471                 });
1472
1473                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1474                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1475                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1476                         short_channel_id: 13,
1477                         timestamp: 1,
1478                         flags: 0,
1479                         cltv_expiry_delta: (13 << 8) | 1,
1480                         htlc_minimum_msat: 0,
1481                         htlc_maximum_msat: OptionalField::Absent,
1482                         fee_base_msat: 0,
1483                         fee_proportional_millionths: 2000000,
1484                         excess_data: Vec::new()
1485                 });
1486                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1487                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1488                         short_channel_id: 13,
1489                         timestamp: 1,
1490                         flags: 1,
1491                         cltv_expiry_delta: (13 << 8) | 2,
1492                         htlc_minimum_msat: 0,
1493                         htlc_maximum_msat: OptionalField::Absent,
1494                         fee_base_msat: 0,
1495                         fee_proportional_millionths: 0,
1496                         excess_data: Vec::new()
1497                 });
1498
1499                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1500
1501                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1502                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1503                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1504                         short_channel_id: 6,
1505                         timestamp: 1,
1506                         flags: 0,
1507                         cltv_expiry_delta: (6 << 8) | 1,
1508                         htlc_minimum_msat: 0,
1509                         htlc_maximum_msat: OptionalField::Absent,
1510                         fee_base_msat: 0,
1511                         fee_proportional_millionths: 0,
1512                         excess_data: Vec::new()
1513                 });
1514                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1515                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1516                         short_channel_id: 6,
1517                         timestamp: 1,
1518                         flags: 1,
1519                         cltv_expiry_delta: (6 << 8) | 2,
1520                         htlc_minimum_msat: 0,
1521                         htlc_maximum_msat: OptionalField::Absent,
1522                         fee_base_msat: 0,
1523                         fee_proportional_millionths: 0,
1524                         excess_data: Vec::new(),
1525                 });
1526
1527                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1528                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1529                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1530                         short_channel_id: 11,
1531                         timestamp: 1,
1532                         flags: 0,
1533                         cltv_expiry_delta: (11 << 8) | 1,
1534                         htlc_minimum_msat: 0,
1535                         htlc_maximum_msat: OptionalField::Absent,
1536                         fee_base_msat: 0,
1537                         fee_proportional_millionths: 0,
1538                         excess_data: Vec::new()
1539                 });
1540                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1541                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1542                         short_channel_id: 11,
1543                         timestamp: 1,
1544                         flags: 1,
1545                         cltv_expiry_delta: (11 << 8) | 2,
1546                         htlc_minimum_msat: 0,
1547                         htlc_maximum_msat: OptionalField::Absent,
1548                         fee_base_msat: 0,
1549                         fee_proportional_millionths: 0,
1550                         excess_data: Vec::new()
1551                 });
1552
1553                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1554
1555                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1556
1557                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1558                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1559                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1560                         short_channel_id: 7,
1561                         timestamp: 1,
1562                         flags: 0,
1563                         cltv_expiry_delta: (7 << 8) | 1,
1564                         htlc_minimum_msat: 0,
1565                         htlc_maximum_msat: OptionalField::Absent,
1566                         fee_base_msat: 0,
1567                         fee_proportional_millionths: 1000000,
1568                         excess_data: Vec::new()
1569                 });
1570                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1571                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1572                         short_channel_id: 7,
1573                         timestamp: 1,
1574                         flags: 1,
1575                         cltv_expiry_delta: (7 << 8) | 2,
1576                         htlc_minimum_msat: 0,
1577                         htlc_maximum_msat: OptionalField::Absent,
1578                         fee_base_msat: 0,
1579                         fee_proportional_millionths: 0,
1580                         excess_data: Vec::new()
1581                 });
1582
1583                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1584
1585                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1586         }
1587
1588         #[test]
1589         fn simple_route_test() {
1590                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1591                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1592
1593                 // Simple route to 2 via 1
1594
1595                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger)) {
1596                         assert_eq!(err, "Cannot send a payment of 0 msat");
1597                 } else { panic!(); }
1598
1599                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1600                 assert_eq!(route.paths[0].len(), 2);
1601
1602                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1603                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1604                 assert_eq!(route.paths[0][0].fee_msat, 100);
1605                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1606                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1607                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1608
1609                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1610                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1611                 assert_eq!(route.paths[0][1].fee_msat, 100);
1612                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1613                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1614                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1615         }
1616
1617         #[test]
1618         fn invalid_first_hop_test() {
1619                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1620                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1621
1622                 // Simple route to 2 via 1
1623
1624                 let our_chans = vec![channelmanager::ChannelDetails {
1625                         channel_id: [0; 32],
1626                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1627                         short_channel_id: Some(2),
1628                         remote_network_id: our_id,
1629                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1630                         channel_value_satoshis: 100000,
1631                         user_id: 0,
1632                         outbound_capacity_msat: 100000,
1633                         inbound_capacity_msat: 100000,
1634                         is_outbound: true, is_funding_locked: true,
1635                         is_usable: true, is_public: true,
1636                         counterparty_forwarding_info: None,
1637                 }];
1638
1639                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
1640                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1641                 } else { panic!(); }
1642
1643                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1644                 assert_eq!(route.paths[0].len(), 2);
1645         }
1646
1647         #[test]
1648         fn htlc_minimum_test() {
1649                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1650                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1651
1652                 // Simple route to 2 via 1
1653
1654                 // Disable other paths
1655                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1656                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1657                         short_channel_id: 12,
1658                         timestamp: 2,
1659                         flags: 2, // to disable
1660                         cltv_expiry_delta: 0,
1661                         htlc_minimum_msat: 0,
1662                         htlc_maximum_msat: OptionalField::Absent,
1663                         fee_base_msat: 0,
1664                         fee_proportional_millionths: 0,
1665                         excess_data: Vec::new()
1666                 });
1667                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1668                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1669                         short_channel_id: 3,
1670                         timestamp: 2,
1671                         flags: 2, // to disable
1672                         cltv_expiry_delta: 0,
1673                         htlc_minimum_msat: 0,
1674                         htlc_maximum_msat: OptionalField::Absent,
1675                         fee_base_msat: 0,
1676                         fee_proportional_millionths: 0,
1677                         excess_data: Vec::new()
1678                 });
1679                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1680                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1681                         short_channel_id: 13,
1682                         timestamp: 2,
1683                         flags: 2, // to disable
1684                         cltv_expiry_delta: 0,
1685                         htlc_minimum_msat: 0,
1686                         htlc_maximum_msat: OptionalField::Absent,
1687                         fee_base_msat: 0,
1688                         fee_proportional_millionths: 0,
1689                         excess_data: Vec::new()
1690                 });
1691                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1693                         short_channel_id: 6,
1694                         timestamp: 2,
1695                         flags: 2, // to disable
1696                         cltv_expiry_delta: 0,
1697                         htlc_minimum_msat: 0,
1698                         htlc_maximum_msat: OptionalField::Absent,
1699                         fee_base_msat: 0,
1700                         fee_proportional_millionths: 0,
1701                         excess_data: Vec::new()
1702                 });
1703                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1704                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1705                         short_channel_id: 7,
1706                         timestamp: 2,
1707                         flags: 2, // to disable
1708                         cltv_expiry_delta: 0,
1709                         htlc_minimum_msat: 0,
1710                         htlc_maximum_msat: OptionalField::Absent,
1711                         fee_base_msat: 0,
1712                         fee_proportional_millionths: 0,
1713                         excess_data: Vec::new()
1714                 });
1715
1716                 // Check against amount_to_transfer_over_msat.
1717                 // Set minimal HTLC of 200_000_000 msat.
1718                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1719                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1720                         short_channel_id: 2,
1721                         timestamp: 3,
1722                         flags: 0,
1723                         cltv_expiry_delta: 0,
1724                         htlc_minimum_msat: 200_000_000,
1725                         htlc_maximum_msat: OptionalField::Absent,
1726                         fee_base_msat: 0,
1727                         fee_proportional_millionths: 0,
1728                         excess_data: Vec::new()
1729                 });
1730
1731                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1732                 // be used.
1733                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1734                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1735                         short_channel_id: 4,
1736                         timestamp: 3,
1737                         flags: 0,
1738                         cltv_expiry_delta: 0,
1739                         htlc_minimum_msat: 0,
1740                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1741                         fee_base_msat: 0,
1742                         fee_proportional_millionths: 0,
1743                         excess_data: Vec::new()
1744                 });
1745
1746                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1747                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)) {
1748                         assert_eq!(err, "Failed to find a path to the given destination");
1749                 } else { panic!(); }
1750
1751                 // Lift the restriction on the first hop.
1752                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1753                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1754                         short_channel_id: 2,
1755                         timestamp: 4,
1756                         flags: 0,
1757                         cltv_expiry_delta: 0,
1758                         htlc_minimum_msat: 0,
1759                         htlc_maximum_msat: OptionalField::Absent,
1760                         fee_base_msat: 0,
1761                         fee_proportional_millionths: 0,
1762                         excess_data: Vec::new()
1763                 });
1764
1765                 // A payment above the minimum should pass
1766                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)).unwrap();
1767                 assert_eq!(route.paths[0].len(), 2);
1768         }
1769
1770         #[test]
1771         fn htlc_minimum_overpay_test() {
1772                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1773                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1774
1775                 // A route to node#2 via two paths.
1776                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1777                 // Thus, they can't send 60 without overpaying.
1778                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1779                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1780                         short_channel_id: 2,
1781                         timestamp: 2,
1782                         flags: 0,
1783                         cltv_expiry_delta: 0,
1784                         htlc_minimum_msat: 35_000,
1785                         htlc_maximum_msat: OptionalField::Present(40_000),
1786                         fee_base_msat: 0,
1787                         fee_proportional_millionths: 0,
1788                         excess_data: Vec::new()
1789                 });
1790                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1791                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1792                         short_channel_id: 12,
1793                         timestamp: 3,
1794                         flags: 0,
1795                         cltv_expiry_delta: 0,
1796                         htlc_minimum_msat: 35_000,
1797                         htlc_maximum_msat: OptionalField::Present(40_000),
1798                         fee_base_msat: 0,
1799                         fee_proportional_millionths: 0,
1800                         excess_data: Vec::new()
1801                 });
1802
1803                 // Make 0 fee.
1804                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1805                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1806                         short_channel_id: 13,
1807                         timestamp: 2,
1808                         flags: 0,
1809                         cltv_expiry_delta: 0,
1810                         htlc_minimum_msat: 0,
1811                         htlc_maximum_msat: OptionalField::Absent,
1812                         fee_base_msat: 0,
1813                         fee_proportional_millionths: 0,
1814                         excess_data: Vec::new()
1815                 });
1816                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1817                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1818                         short_channel_id: 4,
1819                         timestamp: 2,
1820                         flags: 0,
1821                         cltv_expiry_delta: 0,
1822                         htlc_minimum_msat: 0,
1823                         htlc_maximum_msat: OptionalField::Absent,
1824                         fee_base_msat: 0,
1825                         fee_proportional_millionths: 0,
1826                         excess_data: Vec::new()
1827                 });
1828
1829                 // Disable other paths
1830                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1831                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1832                         short_channel_id: 1,
1833                         timestamp: 3,
1834                         flags: 2, // to disable
1835                         cltv_expiry_delta: 0,
1836                         htlc_minimum_msat: 0,
1837                         htlc_maximum_msat: OptionalField::Absent,
1838                         fee_base_msat: 0,
1839                         fee_proportional_millionths: 0,
1840                         excess_data: Vec::new()
1841                 });
1842
1843                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1844                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1845                 // Overpay fees to hit htlc_minimum_msat.
1846                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1847                 // TODO: this could be better balanced to overpay 10k and not 15k.
1848                 assert_eq!(overpaid_fees, 15_000);
1849
1850                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1851                 // while taking even more fee to match htlc_minimum_msat.
1852                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1853                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1854                         short_channel_id: 12,
1855                         timestamp: 4,
1856                         flags: 0,
1857                         cltv_expiry_delta: 0,
1858                         htlc_minimum_msat: 65_000,
1859                         htlc_maximum_msat: OptionalField::Present(80_000),
1860                         fee_base_msat: 0,
1861                         fee_proportional_millionths: 0,
1862                         excess_data: Vec::new()
1863                 });
1864                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1865                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1866                         short_channel_id: 2,
1867                         timestamp: 3,
1868                         flags: 0,
1869                         cltv_expiry_delta: 0,
1870                         htlc_minimum_msat: 0,
1871                         htlc_maximum_msat: OptionalField::Absent,
1872                         fee_base_msat: 0,
1873                         fee_proportional_millionths: 0,
1874                         excess_data: Vec::new()
1875                 });
1876                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1877                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1878                         short_channel_id: 4,
1879                         timestamp: 4,
1880                         flags: 0,
1881                         cltv_expiry_delta: 0,
1882                         htlc_minimum_msat: 0,
1883                         htlc_maximum_msat: OptionalField::Absent,
1884                         fee_base_msat: 0,
1885                         fee_proportional_millionths: 100_000,
1886                         excess_data: Vec::new()
1887                 });
1888
1889                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1890                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1891                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1892                 assert_eq!(route.paths.len(), 1);
1893                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1894                 let fees = route.paths[0][0].fee_msat;
1895                 assert_eq!(fees, 5_000);
1896
1897                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1898                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1899                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1900                 // the other channel.
1901                 assert_eq!(route.paths.len(), 1);
1902                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1903                 let fees = route.paths[0][0].fee_msat;
1904                 assert_eq!(fees, 5_000);
1905         }
1906
1907         #[test]
1908         fn disable_channels_test() {
1909                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1910                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1911
1912                 // // Disable channels 4 and 12 by flags=2
1913                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1914                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1915                         short_channel_id: 4,
1916                         timestamp: 2,
1917                         flags: 2, // to disable
1918                         cltv_expiry_delta: 0,
1919                         htlc_minimum_msat: 0,
1920                         htlc_maximum_msat: OptionalField::Absent,
1921                         fee_base_msat: 0,
1922                         fee_proportional_millionths: 0,
1923                         excess_data: Vec::new()
1924                 });
1925                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1926                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1927                         short_channel_id: 12,
1928                         timestamp: 2,
1929                         flags: 2, // to disable
1930                         cltv_expiry_delta: 0,
1931                         htlc_minimum_msat: 0,
1932                         htlc_maximum_msat: OptionalField::Absent,
1933                         fee_base_msat: 0,
1934                         fee_proportional_millionths: 0,
1935                         excess_data: Vec::new()
1936                 });
1937
1938                 // If all the channels require some features we don't understand, route should fail
1939                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1940                         assert_eq!(err, "Failed to find a path to the given destination");
1941                 } else { panic!(); }
1942
1943                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1944                 let our_chans = vec![channelmanager::ChannelDetails {
1945                         channel_id: [0; 32],
1946                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1947                         short_channel_id: Some(42),
1948                         remote_network_id: nodes[7].clone(),
1949                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1950                         channel_value_satoshis: 0,
1951                         user_id: 0,
1952                         outbound_capacity_msat: 250_000_000,
1953                         inbound_capacity_msat: 0,
1954                         is_outbound: true, is_funding_locked: true,
1955                         is_usable: true, is_public: true,
1956                         counterparty_forwarding_info: None,
1957                 }];
1958                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1959                 assert_eq!(route.paths[0].len(), 2);
1960
1961                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1962                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1963                 assert_eq!(route.paths[0][0].fee_msat, 200);
1964                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1965                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1966                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1967
1968                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1969                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1970                 assert_eq!(route.paths[0][1].fee_msat, 100);
1971                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1972                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1973                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1974         }
1975
1976         #[test]
1977         fn disable_node_test() {
1978                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1979                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1980
1981                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1982                 let mut unknown_features = NodeFeatures::known();
1983                 unknown_features.set_required_unknown_bits();
1984                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1985                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1986                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1987
1988                 // If all nodes require some features we don't understand, route should fail
1989                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1990                         assert_eq!(err, "Failed to find a path to the given destination");
1991                 } else { panic!(); }
1992
1993                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1994                 let our_chans = vec![channelmanager::ChannelDetails {
1995                         channel_id: [0; 32],
1996                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1997                         short_channel_id: Some(42),
1998                         remote_network_id: nodes[7].clone(),
1999                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2000                         channel_value_satoshis: 0,
2001                         user_id: 0,
2002                         outbound_capacity_msat: 250_000_000,
2003                         inbound_capacity_msat: 0,
2004                         is_outbound: true, is_funding_locked: true,
2005                         is_usable: true, is_public: true,
2006                         counterparty_forwarding_info: None,
2007                 }];
2008                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2009                 assert_eq!(route.paths[0].len(), 2);
2010
2011                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2012                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2013                 assert_eq!(route.paths[0][0].fee_msat, 200);
2014                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2015                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2016                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2017
2018                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2019                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2020                 assert_eq!(route.paths[0][1].fee_msat, 100);
2021                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2022                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2023                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2024
2025                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2026                 // naively) assume that the user checked the feature bits on the invoice, which override
2027                 // the node_announcement.
2028         }
2029
2030         #[test]
2031         fn our_chans_test() {
2032                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2033                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2034
2035                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2036                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2037                 assert_eq!(route.paths[0].len(), 3);
2038
2039                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2040                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2041                 assert_eq!(route.paths[0][0].fee_msat, 200);
2042                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2043                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2044                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2045
2046                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2047                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2048                 assert_eq!(route.paths[0][1].fee_msat, 100);
2049                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2050                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2051                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2052
2053                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2054                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2055                 assert_eq!(route.paths[0][2].fee_msat, 100);
2056                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2057                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2058                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2059
2060                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2061                 let our_chans = vec![channelmanager::ChannelDetails {
2062                         channel_id: [0; 32],
2063                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2064                         short_channel_id: Some(42),
2065                         remote_network_id: nodes[7].clone(),
2066                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2067                         channel_value_satoshis: 0,
2068                         user_id: 0,
2069                         outbound_capacity_msat: 250_000_000,
2070                         inbound_capacity_msat: 0,
2071                         is_outbound: true, is_funding_locked: true,
2072                         is_usable: true, is_public: true,
2073                         counterparty_forwarding_info: None,
2074                 }];
2075                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2076                 assert_eq!(route.paths[0].len(), 2);
2077
2078                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2079                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2080                 assert_eq!(route.paths[0][0].fee_msat, 200);
2081                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2082                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2083                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2084
2085                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2086                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2087                 assert_eq!(route.paths[0][1].fee_msat, 100);
2088                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2089                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2090                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2091         }
2092
2093         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2094                 let zero_fees = RoutingFees {
2095                         base_msat: 0,
2096                         proportional_millionths: 0,
2097                 };
2098                 vec![RouteHint(vec![RouteHintHop {
2099                         src_node_id: nodes[3].clone(),
2100                         short_channel_id: 8,
2101                         fees: zero_fees,
2102                         cltv_expiry_delta: (8 << 8) | 1,
2103                         htlc_minimum_msat: None,
2104                         htlc_maximum_msat: None,
2105                 }]), RouteHint(vec![RouteHintHop {
2106                         src_node_id: nodes[4].clone(),
2107                         short_channel_id: 9,
2108                         fees: RoutingFees {
2109                                 base_msat: 1001,
2110                                 proportional_millionths: 0,
2111                         },
2112                         cltv_expiry_delta: (9 << 8) | 1,
2113                         htlc_minimum_msat: None,
2114                         htlc_maximum_msat: None,
2115                 }]), RouteHint(vec![RouteHintHop {
2116                         src_node_id: nodes[5].clone(),
2117                         short_channel_id: 10,
2118                         fees: zero_fees,
2119                         cltv_expiry_delta: (10 << 8) | 1,
2120                         htlc_minimum_msat: None,
2121                         htlc_maximum_msat: None,
2122                 }])]
2123         }
2124
2125         #[test]
2126         fn last_hops_test() {
2127                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2128                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2129
2130                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2131
2132                 // First check that last hop can't have its source as the payee.
2133                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2134                         src_node_id: nodes[6],
2135                         short_channel_id: 8,
2136                         fees: RoutingFees {
2137                                 base_msat: 1000,
2138                                 proportional_millionths: 0,
2139                         },
2140                         cltv_expiry_delta: (8 << 8) | 1,
2141                         htlc_minimum_msat: None,
2142                         htlc_maximum_msat: None,
2143                 }]);
2144
2145                 let mut invalid_last_hops = last_hops(&nodes);
2146                 invalid_last_hops.push(invalid_last_hop);
2147                 {
2148                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)) {
2149                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2150                         } else { panic!(); }
2151                 }
2152
2153                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2154                 assert_eq!(route.paths[0].len(), 5);
2155
2156                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2157                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2158                 assert_eq!(route.paths[0][0].fee_msat, 100);
2159                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2160                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2161                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2162
2163                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2164                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2165                 assert_eq!(route.paths[0][1].fee_msat, 0);
2166                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2167                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2168                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2169
2170                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2171                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2172                 assert_eq!(route.paths[0][2].fee_msat, 0);
2173                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2174                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2175                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2176
2177                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2178                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2179                 assert_eq!(route.paths[0][3].fee_msat, 0);
2180                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2181                 // If we have a peer in the node map, we'll use their features here since we don't have
2182                 // a way of figuring out their features from the invoice:
2183                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2184                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2185
2186                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2187                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2188                 assert_eq!(route.paths[0][4].fee_msat, 100);
2189                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2190                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2191                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2192         }
2193
2194         #[test]
2195         fn our_chans_last_hop_connect_test() {
2196                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2197                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2198
2199                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2200                 let our_chans = vec![channelmanager::ChannelDetails {
2201                         channel_id: [0; 32],
2202                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2203                         short_channel_id: Some(42),
2204                         remote_network_id: nodes[3].clone(),
2205                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2206                         channel_value_satoshis: 0,
2207                         user_id: 0,
2208                         outbound_capacity_msat: 250_000_000,
2209                         inbound_capacity_msat: 0,
2210                         is_outbound: true, is_funding_locked: true,
2211                         is_usable: true, is_public: true,
2212                         counterparty_forwarding_info: None,
2213                 }];
2214                 let mut last_hops = last_hops(&nodes);
2215                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2216                 assert_eq!(route.paths[0].len(), 2);
2217
2218                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2219                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2220                 assert_eq!(route.paths[0][0].fee_msat, 0);
2221                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2222                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2223                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2224
2225                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2226                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2227                 assert_eq!(route.paths[0][1].fee_msat, 100);
2228                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2229                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2230                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2231
2232                 last_hops[0].0[0].fees.base_msat = 1000;
2233
2234                 // Revert to via 6 as the fee on 8 goes up
2235                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2236                 assert_eq!(route.paths[0].len(), 4);
2237
2238                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2239                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2240                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2241                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2242                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2243                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2244
2245                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2246                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2247                 assert_eq!(route.paths[0][1].fee_msat, 100);
2248                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2249                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2250                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2251
2252                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2253                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2254                 assert_eq!(route.paths[0][2].fee_msat, 0);
2255                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2256                 // If we have a peer in the node map, we'll use their features here since we don't have
2257                 // a way of figuring out their features from the invoice:
2258                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2259                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2260
2261                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2262                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2263                 assert_eq!(route.paths[0][3].fee_msat, 100);
2264                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2265                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2266                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2267
2268                 // ...but still use 8 for larger payments as 6 has a variable feerate
2269                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger)).unwrap();
2270                 assert_eq!(route.paths[0].len(), 5);
2271
2272                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2273                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2274                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2275                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2276                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2277                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2278
2279                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2280                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2281                 assert_eq!(route.paths[0][1].fee_msat, 0);
2282                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2283                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2284                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2285
2286                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2287                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2288                 assert_eq!(route.paths[0][2].fee_msat, 0);
2289                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2290                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2291                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2292
2293                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2294                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2295                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2296                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2297                 // If we have a peer in the node map, we'll use their features here since we don't have
2298                 // a way of figuring out their features from the invoice:
2299                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2300                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2301
2302                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2303                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2304                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2305                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2306                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2307                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2308         }
2309
2310         #[test]
2311         fn unannounced_path_test() {
2312                 // We should be able to send a payment to a destination without any help of a routing graph
2313                 // if we have a channel with a common counterparty that appears in the first and last hop
2314                 // hints.
2315                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2316                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2317                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2318
2319                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2320                 let last_hops = RouteHint(vec![RouteHintHop {
2321                         src_node_id: middle_node_id,
2322                         short_channel_id: 8,
2323                         fees: RoutingFees {
2324                                 base_msat: 1000,
2325                                 proportional_millionths: 0,
2326                         },
2327                         cltv_expiry_delta: (8 << 8) | 1,
2328                         htlc_minimum_msat: None,
2329                         htlc_maximum_msat: None,
2330                 }]);
2331                 let our_chans = vec![channelmanager::ChannelDetails {
2332                         channel_id: [0; 32],
2333                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2334                         short_channel_id: Some(42),
2335                         remote_network_id: middle_node_id,
2336                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2337                         channel_value_satoshis: 100000,
2338                         user_id: 0,
2339                         outbound_capacity_msat: 100000,
2340                         inbound_capacity_msat: 100000,
2341                         is_outbound: true, is_funding_locked: true,
2342                         is_usable: true, is_public: true,
2343                         counterparty_forwarding_info: None,
2344                 }];
2345                 let route = get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &vec![&last_hops], 100, 42, Arc::new(test_utils::TestLogger::new())).unwrap();
2346
2347                 assert_eq!(route.paths[0].len(), 2);
2348
2349                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2350                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2351                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2352                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2353                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2354                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2355
2356                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2357                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2358                 assert_eq!(route.paths[0][1].fee_msat, 100);
2359                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2360                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2361                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2362         }
2363
2364         #[test]
2365         fn available_amount_while_routing_test() {
2366                 // Tests whether we choose the correct available channel amount while routing.
2367
2368                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2369                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2370
2371                 // We will use a simple single-path route from
2372                 // our node to node2 via node0: channels {1, 3}.
2373
2374                 // First disable all other paths.
2375                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2376                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2377                         short_channel_id: 2,
2378                         timestamp: 2,
2379                         flags: 2,
2380                         cltv_expiry_delta: 0,
2381                         htlc_minimum_msat: 0,
2382                         htlc_maximum_msat: OptionalField::Present(100_000),
2383                         fee_base_msat: 0,
2384                         fee_proportional_millionths: 0,
2385                         excess_data: Vec::new()
2386                 });
2387                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2388                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2389                         short_channel_id: 12,
2390                         timestamp: 2,
2391                         flags: 2,
2392                         cltv_expiry_delta: 0,
2393                         htlc_minimum_msat: 0,
2394                         htlc_maximum_msat: OptionalField::Present(100_000),
2395                         fee_base_msat: 0,
2396                         fee_proportional_millionths: 0,
2397                         excess_data: Vec::new()
2398                 });
2399
2400                 // Make the first channel (#1) very permissive,
2401                 // and we will be testing all limits on the second channel.
2402                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2403                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2404                         short_channel_id: 1,
2405                         timestamp: 2,
2406                         flags: 0,
2407                         cltv_expiry_delta: 0,
2408                         htlc_minimum_msat: 0,
2409                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2410                         fee_base_msat: 0,
2411                         fee_proportional_millionths: 0,
2412                         excess_data: Vec::new()
2413                 });
2414
2415                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2416                 // In this case, it should be set to 250_000 sats.
2417                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2418                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2419                         short_channel_id: 3,
2420                         timestamp: 2,
2421                         flags: 0,
2422                         cltv_expiry_delta: 0,
2423                         htlc_minimum_msat: 0,
2424                         htlc_maximum_msat: OptionalField::Absent,
2425                         fee_base_msat: 0,
2426                         fee_proportional_millionths: 0,
2427                         excess_data: Vec::new()
2428                 });
2429
2430                 {
2431                         // Attempt to route more than available results in a failure.
2432                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2433                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2434                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2435                         } else { panic!(); }
2436                 }
2437
2438                 {
2439                         // Now, attempt to route an exact amount we have should be fine.
2440                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2441                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2442                         assert_eq!(route.paths.len(), 1);
2443                         let path = route.paths.last().unwrap();
2444                         assert_eq!(path.len(), 2);
2445                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2446                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2447                 }
2448
2449                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2450                 // Disable channel #1 and use another first hop.
2451                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2452                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2453                         short_channel_id: 1,
2454                         timestamp: 3,
2455                         flags: 2,
2456                         cltv_expiry_delta: 0,
2457                         htlc_minimum_msat: 0,
2458                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2459                         fee_base_msat: 0,
2460                         fee_proportional_millionths: 0,
2461                         excess_data: Vec::new()
2462                 });
2463
2464                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2465                 let our_chans = vec![channelmanager::ChannelDetails {
2466                         channel_id: [0; 32],
2467                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2468                         short_channel_id: Some(42),
2469                         remote_network_id: nodes[0].clone(),
2470                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2471                         channel_value_satoshis: 0,
2472                         user_id: 0,
2473                         outbound_capacity_msat: 200_000_000,
2474                         inbound_capacity_msat: 0,
2475                         is_outbound: true, is_funding_locked: true,
2476                         is_usable: true, is_public: true,
2477                         counterparty_forwarding_info: None,
2478                 }];
2479
2480                 {
2481                         // Attempt to route more than available results in a failure.
2482                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2483                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2484                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2485                         } else { panic!(); }
2486                 }
2487
2488                 {
2489                         // Now, attempt to route an exact amount we have should be fine.
2490                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2491                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2492                         assert_eq!(route.paths.len(), 1);
2493                         let path = route.paths.last().unwrap();
2494                         assert_eq!(path.len(), 2);
2495                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2496                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2497                 }
2498
2499                 // Enable channel #1 back.
2500                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2501                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2502                         short_channel_id: 1,
2503                         timestamp: 4,
2504                         flags: 0,
2505                         cltv_expiry_delta: 0,
2506                         htlc_minimum_msat: 0,
2507                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2508                         fee_base_msat: 0,
2509                         fee_proportional_millionths: 0,
2510                         excess_data: Vec::new()
2511                 });
2512
2513
2514                 // Now let's see if routing works if we know only htlc_maximum_msat.
2515                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2516                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2517                         short_channel_id: 3,
2518                         timestamp: 3,
2519                         flags: 0,
2520                         cltv_expiry_delta: 0,
2521                         htlc_minimum_msat: 0,
2522                         htlc_maximum_msat: OptionalField::Present(15_000),
2523                         fee_base_msat: 0,
2524                         fee_proportional_millionths: 0,
2525                         excess_data: Vec::new()
2526                 });
2527
2528                 {
2529                         // Attempt to route more than available results in a failure.
2530                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2531                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 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 an exact amount we have should be fine.
2538                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2539                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2540                         assert_eq!(route.paths.len(), 1);
2541                         let path = route.paths.last().unwrap();
2542                         assert_eq!(path.len(), 2);
2543                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2544                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2545                 }
2546
2547                 // Now let's see if routing works if we know only capacity from the UTXO.
2548
2549                 // We can't change UTXO capacity on the fly, so we'll disable
2550                 // the existing channel and add another one with the capacity we need.
2551                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2552                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2553                         short_channel_id: 3,
2554                         timestamp: 4,
2555                         flags: 2,
2556                         cltv_expiry_delta: 0,
2557                         htlc_minimum_msat: 0,
2558                         htlc_maximum_msat: OptionalField::Absent,
2559                         fee_base_msat: 0,
2560                         fee_proportional_millionths: 0,
2561                         excess_data: Vec::new()
2562                 });
2563
2564                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2565                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2566                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2567                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2568                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2569
2570                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2571                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2572
2573                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2574                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2575                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2576                         short_channel_id: 333,
2577                         timestamp: 1,
2578                         flags: 0,
2579                         cltv_expiry_delta: (3 << 8) | 1,
2580                         htlc_minimum_msat: 0,
2581                         htlc_maximum_msat: OptionalField::Absent,
2582                         fee_base_msat: 0,
2583                         fee_proportional_millionths: 0,
2584                         excess_data: Vec::new()
2585                 });
2586                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2587                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2588                         short_channel_id: 333,
2589                         timestamp: 1,
2590                         flags: 1,
2591                         cltv_expiry_delta: (3 << 8) | 2,
2592                         htlc_minimum_msat: 0,
2593                         htlc_maximum_msat: OptionalField::Absent,
2594                         fee_base_msat: 100,
2595                         fee_proportional_millionths: 0,
2596                         excess_data: Vec::new()
2597                 });
2598
2599                 {
2600                         // Attempt to route more than available results in a failure.
2601                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2602                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2603                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2604                         } else { panic!(); }
2605                 }
2606
2607                 {
2608                         // Now, attempt to route an exact amount we have should be fine.
2609                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2610                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2611                         assert_eq!(route.paths.len(), 1);
2612                         let path = route.paths.last().unwrap();
2613                         assert_eq!(path.len(), 2);
2614                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2615                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2616                 }
2617
2618                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2619                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2620                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2621                         short_channel_id: 333,
2622                         timestamp: 6,
2623                         flags: 0,
2624                         cltv_expiry_delta: 0,
2625                         htlc_minimum_msat: 0,
2626                         htlc_maximum_msat: OptionalField::Present(10_000),
2627                         fee_base_msat: 0,
2628                         fee_proportional_millionths: 0,
2629                         excess_data: Vec::new()
2630                 });
2631
2632                 {
2633                         // Attempt to route more than available results in a failure.
2634                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2635                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2636                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2637                         } else { panic!(); }
2638                 }
2639
2640                 {
2641                         // Now, attempt to route an exact amount we have should be fine.
2642                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2643                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2644                         assert_eq!(route.paths.len(), 1);
2645                         let path = route.paths.last().unwrap();
2646                         assert_eq!(path.len(), 2);
2647                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2648                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2649                 }
2650         }
2651
2652         #[test]
2653         fn available_liquidity_last_hop_test() {
2654                 // Check that available liquidity properly limits the path even when only
2655                 // one of the latter hops is limited.
2656                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2657                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2658
2659                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2660                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2661                 // Total capacity: 50 sats.
2662
2663                 // Disable other potential paths.
2664                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2665                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2666                         short_channel_id: 2,
2667                         timestamp: 2,
2668                         flags: 2,
2669                         cltv_expiry_delta: 0,
2670                         htlc_minimum_msat: 0,
2671                         htlc_maximum_msat: OptionalField::Present(100_000),
2672                         fee_base_msat: 0,
2673                         fee_proportional_millionths: 0,
2674                         excess_data: Vec::new()
2675                 });
2676                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2677                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2678                         short_channel_id: 7,
2679                         timestamp: 2,
2680                         flags: 2,
2681                         cltv_expiry_delta: 0,
2682                         htlc_minimum_msat: 0,
2683                         htlc_maximum_msat: OptionalField::Present(100_000),
2684                         fee_base_msat: 0,
2685                         fee_proportional_millionths: 0,
2686                         excess_data: Vec::new()
2687                 });
2688
2689                 // Limit capacities
2690
2691                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2693                         short_channel_id: 12,
2694                         timestamp: 2,
2695                         flags: 0,
2696                         cltv_expiry_delta: 0,
2697                         htlc_minimum_msat: 0,
2698                         htlc_maximum_msat: OptionalField::Present(100_000),
2699                         fee_base_msat: 0,
2700                         fee_proportional_millionths: 0,
2701                         excess_data: Vec::new()
2702                 });
2703                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2704                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2705                         short_channel_id: 13,
2706                         timestamp: 2,
2707                         flags: 0,
2708                         cltv_expiry_delta: 0,
2709                         htlc_minimum_msat: 0,
2710                         htlc_maximum_msat: OptionalField::Present(100_000),
2711                         fee_base_msat: 0,
2712                         fee_proportional_millionths: 0,
2713                         excess_data: Vec::new()
2714                 });
2715
2716                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2717                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2718                         short_channel_id: 6,
2719                         timestamp: 2,
2720                         flags: 0,
2721                         cltv_expiry_delta: 0,
2722                         htlc_minimum_msat: 0,
2723                         htlc_maximum_msat: OptionalField::Present(50_000),
2724                         fee_base_msat: 0,
2725                         fee_proportional_millionths: 0,
2726                         excess_data: Vec::new()
2727                 });
2728                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2729                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2730                         short_channel_id: 11,
2731                         timestamp: 2,
2732                         flags: 0,
2733                         cltv_expiry_delta: 0,
2734                         htlc_minimum_msat: 0,
2735                         htlc_maximum_msat: OptionalField::Present(100_000),
2736                         fee_base_msat: 0,
2737                         fee_proportional_millionths: 0,
2738                         excess_data: Vec::new()
2739                 });
2740                 {
2741                         // Attempt to route more than available results in a failure.
2742                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2743                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2744                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2745                         } else { panic!(); }
2746                 }
2747
2748                 {
2749                         // Now, attempt to route 49 sats (just a bit below the capacity).
2750                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2751                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2752                         assert_eq!(route.paths.len(), 1);
2753                         let mut total_amount_paid_msat = 0;
2754                         for path in &route.paths {
2755                                 assert_eq!(path.len(), 4);
2756                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2757                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2758                         }
2759                         assert_eq!(total_amount_paid_msat, 49_000);
2760                 }
2761
2762                 {
2763                         // Attempt to route an exact amount is also fine
2764                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2765                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2766                         assert_eq!(route.paths.len(), 1);
2767                         let mut total_amount_paid_msat = 0;
2768                         for path in &route.paths {
2769                                 assert_eq!(path.len(), 4);
2770                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2771                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2772                         }
2773                         assert_eq!(total_amount_paid_msat, 50_000);
2774                 }
2775         }
2776
2777         #[test]
2778         fn ignore_fee_first_hop_test() {
2779                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2780                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2781
2782                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2783                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2784                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2785                         short_channel_id: 1,
2786                         timestamp: 2,
2787                         flags: 0,
2788                         cltv_expiry_delta: 0,
2789                         htlc_minimum_msat: 0,
2790                         htlc_maximum_msat: OptionalField::Present(100_000),
2791                         fee_base_msat: 1_000_000,
2792                         fee_proportional_millionths: 0,
2793                         excess_data: Vec::new()
2794                 });
2795                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2796                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2797                         short_channel_id: 3,
2798                         timestamp: 2,
2799                         flags: 0,
2800                         cltv_expiry_delta: 0,
2801                         htlc_minimum_msat: 0,
2802                         htlc_maximum_msat: OptionalField::Present(50_000),
2803                         fee_base_msat: 0,
2804                         fee_proportional_millionths: 0,
2805                         excess_data: Vec::new()
2806                 });
2807
2808                 {
2809                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2810                         assert_eq!(route.paths.len(), 1);
2811                         let mut total_amount_paid_msat = 0;
2812                         for path in &route.paths {
2813                                 assert_eq!(path.len(), 2);
2814                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2815                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2816                         }
2817                         assert_eq!(total_amount_paid_msat, 50_000);
2818                 }
2819         }
2820
2821         #[test]
2822         fn simple_mpp_route_test() {
2823                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2824                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2825
2826                 // We need a route consisting of 3 paths:
2827                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2828                 // To achieve this, the amount being transferred should be around
2829                 // the total capacity of these 3 paths.
2830
2831                 // First, we set limits on these (previously unlimited) channels.
2832                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2833
2834                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2835                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2836                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2837                         short_channel_id: 1,
2838                         timestamp: 2,
2839                         flags: 0,
2840                         cltv_expiry_delta: 0,
2841                         htlc_minimum_msat: 0,
2842                         htlc_maximum_msat: OptionalField::Present(100_000),
2843                         fee_base_msat: 0,
2844                         fee_proportional_millionths: 0,
2845                         excess_data: Vec::new()
2846                 });
2847                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2848                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2849                         short_channel_id: 3,
2850                         timestamp: 2,
2851                         flags: 0,
2852                         cltv_expiry_delta: 0,
2853                         htlc_minimum_msat: 0,
2854                         htlc_maximum_msat: OptionalField::Present(50_000),
2855                         fee_base_msat: 0,
2856                         fee_proportional_millionths: 0,
2857                         excess_data: Vec::new()
2858                 });
2859
2860                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2861                 // (total limit 60).
2862                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2863                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2864                         short_channel_id: 12,
2865                         timestamp: 2,
2866                         flags: 0,
2867                         cltv_expiry_delta: 0,
2868                         htlc_minimum_msat: 0,
2869                         htlc_maximum_msat: OptionalField::Present(60_000),
2870                         fee_base_msat: 0,
2871                         fee_proportional_millionths: 0,
2872                         excess_data: Vec::new()
2873                 });
2874                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2875                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2876                         short_channel_id: 13,
2877                         timestamp: 2,
2878                         flags: 0,
2879                         cltv_expiry_delta: 0,
2880                         htlc_minimum_msat: 0,
2881                         htlc_maximum_msat: OptionalField::Present(60_000),
2882                         fee_base_msat: 0,
2883                         fee_proportional_millionths: 0,
2884                         excess_data: Vec::new()
2885                 });
2886
2887                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2888                 // (total capacity 180 sats).
2889                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2890                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2891                         short_channel_id: 2,
2892                         timestamp: 2,
2893                         flags: 0,
2894                         cltv_expiry_delta: 0,
2895                         htlc_minimum_msat: 0,
2896                         htlc_maximum_msat: OptionalField::Present(200_000),
2897                         fee_base_msat: 0,
2898                         fee_proportional_millionths: 0,
2899                         excess_data: Vec::new()
2900                 });
2901                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2902                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2903                         short_channel_id: 4,
2904                         timestamp: 2,
2905                         flags: 0,
2906                         cltv_expiry_delta: 0,
2907                         htlc_minimum_msat: 0,
2908                         htlc_maximum_msat: OptionalField::Present(180_000),
2909                         fee_base_msat: 0,
2910                         fee_proportional_millionths: 0,
2911                         excess_data: Vec::new()
2912                 });
2913
2914                 {
2915                         // Attempt to route more than available results in a failure.
2916                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2917                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2918                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2919                         } else { panic!(); }
2920                 }
2921
2922                 {
2923                         // Now, attempt to route 250 sats (just a bit below the capacity).
2924                         // Our algorithm should provide us with these 3 paths.
2925                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2926                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2927                         assert_eq!(route.paths.len(), 3);
2928                         let mut total_amount_paid_msat = 0;
2929                         for path in &route.paths {
2930                                 assert_eq!(path.len(), 2);
2931                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2932                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2933                         }
2934                         assert_eq!(total_amount_paid_msat, 250_000);
2935                 }
2936
2937                 {
2938                         // Attempt to route an exact amount is also fine
2939                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2940                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2941                         assert_eq!(route.paths.len(), 3);
2942                         let mut total_amount_paid_msat = 0;
2943                         for path in &route.paths {
2944                                 assert_eq!(path.len(), 2);
2945                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2946                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2947                         }
2948                         assert_eq!(total_amount_paid_msat, 290_000);
2949                 }
2950         }
2951
2952         #[test]
2953         fn long_mpp_route_test() {
2954                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2955                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2956
2957                 // We need a route consisting of 3 paths:
2958                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2959                 // Note that these paths overlap (channels 5, 12, 13).
2960                 // We will route 300 sats.
2961                 // Each path will have 100 sats capacity, those channels which
2962                 // are used twice will have 200 sats capacity.
2963
2964                 // Disable other potential paths.
2965                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2966                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2967                         short_channel_id: 2,
2968                         timestamp: 2,
2969                         flags: 2,
2970                         cltv_expiry_delta: 0,
2971                         htlc_minimum_msat: 0,
2972                         htlc_maximum_msat: OptionalField::Present(100_000),
2973                         fee_base_msat: 0,
2974                         fee_proportional_millionths: 0,
2975                         excess_data: Vec::new()
2976                 });
2977                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2978                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2979                         short_channel_id: 7,
2980                         timestamp: 2,
2981                         flags: 2,
2982                         cltv_expiry_delta: 0,
2983                         htlc_minimum_msat: 0,
2984                         htlc_maximum_msat: OptionalField::Present(100_000),
2985                         fee_base_msat: 0,
2986                         fee_proportional_millionths: 0,
2987                         excess_data: Vec::new()
2988                 });
2989
2990                 // Path via {node0, node2} is channels {1, 3, 5}.
2991                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2992                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2993                         short_channel_id: 1,
2994                         timestamp: 2,
2995                         flags: 0,
2996                         cltv_expiry_delta: 0,
2997                         htlc_minimum_msat: 0,
2998                         htlc_maximum_msat: OptionalField::Present(100_000),
2999                         fee_base_msat: 0,
3000                         fee_proportional_millionths: 0,
3001                         excess_data: Vec::new()
3002                 });
3003                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3004                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3005                         short_channel_id: 3,
3006                         timestamp: 2,
3007                         flags: 0,
3008                         cltv_expiry_delta: 0,
3009                         htlc_minimum_msat: 0,
3010                         htlc_maximum_msat: OptionalField::Present(100_000),
3011                         fee_base_msat: 0,
3012                         fee_proportional_millionths: 0,
3013                         excess_data: Vec::new()
3014                 });
3015
3016                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3017                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3018                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3019                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3020                         short_channel_id: 5,
3021                         timestamp: 2,
3022                         flags: 0,
3023                         cltv_expiry_delta: 0,
3024                         htlc_minimum_msat: 0,
3025                         htlc_maximum_msat: OptionalField::Present(200_000),
3026                         fee_base_msat: 0,
3027                         fee_proportional_millionths: 0,
3028                         excess_data: Vec::new()
3029                 });
3030
3031                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3032                 // Add 100 sats to the capacities of {12, 13}, because these channels
3033                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3034                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3035                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3036                         short_channel_id: 12,
3037                         timestamp: 2,
3038                         flags: 0,
3039                         cltv_expiry_delta: 0,
3040                         htlc_minimum_msat: 0,
3041                         htlc_maximum_msat: OptionalField::Present(200_000),
3042                         fee_base_msat: 0,
3043                         fee_proportional_millionths: 0,
3044                         excess_data: Vec::new()
3045                 });
3046                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3047                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3048                         short_channel_id: 13,
3049                         timestamp: 2,
3050                         flags: 0,
3051                         cltv_expiry_delta: 0,
3052                         htlc_minimum_msat: 0,
3053                         htlc_maximum_msat: OptionalField::Present(200_000),
3054                         fee_base_msat: 0,
3055                         fee_proportional_millionths: 0,
3056                         excess_data: Vec::new()
3057                 });
3058
3059                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3060                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3061                         short_channel_id: 6,
3062                         timestamp: 2,
3063                         flags: 0,
3064                         cltv_expiry_delta: 0,
3065                         htlc_minimum_msat: 0,
3066                         htlc_maximum_msat: OptionalField::Present(100_000),
3067                         fee_base_msat: 0,
3068                         fee_proportional_millionths: 0,
3069                         excess_data: Vec::new()
3070                 });
3071                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3072                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3073                         short_channel_id: 11,
3074                         timestamp: 2,
3075                         flags: 0,
3076                         cltv_expiry_delta: 0,
3077                         htlc_minimum_msat: 0,
3078                         htlc_maximum_msat: OptionalField::Present(100_000),
3079                         fee_base_msat: 0,
3080                         fee_proportional_millionths: 0,
3081                         excess_data: Vec::new()
3082                 });
3083
3084                 // Path via {node7, node2} is channels {12, 13, 5}.
3085                 // We already limited them to 200 sats (they are used twice for 100 sats).
3086                 // Nothing to do here.
3087
3088                 {
3089                         // Attempt to route more than available results in a failure.
3090                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3091                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3092                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3093                         } else { panic!(); }
3094                 }
3095
3096                 {
3097                         // Now, attempt to route 300 sats (exact amount we can route).
3098                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3099                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3100                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3101                         assert_eq!(route.paths.len(), 3);
3102
3103                         let mut total_amount_paid_msat = 0;
3104                         for path in &route.paths {
3105                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3106                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3107                         }
3108                         assert_eq!(total_amount_paid_msat, 300_000);
3109                 }
3110
3111         }
3112
3113         #[test]
3114         fn mpp_cheaper_route_test() {
3115                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3116                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3117
3118                 // This test checks that if we have two cheaper paths and one more expensive path,
3119                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3120                 // two cheaper paths will be taken.
3121                 // These paths have equal available liquidity.
3122
3123                 // We need a combination of 3 paths:
3124                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3125                 // Note that these paths overlap (channels 5, 12, 13).
3126                 // Each path will have 100 sats capacity, those channels which
3127                 // are used twice will have 200 sats capacity.
3128
3129                 // Disable other potential paths.
3130                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3131                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3132                         short_channel_id: 2,
3133                         timestamp: 2,
3134                         flags: 2,
3135                         cltv_expiry_delta: 0,
3136                         htlc_minimum_msat: 0,
3137                         htlc_maximum_msat: OptionalField::Present(100_000),
3138                         fee_base_msat: 0,
3139                         fee_proportional_millionths: 0,
3140                         excess_data: Vec::new()
3141                 });
3142                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3143                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3144                         short_channel_id: 7,
3145                         timestamp: 2,
3146                         flags: 2,
3147                         cltv_expiry_delta: 0,
3148                         htlc_minimum_msat: 0,
3149                         htlc_maximum_msat: OptionalField::Present(100_000),
3150                         fee_base_msat: 0,
3151                         fee_proportional_millionths: 0,
3152                         excess_data: Vec::new()
3153                 });
3154
3155                 // Path via {node0, node2} is channels {1, 3, 5}.
3156                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3157                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3158                         short_channel_id: 1,
3159                         timestamp: 2,
3160                         flags: 0,
3161                         cltv_expiry_delta: 0,
3162                         htlc_minimum_msat: 0,
3163                         htlc_maximum_msat: OptionalField::Present(100_000),
3164                         fee_base_msat: 0,
3165                         fee_proportional_millionths: 0,
3166                         excess_data: Vec::new()
3167                 });
3168                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3169                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3170                         short_channel_id: 3,
3171                         timestamp: 2,
3172                         flags: 0,
3173                         cltv_expiry_delta: 0,
3174                         htlc_minimum_msat: 0,
3175                         htlc_maximum_msat: OptionalField::Present(100_000),
3176                         fee_base_msat: 0,
3177                         fee_proportional_millionths: 0,
3178                         excess_data: Vec::new()
3179                 });
3180
3181                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3182                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3183                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3184                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3185                         short_channel_id: 5,
3186                         timestamp: 2,
3187                         flags: 0,
3188                         cltv_expiry_delta: 0,
3189                         htlc_minimum_msat: 0,
3190                         htlc_maximum_msat: OptionalField::Present(200_000),
3191                         fee_base_msat: 0,
3192                         fee_proportional_millionths: 0,
3193                         excess_data: Vec::new()
3194                 });
3195
3196                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3197                 // Add 100 sats to the capacities of {12, 13}, because these channels
3198                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3199                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3200                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3201                         short_channel_id: 12,
3202                         timestamp: 2,
3203                         flags: 0,
3204                         cltv_expiry_delta: 0,
3205                         htlc_minimum_msat: 0,
3206                         htlc_maximum_msat: OptionalField::Present(200_000),
3207                         fee_base_msat: 0,
3208                         fee_proportional_millionths: 0,
3209                         excess_data: Vec::new()
3210                 });
3211                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3212                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3213                         short_channel_id: 13,
3214                         timestamp: 2,
3215                         flags: 0,
3216                         cltv_expiry_delta: 0,
3217                         htlc_minimum_msat: 0,
3218                         htlc_maximum_msat: OptionalField::Present(200_000),
3219                         fee_base_msat: 0,
3220                         fee_proportional_millionths: 0,
3221                         excess_data: Vec::new()
3222                 });
3223
3224                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3225                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3226                         short_channel_id: 6,
3227                         timestamp: 2,
3228                         flags: 0,
3229                         cltv_expiry_delta: 0,
3230                         htlc_minimum_msat: 0,
3231                         htlc_maximum_msat: OptionalField::Present(100_000),
3232                         fee_base_msat: 1_000,
3233                         fee_proportional_millionths: 0,
3234                         excess_data: Vec::new()
3235                 });
3236                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3237                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3238                         short_channel_id: 11,
3239                         timestamp: 2,
3240                         flags: 0,
3241                         cltv_expiry_delta: 0,
3242                         htlc_minimum_msat: 0,
3243                         htlc_maximum_msat: OptionalField::Present(100_000),
3244                         fee_base_msat: 0,
3245                         fee_proportional_millionths: 0,
3246                         excess_data: Vec::new()
3247                 });
3248
3249                 // Path via {node7, node2} is channels {12, 13, 5}.
3250                 // We already limited them to 200 sats (they are used twice for 100 sats).
3251                 // Nothing to do here.
3252
3253                 {
3254                         // Now, attempt to route 180 sats.
3255                         // Our algorithm should provide us with these 2 paths.
3256                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3257                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3258                         assert_eq!(route.paths.len(), 2);
3259
3260                         let mut total_value_transferred_msat = 0;
3261                         let mut total_paid_msat = 0;
3262                         for path in &route.paths {
3263                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3264                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3265                                 for hop in path {
3266                                         total_paid_msat += hop.fee_msat;
3267                                 }
3268                         }
3269                         // If we paid fee, this would be higher.
3270                         assert_eq!(total_value_transferred_msat, 180_000);
3271                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3272                         assert_eq!(total_fees_paid, 0);
3273                 }
3274         }
3275
3276         #[test]
3277         fn fees_on_mpp_route_test() {
3278                 // This test makes sure that MPP algorithm properly takes into account
3279                 // fees charged on the channels, by making the fees impactful:
3280                 // if the fee is not properly accounted for, the behavior is different.
3281                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3282                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3283
3284                 // We need a route consisting of 2 paths:
3285                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3286                 // We will route 200 sats, Each path will have 100 sats capacity.
3287
3288                 // This test is not particularly stable: e.g.,
3289                 // there's a way to route via {node0, node2, node4}.
3290                 // It works while pathfinding is deterministic, but can be broken otherwise.
3291                 // It's fine to ignore this concern for now.
3292
3293                 // Disable other potential paths.
3294                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3295                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3296                         short_channel_id: 2,
3297                         timestamp: 2,
3298                         flags: 2,
3299                         cltv_expiry_delta: 0,
3300                         htlc_minimum_msat: 0,
3301                         htlc_maximum_msat: OptionalField::Present(100_000),
3302                         fee_base_msat: 0,
3303                         fee_proportional_millionths: 0,
3304                         excess_data: Vec::new()
3305                 });
3306
3307                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3308                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3309                         short_channel_id: 7,
3310                         timestamp: 2,
3311                         flags: 2,
3312                         cltv_expiry_delta: 0,
3313                         htlc_minimum_msat: 0,
3314                         htlc_maximum_msat: OptionalField::Present(100_000),
3315                         fee_base_msat: 0,
3316                         fee_proportional_millionths: 0,
3317                         excess_data: Vec::new()
3318                 });
3319
3320                 // Path via {node0, node2} is channels {1, 3, 5}.
3321                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3322                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3323                         short_channel_id: 1,
3324                         timestamp: 2,
3325                         flags: 0,
3326                         cltv_expiry_delta: 0,
3327                         htlc_minimum_msat: 0,
3328                         htlc_maximum_msat: OptionalField::Present(100_000),
3329                         fee_base_msat: 0,
3330                         fee_proportional_millionths: 0,
3331                         excess_data: Vec::new()
3332                 });
3333                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3334                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3335                         short_channel_id: 3,
3336                         timestamp: 2,
3337                         flags: 0,
3338                         cltv_expiry_delta: 0,
3339                         htlc_minimum_msat: 0,
3340                         htlc_maximum_msat: OptionalField::Present(100_000),
3341                         fee_base_msat: 0,
3342                         fee_proportional_millionths: 0,
3343                         excess_data: Vec::new()
3344                 });
3345
3346                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3347                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3348                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3349                         short_channel_id: 5,
3350                         timestamp: 2,
3351                         flags: 0,
3352                         cltv_expiry_delta: 0,
3353                         htlc_minimum_msat: 0,
3354                         htlc_maximum_msat: OptionalField::Present(100_000),
3355                         fee_base_msat: 0,
3356                         fee_proportional_millionths: 0,
3357                         excess_data: Vec::new()
3358                 });
3359
3360                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3361                 // All channels should be 100 sats capacity. But for the fee experiment,
3362                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3363                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3364                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3365                 // so no matter how large are other channels,
3366                 // the whole path will be limited by 100 sats with just these 2 conditions:
3367                 // - channel 12 capacity is 250 sats
3368                 // - fee for channel 6 is 150 sats
3369                 // Let's test this by enforcing these 2 conditions and removing other limits.
3370                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3371                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3372                         short_channel_id: 12,
3373                         timestamp: 2,
3374                         flags: 0,
3375                         cltv_expiry_delta: 0,
3376                         htlc_minimum_msat: 0,
3377                         htlc_maximum_msat: OptionalField::Present(250_000),
3378                         fee_base_msat: 0,
3379                         fee_proportional_millionths: 0,
3380                         excess_data: Vec::new()
3381                 });
3382                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3383                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3384                         short_channel_id: 13,
3385                         timestamp: 2,
3386                         flags: 0,
3387                         cltv_expiry_delta: 0,
3388                         htlc_minimum_msat: 0,
3389                         htlc_maximum_msat: OptionalField::Absent,
3390                         fee_base_msat: 0,
3391                         fee_proportional_millionths: 0,
3392                         excess_data: Vec::new()
3393                 });
3394
3395                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3396                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3397                         short_channel_id: 6,
3398                         timestamp: 2,
3399                         flags: 0,
3400                         cltv_expiry_delta: 0,
3401                         htlc_minimum_msat: 0,
3402                         htlc_maximum_msat: OptionalField::Absent,
3403                         fee_base_msat: 150_000,
3404                         fee_proportional_millionths: 0,
3405                         excess_data: Vec::new()
3406                 });
3407                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3408                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3409                         short_channel_id: 11,
3410                         timestamp: 2,
3411                         flags: 0,
3412                         cltv_expiry_delta: 0,
3413                         htlc_minimum_msat: 0,
3414                         htlc_maximum_msat: OptionalField::Absent,
3415                         fee_base_msat: 0,
3416                         fee_proportional_millionths: 0,
3417                         excess_data: Vec::new()
3418                 });
3419
3420                 {
3421                         // Attempt to route more than available results in a failure.
3422                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3423                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3424                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3425                         } else { panic!(); }
3426                 }
3427
3428                 {
3429                         // Now, attempt to route 200 sats (exact amount we can route).
3430                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3431                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3432                         assert_eq!(route.paths.len(), 2);
3433
3434                         let mut total_amount_paid_msat = 0;
3435                         for path in &route.paths {
3436                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3437                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3438                         }
3439                         assert_eq!(total_amount_paid_msat, 200_000);
3440                 }
3441
3442         }
3443
3444         #[test]
3445         fn drop_lowest_channel_mpp_route_test() {
3446                 // This test checks that low-capacity channel is dropped when after
3447                 // path finding we realize that we found more capacity than we need.
3448                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3449                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3450
3451                 // We need a route consisting of 3 paths:
3452                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3453
3454                 // The first and the second paths should be sufficient, but the third should be
3455                 // cheaper, so that we select it but drop later.
3456
3457                 // First, we set limits on these (previously unlimited) channels.
3458                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3459
3460                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3461                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3462                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3463                         short_channel_id: 1,
3464                         timestamp: 2,
3465                         flags: 0,
3466                         cltv_expiry_delta: 0,
3467                         htlc_minimum_msat: 0,
3468                         htlc_maximum_msat: OptionalField::Present(100_000),
3469                         fee_base_msat: 0,
3470                         fee_proportional_millionths: 0,
3471                         excess_data: Vec::new()
3472                 });
3473                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3474                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3475                         short_channel_id: 3,
3476                         timestamp: 2,
3477                         flags: 0,
3478                         cltv_expiry_delta: 0,
3479                         htlc_minimum_msat: 0,
3480                         htlc_maximum_msat: OptionalField::Present(50_000),
3481                         fee_base_msat: 100,
3482                         fee_proportional_millionths: 0,
3483                         excess_data: Vec::new()
3484                 });
3485
3486                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3487                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3488                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3489                         short_channel_id: 12,
3490                         timestamp: 2,
3491                         flags: 0,
3492                         cltv_expiry_delta: 0,
3493                         htlc_minimum_msat: 0,
3494                         htlc_maximum_msat: OptionalField::Present(60_000),
3495                         fee_base_msat: 100,
3496                         fee_proportional_millionths: 0,
3497                         excess_data: Vec::new()
3498                 });
3499                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3500                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3501                         short_channel_id: 13,
3502                         timestamp: 2,
3503                         flags: 0,
3504                         cltv_expiry_delta: 0,
3505                         htlc_minimum_msat: 0,
3506                         htlc_maximum_msat: OptionalField::Present(60_000),
3507                         fee_base_msat: 0,
3508                         fee_proportional_millionths: 0,
3509                         excess_data: Vec::new()
3510                 });
3511
3512                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3513                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3514                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3515                         short_channel_id: 2,
3516                         timestamp: 2,
3517                         flags: 0,
3518                         cltv_expiry_delta: 0,
3519                         htlc_minimum_msat: 0,
3520                         htlc_maximum_msat: OptionalField::Present(20_000),
3521                         fee_base_msat: 0,
3522                         fee_proportional_millionths: 0,
3523                         excess_data: Vec::new()
3524                 });
3525                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3526                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3527                         short_channel_id: 4,
3528                         timestamp: 2,
3529                         flags: 0,
3530                         cltv_expiry_delta: 0,
3531                         htlc_minimum_msat: 0,
3532                         htlc_maximum_msat: OptionalField::Present(20_000),
3533                         fee_base_msat: 0,
3534                         fee_proportional_millionths: 0,
3535                         excess_data: Vec::new()
3536                 });
3537
3538                 {
3539                         // Attempt to route more than available results in a failure.
3540                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3541                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3542                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3543                         } else { panic!(); }
3544                 }
3545
3546                 {
3547                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3548                         // Our algorithm should provide us with these 3 paths.
3549                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3550                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3551                         assert_eq!(route.paths.len(), 3);
3552                         let mut total_amount_paid_msat = 0;
3553                         for path in &route.paths {
3554                                 assert_eq!(path.len(), 2);
3555                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3556                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3557                         }
3558                         assert_eq!(total_amount_paid_msat, 125_000);
3559                 }
3560
3561                 {
3562                         // Attempt to route without the last small cheap channel
3563                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3564                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3565                         assert_eq!(route.paths.len(), 2);
3566                         let mut total_amount_paid_msat = 0;
3567                         for path in &route.paths {
3568                                 assert_eq!(path.len(), 2);
3569                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3570                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3571                         }
3572                         assert_eq!(total_amount_paid_msat, 90_000);
3573                 }
3574         }
3575
3576         #[test]
3577         fn min_criteria_consistency() {
3578                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3579                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3580                 // was updated with a different criterion from the heap sorting, resulting in loops in
3581                 // calculated paths. We test for that specific case here.
3582
3583                 // We construct a network that looks like this:
3584                 //
3585                 //            node2 -1(3)2- node3
3586                 //              2          2
3587                 //               (2)     (4)
3588                 //                  1   1
3589                 //    node1 -1(5)2- node4 -1(1)2- node6
3590                 //    2
3591                 //   (6)
3592                 //        1
3593                 // our_node
3594                 //
3595                 // We create a loop on the side of our real path - our destination is node 6, with a
3596                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3597                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3598                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3599                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3600                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3601                 // "previous hop" being set to node 3, creating a loop in the path.
3602                 let secp_ctx = Secp256k1::new();
3603                 let logger = Arc::new(test_utils::TestLogger::new());
3604                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3605                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3606
3607                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3608                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3609                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3610                         short_channel_id: 6,
3611                         timestamp: 1,
3612                         flags: 0,
3613                         cltv_expiry_delta: (6 << 8) | 0,
3614                         htlc_minimum_msat: 0,
3615                         htlc_maximum_msat: OptionalField::Absent,
3616                         fee_base_msat: 0,
3617                         fee_proportional_millionths: 0,
3618                         excess_data: Vec::new()
3619                 });
3620                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3621
3622                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3623                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3624                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3625                         short_channel_id: 5,
3626                         timestamp: 1,
3627                         flags: 0,
3628                         cltv_expiry_delta: (5 << 8) | 0,
3629                         htlc_minimum_msat: 0,
3630                         htlc_maximum_msat: OptionalField::Absent,
3631                         fee_base_msat: 100,
3632                         fee_proportional_millionths: 0,
3633                         excess_data: Vec::new()
3634                 });
3635                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3636
3637                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3638                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3639                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3640                         short_channel_id: 4,
3641                         timestamp: 1,
3642                         flags: 0,
3643                         cltv_expiry_delta: (4 << 8) | 0,
3644                         htlc_minimum_msat: 0,
3645                         htlc_maximum_msat: OptionalField::Absent,
3646                         fee_base_msat: 0,
3647                         fee_proportional_millionths: 0,
3648                         excess_data: Vec::new()
3649                 });
3650                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3651
3652                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3653                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3654                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3655                         short_channel_id: 3,
3656                         timestamp: 1,
3657                         flags: 0,
3658                         cltv_expiry_delta: (3 << 8) | 0,
3659                         htlc_minimum_msat: 0,
3660                         htlc_maximum_msat: OptionalField::Absent,
3661                         fee_base_msat: 0,
3662                         fee_proportional_millionths: 0,
3663                         excess_data: Vec::new()
3664                 });
3665                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
3666
3667                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
3668                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3669                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3670                         short_channel_id: 2,
3671                         timestamp: 1,
3672                         flags: 0,
3673                         cltv_expiry_delta: (2 << 8) | 0,
3674                         htlc_minimum_msat: 0,
3675                         htlc_maximum_msat: OptionalField::Absent,
3676                         fee_base_msat: 0,
3677                         fee_proportional_millionths: 0,
3678                         excess_data: Vec::new()
3679                 });
3680
3681                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
3682                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3683                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3684                         short_channel_id: 1,
3685                         timestamp: 1,
3686                         flags: 0,
3687                         cltv_expiry_delta: (1 << 8) | 0,
3688                         htlc_minimum_msat: 100,
3689                         htlc_maximum_msat: OptionalField::Absent,
3690                         fee_base_msat: 0,
3691                         fee_proportional_millionths: 0,
3692                         excess_data: Vec::new()
3693                 });
3694                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
3695
3696                 {
3697                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
3698                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
3699                         assert_eq!(route.paths.len(), 1);
3700                         assert_eq!(route.paths[0].len(), 3);
3701
3702                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
3703                         assert_eq!(route.paths[0][0].short_channel_id, 6);
3704                         assert_eq!(route.paths[0][0].fee_msat, 100);
3705                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
3706                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
3707                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
3708
3709                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
3710                         assert_eq!(route.paths[0][1].short_channel_id, 5);
3711                         assert_eq!(route.paths[0][1].fee_msat, 0);
3712                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
3713                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
3714                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
3715
3716                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
3717                         assert_eq!(route.paths[0][2].short_channel_id, 1);
3718                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
3719                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
3720                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
3721                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
3722                 }
3723         }
3724
3725
3726         #[test]
3727         fn exact_fee_liquidity_limit() {
3728                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
3729                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
3730                 // we calculated fees on a higher value, resulting in us ignoring such paths.
3731                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3732                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
3733
3734                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
3735                 // send.
3736                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3737                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3738                         short_channel_id: 2,
3739                         timestamp: 2,
3740                         flags: 0,
3741                         cltv_expiry_delta: 0,
3742                         htlc_minimum_msat: 0,
3743                         htlc_maximum_msat: OptionalField::Present(85_000),
3744                         fee_base_msat: 0,
3745                         fee_proportional_millionths: 0,
3746                         excess_data: Vec::new()
3747                 });
3748
3749                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3750                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3751                         short_channel_id: 12,
3752                         timestamp: 2,
3753                         flags: 0,
3754                         cltv_expiry_delta: (4 << 8) | 1,
3755                         htlc_minimum_msat: 0,
3756                         htlc_maximum_msat: OptionalField::Present(270_000),
3757                         fee_base_msat: 0,
3758                         fee_proportional_millionths: 1000000,
3759                         excess_data: Vec::new()
3760                 });
3761
3762                 {
3763                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
3764                         // 200% fee charged channel 13 in the 1-to-2 direction.
3765                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3766                         assert_eq!(route.paths.len(), 1);
3767                         assert_eq!(route.paths[0].len(), 2);
3768
3769                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3770                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3771                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3772                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3773                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3774                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3775
3776                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3777                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3778                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3779                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3780                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
3781                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3782                 }
3783         }
3784
3785         #[test]
3786         fn htlc_max_reduction_below_min() {
3787                 // Test that if, while walking the graph, we reduce the value being sent to meet an
3788                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
3789                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
3790                 // resulting in us thinking there is no possible path, even if other paths exist.
3791                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3792                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3793
3794                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
3795                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
3796                 // then try to send 90_000.
3797                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3798                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3799                         short_channel_id: 2,
3800                         timestamp: 2,
3801                         flags: 0,
3802                         cltv_expiry_delta: 0,
3803                         htlc_minimum_msat: 0,
3804                         htlc_maximum_msat: OptionalField::Present(80_000),
3805                         fee_base_msat: 0,
3806                         fee_proportional_millionths: 0,
3807                         excess_data: Vec::new()
3808                 });
3809                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3810                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3811                         short_channel_id: 4,
3812                         timestamp: 2,
3813                         flags: 0,
3814                         cltv_expiry_delta: (4 << 8) | 1,
3815                         htlc_minimum_msat: 90_000,
3816                         htlc_maximum_msat: OptionalField::Absent,
3817                         fee_base_msat: 0,
3818                         fee_proportional_millionths: 0,
3819                         excess_data: Vec::new()
3820                 });
3821
3822                 {
3823                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
3824                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
3825                         // expensive) channels 12-13 path.
3826                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3827                         assert_eq!(route.paths.len(), 1);
3828                         assert_eq!(route.paths[0].len(), 2);
3829
3830                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3831                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3832                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3833                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3834                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3835                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3836
3837                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3838                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3839                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3840                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3841                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
3842                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3843                 }
3844         }
3845
3846         pub(super) fn random_init_seed() -> u64 {
3847                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
3848                 use core::hash::{BuildHasher, Hasher};
3849                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
3850                 println!("Using seed of {}", seed);
3851                 seed
3852         }
3853         use util::ser::Readable;
3854
3855         #[test]
3856         fn generate_routes() {
3857                 let mut d = match super::test_utils::get_route_file() {
3858                         Ok(f) => f,
3859                         Err(e) => {
3860                                 eprintln!("{}", e);
3861                                 return;
3862                         },
3863                 };
3864                 let graph = NetworkGraph::read(&mut d).unwrap();
3865
3866                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3867                 let mut seed = random_init_seed() as usize;
3868                 'load_endpoints: for _ in 0..10 {
3869                         loop {
3870                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3871                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3872                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3873                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3874                                 let amt = seed as u64 % 200_000_000;
3875                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3876                                         continue 'load_endpoints;
3877                                 }
3878                         }
3879                 }
3880         }
3881
3882         #[test]
3883         fn generate_routes_mpp() {
3884                 let mut d = match super::test_utils::get_route_file() {
3885                         Ok(f) => f,
3886                         Err(e) => {
3887                                 eprintln!("{}", e);
3888                                 return;
3889                         },
3890                 };
3891                 let graph = NetworkGraph::read(&mut d).unwrap();
3892
3893                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3894                 let mut seed = random_init_seed() as usize;
3895                 'load_endpoints: for _ in 0..10 {
3896                         loop {
3897                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3898                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3899                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3900                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3901                                 let amt = seed as u64 % 200_000_000;
3902                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3903                                         continue 'load_endpoints;
3904                                 }
3905                         }
3906                 }
3907         }
3908 }
3909
3910 #[cfg(test)]
3911 pub(crate) mod test_utils {
3912         use std::fs::File;
3913         /// Tries to open a network graph file, or panics with a URL to fetch it.
3914         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
3915                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
3916                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
3917                         .or_else(|_| { // Fall back to guessing based on the binary location
3918                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
3919                                 let mut path = std::env::current_exe().unwrap();
3920                                 path.pop(); // lightning-...
3921                                 path.pop(); // deps
3922                                 path.pop(); // debug
3923                                 path.pop(); // target
3924                                 path.push("lightning");
3925                                 path.push("net_graph-2021-05-31.bin");
3926                                 eprintln!("{}", path.to_str().unwrap());
3927                                 File::open(path)
3928                         })
3929                 .map_err(|_| "Please fetch https://bitcoin.ninja/ldk-net_graph-v0.0.15-2021-05-31.bin and place it at lightning/net_graph-2021-05-31.bin");
3930                 #[cfg(require_route_graph_test)]
3931                 return Ok(res.unwrap());
3932                 #[cfg(not(require_route_graph_test))]
3933                 return res;
3934         }
3935 }
3936
3937 #[cfg(all(test, feature = "unstable"))]
3938 mod benches {
3939         use super::*;
3940         use util::logger::{Logger, Record};
3941
3942         use test::Bencher;
3943
3944         struct DummyLogger {}
3945         impl Logger for DummyLogger {
3946                 fn log(&self, _record: &Record) {}
3947         }
3948
3949         #[bench]
3950         fn generate_routes(bench: &mut Bencher) {
3951                 let mut d = test_utils::get_route_file().unwrap();
3952                 let graph = NetworkGraph::read(&mut d).unwrap();
3953
3954                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3955                 let mut path_endpoints = Vec::new();
3956                 let mut seed: usize = 0xdeadbeef;
3957                 'load_endpoints: for _ in 0..100 {
3958                         loop {
3959                                 seed *= 0xdeadbeef;
3960                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3961                                 seed *= 0xdeadbeef;
3962                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3963                                 let amt = seed as u64 % 1_000_000;
3964                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3965                                         path_endpoints.push((src, dst, amt));
3966                                         continue 'load_endpoints;
3967                                 }
3968                         }
3969                 }
3970
3971                 // ...then benchmark finding paths between the nodes we learned.
3972                 let mut idx = 0;
3973                 bench.iter(|| {
3974                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3975                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3976                         idx += 1;
3977                 });
3978         }
3979
3980         #[bench]
3981         fn generate_mpp_routes(bench: &mut Bencher) {
3982                 let mut d = test_utils::get_route_file().unwrap();
3983                 let graph = NetworkGraph::read(&mut d).unwrap();
3984
3985                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3986                 let mut path_endpoints = Vec::new();
3987                 let mut seed: usize = 0xdeadbeef;
3988                 'load_endpoints: for _ in 0..100 {
3989                         loop {
3990                                 seed *= 0xdeadbeef;
3991                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3992                                 seed *= 0xdeadbeef;
3993                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3994                                 let amt = seed as u64 % 1_000_000;
3995                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3996                                         path_endpoints.push((src, dst, amt));
3997                                         continue 'load_endpoints;
3998                                 }
3999                         }
4000                 }
4001
4002                 // ...then benchmark finding paths between the nodes we learned.
4003                 let mut idx = 0;
4004                 bench.iter(|| {
4005                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4006                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
4007                         idx += 1;
4008                 });
4009         }
4010 }