_ 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, NodeId};
  21 use util::ser::{Writeable, Readable};
  22 use util::logger::{Level, Logger};
  23
  24 use io;
  25 use prelude::*;
  26 use alloc::collections::BinaryHeap;
  27 use core::cmp;
  28 use core::ops::Deref;
  29
  30 /// A hop in a route
  31 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  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, required),
  54         (2, node_features, required),
  55         (4, short_channel_id, required),
  56         (6, channel_features, required),
  57         (8, fee_msat, required),
  58         (10, cltv_expiry_delta, required),
  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, Hash, PartialEq, Eq)]
  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 impl Route {
  75         /// Returns the total amount of fees paid on this [`Route`].
  76         ///
  77         /// This doesn't include any extra payment made to the recipient, which can happen in excess of
  78         /// the amount passed to [`get_route`]'s `final_value_msat`.
  79         pub fn get_total_fees(&self) -> u64 {
  80                 // Do not count last hop of each path since that's the full value of the payment
  81                 return self.paths.iter()
  82                         .flat_map(|path| path.split_last().map(|(_, path_prefix)| path_prefix).unwrap_or(&[]))
  83                         .map(|hop| &hop.fee_msat)
  84                         .sum();
  85         }
  86
  87         /// Returns the total amount paid on this [`Route`], excluding the fees.
  88         pub fn get_total_amount(&self) -> u64 {
  89                 return self.paths.iter()
  90                         .map(|path| path.split_last().map(|(hop, _)| hop.fee_msat).unwrap_or(0))
  91                         .sum();
  92         }
  93 }
  94
  95 const SERIALIZATION_VERSION: u8 = 1;
  96 const MIN_SERIALIZATION_VERSION: u8 = 1;
  97
  98 impl Writeable for Route {
  99         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 100                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
 101                 (self.paths.len() as u64).write(writer)?;
 102                 for hops in self.paths.iter() {
 103                         (hops.len() as u8).write(writer)?;
 104                         for hop in hops.iter() {
 105                                 hop.write(writer)?;
 106                         }
 107                 }
 108                 write_tlv_fields!(writer, {});
 109                 Ok(())
 110         }
 111 }
 112
 113 impl Readable for Route {
 114         fn read<R: io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 115                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 116                 let path_count: u64 = Readable::read(reader)?;
 117                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 118                 for _ in 0..path_count {
 119                         let hop_count: u8 = Readable::read(reader)?;
 120                         let mut hops = Vec::with_capacity(hop_count as usize);
 121                         for _ in 0..hop_count {
 122                                 hops.push(Readable::read(reader)?);
 123                         }
 124                         paths.push(hops);
 125                 }
 126                 read_tlv_fields!(reader, {});
 127                 Ok(Route { paths })
 128         }
 129 }
 130
 131 /// A list of hops along a payment path terminating with a channel to the recipient.
 132 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 133 pub struct RouteHint(pub Vec<RouteHintHop>);
 134
 135 /// A channel descriptor for a hop along a payment path.
 136 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 137 pub struct RouteHintHop {
 138         /// The node_id of the non-target end of the route
 139         pub src_node_id: PublicKey,
 140         /// The short_channel_id of this channel
 141         pub short_channel_id: u64,
 142         /// The fees which must be paid to use this channel
 143         pub fees: RoutingFees,
 144         /// The difference in CLTV values between this node and the next node.
 145         pub cltv_expiry_delta: u16,
 146         /// The minimum value, in msat, which must be relayed to the next hop.
 147         pub htlc_minimum_msat: Option<u64>,
 148         /// The maximum value in msat available for routing with a single HTLC.
 149         pub htlc_maximum_msat: Option<u64>,
 150 }
 151
 152 #[derive(Eq, PartialEq)]
 153 struct RouteGraphNode {
 154         node_id: NodeId,
 155         lowest_fee_to_peer_through_node: u64,
 156         lowest_fee_to_node: u64,
 157         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 158         // This value is upper-bounded by us by:
 159         // - how much is needed for a path being constructed
 160         // - how much value can channels following this node (up to the destination) can contribute,
 161         //   considering their capacity and fees
 162         value_contribution_msat: u64,
 163         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 164         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 165         path_htlc_minimum_msat: u64,
 166 }
 167
 168 impl cmp::Ord for RouteGraphNode {
 169         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 170                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 171                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 172                 other_score.cmp(&self_score).then_with(|| other.node_id.cmp(&self.node_id))
 173         }
 174 }
 175
 176 impl cmp::PartialOrd for RouteGraphNode {
 177         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 178                 Some(self.cmp(other))
 179         }
 180 }
 181
 182 struct DummyDirectionalChannelInfo {
 183         cltv_expiry_delta: u32,
 184         htlc_minimum_msat: u64,
 185         htlc_maximum_msat: Option<u64>,
 186         fees: RoutingFees,
 187 }
 188
 189 /// It's useful to keep track of the hops associated with the fees required to use them,
 190 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 191 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 192 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 193 #[derive(Clone, Debug)]
 194 struct PathBuildingHop<'a> {
 195         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 196         // Note that node_features is calculated separately after our initial graph walk.
 197         node_id: NodeId,
 198         short_channel_id: u64,
 199         channel_features: &'a ChannelFeatures,
 200         fee_msat: u64,
 201         cltv_expiry_delta: u32,
 202
 203         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 204         src_lowest_inbound_fees: RoutingFees,
 205         /// Fees of the channel used in this hop.
 206         channel_fees: RoutingFees,
 207         /// All the fees paid *after* this channel on the way to the destination
 208         next_hops_fee_msat: u64,
 209         /// Fee paid for the use of the current channel (see channel_fees).
 210         /// The value will be actually deducted from the counterparty balance on the previous link.
 211         hop_use_fee_msat: u64,
 212         /// Used to compare channels when choosing the for routing.
 213         /// Includes paying for the use of a hop and the following hops, as well as
 214         /// an estimated cost of reaching this hop.
 215         /// Might get stale when fees are recomputed. Primarily for internal use.
 216         total_fee_msat: u64,
 217         /// This is useful for update_value_and_recompute_fees to make sure
 218         /// we don't fall below the minimum. Should not be updated manually and
 219         /// generally should not be accessed.
 220         htlc_minimum_msat: u64,
 221         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 222         /// walk and may be invalid thereafter.
 223         path_htlc_minimum_msat: u64,
 224         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 225         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 226         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 227         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 228         /// avoid processing them again.
 229         was_processed: bool,
 230         #[cfg(any(test, feature = "fuzztarget"))]
 231         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 232         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 233         // value_contribution_msat, which requires tracking it here. See comments below where it is
 234         // used for more info.
 235         value_contribution_msat: u64,
 236 }
 237
 238 // Instantiated with a list of hops with correct data in them collected during path finding,
 239 // an instance of this struct should be further modified only via given methods.
 240 #[derive(Clone)]
 241 struct PaymentPath<'a> {
 242         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 243 }
 244
 245 impl<'a> PaymentPath<'a> {
 246         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 247         fn get_value_msat(&self) -> u64 {
 248                 self.hops.last().unwrap().0.fee_msat
 249         }
 250
 251         fn get_total_fee_paid_msat(&self) -> u64 {
 252                 if self.hops.len() < 1 {
 253                         return 0;
 254                 }
 255                 let mut result = 0;
 256                 // Can't use next_hops_fee_msat because it gets outdated.
 257                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 258                         if i != self.hops.len() - 1 {
 259                                 result += hop.fee_msat;
 260                         }
 261                 }
 262                 return result;
 263         }
 264
 265         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 266         // to change fees may result in an inconsistency.
 267         //
 268         // Sometimes we call this function right after constructing a path which is inconsistent in
 269         // that it the value being transferred has decreased while we were doing path finding, leading
 270         // to the fees being paid not lining up with the actual limits.
 271         //
 272         // Note that this function is not aware of the available_liquidity limit, and thus does not
 273         // support increasing the value being transferred.
 274         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 275                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 276
 277                 let mut total_fee_paid_msat = 0 as u64;
 278                 for i in (0..self.hops.len()).rev() {
 279                         let last_hop = i == self.hops.len() - 1;
 280
 281                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 282                         // will consist of the fees for the use of the next hop, and extra fees to match
 283                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 284                         let mut cur_hop_fees_msat = 0;
 285                         if !last_hop {
 286                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 287                         }
 288
 289                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 290                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 291                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 292                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 293                         // set it too high just to maliciously take more fees by exploiting this
 294                         // match htlc_minimum_msat logic.
 295                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 296                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 297                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 298                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 299                                 //
 300                                 // This might make us end up with a broken route, although this should be super-rare
 301                                 // in practice, both because of how healthy channels look like, and how we pick
 302                                 // channels in add_entry.
 303                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 304                                 // all payments*.
 305                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 306                                 total_fee_paid_msat += extra_fees_msat;
 307                                 cur_hop_fees_msat += extra_fees_msat;
 308                         }
 309
 310                         if last_hop {
 311                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 312                                 // it still could overpay for the htlc_minimum_msat.
 313                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 314                         } else {
 315                                 // Propagate updated fees for the use of the channels to one hop back, where they
 316                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 317                                 cur_hop.fee_msat = cur_hop_fees_msat;
 318                         }
 319
 320                         // Fee for the use of the current hop which will be deducted on the previous hop.
 321                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 322                         // this channel is free for us.
 323                         if i != 0 {
 324                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 325                                         cur_hop.hop_use_fee_msat = new_fee;
 326                                         total_fee_paid_msat += new_fee;
 327                                 } else {
 328                                         // It should not be possible because this function is called only to reduce the
 329                                         // value. In that case, compute_fee was already called with the same fees for
 330                                         // larger amount and there was no overflow.
 331                                         unreachable!();
 332                                 }
 333                         }
 334                 }
 335         }
 336 }
 337
 338 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 339         let proportional_fee_millions =
 340                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 341         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 342                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 343
 344                 Some(new_fee)
 345         } else {
 346                 // This function may be (indirectly) called without any verification,
 347                 // with channel_fees provided by a caller. We should handle it gracefully.
 348                 None
 349         }
 350 }
 351
 352 /// Gets a keysend route from us (payer) to the given target node (payee). This is needed because
 353 /// keysend payments do not have an invoice from which to pull the payee's supported features, which
 354 /// makes it tricky to otherwise supply the `payee_features` parameter of `get_route`.
 355 pub fn get_keysend_route<L: Deref>(our_node_pubkey: &PublicKey, network: &NetworkGraph, payee:
 356                        &PublicKey, first_hops: Option<&[&ChannelDetails]>, last_hops: &[&RouteHint],
 357                        final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route,
 358                        LightningError> where L::Target: Logger {
 359         let invoice_features = InvoiceFeatures::for_keysend();
 360         get_route(our_node_pubkey, network, payee, Some(invoice_features), first_hops, last_hops,
 361             final_value_msat, final_cltv, logger)
 362 }
 363
 364 /// Gets a route from us (payer) to the given target node (payee).
 365 ///
 366 /// If the payee provided features in their invoice, they should be provided via payee_features.
 367 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 368 ///
 369 /// Private routing paths between a public node and the target may be included in `last_hops`.
 370 /// Currently, only the last hop in each path is considered.
 371 ///
 372 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 373 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 374 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 375 /// in first_hops will be used.
 376 ///
 377 /// Panics if first_hops contains channels without short_channel_ids
 378 /// (ChannelManager::list_usable_channels will never include such channels).
 379 ///
 380 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 381 /// equal), however the enabled/disabled bit on such channels as well as the
 382 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 383 pub fn get_route<L: Deref>(our_node_pubkey: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 384         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 385         let payee_node_id = NodeId::from_pubkey(&payee);
 386         let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
 387
 388         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 389         // uptime/success in using a node in the past.
 390         if payee_node_id == our_node_id {
 391                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 392         }
 393
 394         if final_value_msat > MAX_VALUE_MSAT {
 395                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 396         }
 397
 398         if final_value_msat == 0 {
 399                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 400         }
 401
 402         for route in last_hops.iter() {
 403                 for hop in &route.0 {
 404                         if hop.src_node_id == *payee {
 405                                 return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 406                         }
 407                 }
 408         }
 409
 410         // The general routing idea is the following:
 411         // 1. Fill first/last hops communicated by the caller.
 412         // 2. Attempt to construct a path from payer to payee for transferring
 413         //    any ~sufficient (described later) value.
 414         //    If succeed, remember which channels were used and how much liquidity they have available,
 415         //    so that future paths don't rely on the same liquidity.
 416         // 3. Prooceed to the next step if:
 417         //    - we hit the recommended target value;
 418         //    - OR if we could not construct a new path. Any next attempt will fail too.
 419         //    Otherwise, repeat step 2.
 420         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 421         //    (not recommended value). If yes, proceed. If not, fail routing.
 422         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 423         // 6. Of all the found paths, select only those with the lowest total fee.
 424         // 7. The last path in every selected route is likely to be more than we need.
 425         //    Reduce its value-to-transfer and recompute fees.
 426         // 8. Choose the best route by the lowest total fee.
 427
 428         // As for the actual search algorithm,
 429         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 430         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 431         //
 432         // We are not a faithful Dijkstra's implementation because we can change values which impact
 433         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 434         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 435         // the value we are currently attempting to send over a path, we simply reduce the value being
 436         // sent along the path for any hops after that channel. This may imply that later fees (which
 437         // we've already tabulated) are lower because a smaller value is passing through the channels
 438         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 439         // channels which were selected earlier (and which may still be used for other paths without a
 440         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 441         // de-preferenced.
 442         //
 443         // One potentially problematic case for this algorithm would be if there are many
 444         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 445         // graph walking), we may never find a path which is not liquidity-limited and has lower
 446         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 447         // Because we only consider paths with at least 5% of the total value being sent, the damage
 448         // from such a case should be limited, however this could be further reduced in the future by
 449         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 450         // limits for the purposes of fee calculation.
 451         //
 452         // Alternatively, we could store more detailed path information in the heap (targets, below)
 453         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 454         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 455         // and practically (as we would need to store dynamically-allocated path information in heap
 456         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 457         // results of such an algorithm would likely be biased towards lower-value paths.
 458         //
 459         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 460         // outside of our current search value, running a path search more times to gather candidate
 461         // paths at different values. While this may be acceptable, further path searches may increase
 462         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 463         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 464         // the same time, remaining generic across different payment values.
 465         //
 466         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 467         // to use as the A* heuristic beyond just the cost to get one node further than the current
 468         // one.
 469
 470         let network_graph = network.read_only();
 471         let network_channels = network_graph.channels();
 472         let network_nodes = network_graph.nodes();
 473         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 474                 cltv_expiry_delta: 0,
 475                 htlc_minimum_msat: 0,
 476                 htlc_maximum_msat: None,
 477                 fees: RoutingFees {
 478                         base_msat: 0,
 479                         proportional_millionths: 0,
 480                 }
 481         };
 482
 483         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 484         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 485         // work reliably.
 486         let allow_mpp = if let Some(features) = &payee_features {
 487                 features.supports_basic_mpp()
 488         } else if let Some(node) = network_nodes.get(&payee_node_id) {
 489                 if let Some(node_info) = node.announcement_info.as_ref() {
 490                         node_info.features.supports_basic_mpp()
 491                 } else { false }
 492         } else { false };
 493         log_trace!(logger, "Searching for a route from payer {} to payee {} {} MPP", our_node_pubkey, payee,
 494                 if allow_mpp { "with" } else { "without" });
 495
 496         // Step (1).
 497         // Prepare the data we'll use for payee-to-payer search by
 498         // inserting first hops suggested by the caller as targets.
 499         // Our search will then attempt to reach them while traversing from the payee node.
 500         let mut first_hop_targets: HashMap<_, Vec<(_, ChannelFeatures, _, NodeFeatures)>> =
 501                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 502         if let Some(hops) = first_hops {
 503                 for chan in hops {
 504                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 505                         if chan.counterparty.node_id == *our_node_pubkey {
 506                                 return Err(LightningError{err: "First hop cannot have our_node_pubkey as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 507                         }
 508                         first_hop_targets.entry(NodeId::from_pubkey(&chan.counterparty.node_id)).or_insert(Vec::new())
 509                                 .push((short_channel_id, chan.counterparty.features.to_context(), chan.outbound_capacity_msat, chan.counterparty.features.to_context()));
 510                 }
 511                 if first_hop_targets.is_empty() {
 512                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 513                 }
 514         }
 515
 516         let empty_channel_features = ChannelFeatures::empty();
 517
 518         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 519         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 520         // adding duplicate entries when we find a better path to a given node.
 521         let mut targets = BinaryHeap::new();
 522
 523         // Map from node_id to information about the best current path to that node, including feerate
 524         // information.
 525         let mut dist = HashMap::with_capacity(network_nodes.len());
 526
 527         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 528         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 529         // htlc_minimum with extra fees while still finding a cheaper path.
 530         let mut hit_minimum_limit;
 531
 532         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 533         // We start with a path_value of the exact amount we want, and if that generates a route we may
 534         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 535         // amount we want in total across paths, selecting the best subset at the end.
 536         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 537         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 538         let mut path_value_msat = final_value_msat;
 539
 540         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 541         // This map allows paths to be aware of the channel use by other paths in the same call.
 542         // This would help to make a better path finding decisions and not "overbook" channels.
 543         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 544         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network_nodes.len());
 545
 546         // Keeping track of how much value we already collected across other paths. Helps to decide:
 547         // - how much a new path should be transferring (upper bound);
 548         // - whether a channel should be disregarded because
 549         //   it's available liquidity is too small comparing to how much more we need to collect;
 550         // - when we want to stop looking for new paths.
 551         let mut already_collected_value_msat = 0;
 552
 553         log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payee, our_node_pubkey, final_value_msat);
 554
 555         macro_rules! add_entry {
 556                 // Adds entry which goes from $src_node_id to $dest_node_id
 557                 // over the channel with id $chan_id with fees described in
 558                 // $directional_info.
 559                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 560                 // since that value has to be transferred over this channel.
 561                 // Returns whether this channel caused an update to `targets`.
 562                 ( $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,
 563                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => { {
 564                         // We "return" whether we updated the path at the end, via this:
 565                         let mut did_add_update_path_to_src_node = false;
 566                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 567                         // practice these cases should be caught earlier:
 568                         // - for regular channels at channel announcement (TODO)
 569                         // - for first and last hops early in get_route
 570                         if $src_node_id != $dest_node_id.clone() {
 571                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 572                                         let mut initial_liquidity_available_msat = None;
 573                                         if let Some(capacity_sats) = $capacity_sats {
 574                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 575                                         }
 576
 577                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 578                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 579                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 580                                                 } else {
 581                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 582                                                 }
 583                                         }
 584
 585                                         match initial_liquidity_available_msat {
 586                                                 Some(available_msat) => available_msat,
 587                                                 // We assume channels with unknown balance have
 588                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 589                                                 None => 250_000 * 1000
 590                                         }
 591                                 });
 592
 593                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 594                                 // It may be misleading because we might later choose to reduce the value transferred
 595                                 // over these channels, and the channel which was insufficient might become sufficient.
 596                                 // Worst case: we drop a good channel here because it can't cover the high following
 597                                 // fees caused by one expensive channel, but then this channel could have been used
 598                                 // if the amount being transferred over this path is lower.
 599                                 // We do this for now, but this is a subject for removal.
 600                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 601
 602                                         // Routing Fragmentation Mitigation heuristic:
 603                                         //
 604                                         // Routing fragmentation across many payment paths increases the overall routing
 605                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 606                                         // Taking too many smaller paths also increases the chance of payment failure.
 607                                         // Thus to avoid this effect, we require from our collected links to provide
 608                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 609                                         //
 610                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 611                                         // This means as we successfully advance in our collection,
 612                                         // the absolute liquidity contribution is lowered,
 613                                         // thus increasing the number of potential channels to be selected.
 614
 615                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 616                                         // or 100% if we're not allowed to do multipath payments.
 617                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 618                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 619                                         } else {
 620                                                 final_value_msat
 621                                         };
 622                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 623                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 624
 625                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 626                                         // Includes paying fees for the use of the following channels.
 627                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 628                                                 Some(result) => result,
 629                                                 // Can't overflow due to how the values were computed right above.
 630                                                 None => unreachable!(),
 631                                         };
 632                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 633                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 634                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 635
 636                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 637                                         // bother considering this channel.
 638                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 639                                         // be only reduced later (not increased), so this channel should just be skipped
 640                                         // as not sufficient.
 641                                         if !over_path_minimum_msat {
 642                                                 hit_minimum_limit = true;
 643                                         } else if contributes_sufficient_value {
 644                                                 // Note that low contribution here (limited by available_liquidity_msat)
 645                                                 // might violate htlc_minimum_msat on the hops which are next along the
 646                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 647                                                 // path fees knowing the final path contribution after constructing it.
 648                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 649                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 650                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 651                                                         _ => u64::max_value()
 652                                                 };
 653                                                 let hm_entry = dist.entry($src_node_id);
 654                                                 let old_entry = hm_entry.or_insert_with(|| {
 655                                                         // If there was previously no known way to access
 656                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 657                                                         // a semi-dummy record just to compute the fees to reach the source node.
 658                                                         // This will affect our decision on selecting $chan_id
 659                                                         // as a way to reach the $dest_node_id.
 660                                                         let mut fee_base_msat = u32::max_value();
 661                                                         let mut fee_proportional_millionths = u32::max_value();
 662                                                         if let Some(Some(fees)) = network_nodes.get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 663                                                                 fee_base_msat = fees.base_msat;
 664                                                                 fee_proportional_millionths = fees.proportional_millionths;
 665                                                         }
 666                                                         PathBuildingHop {
 667                                                                 node_id: $dest_node_id.clone(),
 668                                                                 short_channel_id: 0,
 669                                                                 channel_features: $chan_features,
 670                                                                 fee_msat: 0,
 671                                                                 cltv_expiry_delta: 0,
 672                                                                 src_lowest_inbound_fees: RoutingFees {
 673                                                                         base_msat: fee_base_msat,
 674                                                                         proportional_millionths: fee_proportional_millionths,
 675                                                                 },
 676                                                                 channel_fees: $directional_info.fees,
 677                                                                 next_hops_fee_msat: u64::max_value(),
 678                                                                 hop_use_fee_msat: u64::max_value(),
 679                                                                 total_fee_msat: u64::max_value(),
 680                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 681                                                                 path_htlc_minimum_msat,
 682                                                                 was_processed: false,
 683                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 684                                                                 value_contribution_msat,
 685                                                         }
 686                                                 });
 687
 688                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 689                                                 let mut should_process = !old_entry.was_processed;
 690                                                 #[cfg(any(test, feature = "fuzztarget"))]
 691                                                 {
 692                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 693                                                         // of already-seen nodes only happens in cases we expect (see below).
 694                                                         if !should_process { should_process = true; }
 695                                                 }
 696
 697                                                 if should_process {
 698                                                         let mut hop_use_fee_msat = 0;
 699                                                         let mut total_fee_msat = $next_hops_fee_msat;
 700
 701                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 702                                                         // will have the same effective-fee
 703                                                         if $src_node_id != our_node_id {
 704                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 705                                                                         // max_value means we'll always fail
 706                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 707                                                                         None => total_fee_msat = u64::max_value(),
 708                                                                         Some(fee_msat) => {
 709                                                                                 hop_use_fee_msat = fee_msat;
 710                                                                                 total_fee_msat += hop_use_fee_msat;
 711                                                                                 // When calculating the lowest inbound fees to a node, we
 712                                                                                 // calculate fees here not based on the actual value we think
 713                                                                                 // will flow over this channel, but on the minimum value that
 714                                                                                 // we'll accept flowing over it. The minimum accepted value
 715                                                                                 // is a constant through each path collection run, ensuring
 716                                                                                 // consistent basis. Otherwise we may later find a
 717                                                                                 // different path to the source node that is more expensive,
 718                                                                                 // but which we consider to be cheaper because we are capacity
 719                                                                                 // constrained and the relative fee becomes lower.
 720                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 721                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 722                                                                                         Some(Some(v)) => {
 723                                                                                                 total_fee_msat = v;
 724                                                                                         },
 725                                                                                         _ => {
 726                                                                                                 total_fee_msat = u64::max_value();
 727                                                                                         }
 728                                                                                 };
 729                                                                         }
 730                                                                 }
 731                                                         }
 732
 733                                                         let new_graph_node = RouteGraphNode {
 734                                                                 node_id: $src_node_id,
 735                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 736                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 737                                                                 value_contribution_msat: value_contribution_msat,
 738                                                                 path_htlc_minimum_msat,
 739                                                         };
 740
 741                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 742                                                         // if this way is cheaper than the already known
 743                                                         // (considering the cost to "reach" this channel from the route destination,
 744                                                         // the cost of using this channel,
 745                                                         // and the cost of routing to the source node of this channel).
 746                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 747                                                         // paying it. Consider the following exploit:
 748                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 749                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 750                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 751                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 752                                                         // to this channel.
 753                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 754                                                         // but it may require additional tracking - we don't want to double-count
 755                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 756                                                         // can't use something that may decrease on future hops.
 757                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 758                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 759
 760                                                         if !old_entry.was_processed && new_cost < old_cost {
 761                                                                 targets.push(new_graph_node);
 762                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 763                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 764                                                                 old_entry.total_fee_msat = total_fee_msat;
 765                                                                 old_entry.node_id = $dest_node_id.clone();
 766                                                                 old_entry.short_channel_id = $chan_id.clone();
 767                                                                 old_entry.channel_features = $chan_features;
 768                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 769                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 770                                                                 old_entry.channel_fees = $directional_info.fees;
 771                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 772                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 773                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 774                                                                 {
 775                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 776                                                                 }
 777                                                                 did_add_update_path_to_src_node = true;
 778                                                         } else if old_entry.was_processed && new_cost < old_cost {
 779                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 780                                                                 {
 781                                                                         // If we're skipping processing a node which was previously
 782                                                                         // processed even though we found another path to it with a
 783                                                                         // cheaper fee, check that it was because the second path we
 784                                                                         // found (which we are processing now) has a lower value
 785                                                                         // contribution due to an HTLC minimum limit.
 786                                                                         //
 787                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 788                                                                         // through channel A, and one through channel B. Channel A and
 789                                                                         // B are both in the to-process heap, with their scores set by
 790                                                                         // a higher htlc_minimum than fee.
 791                                                                         // Channel A is processed first, and the channels onwards from
 792                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 793                                                                         // Channel B off of the heap, note that it has a much more
 794                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 795                                                                         // all of node 1's channels using the new, reduced, amount.
 796                                                                         //
 797                                                                         // This would be bogus - we'd be selecting a higher-fee path
 798                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 799                                                                         // already decided to use.
 800                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 801                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 802                                                                 }
 803                                                         }
 804                                                 }
 805                                         }
 806                                 }
 807                         }
 808                         did_add_update_path_to_src_node
 809                 } }
 810         }
 811
 812         let empty_node_features = NodeFeatures::empty();
 813         // Find ways (channels with destination) to reach a given node and store them
 814         // in the corresponding data structures (routing graph etc).
 815         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 816         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 817         // This data can later be helpful to optimize routing (pay lower fees).
 818         macro_rules! add_entries_to_cheapest_to_target_node {
 819                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 820                         let skip_node = if let Some(elem) = dist.get_mut(&$node_id) {
 821                                 let was_processed = elem.was_processed;
 822                                 elem.was_processed = true;
 823                                 was_processed
 824                         } else {
 825                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 826                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 827                                 // If we're processing any other node, it is always be the result of a channel from it.
 828                                 assert_eq!($node_id, payee_node_id);
 829                                 false
 830                         };
 831
 832                         if !skip_node {
 833                                 if let Some(first_channels) = first_hop_targets.get(&$node_id) {
 834                                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
 835                                                 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);
 836                                         }
 837                                 }
 838
 839                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 840                                         &node_info.features
 841                                 } else {
 842                                         &empty_node_features
 843                                 };
 844
 845                                 if !features.requires_unknown_bits() {
 846                                         for chan_id in $node.channels.iter() {
 847                                                 let chan = network_channels.get(chan_id).unwrap();
 848                                                 if !chan.features.requires_unknown_bits() {
 849                                                         if chan.node_one == $node_id {
 850                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 851                                                                 if first_hops.is_none() || chan.node_two != our_node_id {
 852                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 853                                                                                 if two_to_one.enabled {
 854                                                                                         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);
 855                                                                                 }
 856                                                                         }
 857                                                                 }
 858                                                         } else {
 859                                                                 if first_hops.is_none() || chan.node_one != our_node_id{
 860                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 861                                                                                 if one_to_two.enabled {
 862                                                                                         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);
 863                                                                                 }
 864                                                                         }
 865                                                                 }
 866                                                         }
 867                                                 }
 868                                         }
 869                                 }
 870                         }
 871                 };
 872         }
 873
 874         let mut payment_paths = Vec::<PaymentPath>::new();
 875
 876         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 877         'paths_collection: loop {
 878                 // For every new path, start from scratch, except
 879                 // bookkeeped_channels_liquidity_available_msat, which will improve
 880                 // the further iterations of path finding. Also don't erase first_hop_targets.
 881                 targets.clear();
 882                 dist.clear();
 883                 hit_minimum_limit = false;
 884
 885                 // If first hop is a private channel and the only way to reach the payee, this is the only
 886                 // place where it could be added.
 887                 if let Some(first_channels) = first_hop_targets.get(&payee_node_id) {
 888                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
 889                                 let added = add_entry!(first_hop, our_node_id, payee_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 890                                 log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, first_hop);
 891                         }
 892                 }
 893
 894                 // Add the payee as a target, so that the payee-to-payer
 895                 // search algorithm knows what to start with.
 896                 match network_nodes.get(&payee_node_id) {
 897                         // The payee is not in our network graph, so nothing to add here.
 898                         // There is still a chance of reaching them via last_hops though,
 899                         // so don't yet fail the payment here.
 900                         // If not, targets.pop() will not even let us enter the loop in step 2.
 901                         None => {},
 902                         Some(node) => {
 903                                 add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0);
 904                         },
 905                 }
 906
 907                 // Step (2).
 908                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 909                 // earlier than general path finding, they will be somewhat prioritized, although currently
 910                 // it matters only if the fees are exactly the same.
 911                 for route in last_hops.iter().filter(|route| !route.0.is_empty()) {
 912                         let first_hop_in_route = &(route.0)[0];
 913                         let have_hop_src_in_graph =
 914                                 // Only add the hops in this route to our candidate set if either
 915                                 // we have a direct channel to the first hop or the first hop is
 916                                 // in the regular network graph.
 917                                 first_hop_targets.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some() ||
 918                                 network_nodes.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some();
 919                         if have_hop_src_in_graph {
 920                                 // We start building the path from reverse, i.e., from payee
 921                                 // to the first RouteHintHop in the path.
 922                                 let hop_iter = route.0.iter().rev();
 923                                 let prev_hop_iter = core::iter::once(payee).chain(
 924                                         route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
 925                                 let mut hop_used = true;
 926                                 let mut aggregate_next_hops_fee_msat: u64 = 0;
 927                                 let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
 928
 929                                 for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
 930                                         // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 931                                         // really sucks, cause we're gonna need that eventually.
 932                                         let hop_htlc_minimum_msat: u64 = hop.htlc_minimum_msat.unwrap_or(0);
 933
 934                                         let directional_info = DummyDirectionalChannelInfo {
 935                                                 cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 936                                                 htlc_minimum_msat: hop_htlc_minimum_msat,
 937                                                 htlc_maximum_msat: hop.htlc_maximum_msat,
 938                                                 fees: hop.fees,
 939                                         };
 940
 941                                         let reqd_channel_cap = if let Some (val) = final_value_msat.checked_add(match idx {
 942                                                 0 => 999,
 943                                                 _ => aggregate_next_hops_fee_msat.checked_add(999).unwrap_or(u64::max_value())
 944                                         }) { Some( val / 1000 ) } else { break; }; // converting from msat or breaking if max ~ infinity
 945
 946                                         // We assume that the recipient only included route hints for routes which had
 947                                         // sufficient value to route `final_value_msat`. Note that in the case of "0-value"
 948                                         // invoices where the invoice does not specify value this may not be the case, but
 949                                         // better to include the hints than not.
 950                                         if !add_entry!(hop.short_channel_id, NodeId::from_pubkey(&hop.src_node_id), NodeId::from_pubkey(&prev_hop_id), directional_info, reqd_channel_cap, &empty_channel_features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat) {
 951                                                 // If this hop was not used then there is no use checking the preceding hops
 952                                                 // in the RouteHint. We can break by just searching for a direct channel between
 953                                                 // last checked hop and first_hop_targets
 954                                                 hop_used = false;
 955                                         }
 956
 957                                         // Searching for a direct channel between last checked hop and first_hop_targets
 958                                         if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
 959                                                 for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
 960                                                         add_entry!(first_hop, our_node_id , NodeId::from_pubkey(&prev_hop_id), dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat);
 961                                                 }
 962                                         }
 963
 964                                         if !hop_used {
 965                                                 break;
 966                                         }
 967
 968                                         // In the next values of the iterator, the aggregate fees already reflects
 969                                         // the sum of value sent from payer (final_value_msat) and routing fees
 970                                         // for the last node in the RouteHint. We need to just add the fees to
 971                                         // route through the current node so that the preceeding node (next iteration)
 972                                         // can use it.
 973                                         let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
 974                                                 .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
 975                                         aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
 976
 977                                         let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
 978                                         let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
 979                                                 .checked_add(hop_htlc_minimum_msat_inc);
 980                                         aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
 981
 982                                         if idx == route.0.len() - 1 {
 983                                                 // The last hop in this iterator is the first hop in
 984                                                 // overall RouteHint.
 985                                                 // If this hop connects to a node with which we have a direct channel,
 986                                                 // ignore the network graph and, if the last hop was added, add our
 987                                                 // direct channel to the candidate set.
 988                                                 //
 989                                                 // Note that we *must* check if the last hop was added as `add_entry`
 990                                                 // always assumes that the third argument is a node to which we have a
 991                                                 // path.
 992                                                 if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
 993                                                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
 994                                                                 add_entry!(first_hop, our_node_id , NodeId::from_pubkey(&hop.src_node_id), dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat);
 995                                                         }
 996                                                 }
 997                                         }
 998                                 }
 999                         }
1000                 }
1001
1002                 log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
1003
1004                 // At this point, targets are filled with the data from first and
1005                 // last hops communicated by the caller, and the payment receiver.
1006                 let mut found_new_path = false;
1007
1008                 // Step (3).
1009                 // If this loop terminates due the exhaustion of targets, two situations are possible:
1010                 // - not enough outgoing liquidity:
1011                 //   0 < already_collected_value_msat < final_value_msat
1012                 // - enough outgoing liquidity:
1013                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
1014                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
1015                 // paths_collection will be stopped because found_new_path==false.
1016                 // This is not necessarily a routing failure.
1017                 'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
1018
1019                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
1020                         // traversing the graph and arrange the path out of what we found.
1021                         if node_id == our_node_id {
1022                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
1023                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
1024
1025                                 'path_walk: loop {
1026                                         let mut features_set = false;
1027                                         if let Some(first_channels) = first_hop_targets.get(&ordered_hops.last().unwrap().0.node_id) {
1028                                                 for (scid, _, _, ref features) in first_channels {
1029                                                         if *scid == ordered_hops.last().unwrap().0.short_channel_id {
1030                                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
1031                                                                 features_set = true;
1032                                                                 break;
1033                                                         }
1034                                                 }
1035                                         }
1036                                         if !features_set {
1037                                                 if let Some(node) = network_nodes.get(&ordered_hops.last().unwrap().0.node_id) {
1038                                                         if let Some(node_info) = node.announcement_info.as_ref() {
1039                                                                 ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
1040                                                         } else {
1041                                                                 ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
1042                                                         }
1043                                                 } else {
1044                                                         // We should be able to fill in features for everything except the last
1045                                                         // hop, if the last hop was provided via a BOLT 11 invoice (though we
1046                                                         // should be able to extend it further as BOLT 11 does have feature
1047                                                         // flags for the last hop node itself).
1048                                                         assert!(ordered_hops.last().unwrap().0.node_id == payee_node_id);
1049                                                 }
1050                                         }
1051
1052                                         // Means we succesfully traversed from the payer to the payee, now
1053                                         // save this path for the payment route. Also, update the liquidity
1054                                         // remaining on the used hops, so that we take them into account
1055                                         // while looking for more paths.
1056                                         if ordered_hops.last().unwrap().0.node_id == payee_node_id {
1057                                                 break 'path_walk;
1058                                         }
1059
1060                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.node_id) {
1061                                                 Some(payment_hop) => payment_hop,
1062                                                 // We can't arrive at None because, if we ever add an entry to targets,
1063                                                 // we also fill in the entry in dist (see add_entry!).
1064                                                 None => unreachable!(),
1065                                         };
1066                                         // We "propagate" the fees one hop backward (topologically) here,
1067                                         // so that fees paid for a HTLC forwarding on the current channel are
1068                                         // associated with the previous channel (where they will be subtracted).
1069                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
1070                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
1071                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
1072                                 }
1073                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
1074                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
1075                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
1076
1077                                 log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
1078                                         ordered_hops.len(), value_contribution_msat, ordered_hops);
1079
1080                                 let mut payment_path = PaymentPath {hops: ordered_hops};
1081
1082                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
1083                                 // value being transferred along the way, we could have violated htlc_minimum_msat
1084                                 // on some channels we already passed (assuming dest->source direction). Here, we
1085                                 // recompute the fees again, so that if that's the case, we match the currently
1086                                 // underpaid htlc_minimum_msat with fees.
1087                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
1088
1089                                 // Since a path allows to transfer as much value as
1090                                 // the smallest channel it has ("bottleneck"), we should recompute
1091                                 // the fees so sender HTLC don't overpay fees when traversing
1092                                 // larger channels than the bottleneck. This may happen because
1093                                 // when we were selecting those channels we were not aware how much value
1094                                 // this path will transfer, and the relative fee for them
1095                                 // might have been computed considering a larger value.
1096                                 // Remember that we used these channels so that we don't rely
1097                                 // on the same liquidity in future paths.
1098                                 let mut prevented_redundant_path_selection = false;
1099                                 for (payment_hop, _) in payment_path.hops.iter() {
1100                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
1101                                         let mut spent_on_hop_msat = value_contribution_msat;
1102                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
1103                                         spent_on_hop_msat += next_hops_fee_msat;
1104                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
1105                                                 // If this path used all of this channel's available liquidity, we know
1106                                                 // this path will not be selected again in the next loop iteration.
1107                                                 prevented_redundant_path_selection = true;
1108                                         }
1109                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
1110                                 }
1111                                 if !prevented_redundant_path_selection {
1112                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
1113                                         // we'll probably end up picking the same path again on the next iteration.
1114                                         // Decrease the available liquidity of a hop in the middle of the path.
1115                                         let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
1116                                         log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
1117                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
1118                                         *victim_liquidity = 0;
1119                                 }
1120
1121                                 // Track the total amount all our collected paths allow to send so that we:
1122                                 // - know when to stop looking for more paths
1123                                 // - know which of the hops are useless considering how much more sats we need
1124                                 //   (contributes_sufficient_value)
1125                                 already_collected_value_msat += value_contribution_msat;
1126
1127                                 payment_paths.push(payment_path);
1128                                 found_new_path = true;
1129                                 break 'path_construction;
1130                         }
1131
1132                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1133                         // the equivalent of the `elem.was_processed` check in
1134                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1135                         if node_id == payee_node_id { continue 'path_construction; }
1136
1137                         // Otherwise, since the current target node is not us,
1138                         // keep "unrolling" the payment graph from payee to payer by
1139                         // finding a way to reach the current target from the payer side.
1140                         match network_nodes.get(&node_id) {
1141                                 None => {},
1142                                 Some(node) => {
1143                                         add_entries_to_cheapest_to_target_node!(node, node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1144                                 },
1145                         }
1146                 }
1147
1148                 if !allow_mpp {
1149                         // If we don't support MPP, no use trying to gather more value ever.
1150                         break 'paths_collection;
1151                 }
1152
1153                 // Step (4).
1154                 // Stop either when the recommended value is reached or if no new path was found in this
1155                 // iteration.
1156                 // In the latter case, making another path finding attempt won't help,
1157                 // because we deterministically terminated the search due to low liquidity.
1158                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1159                         log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
1160                                 already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
1161                         break 'paths_collection;
1162                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1163                         // Further, if this was our first walk of the graph, and we weren't limited by an
1164                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1165                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1166                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1167                         // still keeping a lower total fee than this path.
1168                         if !hit_minimum_limit {
1169                                 log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
1170                                 break 'paths_collection;
1171                         }
1172                         log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
1173                         path_value_msat = recommended_value_msat;
1174                 }
1175         }
1176
1177         // Step (5).
1178         if payment_paths.len() == 0 {
1179                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1180         }
1181
1182         if already_collected_value_msat < final_value_msat {
1183                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1184         }
1185
1186         // Sort by total fees and take the best paths.
1187         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1188         if payment_paths.len() > 50 {
1189                 payment_paths.truncate(50);
1190         }
1191
1192         // Draw multiple sufficient routes by randomly combining the selected paths.
1193         let mut drawn_routes = Vec::new();
1194         for i in 0..payment_paths.len() {
1195                 let mut cur_route = Vec::<PaymentPath>::new();
1196                 let mut aggregate_route_value_msat = 0;
1197
1198                 // Step (6).
1199                 // TODO: real random shuffle
1200                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1201                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1202
1203                 // Step (7).
1204                 for payment_path in cur_payment_paths {
1205                         cur_route.push(payment_path.clone());
1206                         aggregate_route_value_msat += payment_path.get_value_msat();
1207                         if aggregate_route_value_msat > final_value_msat {
1208                                 // Last path likely overpaid. Substract it from the most expensive
1209                                 // (in terms of proportional fee) path in this route and recompute fees.
1210                                 // This might be not the most economically efficient way, but fewer paths
1211                                 // also makes routing more reliable.
1212                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1213
1214                                 // First, drop some expensive low-value paths entirely if possible.
1215                                 // Sort by value so that we drop many really-low values first, since
1216                                 // fewer paths is better: the payment is less likely to fail.
1217                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1218                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1219                                 cur_route.sort_by_key(|path| path.get_value_msat());
1220                                 // We should make sure that at least 1 path left.
1221                                 let mut paths_left = cur_route.len();
1222                                 cur_route.retain(|path| {
1223                                         if paths_left == 1 {
1224                                                 return true
1225                                         }
1226                                         let mut keep = true;
1227                                         let path_value_msat = path.get_value_msat();
1228                                         if path_value_msat <= overpaid_value_msat {
1229                                                 keep = false;
1230                                                 overpaid_value_msat -= path_value_msat;
1231                                                 paths_left -= 1;
1232                                         }
1233                                         keep
1234                                 });
1235
1236                                 if overpaid_value_msat == 0 {
1237                                         break;
1238                                 }
1239
1240                                 assert!(cur_route.len() > 0);
1241
1242                                 // Step (8).
1243                                 // Now, substract the overpaid value from the most-expensive path.
1244                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1245                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1246                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1247                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1248                                 // We already dropped all the small channels above, meaning all the
1249                                 // remaining channels are larger than remaining overpaid_value_msat.
1250                                 // Thus, this can't be negative.
1251                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1252                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1253                                 break;
1254                         }
1255                 }
1256                 drawn_routes.push(cur_route);
1257         }
1258
1259         // Step (9).
1260         // Select the best route by lowest total fee.
1261         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1262         let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
1263         for payment_path in drawn_routes.first().unwrap() {
1264                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1265                         Ok(RouteHop {
1266                                 pubkey: PublicKey::from_slice(payment_hop.node_id.as_slice()).map_err(|_| LightningError{err: format!("Public key {:?} is invalid", &payment_hop.node_id), action: ErrorAction::IgnoreAndLog(Level::Trace)})?,
1267                                 node_features: node_features.clone(),
1268                                 short_channel_id: payment_hop.short_channel_id,
1269                                 channel_features: payment_hop.channel_features.clone(),
1270                                 fee_msat: payment_hop.fee_msat,
1271                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1272                         })
1273                 }).collect());
1274         }
1275
1276         if let Some(features) = &payee_features {
1277                 for path in selected_paths.iter_mut() {
1278                         if let Ok(route_hop) = path.last_mut().unwrap() {
1279                                 route_hop.node_features = features.to_context();
1280                         }
1281                 }
1282         }
1283
1284         let route = Route { paths: selected_paths.into_iter().map(|path| path.into_iter().collect()).collect::<Result<Vec<_>, _>>()? };
1285         log_info!(logger, "Got route to {}: {}", payee, log_route!(route));
1286         Ok(route)
1287 }
1288
1289 #[cfg(test)]
1290 mod tests {
1291         use routing::router::{get_route, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
1292         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1293         use chain::transaction::OutPoint;
1294         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1295         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1296            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1297         use ln::channelmanager;
1298         use util::test_utils;
1299         use util::ser::Writeable;
1300
1301         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1302         use bitcoin::hashes::Hash;
1303         use bitcoin::network::constants::Network;
1304         use bitcoin::blockdata::constants::genesis_block;
1305         use bitcoin::blockdata::script::Builder;
1306         use bitcoin::blockdata::opcodes;
1307         use bitcoin::blockdata::transaction::TxOut;
1308
1309         use hex;
1310
1311         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1312         use bitcoin::secp256k1::{Secp256k1, All};
1313
1314         use prelude::*;
1315         use sync::{self, Arc};
1316
1317         fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
1318                         features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
1319                 channelmanager::ChannelDetails {
1320                         channel_id: [0; 32],
1321                         counterparty: channelmanager::ChannelCounterparty {
1322                                 features,
1323                                 node_id,
1324                                 unspendable_punishment_reserve: 0,
1325                                 forwarding_info: None,
1326                         },
1327                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1328                         short_channel_id,
1329                         channel_value_satoshis: 0,
1330                         user_channel_id: 0,
1331                         outbound_capacity_msat,
1332                         inbound_capacity_msat: 42,
1333                         unspendable_punishment_reserve: None,
1334                         confirmations_required: None,
1335                         force_close_spend_delay: None,
1336                         is_outbound: true, is_funding_locked: true,
1337                         is_usable: true, is_public: true,
1338                 }
1339         }
1340
1341         // Using the same keys for LN and BTC ids
1342         fn add_channel(
1343                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1344                 secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey, node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64
1345         ) {
1346                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1347                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1348
1349                 let unsigned_announcement = UnsignedChannelAnnouncement {
1350                         features,
1351                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1352                         short_channel_id,
1353                         node_id_1,
1354                         node_id_2,
1355                         bitcoin_key_1: node_id_1,
1356                         bitcoin_key_2: node_id_2,
1357                         excess_data: Vec::new(),
1358                 };
1359
1360                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1361                 let valid_announcement = ChannelAnnouncement {
1362                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1363                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1364                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1365                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1366                         contents: unsigned_announcement.clone(),
1367                 };
1368                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1369                         Ok(res) => assert!(res),
1370                         _ => panic!()
1371                 };
1372         }
1373
1374         fn update_channel(
1375                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1376                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate
1377         ) {
1378                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1379                 let valid_channel_update = ChannelUpdate {
1380                         signature: secp_ctx.sign(&msghash, node_privkey),
1381                         contents: update.clone()
1382                 };
1383
1384                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1385                         Ok(res) => assert!(res),
1386                         Err(_) => panic!()
1387                 };
1388         }
1389
1390         fn add_or_update_node(
1391                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1392                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, features: NodeFeatures, timestamp: u32
1393         ) {
1394                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1395                 let unsigned_announcement = UnsignedNodeAnnouncement {
1396                         features,
1397                         timestamp,
1398                         node_id,
1399                         rgb: [0; 3],
1400                         alias: [0; 32],
1401                         addresses: Vec::new(),
1402                         excess_address_data: Vec::new(),
1403                         excess_data: Vec::new(),
1404                 };
1405                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1406                 let valid_announcement = NodeAnnouncement {
1407                         signature: secp_ctx.sign(&msghash, node_privkey),
1408                         contents: unsigned_announcement.clone()
1409                 };
1410
1411                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1412                         Ok(_) => (),
1413                         Err(_) => panic!()
1414                 };
1415         }
1416
1417         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1418                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1419                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1420                 }).collect();
1421
1422                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1423
1424                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1425                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1426
1427                 (our_privkey, our_id, privkeys, pubkeys)
1428         }
1429
1430         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1431                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1432                 // test for it later.
1433                 let idx = (id - 1) * 2 + 1;
1434                 if idx > 8*3 {
1435                         vec![1 << (idx - 8*3), 0, 0, 0]
1436                 } else if idx > 8*2 {
1437                         vec![1 << (idx - 8*2), 0, 0]
1438                 } else if idx > 8*1 {
1439                         vec![1 << (idx - 8*1), 0]
1440                 } else {
1441                         vec![1 << idx]
1442                 }
1443         }
1444
1445         fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>, sync::Arc<test_utils::TestChainSource>, sync::Arc<test_utils::TestLogger>) {
1446                 let secp_ctx = Secp256k1::new();
1447                 let logger = Arc::new(test_utils::TestLogger::new());
1448                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1449                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
1450                 let net_graph_msg_handler = NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger));
1451                 // Build network from our_id to node6:
1452                 //
1453                 //        -1(1)2-  node0  -1(3)2-
1454                 //       /                       \
1455                 // our_id -1(12)2- node7 -1(13)2--- node2
1456                 //       \                       /
1457                 //        -1(2)2-  node1  -1(4)2-
1458                 //
1459                 //
1460                 // chan1  1-to-2: disabled
1461                 // chan1  2-to-1: enabled, 0 fee
1462                 //
1463                 // chan2  1-to-2: enabled, ignored fee
1464                 // chan2  2-to-1: enabled, 0 fee
1465                 //
1466                 // chan3  1-to-2: enabled, 0 fee
1467                 // chan3  2-to-1: enabled, 100 msat fee
1468                 //
1469                 // chan4  1-to-2: enabled, 100% fee
1470                 // chan4  2-to-1: enabled, 0 fee
1471                 //
1472                 // chan12 1-to-2: enabled, ignored fee
1473                 // chan12 2-to-1: enabled, 0 fee
1474                 //
1475                 // chan13 1-to-2: enabled, 200% fee
1476                 // chan13 2-to-1: enabled, 0 fee
1477                 //
1478                 //
1479                 //       -1(5)2- node3 -1(8)2--
1480                 //       |         2          |
1481                 //       |       (11)         |
1482                 //      /          1           \
1483                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1484                 //      \                      /
1485                 //       -1(7)2- node5 -1(10)2-
1486                 //
1487                 // Channels 5, 8, 9 and 10 are private channels.
1488                 //
1489                 // chan5  1-to-2: enabled, 100 msat fee
1490                 // chan5  2-to-1: enabled, 0 fee
1491                 //
1492                 // chan6  1-to-2: enabled, 0 fee
1493                 // chan6  2-to-1: enabled, 0 fee
1494                 //
1495                 // chan7  1-to-2: enabled, 100% fee
1496                 // chan7  2-to-1: enabled, 0 fee
1497                 //
1498                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1499                 // chan8  2-to-1: enabled, 0 fee
1500                 //
1501                 // chan9  1-to-2: enabled, 1001 msat fee
1502                 // chan9  2-to-1: enabled, 0 fee
1503                 //
1504                 // chan10 1-to-2: enabled, 0 fee
1505                 // chan10 2-to-1: enabled, 0 fee
1506                 //
1507                 // chan11 1-to-2: enabled, 0 fee
1508                 // chan11 2-to-1: enabled, 0 fee
1509
1510                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1511
1512                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1513                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1514                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1515                         short_channel_id: 1,
1516                         timestamp: 1,
1517                         flags: 1,
1518                         cltv_expiry_delta: 0,
1519                         htlc_minimum_msat: 0,
1520                         htlc_maximum_msat: OptionalField::Absent,
1521                         fee_base_msat: 0,
1522                         fee_proportional_millionths: 0,
1523                         excess_data: Vec::new()
1524                 });
1525
1526                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1527
1528                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1529                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1530                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1531                         short_channel_id: 2,
1532                         timestamp: 1,
1533                         flags: 0,
1534                         cltv_expiry_delta: u16::max_value(),
1535                         htlc_minimum_msat: 0,
1536                         htlc_maximum_msat: OptionalField::Absent,
1537                         fee_base_msat: u32::max_value(),
1538                         fee_proportional_millionths: u32::max_value(),
1539                         excess_data: Vec::new()
1540                 });
1541                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1542                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1543                         short_channel_id: 2,
1544                         timestamp: 1,
1545                         flags: 1,
1546                         cltv_expiry_delta: 0,
1547                         htlc_minimum_msat: 0,
1548                         htlc_maximum_msat: OptionalField::Absent,
1549                         fee_base_msat: 0,
1550                         fee_proportional_millionths: 0,
1551                         excess_data: Vec::new()
1552                 });
1553
1554                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1555
1556                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1557                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1558                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1559                         short_channel_id: 12,
1560                         timestamp: 1,
1561                         flags: 0,
1562                         cltv_expiry_delta: u16::max_value(),
1563                         htlc_minimum_msat: 0,
1564                         htlc_maximum_msat: OptionalField::Absent,
1565                         fee_base_msat: u32::max_value(),
1566                         fee_proportional_millionths: u32::max_value(),
1567                         excess_data: Vec::new()
1568                 });
1569                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1570                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1571                         short_channel_id: 12,
1572                         timestamp: 1,
1573                         flags: 1,
1574                         cltv_expiry_delta: 0,
1575                         htlc_minimum_msat: 0,
1576                         htlc_maximum_msat: OptionalField::Absent,
1577                         fee_base_msat: 0,
1578                         fee_proportional_millionths: 0,
1579                         excess_data: Vec::new()
1580                 });
1581
1582                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1583
1584                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1585                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1586                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1587                         short_channel_id: 3,
1588                         timestamp: 1,
1589                         flags: 0,
1590                         cltv_expiry_delta: (3 << 8) | 1,
1591                         htlc_minimum_msat: 0,
1592                         htlc_maximum_msat: OptionalField::Absent,
1593                         fee_base_msat: 0,
1594                         fee_proportional_millionths: 0,
1595                         excess_data: Vec::new()
1596                 });
1597                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1598                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1599                         short_channel_id: 3,
1600                         timestamp: 1,
1601                         flags: 1,
1602                         cltv_expiry_delta: (3 << 8) | 2,
1603                         htlc_minimum_msat: 0,
1604                         htlc_maximum_msat: OptionalField::Absent,
1605                         fee_base_msat: 100,
1606                         fee_proportional_millionths: 0,
1607                         excess_data: Vec::new()
1608                 });
1609
1610                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1611                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1612                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1613                         short_channel_id: 4,
1614                         timestamp: 1,
1615                         flags: 0,
1616                         cltv_expiry_delta: (4 << 8) | 1,
1617                         htlc_minimum_msat: 0,
1618                         htlc_maximum_msat: OptionalField::Absent,
1619                         fee_base_msat: 0,
1620                         fee_proportional_millionths: 1000000,
1621                         excess_data: Vec::new()
1622                 });
1623                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1624                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1625                         short_channel_id: 4,
1626                         timestamp: 1,
1627                         flags: 1,
1628                         cltv_expiry_delta: (4 << 8) | 2,
1629                         htlc_minimum_msat: 0,
1630                         htlc_maximum_msat: OptionalField::Absent,
1631                         fee_base_msat: 0,
1632                         fee_proportional_millionths: 0,
1633                         excess_data: Vec::new()
1634                 });
1635
1636                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1637                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1638                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1639                         short_channel_id: 13,
1640                         timestamp: 1,
1641                         flags: 0,
1642                         cltv_expiry_delta: (13 << 8) | 1,
1643                         htlc_minimum_msat: 0,
1644                         htlc_maximum_msat: OptionalField::Absent,
1645                         fee_base_msat: 0,
1646                         fee_proportional_millionths: 2000000,
1647                         excess_data: Vec::new()
1648                 });
1649                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1650                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1651                         short_channel_id: 13,
1652                         timestamp: 1,
1653                         flags: 1,
1654                         cltv_expiry_delta: (13 << 8) | 2,
1655                         htlc_minimum_msat: 0,
1656                         htlc_maximum_msat: OptionalField::Absent,
1657                         fee_base_msat: 0,
1658                         fee_proportional_millionths: 0,
1659                         excess_data: Vec::new()
1660                 });
1661
1662                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1663
1664                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1665                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1666                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1667                         short_channel_id: 6,
1668                         timestamp: 1,
1669                         flags: 0,
1670                         cltv_expiry_delta: (6 << 8) | 1,
1671                         htlc_minimum_msat: 0,
1672                         htlc_maximum_msat: OptionalField::Absent,
1673                         fee_base_msat: 0,
1674                         fee_proportional_millionths: 0,
1675                         excess_data: Vec::new()
1676                 });
1677                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1678                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1679                         short_channel_id: 6,
1680                         timestamp: 1,
1681                         flags: 1,
1682                         cltv_expiry_delta: (6 << 8) | 2,
1683                         htlc_minimum_msat: 0,
1684                         htlc_maximum_msat: OptionalField::Absent,
1685                         fee_base_msat: 0,
1686                         fee_proportional_millionths: 0,
1687                         excess_data: Vec::new(),
1688                 });
1689
1690                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1691                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1693                         short_channel_id: 11,
1694                         timestamp: 1,
1695                         flags: 0,
1696                         cltv_expiry_delta: (11 << 8) | 1,
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[3], UnsignedChannelUpdate {
1704                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1705                         short_channel_id: 11,
1706                         timestamp: 1,
1707                         flags: 1,
1708                         cltv_expiry_delta: (11 << 8) | 2,
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                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1717
1718                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1719
1720                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1721                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1722                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1723                         short_channel_id: 7,
1724                         timestamp: 1,
1725                         flags: 0,
1726                         cltv_expiry_delta: (7 << 8) | 1,
1727                         htlc_minimum_msat: 0,
1728                         htlc_maximum_msat: OptionalField::Absent,
1729                         fee_base_msat: 0,
1730                         fee_proportional_millionths: 1000000,
1731                         excess_data: Vec::new()
1732                 });
1733                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1734                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1735                         short_channel_id: 7,
1736                         timestamp: 1,
1737                         flags: 1,
1738                         cltv_expiry_delta: (7 << 8) | 2,
1739                         htlc_minimum_msat: 0,
1740                         htlc_maximum_msat: OptionalField::Absent,
1741                         fee_base_msat: 0,
1742                         fee_proportional_millionths: 0,
1743                         excess_data: Vec::new()
1744                 });
1745
1746                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1747
1748                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1749         }
1750
1751         #[test]
1752         fn simple_route_test() {
1753                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1754                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1755
1756                 // Simple route to 2 via 1
1757
1758                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger)) {
1759                         assert_eq!(err, "Cannot send a payment of 0 msat");
1760                 } else { panic!(); }
1761
1762                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1763                 assert_eq!(route.paths[0].len(), 2);
1764
1765                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1766                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1767                 assert_eq!(route.paths[0][0].fee_msat, 100);
1768                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1769                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1770                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1771
1772                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1773                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1774                 assert_eq!(route.paths[0][1].fee_msat, 100);
1775                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1776                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1777                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1778         }
1779
1780         #[test]
1781         fn invalid_first_hop_test() {
1782                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1783                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1784
1785                 // Simple route to 2 via 1
1786
1787                 let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
1788
1789                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
1790                         assert_eq!(err, "First hop cannot have our_node_pubkey as a destination.");
1791                 } else { panic!(); }
1792
1793                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1794                 assert_eq!(route.paths[0].len(), 2);
1795         }
1796
1797         #[test]
1798         fn htlc_minimum_test() {
1799                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1800                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1801
1802                 // Simple route to 2 via 1
1803
1804                 // Disable other paths
1805                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1806                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1807                         short_channel_id: 12,
1808                         timestamp: 2,
1809                         flags: 2, // to disable
1810                         cltv_expiry_delta: 0,
1811                         htlc_minimum_msat: 0,
1812                         htlc_maximum_msat: OptionalField::Absent,
1813                         fee_base_msat: 0,
1814                         fee_proportional_millionths: 0,
1815                         excess_data: Vec::new()
1816                 });
1817                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1818                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1819                         short_channel_id: 3,
1820                         timestamp: 2,
1821                         flags: 2, // to disable
1822                         cltv_expiry_delta: 0,
1823                         htlc_minimum_msat: 0,
1824                         htlc_maximum_msat: OptionalField::Absent,
1825                         fee_base_msat: 0,
1826                         fee_proportional_millionths: 0,
1827                         excess_data: Vec::new()
1828                 });
1829                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1830                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1831                         short_channel_id: 13,
1832                         timestamp: 2,
1833                         flags: 2, // to disable
1834                         cltv_expiry_delta: 0,
1835                         htlc_minimum_msat: 0,
1836                         htlc_maximum_msat: OptionalField::Absent,
1837                         fee_base_msat: 0,
1838                         fee_proportional_millionths: 0,
1839                         excess_data: Vec::new()
1840                 });
1841                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1842                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1843                         short_channel_id: 6,
1844                         timestamp: 2,
1845                         flags: 2, // to disable
1846                         cltv_expiry_delta: 0,
1847                         htlc_minimum_msat: 0,
1848                         htlc_maximum_msat: OptionalField::Absent,
1849                         fee_base_msat: 0,
1850                         fee_proportional_millionths: 0,
1851                         excess_data: Vec::new()
1852                 });
1853                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1854                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1855                         short_channel_id: 7,
1856                         timestamp: 2,
1857                         flags: 2, // to disable
1858                         cltv_expiry_delta: 0,
1859                         htlc_minimum_msat: 0,
1860                         htlc_maximum_msat: OptionalField::Absent,
1861                         fee_base_msat: 0,
1862                         fee_proportional_millionths: 0,
1863                         excess_data: Vec::new()
1864                 });
1865
1866                 // Check against amount_to_transfer_over_msat.
1867                 // Set minimal HTLC of 200_000_000 msat.
1868                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1869                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1870                         short_channel_id: 2,
1871                         timestamp: 3,
1872                         flags: 0,
1873                         cltv_expiry_delta: 0,
1874                         htlc_minimum_msat: 200_000_000,
1875                         htlc_maximum_msat: OptionalField::Absent,
1876                         fee_base_msat: 0,
1877                         fee_proportional_millionths: 0,
1878                         excess_data: Vec::new()
1879                 });
1880
1881                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1882                 // be used.
1883                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1884                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1885                         short_channel_id: 4,
1886                         timestamp: 3,
1887                         flags: 0,
1888                         cltv_expiry_delta: 0,
1889                         htlc_minimum_msat: 0,
1890                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1891                         fee_base_msat: 0,
1892                         fee_proportional_millionths: 0,
1893                         excess_data: Vec::new()
1894                 });
1895
1896                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1897                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)) {
1898                         assert_eq!(err, "Failed to find a path to the given destination");
1899                 } else { panic!(); }
1900
1901                 // Lift the restriction on the first hop.
1902                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1903                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1904                         short_channel_id: 2,
1905                         timestamp: 4,
1906                         flags: 0,
1907                         cltv_expiry_delta: 0,
1908                         htlc_minimum_msat: 0,
1909                         htlc_maximum_msat: OptionalField::Absent,
1910                         fee_base_msat: 0,
1911                         fee_proportional_millionths: 0,
1912                         excess_data: Vec::new()
1913                 });
1914
1915                 // A payment above the minimum should pass
1916                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)).unwrap();
1917                 assert_eq!(route.paths[0].len(), 2);
1918         }
1919
1920         #[test]
1921         fn htlc_minimum_overpay_test() {
1922                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1923                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1924
1925                 // A route to node#2 via two paths.
1926                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1927                 // Thus, they can't send 60 without overpaying.
1928                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1929                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1930                         short_channel_id: 2,
1931                         timestamp: 2,
1932                         flags: 0,
1933                         cltv_expiry_delta: 0,
1934                         htlc_minimum_msat: 35_000,
1935                         htlc_maximum_msat: OptionalField::Present(40_000),
1936                         fee_base_msat: 0,
1937                         fee_proportional_millionths: 0,
1938                         excess_data: Vec::new()
1939                 });
1940                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1941                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1942                         short_channel_id: 12,
1943                         timestamp: 3,
1944                         flags: 0,
1945                         cltv_expiry_delta: 0,
1946                         htlc_minimum_msat: 35_000,
1947                         htlc_maximum_msat: OptionalField::Present(40_000),
1948                         fee_base_msat: 0,
1949                         fee_proportional_millionths: 0,
1950                         excess_data: Vec::new()
1951                 });
1952
1953                 // Make 0 fee.
1954                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1955                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1956                         short_channel_id: 13,
1957                         timestamp: 2,
1958                         flags: 0,
1959                         cltv_expiry_delta: 0,
1960                         htlc_minimum_msat: 0,
1961                         htlc_maximum_msat: OptionalField::Absent,
1962                         fee_base_msat: 0,
1963                         fee_proportional_millionths: 0,
1964                         excess_data: Vec::new()
1965                 });
1966                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1967                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1968                         short_channel_id: 4,
1969                         timestamp: 2,
1970                         flags: 0,
1971                         cltv_expiry_delta: 0,
1972                         htlc_minimum_msat: 0,
1973                         htlc_maximum_msat: OptionalField::Absent,
1974                         fee_base_msat: 0,
1975                         fee_proportional_millionths: 0,
1976                         excess_data: Vec::new()
1977                 });
1978
1979                 // Disable other paths
1980                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1981                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1982                         short_channel_id: 1,
1983                         timestamp: 3,
1984                         flags: 2, // to disable
1985                         cltv_expiry_delta: 0,
1986                         htlc_minimum_msat: 0,
1987                         htlc_maximum_msat: OptionalField::Absent,
1988                         fee_base_msat: 0,
1989                         fee_proportional_millionths: 0,
1990                         excess_data: Vec::new()
1991                 });
1992
1993                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
1994                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1995                 // Overpay fees to hit htlc_minimum_msat.
1996                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1997                 // TODO: this could be better balanced to overpay 10k and not 15k.
1998                 assert_eq!(overpaid_fees, 15_000);
1999
2000                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
2001                 // while taking even more fee to match htlc_minimum_msat.
2002                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2003                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2004                         short_channel_id: 12,
2005                         timestamp: 4,
2006                         flags: 0,
2007                         cltv_expiry_delta: 0,
2008                         htlc_minimum_msat: 65_000,
2009                         htlc_maximum_msat: OptionalField::Present(80_000),
2010                         fee_base_msat: 0,
2011                         fee_proportional_millionths: 0,
2012                         excess_data: Vec::new()
2013                 });
2014                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2015                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2016                         short_channel_id: 2,
2017                         timestamp: 3,
2018                         flags: 0,
2019                         cltv_expiry_delta: 0,
2020                         htlc_minimum_msat: 0,
2021                         htlc_maximum_msat: OptionalField::Absent,
2022                         fee_base_msat: 0,
2023                         fee_proportional_millionths: 0,
2024                         excess_data: Vec::new()
2025                 });
2026                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2027                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2028                         short_channel_id: 4,
2029                         timestamp: 4,
2030                         flags: 0,
2031                         cltv_expiry_delta: 0,
2032                         htlc_minimum_msat: 0,
2033                         htlc_maximum_msat: OptionalField::Absent,
2034                         fee_base_msat: 0,
2035                         fee_proportional_millionths: 100_000,
2036                         excess_data: Vec::new()
2037                 });
2038
2039                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2040                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
2041                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
2042                 assert_eq!(route.paths.len(), 1);
2043                 assert_eq!(route.paths[0][0].short_channel_id, 12);
2044                 let fees = route.paths[0][0].fee_msat;
2045                 assert_eq!(fees, 5_000);
2046
2047                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2048                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2049                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
2050                 // the other channel.
2051                 assert_eq!(route.paths.len(), 1);
2052                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2053                 let fees = route.paths[0][0].fee_msat;
2054                 assert_eq!(fees, 5_000);
2055         }
2056
2057         #[test]
2058         fn disable_channels_test() {
2059                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2060                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2061
2062                 // // Disable channels 4 and 12 by flags=2
2063                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2064                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2065                         short_channel_id: 4,
2066                         timestamp: 2,
2067                         flags: 2, // to disable
2068                         cltv_expiry_delta: 0,
2069                         htlc_minimum_msat: 0,
2070                         htlc_maximum_msat: OptionalField::Absent,
2071                         fee_base_msat: 0,
2072                         fee_proportional_millionths: 0,
2073                         excess_data: Vec::new()
2074                 });
2075                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2076                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2077                         short_channel_id: 12,
2078                         timestamp: 2,
2079                         flags: 2, // to disable
2080                         cltv_expiry_delta: 0,
2081                         htlc_minimum_msat: 0,
2082                         htlc_maximum_msat: OptionalField::Absent,
2083                         fee_base_msat: 0,
2084                         fee_proportional_millionths: 0,
2085                         excess_data: Vec::new()
2086                 });
2087
2088                 // If all the channels require some features we don't understand, route should fail
2089                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
2090                         assert_eq!(err, "Failed to find a path to the given destination");
2091                 } else { panic!(); }
2092
2093                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2094                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2095                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2096                 assert_eq!(route.paths[0].len(), 2);
2097
2098                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2099                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2100                 assert_eq!(route.paths[0][0].fee_msat, 200);
2101                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2102                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2103                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2104
2105                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2106                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2107                 assert_eq!(route.paths[0][1].fee_msat, 100);
2108                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2109                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2110                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2111         }
2112
2113         #[test]
2114         fn disable_node_test() {
2115                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2116                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2117
2118                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
2119                 let unknown_features = NodeFeatures::known().set_unknown_feature_required();
2120                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
2121                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
2122                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
2123
2124                 // If all nodes require some features we don't understand, route should fail
2125                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
2126                         assert_eq!(err, "Failed to find a path to the given destination");
2127                 } else { panic!(); }
2128
2129                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2130                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2131                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2132                 assert_eq!(route.paths[0].len(), 2);
2133
2134                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2135                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2136                 assert_eq!(route.paths[0][0].fee_msat, 200);
2137                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2138                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2139                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2140
2141                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2142                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2143                 assert_eq!(route.paths[0][1].fee_msat, 100);
2144                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2145                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2146                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2147
2148                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2149                 // naively) assume that the user checked the feature bits on the invoice, which override
2150                 // the node_announcement.
2151         }
2152
2153         #[test]
2154         fn our_chans_test() {
2155                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2156                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2157
2158                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2159                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2160                 assert_eq!(route.paths[0].len(), 3);
2161
2162                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2163                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2164                 assert_eq!(route.paths[0][0].fee_msat, 200);
2165                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2166                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2167                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2168
2169                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2170                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2171                 assert_eq!(route.paths[0][1].fee_msat, 100);
2172                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2173                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2174                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2175
2176                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2177                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2178                 assert_eq!(route.paths[0][2].fee_msat, 100);
2179                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2180                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2181                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2182
2183                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2184                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2185                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2186                 assert_eq!(route.paths[0].len(), 2);
2187
2188                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2189                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2190                 assert_eq!(route.paths[0][0].fee_msat, 200);
2191                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2192                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2193                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2194
2195                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2196                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2197                 assert_eq!(route.paths[0][1].fee_msat, 100);
2198                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2199                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2200                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2201         }
2202
2203         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2204                 let zero_fees = RoutingFees {
2205                         base_msat: 0,
2206                         proportional_millionths: 0,
2207                 };
2208                 vec![RouteHint(vec![RouteHintHop {
2209                         src_node_id: nodes[3],
2210                         short_channel_id: 8,
2211                         fees: zero_fees,
2212                         cltv_expiry_delta: (8 << 8) | 1,
2213                         htlc_minimum_msat: None,
2214                         htlc_maximum_msat: None,
2215                 }
2216                 ]), RouteHint(vec![RouteHintHop {
2217                         src_node_id: nodes[4],
2218                         short_channel_id: 9,
2219                         fees: RoutingFees {
2220                                 base_msat: 1001,
2221                                 proportional_millionths: 0,
2222                         },
2223                         cltv_expiry_delta: (9 << 8) | 1,
2224                         htlc_minimum_msat: None,
2225                         htlc_maximum_msat: None,
2226                 }]), RouteHint(vec![RouteHintHop {
2227                         src_node_id: nodes[5],
2228                         short_channel_id: 10,
2229                         fees: zero_fees,
2230                         cltv_expiry_delta: (10 << 8) | 1,
2231                         htlc_minimum_msat: None,
2232                         htlc_maximum_msat: None,
2233                 }])]
2234         }
2235
2236         fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2237                 let zero_fees = RoutingFees {
2238                         base_msat: 0,
2239                         proportional_millionths: 0,
2240                 };
2241                 vec![RouteHint(vec![RouteHintHop {
2242                         src_node_id: nodes[2],
2243                         short_channel_id: 5,
2244                         fees: RoutingFees {
2245                                 base_msat: 100,
2246                                 proportional_millionths: 0,
2247                         },
2248                         cltv_expiry_delta: (5 << 8) | 1,
2249                         htlc_minimum_msat: None,
2250                         htlc_maximum_msat: None,
2251                 }, RouteHintHop {
2252                         src_node_id: nodes[3],
2253                         short_channel_id: 8,
2254                         fees: zero_fees,
2255                         cltv_expiry_delta: (8 << 8) | 1,
2256                         htlc_minimum_msat: None,
2257                         htlc_maximum_msat: None,
2258                 }
2259                 ]), RouteHint(vec![RouteHintHop {
2260                         src_node_id: nodes[4],
2261                         short_channel_id: 9,
2262                         fees: RoutingFees {
2263                                 base_msat: 1001,
2264                                 proportional_millionths: 0,
2265                         },
2266                         cltv_expiry_delta: (9 << 8) | 1,
2267                         htlc_minimum_msat: None,
2268                         htlc_maximum_msat: None,
2269                 }]), RouteHint(vec![RouteHintHop {
2270                         src_node_id: nodes[5],
2271                         short_channel_id: 10,
2272                         fees: zero_fees,
2273                         cltv_expiry_delta: (10 << 8) | 1,
2274                         htlc_minimum_msat: None,
2275                         htlc_maximum_msat: None,
2276                 }])]
2277         }
2278
2279         #[test]
2280         fn partial_route_hint_test() {
2281                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2282                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2283
2284                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2285                 // Tests the behaviour when the RouteHint contains a suboptimal hop.
2286                 // RouteHint may be partially used by the algo to build the best path.
2287
2288                 // First check that last hop can't have its source as the payee.
2289                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2290                         src_node_id: nodes[6],
2291                         short_channel_id: 8,
2292                         fees: RoutingFees {
2293                                 base_msat: 1000,
2294                                 proportional_millionths: 0,
2295                         },
2296                         cltv_expiry_delta: (8 << 8) | 1,
2297                         htlc_minimum_msat: None,
2298                         htlc_maximum_msat: None,
2299                 }]);
2300
2301                 let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
2302                 invalid_last_hops.push(invalid_last_hop);
2303                 {
2304                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)) {
2305                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2306                         } else { panic!(); }
2307                 }
2308
2309                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops_multi_private_channels(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2310                 assert_eq!(route.paths[0].len(), 5);
2311
2312                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2313                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2314                 assert_eq!(route.paths[0][0].fee_msat, 100);
2315                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2316                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2317                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2318
2319                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2320                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2321                 assert_eq!(route.paths[0][1].fee_msat, 0);
2322                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2323                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2324                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2325
2326                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2327                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2328                 assert_eq!(route.paths[0][2].fee_msat, 0);
2329                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2330                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2331                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2332
2333                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2334                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2335                 assert_eq!(route.paths[0][3].fee_msat, 0);
2336                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2337                 // If we have a peer in the node map, we'll use their features here since we don't have
2338                 // a way of figuring out their features from the invoice:
2339                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2340                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2341
2342                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2343                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2344                 assert_eq!(route.paths[0][4].fee_msat, 100);
2345                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2346                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2347                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2348         }
2349
2350         fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2351                 let zero_fees = RoutingFees {
2352                         base_msat: 0,
2353                         proportional_millionths: 0,
2354                 };
2355                 vec![RouteHint(vec![RouteHintHop {
2356                         src_node_id: nodes[3],
2357                         short_channel_id: 8,
2358                         fees: zero_fees,
2359                         cltv_expiry_delta: (8 << 8) | 1,
2360                         htlc_minimum_msat: None,
2361                         htlc_maximum_msat: None,
2362                 }]), RouteHint(vec![
2363
2364                 ]), RouteHint(vec![RouteHintHop {
2365                         src_node_id: nodes[5],
2366                         short_channel_id: 10,
2367                         fees: zero_fees,
2368                         cltv_expiry_delta: (10 << 8) | 1,
2369                         htlc_minimum_msat: None,
2370                         htlc_maximum_msat: None,
2371                 }])]
2372         }
2373
2374         #[test]
2375         fn ignores_empty_last_hops_test() {
2376                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2377                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2378
2379                 // Test handling of an empty RouteHint passed in Invoice.
2380
2381                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &empty_last_hop(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2382                 assert_eq!(route.paths[0].len(), 5);
2383
2384                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2385                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2386                 assert_eq!(route.paths[0][0].fee_msat, 100);
2387                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2388                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2389                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2390
2391                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2392                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2393                 assert_eq!(route.paths[0][1].fee_msat, 0);
2394                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2395                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2396                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2397
2398                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2399                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2400                 assert_eq!(route.paths[0][2].fee_msat, 0);
2401                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2402                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2403                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2404
2405                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2406                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2407                 assert_eq!(route.paths[0][3].fee_msat, 0);
2408                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2409                 // If we have a peer in the node map, we'll use their features here since we don't have
2410                 // a way of figuring out their features from the invoice:
2411                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2412                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2413
2414                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2415                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2416                 assert_eq!(route.paths[0][4].fee_msat, 100);
2417                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2418                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2419                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2420         }
2421
2422         fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2423                 let zero_fees = RoutingFees {
2424                         base_msat: 0,
2425                         proportional_millionths: 0,
2426                 };
2427                 vec![RouteHint(vec![RouteHintHop {
2428                         src_node_id: nodes[2],
2429                         short_channel_id: 5,
2430                         fees: RoutingFees {
2431                                 base_msat: 100,
2432                                 proportional_millionths: 0,
2433                         },
2434                         cltv_expiry_delta: (5 << 8) | 1,
2435                         htlc_minimum_msat: None,
2436                         htlc_maximum_msat: None,
2437                 }, RouteHintHop {
2438                         src_node_id: nodes[3],
2439                         short_channel_id: 8,
2440                         fees: zero_fees,
2441                         cltv_expiry_delta: (8 << 8) | 1,
2442                         htlc_minimum_msat: None,
2443                         htlc_maximum_msat: None,
2444                 }]), RouteHint(vec![RouteHintHop {
2445                         src_node_id: nodes[5],
2446                         short_channel_id: 10,
2447                         fees: zero_fees,
2448                         cltv_expiry_delta: (10 << 8) | 1,
2449                         htlc_minimum_msat: None,
2450                         htlc_maximum_msat: None,
2451                 }])]
2452         }
2453
2454         #[test]
2455         fn multi_hint_last_hops_test() {
2456                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2457                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2458                 // Test through channels 2, 3, 5, 8.
2459                 // Test shows that multiple hop hints are considered.
2460
2461                 // Disabling channels 6 & 7 by flags=2
2462                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2463                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2464                         short_channel_id: 6,
2465                         timestamp: 2,
2466                         flags: 2, // to disable
2467                         cltv_expiry_delta: 0,
2468                         htlc_minimum_msat: 0,
2469                         htlc_maximum_msat: OptionalField::Absent,
2470                         fee_base_msat: 0,
2471                         fee_proportional_millionths: 0,
2472                         excess_data: Vec::new()
2473                 });
2474                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2475                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2476                         short_channel_id: 7,
2477                         timestamp: 2,
2478                         flags: 2, // to disable
2479                         cltv_expiry_delta: 0,
2480                         htlc_minimum_msat: 0,
2481                         htlc_maximum_msat: OptionalField::Absent,
2482                         fee_base_msat: 0,
2483                         fee_proportional_millionths: 0,
2484                         excess_data: Vec::new()
2485                 });
2486
2487                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &multi_hint_last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2488                 assert_eq!(route.paths[0].len(), 4);
2489
2490                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2491                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2492                 assert_eq!(route.paths[0][0].fee_msat, 200);
2493                 assert_eq!(route.paths[0][0].cltv_expiry_delta, 1025);
2494                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2495                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2496
2497                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2498                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2499                 assert_eq!(route.paths[0][1].fee_msat, 100);
2500                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 1281);
2501                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2502                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2503
2504                 assert_eq!(route.paths[0][2].pubkey, nodes[3]);
2505                 assert_eq!(route.paths[0][2].short_channel_id, 5);
2506                 assert_eq!(route.paths[0][2].fee_msat, 0);
2507                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 2049);
2508                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
2509                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
2510
2511                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2512                 assert_eq!(route.paths[0][3].short_channel_id, 8);
2513                 assert_eq!(route.paths[0][3].fee_msat, 100);
2514                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2515                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2516                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2517         }
2518
2519         fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2520                 let zero_fees = RoutingFees {
2521                         base_msat: 0,
2522                         proportional_millionths: 0,
2523                 };
2524                 vec![RouteHint(vec![RouteHintHop {
2525                         src_node_id: nodes[4],
2526                         short_channel_id: 11,
2527                         fees: zero_fees,
2528                         cltv_expiry_delta: (11 << 8) | 1,
2529                         htlc_minimum_msat: None,
2530                         htlc_maximum_msat: None,
2531                 }, RouteHintHop {
2532                         src_node_id: nodes[3],
2533                         short_channel_id: 8,
2534                         fees: zero_fees,
2535                         cltv_expiry_delta: (8 << 8) | 1,
2536                         htlc_minimum_msat: None,
2537                         htlc_maximum_msat: None,
2538                 }]), RouteHint(vec![RouteHintHop {
2539                         src_node_id: nodes[4],
2540                         short_channel_id: 9,
2541                         fees: RoutingFees {
2542                                 base_msat: 1001,
2543                                 proportional_millionths: 0,
2544                         },
2545                         cltv_expiry_delta: (9 << 8) | 1,
2546                         htlc_minimum_msat: None,
2547                         htlc_maximum_msat: None,
2548                 }]), RouteHint(vec![RouteHintHop {
2549                         src_node_id: nodes[5],
2550                         short_channel_id: 10,
2551                         fees: zero_fees,
2552                         cltv_expiry_delta: (10 << 8) | 1,
2553                         htlc_minimum_msat: None,
2554                         htlc_maximum_msat: None,
2555                 }])]
2556         }
2557
2558         #[test]
2559         fn last_hops_with_public_channel_test() {
2560                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2561                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2562                 // This test shows that public routes can be present in the invoice
2563                 // which would be handled in the same manner.
2564
2565                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops_with_public_channel(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2566                 assert_eq!(route.paths[0].len(), 5);
2567
2568                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2569                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2570                 assert_eq!(route.paths[0][0].fee_msat, 100);
2571                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2572                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2573                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2574
2575                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2576                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2577                 assert_eq!(route.paths[0][1].fee_msat, 0);
2578                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2579                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2580                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2581
2582                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2583                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2584                 assert_eq!(route.paths[0][2].fee_msat, 0);
2585                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2586                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2587                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2588
2589                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2590                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2591                 assert_eq!(route.paths[0][3].fee_msat, 0);
2592                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2593                 // If we have a peer in the node map, we'll use their features here since we don't have
2594                 // a way of figuring out their features from the invoice:
2595                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2596                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new());
2597
2598                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2599                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2600                 assert_eq!(route.paths[0][4].fee_msat, 100);
2601                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2602                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2603                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2604         }
2605
2606         #[test]
2607         fn our_chans_last_hop_connect_test() {
2608                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2609                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2610
2611                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2612                 let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2613                 let mut last_hops = last_hops(&nodes);
2614                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2615                 assert_eq!(route.paths[0].len(), 2);
2616
2617                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2618                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2619                 assert_eq!(route.paths[0][0].fee_msat, 0);
2620                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2621                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2622                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2623
2624                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2625                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2626                 assert_eq!(route.paths[0][1].fee_msat, 100);
2627                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2628                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2629                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2630
2631                 last_hops[0].0[0].fees.base_msat = 1000;
2632
2633                 // Revert to via 6 as the fee on 8 goes up
2634                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2635                 assert_eq!(route.paths[0].len(), 4);
2636
2637                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2638                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2639                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2640                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2641                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2642                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2643
2644                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2645                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2646                 assert_eq!(route.paths[0][1].fee_msat, 100);
2647                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2648                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2649                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2650
2651                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2652                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2653                 assert_eq!(route.paths[0][2].fee_msat, 0);
2654                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2655                 // If we have a peer in the node map, we'll use their features here since we don't have
2656                 // a way of figuring out their features from the invoice:
2657                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2658                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2659
2660                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2661                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2662                 assert_eq!(route.paths[0][3].fee_msat, 100);
2663                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2664                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2665                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2666
2667                 // ...but still use 8 for larger payments as 6 has a variable feerate
2668                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger)).unwrap();
2669                 assert_eq!(route.paths[0].len(), 5);
2670
2671                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2672                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2673                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2674                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2675                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2676                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2677
2678                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2679                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2680                 assert_eq!(route.paths[0][1].fee_msat, 0);
2681                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2682                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2683                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2684
2685                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2686                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2687                 assert_eq!(route.paths[0][2].fee_msat, 0);
2688                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2689                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2690                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2691
2692                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2693                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2694                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2695                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2696                 // If we have a peer in the node map, we'll use their features here since we don't have
2697                 // a way of figuring out their features from the invoice:
2698                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2699                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2700
2701                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2702                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2703                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2704                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2705                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2706                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2707         }
2708
2709         fn do_unannounced_path_test(last_hop_htlc_max: Option<u64>, last_hop_fee_prop: u32, outbound_capacity_msat: u64, route_val: u64) -> Result<Route, LightningError> {
2710                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2711                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2712                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2713
2714                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2715                 let last_hops = RouteHint(vec![RouteHintHop {
2716                         src_node_id: middle_node_id,
2717                         short_channel_id: 8,
2718                         fees: RoutingFees {
2719                                 base_msat: 1000,
2720                                 proportional_millionths: last_hop_fee_prop,
2721                         },
2722                         cltv_expiry_delta: (8 << 8) | 1,
2723                         htlc_minimum_msat: None,
2724                         htlc_maximum_msat: last_hop_htlc_max,
2725                 }]);
2726                 let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
2727                 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], route_val, 42, Arc::new(test_utils::TestLogger::new()))
2728         }
2729
2730         #[test]
2731         fn unannounced_path_test() {
2732                 // We should be able to send a payment to a destination without any help of a routing graph
2733                 // if we have a channel with a common counterparty that appears in the first and last hop
2734                 // hints.
2735                 let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
2736
2737                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2738                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2739                 assert_eq!(route.paths[0].len(), 2);
2740
2741                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2742                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2743                 assert_eq!(route.paths[0][0].fee_msat, 1001);
2744                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2745                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2746                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2747
2748                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2749                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2750                 assert_eq!(route.paths[0][1].fee_msat, 1000000);
2751                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2752                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2753                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2754         }
2755
2756         #[test]
2757         fn overflow_unannounced_path_test_liquidity_underflow() {
2758                 // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
2759                 // the last-hop had a fee which overflowed a u64, we'd panic.
2760                 // This was due to us adding the first-hop from us unconditionally, causing us to think
2761                 // we'd built a path (as our node is in the "best candidate" set), when we had not.
2762                 // In this test, we previously hit a subtraction underflow due to having less available
2763                 // liquidity at the last hop than 0.
2764                 assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 0, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
2765         }
2766
2767         #[test]
2768         fn overflow_unannounced_path_test_feerate_overflow() {
2769                 // This tests for the same case as above, except instead of hitting a subtraction
2770                 // underflow, we hit a case where the fee charged at a hop overflowed.
2771                 assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 50000, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
2772         }
2773
2774         #[test]
2775         fn available_amount_while_routing_test() {
2776                 // Tests whether we choose the correct available channel amount while routing.
2777
2778                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2779                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2780
2781                 // We will use a simple single-path route from
2782                 // our node to node2 via node0: channels {1, 3}.
2783
2784                 // First disable all other paths.
2785                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2786                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2787                         short_channel_id: 2,
2788                         timestamp: 2,
2789                         flags: 2,
2790                         cltv_expiry_delta: 0,
2791                         htlc_minimum_msat: 0,
2792                         htlc_maximum_msat: OptionalField::Present(100_000),
2793                         fee_base_msat: 0,
2794                         fee_proportional_millionths: 0,
2795                         excess_data: Vec::new()
2796                 });
2797                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2798                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2799                         short_channel_id: 12,
2800                         timestamp: 2,
2801                         flags: 2,
2802                         cltv_expiry_delta: 0,
2803                         htlc_minimum_msat: 0,
2804                         htlc_maximum_msat: OptionalField::Present(100_000),
2805                         fee_base_msat: 0,
2806                         fee_proportional_millionths: 0,
2807                         excess_data: Vec::new()
2808                 });
2809
2810                 // Make the first channel (#1) very permissive,
2811                 // and we will be testing all limits on the second channel.
2812                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2813                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2814                         short_channel_id: 1,
2815                         timestamp: 2,
2816                         flags: 0,
2817                         cltv_expiry_delta: 0,
2818                         htlc_minimum_msat: 0,
2819                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2820                         fee_base_msat: 0,
2821                         fee_proportional_millionths: 0,
2822                         excess_data: Vec::new()
2823                 });
2824
2825                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2826                 // In this case, it should be set to 250_000 sats.
2827                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2828                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2829                         short_channel_id: 3,
2830                         timestamp: 2,
2831                         flags: 0,
2832                         cltv_expiry_delta: 0,
2833                         htlc_minimum_msat: 0,
2834                         htlc_maximum_msat: OptionalField::Absent,
2835                         fee_base_msat: 0,
2836                         fee_proportional_millionths: 0,
2837                         excess_data: Vec::new()
2838                 });
2839
2840                 {
2841                         // Attempt to route more than available results in a failure.
2842                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2843                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2844                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2845                         } else { panic!(); }
2846                 }
2847
2848                 {
2849                         // Now, attempt to route an exact amount we have should be fine.
2850                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2851                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2852                         assert_eq!(route.paths.len(), 1);
2853                         let path = route.paths.last().unwrap();
2854                         assert_eq!(path.len(), 2);
2855                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2856                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2857                 }
2858
2859                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2860                 // Disable channel #1 and use another first hop.
2861                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2862                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2863                         short_channel_id: 1,
2864                         timestamp: 3,
2865                         flags: 2,
2866                         cltv_expiry_delta: 0,
2867                         htlc_minimum_msat: 0,
2868                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2869                         fee_base_msat: 0,
2870                         fee_proportional_millionths: 0,
2871                         excess_data: Vec::new()
2872                 });
2873
2874                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2875                 let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
2876
2877                 {
2878                         // Attempt to route more than available results in a failure.
2879                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2880                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2881                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2882                         } else { panic!(); }
2883                 }
2884
2885                 {
2886                         // Now, attempt to route an exact amount we have should be fine.
2887                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2888                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2889                         assert_eq!(route.paths.len(), 1);
2890                         let path = route.paths.last().unwrap();
2891                         assert_eq!(path.len(), 2);
2892                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2893                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2894                 }
2895
2896                 // Enable channel #1 back.
2897                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2898                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2899                         short_channel_id: 1,
2900                         timestamp: 4,
2901                         flags: 0,
2902                         cltv_expiry_delta: 0,
2903                         htlc_minimum_msat: 0,
2904                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2905                         fee_base_msat: 0,
2906                         fee_proportional_millionths: 0,
2907                         excess_data: Vec::new()
2908                 });
2909
2910
2911                 // Now let's see if routing works if we know only htlc_maximum_msat.
2912                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2913                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2914                         short_channel_id: 3,
2915                         timestamp: 3,
2916                         flags: 0,
2917                         cltv_expiry_delta: 0,
2918                         htlc_minimum_msat: 0,
2919                         htlc_maximum_msat: OptionalField::Present(15_000),
2920                         fee_base_msat: 0,
2921                         fee_proportional_millionths: 0,
2922                         excess_data: Vec::new()
2923                 });
2924
2925                 {
2926                         // Attempt to route more than available results in a failure.
2927                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2928                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2929                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2930                         } else { panic!(); }
2931                 }
2932
2933                 {
2934                         // Now, attempt to route an exact amount we have should be fine.
2935                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2936                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2937                         assert_eq!(route.paths.len(), 1);
2938                         let path = route.paths.last().unwrap();
2939                         assert_eq!(path.len(), 2);
2940                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2941                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2942                 }
2943
2944                 // Now let's see if routing works if we know only capacity from the UTXO.
2945
2946                 // We can't change UTXO capacity on the fly, so we'll disable
2947                 // the existing channel and add another one with the capacity we need.
2948                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2949                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2950                         short_channel_id: 3,
2951                         timestamp: 4,
2952                         flags: 2,
2953                         cltv_expiry_delta: 0,
2954                         htlc_minimum_msat: 0,
2955                         htlc_maximum_msat: OptionalField::Absent,
2956                         fee_base_msat: 0,
2957                         fee_proportional_millionths: 0,
2958                         excess_data: Vec::new()
2959                 });
2960
2961                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2962                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2963                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2964                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2965                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2966
2967                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2968                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2969
2970                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2971                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2972                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2973                         short_channel_id: 333,
2974                         timestamp: 1,
2975                         flags: 0,
2976                         cltv_expiry_delta: (3 << 8) | 1,
2977                         htlc_minimum_msat: 0,
2978                         htlc_maximum_msat: OptionalField::Absent,
2979                         fee_base_msat: 0,
2980                         fee_proportional_millionths: 0,
2981                         excess_data: Vec::new()
2982                 });
2983                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2984                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2985                         short_channel_id: 333,
2986                         timestamp: 1,
2987                         flags: 1,
2988                         cltv_expiry_delta: (3 << 8) | 2,
2989                         htlc_minimum_msat: 0,
2990                         htlc_maximum_msat: OptionalField::Absent,
2991                         fee_base_msat: 100,
2992                         fee_proportional_millionths: 0,
2993                         excess_data: Vec::new()
2994                 });
2995
2996                 {
2997                         // Attempt to route more than available results in a failure.
2998                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2999                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
3000                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3001                         } else { panic!(); }
3002                 }
3003
3004                 {
3005                         // Now, attempt to route an exact amount we have should be fine.
3006                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3007                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
3008                         assert_eq!(route.paths.len(), 1);
3009                         let path = route.paths.last().unwrap();
3010                         assert_eq!(path.len(), 2);
3011                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3012                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3013                 }
3014
3015                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
3016                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3017                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3018                         short_channel_id: 333,
3019                         timestamp: 6,
3020                         flags: 0,
3021                         cltv_expiry_delta: 0,
3022                         htlc_minimum_msat: 0,
3023                         htlc_maximum_msat: OptionalField::Present(10_000),
3024                         fee_base_msat: 0,
3025                         fee_proportional_millionths: 0,
3026                         excess_data: Vec::new()
3027                 });
3028
3029                 {
3030                         // Attempt to route more than available results in a failure.
3031                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3032                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
3033                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3034                         } else { panic!(); }
3035                 }
3036
3037                 {
3038                         // Now, attempt to route an exact amount we have should be fine.
3039                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3040                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
3041                         assert_eq!(route.paths.len(), 1);
3042                         let path = route.paths.last().unwrap();
3043                         assert_eq!(path.len(), 2);
3044                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3045                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
3046                 }
3047         }
3048
3049         #[test]
3050         fn available_liquidity_last_hop_test() {
3051                 // Check that available liquidity properly limits the path even when only
3052                 // one of the latter hops is limited.
3053                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3054                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3055
3056                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3057                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
3058                 // Total capacity: 50 sats.
3059
3060                 // Disable other potential paths.
3061                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3062                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3063                         short_channel_id: 2,
3064                         timestamp: 2,
3065                         flags: 2,
3066                         cltv_expiry_delta: 0,
3067                         htlc_minimum_msat: 0,
3068                         htlc_maximum_msat: OptionalField::Present(100_000),
3069                         fee_base_msat: 0,
3070                         fee_proportional_millionths: 0,
3071                         excess_data: Vec::new()
3072                 });
3073                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3074                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3075                         short_channel_id: 7,
3076                         timestamp: 2,
3077                         flags: 2,
3078                         cltv_expiry_delta: 0,
3079                         htlc_minimum_msat: 0,
3080                         htlc_maximum_msat: OptionalField::Present(100_000),
3081                         fee_base_msat: 0,
3082                         fee_proportional_millionths: 0,
3083                         excess_data: Vec::new()
3084                 });
3085
3086                 // Limit capacities
3087
3088                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3089                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3090                         short_channel_id: 12,
3091                         timestamp: 2,
3092                         flags: 0,
3093                         cltv_expiry_delta: 0,
3094                         htlc_minimum_msat: 0,
3095                         htlc_maximum_msat: OptionalField::Present(100_000),
3096                         fee_base_msat: 0,
3097                         fee_proportional_millionths: 0,
3098                         excess_data: Vec::new()
3099                 });
3100                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3101                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3102                         short_channel_id: 13,
3103                         timestamp: 2,
3104                         flags: 0,
3105                         cltv_expiry_delta: 0,
3106                         htlc_minimum_msat: 0,
3107                         htlc_maximum_msat: OptionalField::Present(100_000),
3108                         fee_base_msat: 0,
3109                         fee_proportional_millionths: 0,
3110                         excess_data: Vec::new()
3111                 });
3112
3113                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3114                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3115                         short_channel_id: 6,
3116                         timestamp: 2,
3117                         flags: 0,
3118                         cltv_expiry_delta: 0,
3119                         htlc_minimum_msat: 0,
3120                         htlc_maximum_msat: OptionalField::Present(50_000),
3121                         fee_base_msat: 0,
3122                         fee_proportional_millionths: 0,
3123                         excess_data: Vec::new()
3124                 });
3125                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3126                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3127                         short_channel_id: 11,
3128                         timestamp: 2,
3129                         flags: 0,
3130                         cltv_expiry_delta: 0,
3131                         htlc_minimum_msat: 0,
3132                         htlc_maximum_msat: OptionalField::Present(100_000),
3133                         fee_base_msat: 0,
3134                         fee_proportional_millionths: 0,
3135                         excess_data: Vec::new()
3136                 });
3137                 {
3138                         // Attempt to route more than available results in a failure.
3139                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3140                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
3141                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3142                         } else { panic!(); }
3143                 }
3144
3145                 {
3146                         // Now, attempt to route 49 sats (just a bit below the capacity).
3147                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3148                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
3149                         assert_eq!(route.paths.len(), 1);
3150                         let mut total_amount_paid_msat = 0;
3151                         for path in &route.paths {
3152                                 assert_eq!(path.len(), 4);
3153                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3154                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3155                         }
3156                         assert_eq!(total_amount_paid_msat, 49_000);
3157                 }
3158
3159                 {
3160                         // Attempt to route an exact amount is also fine
3161                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3162                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
3163                         assert_eq!(route.paths.len(), 1);
3164                         let mut total_amount_paid_msat = 0;
3165                         for path in &route.paths {
3166                                 assert_eq!(path.len(), 4);
3167                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3168                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3169                         }
3170                         assert_eq!(total_amount_paid_msat, 50_000);
3171                 }
3172         }
3173
3174         #[test]
3175         fn ignore_fee_first_hop_test() {
3176                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3177                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3178
3179                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3180                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3181                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3182                         short_channel_id: 1,
3183                         timestamp: 2,
3184                         flags: 0,
3185                         cltv_expiry_delta: 0,
3186                         htlc_minimum_msat: 0,
3187                         htlc_maximum_msat: OptionalField::Present(100_000),
3188                         fee_base_msat: 1_000_000,
3189                         fee_proportional_millionths: 0,
3190                         excess_data: Vec::new()
3191                 });
3192                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3193                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3194                         short_channel_id: 3,
3195                         timestamp: 2,
3196                         flags: 0,
3197                         cltv_expiry_delta: 0,
3198                         htlc_minimum_msat: 0,
3199                         htlc_maximum_msat: OptionalField::Present(50_000),
3200                         fee_base_msat: 0,
3201                         fee_proportional_millionths: 0,
3202                         excess_data: Vec::new()
3203                 });
3204
3205                 {
3206                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
3207                         assert_eq!(route.paths.len(), 1);
3208                         let mut total_amount_paid_msat = 0;
3209                         for path in &route.paths {
3210                                 assert_eq!(path.len(), 2);
3211                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3212                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3213                         }
3214                         assert_eq!(total_amount_paid_msat, 50_000);
3215                 }
3216         }
3217
3218         #[test]
3219         fn simple_mpp_route_test() {
3220                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3221                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3222
3223                 // We need a route consisting of 3 paths:
3224                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3225                 // To achieve this, the amount being transferred should be around
3226                 // the total capacity of these 3 paths.
3227
3228                 // First, we set limits on these (previously unlimited) channels.
3229                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
3230
3231                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3232                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3233                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3234                         short_channel_id: 1,
3235                         timestamp: 2,
3236                         flags: 0,
3237                         cltv_expiry_delta: 0,
3238                         htlc_minimum_msat: 0,
3239                         htlc_maximum_msat: OptionalField::Present(100_000),
3240                         fee_base_msat: 0,
3241                         fee_proportional_millionths: 0,
3242                         excess_data: Vec::new()
3243                 });
3244                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3245                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3246                         short_channel_id: 3,
3247                         timestamp: 2,
3248                         flags: 0,
3249                         cltv_expiry_delta: 0,
3250                         htlc_minimum_msat: 0,
3251                         htlc_maximum_msat: OptionalField::Present(50_000),
3252                         fee_base_msat: 0,
3253                         fee_proportional_millionths: 0,
3254                         excess_data: Vec::new()
3255                 });
3256
3257                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
3258                 // (total limit 60).
3259                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3260                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3261                         short_channel_id: 12,
3262                         timestamp: 2,
3263                         flags: 0,
3264                         cltv_expiry_delta: 0,
3265                         htlc_minimum_msat: 0,
3266                         htlc_maximum_msat: OptionalField::Present(60_000),
3267                         fee_base_msat: 0,
3268                         fee_proportional_millionths: 0,
3269                         excess_data: Vec::new()
3270                 });
3271                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3272                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3273                         short_channel_id: 13,
3274                         timestamp: 2,
3275                         flags: 0,
3276                         cltv_expiry_delta: 0,
3277                         htlc_minimum_msat: 0,
3278                         htlc_maximum_msat: OptionalField::Present(60_000),
3279                         fee_base_msat: 0,
3280                         fee_proportional_millionths: 0,
3281                         excess_data: Vec::new()
3282                 });
3283
3284                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
3285                 // (total capacity 180 sats).
3286                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3287                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3288                         short_channel_id: 2,
3289                         timestamp: 2,
3290                         flags: 0,
3291                         cltv_expiry_delta: 0,
3292                         htlc_minimum_msat: 0,
3293                         htlc_maximum_msat: OptionalField::Present(200_000),
3294                         fee_base_msat: 0,
3295                         fee_proportional_millionths: 0,
3296                         excess_data: Vec::new()
3297                 });
3298                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3299                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3300                         short_channel_id: 4,
3301                         timestamp: 2,
3302                         flags: 0,
3303                         cltv_expiry_delta: 0,
3304                         htlc_minimum_msat: 0,
3305                         htlc_maximum_msat: OptionalField::Present(180_000),
3306                         fee_base_msat: 0,
3307                         fee_proportional_millionths: 0,
3308                         excess_data: Vec::new()
3309                 });
3310
3311                 {
3312                         // Attempt to route more than available results in a failure.
3313                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph,
3314                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
3315                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3316                         } else { panic!(); }
3317                 }
3318
3319                 {
3320                         // Now, attempt to route 250 sats (just a bit below the capacity).
3321                         // Our algorithm should provide us with these 3 paths.
3322                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3323                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
3324                         assert_eq!(route.paths.len(), 3);
3325                         let mut total_amount_paid_msat = 0;
3326                         for path in &route.paths {
3327                                 assert_eq!(path.len(), 2);
3328                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3329                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3330                         }
3331                         assert_eq!(total_amount_paid_msat, 250_000);
3332                 }
3333
3334                 {
3335                         // Attempt to route an exact amount is also fine
3336                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3337                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
3338                         assert_eq!(route.paths.len(), 3);
3339                         let mut total_amount_paid_msat = 0;
3340                         for path in &route.paths {
3341                                 assert_eq!(path.len(), 2);
3342                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3343                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3344                         }
3345                         assert_eq!(total_amount_paid_msat, 290_000);
3346                 }
3347         }
3348
3349         #[test]
3350         fn long_mpp_route_test() {
3351                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3352                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3353
3354                 // We need a route consisting of 3 paths:
3355                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3356                 // Note that these paths overlap (channels 5, 12, 13).
3357                 // We will route 300 sats.
3358                 // Each path will have 100 sats capacity, those channels which
3359                 // are used twice will have 200 sats capacity.
3360
3361                 // Disable other potential paths.
3362                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3363                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3364                         short_channel_id: 2,
3365                         timestamp: 2,
3366                         flags: 2,
3367                         cltv_expiry_delta: 0,
3368                         htlc_minimum_msat: 0,
3369                         htlc_maximum_msat: OptionalField::Present(100_000),
3370                         fee_base_msat: 0,
3371                         fee_proportional_millionths: 0,
3372                         excess_data: Vec::new()
3373                 });
3374                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3375                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3376                         short_channel_id: 7,
3377                         timestamp: 2,
3378                         flags: 2,
3379                         cltv_expiry_delta: 0,
3380                         htlc_minimum_msat: 0,
3381                         htlc_maximum_msat: OptionalField::Present(100_000),
3382                         fee_base_msat: 0,
3383                         fee_proportional_millionths: 0,
3384                         excess_data: Vec::new()
3385                 });
3386
3387                 // Path via {node0, node2} is channels {1, 3, 5}.
3388                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3389                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3390                         short_channel_id: 1,
3391                         timestamp: 2,
3392                         flags: 0,
3393                         cltv_expiry_delta: 0,
3394                         htlc_minimum_msat: 0,
3395                         htlc_maximum_msat: OptionalField::Present(100_000),
3396                         fee_base_msat: 0,
3397                         fee_proportional_millionths: 0,
3398                         excess_data: Vec::new()
3399                 });
3400                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3401                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3402                         short_channel_id: 3,
3403                         timestamp: 2,
3404                         flags: 0,
3405                         cltv_expiry_delta: 0,
3406                         htlc_minimum_msat: 0,
3407                         htlc_maximum_msat: OptionalField::Present(100_000),
3408                         fee_base_msat: 0,
3409                         fee_proportional_millionths: 0,
3410                         excess_data: Vec::new()
3411                 });
3412
3413                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3414                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3415                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3416                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3417                         short_channel_id: 5,
3418                         timestamp: 2,
3419                         flags: 0,
3420                         cltv_expiry_delta: 0,
3421                         htlc_minimum_msat: 0,
3422                         htlc_maximum_msat: OptionalField::Present(200_000),
3423                         fee_base_msat: 0,
3424                         fee_proportional_millionths: 0,
3425                         excess_data: Vec::new()
3426                 });
3427
3428                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3429                 // Add 100 sats to the capacities of {12, 13}, because these channels
3430                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3431                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3432                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3433                         short_channel_id: 12,
3434                         timestamp: 2,
3435                         flags: 0,
3436                         cltv_expiry_delta: 0,
3437                         htlc_minimum_msat: 0,
3438                         htlc_maximum_msat: OptionalField::Present(200_000),
3439                         fee_base_msat: 0,
3440                         fee_proportional_millionths: 0,
3441                         excess_data: Vec::new()
3442                 });
3443                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3444                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3445                         short_channel_id: 13,
3446                         timestamp: 2,
3447                         flags: 0,
3448                         cltv_expiry_delta: 0,
3449                         htlc_minimum_msat: 0,
3450                         htlc_maximum_msat: OptionalField::Present(200_000),
3451                         fee_base_msat: 0,
3452                         fee_proportional_millionths: 0,
3453                         excess_data: Vec::new()
3454                 });
3455
3456                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3457                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3458                         short_channel_id: 6,
3459                         timestamp: 2,
3460                         flags: 0,
3461                         cltv_expiry_delta: 0,
3462                         htlc_minimum_msat: 0,
3463                         htlc_maximum_msat: OptionalField::Present(100_000),
3464                         fee_base_msat: 0,
3465                         fee_proportional_millionths: 0,
3466                         excess_data: Vec::new()
3467                 });
3468                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3469                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3470                         short_channel_id: 11,
3471                         timestamp: 2,
3472                         flags: 0,
3473                         cltv_expiry_delta: 0,
3474                         htlc_minimum_msat: 0,
3475                         htlc_maximum_msat: OptionalField::Present(100_000),
3476                         fee_base_msat: 0,
3477                         fee_proportional_millionths: 0,
3478                         excess_data: Vec::new()
3479                 });
3480
3481                 // Path via {node7, node2} is channels {12, 13, 5}.
3482                 // We already limited them to 200 sats (they are used twice for 100 sats).
3483                 // Nothing to do here.
3484
3485                 {
3486                         // Attempt to route more than available results in a failure.
3487                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3488                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3489                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3490                         } else { panic!(); }
3491                 }
3492
3493                 {
3494                         // Now, attempt to route 300 sats (exact amount we can route).
3495                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3496                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3497                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3498                         assert_eq!(route.paths.len(), 3);
3499
3500                         let mut total_amount_paid_msat = 0;
3501                         for path in &route.paths {
3502                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3503                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3504                         }
3505                         assert_eq!(total_amount_paid_msat, 300_000);
3506                 }
3507
3508         }
3509
3510         #[test]
3511         fn mpp_cheaper_route_test() {
3512                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3513                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3514
3515                 // This test checks that if we have two cheaper paths and one more expensive path,
3516                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3517                 // two cheaper paths will be taken.
3518                 // These paths have equal available liquidity.
3519
3520                 // We need a combination of 3 paths:
3521                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3522                 // Note that these paths overlap (channels 5, 12, 13).
3523                 // Each path will have 100 sats capacity, those channels which
3524                 // are used twice will have 200 sats capacity.
3525
3526                 // Disable other potential paths.
3527                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3528                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3529                         short_channel_id: 2,
3530                         timestamp: 2,
3531                         flags: 2,
3532                         cltv_expiry_delta: 0,
3533                         htlc_minimum_msat: 0,
3534                         htlc_maximum_msat: OptionalField::Present(100_000),
3535                         fee_base_msat: 0,
3536                         fee_proportional_millionths: 0,
3537                         excess_data: Vec::new()
3538                 });
3539                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3540                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3541                         short_channel_id: 7,
3542                         timestamp: 2,
3543                         flags: 2,
3544                         cltv_expiry_delta: 0,
3545                         htlc_minimum_msat: 0,
3546                         htlc_maximum_msat: OptionalField::Present(100_000),
3547                         fee_base_msat: 0,
3548                         fee_proportional_millionths: 0,
3549                         excess_data: Vec::new()
3550                 });
3551
3552                 // Path via {node0, node2} is channels {1, 3, 5}.
3553                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3554                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3555                         short_channel_id: 1,
3556                         timestamp: 2,
3557                         flags: 0,
3558                         cltv_expiry_delta: 0,
3559                         htlc_minimum_msat: 0,
3560                         htlc_maximum_msat: OptionalField::Present(100_000),
3561                         fee_base_msat: 0,
3562                         fee_proportional_millionths: 0,
3563                         excess_data: Vec::new()
3564                 });
3565                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3566                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3567                         short_channel_id: 3,
3568                         timestamp: 2,
3569                         flags: 0,
3570                         cltv_expiry_delta: 0,
3571                         htlc_minimum_msat: 0,
3572                         htlc_maximum_msat: OptionalField::Present(100_000),
3573                         fee_base_msat: 0,
3574                         fee_proportional_millionths: 0,
3575                         excess_data: Vec::new()
3576                 });
3577
3578                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3579                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3580                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3581                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3582                         short_channel_id: 5,
3583                         timestamp: 2,
3584                         flags: 0,
3585                         cltv_expiry_delta: 0,
3586                         htlc_minimum_msat: 0,
3587                         htlc_maximum_msat: OptionalField::Present(200_000),
3588                         fee_base_msat: 0,
3589                         fee_proportional_millionths: 0,
3590                         excess_data: Vec::new()
3591                 });
3592
3593                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3594                 // Add 100 sats to the capacities of {12, 13}, because these channels
3595                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3596                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3597                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3598                         short_channel_id: 12,
3599                         timestamp: 2,
3600                         flags: 0,
3601                         cltv_expiry_delta: 0,
3602                         htlc_minimum_msat: 0,
3603                         htlc_maximum_msat: OptionalField::Present(200_000),
3604                         fee_base_msat: 0,
3605                         fee_proportional_millionths: 0,
3606                         excess_data: Vec::new()
3607                 });
3608                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3609                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3610                         short_channel_id: 13,
3611                         timestamp: 2,
3612                         flags: 0,
3613                         cltv_expiry_delta: 0,
3614                         htlc_minimum_msat: 0,
3615                         htlc_maximum_msat: OptionalField::Present(200_000),
3616                         fee_base_msat: 0,
3617                         fee_proportional_millionths: 0,
3618                         excess_data: Vec::new()
3619                 });
3620
3621                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3622                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3623                         short_channel_id: 6,
3624                         timestamp: 2,
3625                         flags: 0,
3626                         cltv_expiry_delta: 0,
3627                         htlc_minimum_msat: 0,
3628                         htlc_maximum_msat: OptionalField::Present(100_000),
3629                         fee_base_msat: 1_000,
3630                         fee_proportional_millionths: 0,
3631                         excess_data: Vec::new()
3632                 });
3633                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3634                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3635                         short_channel_id: 11,
3636                         timestamp: 2,
3637                         flags: 0,
3638                         cltv_expiry_delta: 0,
3639                         htlc_minimum_msat: 0,
3640                         htlc_maximum_msat: OptionalField::Present(100_000),
3641                         fee_base_msat: 0,
3642                         fee_proportional_millionths: 0,
3643                         excess_data: Vec::new()
3644                 });
3645
3646                 // Path via {node7, node2} is channels {12, 13, 5}.
3647                 // We already limited them to 200 sats (they are used twice for 100 sats).
3648                 // Nothing to do here.
3649
3650                 {
3651                         // Now, attempt to route 180 sats.
3652                         // Our algorithm should provide us with these 2 paths.
3653                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3654                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3655                         assert_eq!(route.paths.len(), 2);
3656
3657                         let mut total_value_transferred_msat = 0;
3658                         let mut total_paid_msat = 0;
3659                         for path in &route.paths {
3660                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3661                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3662                                 for hop in path {
3663                                         total_paid_msat += hop.fee_msat;
3664                                 }
3665                         }
3666                         // If we paid fee, this would be higher.
3667                         assert_eq!(total_value_transferred_msat, 180_000);
3668                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3669                         assert_eq!(total_fees_paid, 0);
3670                 }
3671         }
3672
3673         #[test]
3674         fn fees_on_mpp_route_test() {
3675                 // This test makes sure that MPP algorithm properly takes into account
3676                 // fees charged on the channels, by making the fees impactful:
3677                 // if the fee is not properly accounted for, the behavior is different.
3678                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3679                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3680
3681                 // We need a route consisting of 2 paths:
3682                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3683                 // We will route 200 sats, Each path will have 100 sats capacity.
3684
3685                 // This test is not particularly stable: e.g.,
3686                 // there's a way to route via {node0, node2, node4}.
3687                 // It works while pathfinding is deterministic, but can be broken otherwise.
3688                 // It's fine to ignore this concern for now.
3689
3690                 // Disable other potential paths.
3691                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3693                         short_channel_id: 2,
3694                         timestamp: 2,
3695                         flags: 2,
3696                         cltv_expiry_delta: 0,
3697                         htlc_minimum_msat: 0,
3698                         htlc_maximum_msat: OptionalField::Present(100_000),
3699                         fee_base_msat: 0,
3700                         fee_proportional_millionths: 0,
3701                         excess_data: Vec::new()
3702                 });
3703
3704                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3705                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3706                         short_channel_id: 7,
3707                         timestamp: 2,
3708                         flags: 2,
3709                         cltv_expiry_delta: 0,
3710                         htlc_minimum_msat: 0,
3711                         htlc_maximum_msat: OptionalField::Present(100_000),
3712                         fee_base_msat: 0,
3713                         fee_proportional_millionths: 0,
3714                         excess_data: Vec::new()
3715                 });
3716
3717                 // Path via {node0, node2} is channels {1, 3, 5}.
3718                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3719                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3720                         short_channel_id: 1,
3721                         timestamp: 2,
3722                         flags: 0,
3723                         cltv_expiry_delta: 0,
3724                         htlc_minimum_msat: 0,
3725                         htlc_maximum_msat: OptionalField::Present(100_000),
3726                         fee_base_msat: 0,
3727                         fee_proportional_millionths: 0,
3728                         excess_data: Vec::new()
3729                 });
3730                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3731                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3732                         short_channel_id: 3,
3733                         timestamp: 2,
3734                         flags: 0,
3735                         cltv_expiry_delta: 0,
3736                         htlc_minimum_msat: 0,
3737                         htlc_maximum_msat: OptionalField::Present(100_000),
3738                         fee_base_msat: 0,
3739                         fee_proportional_millionths: 0,
3740                         excess_data: Vec::new()
3741                 });
3742
3743                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3744                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3745                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3746                         short_channel_id: 5,
3747                         timestamp: 2,
3748                         flags: 0,
3749                         cltv_expiry_delta: 0,
3750                         htlc_minimum_msat: 0,
3751                         htlc_maximum_msat: OptionalField::Present(100_000),
3752                         fee_base_msat: 0,
3753                         fee_proportional_millionths: 0,
3754                         excess_data: Vec::new()
3755                 });
3756
3757                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3758                 // All channels should be 100 sats capacity. But for the fee experiment,
3759                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3760                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3761                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3762                 // so no matter how large are other channels,
3763                 // the whole path will be limited by 100 sats with just these 2 conditions:
3764                 // - channel 12 capacity is 250 sats
3765                 // - fee for channel 6 is 150 sats
3766                 // Let's test this by enforcing these 2 conditions and removing other limits.
3767                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3768                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3769                         short_channel_id: 12,
3770                         timestamp: 2,
3771                         flags: 0,
3772                         cltv_expiry_delta: 0,
3773                         htlc_minimum_msat: 0,
3774                         htlc_maximum_msat: OptionalField::Present(250_000),
3775                         fee_base_msat: 0,
3776                         fee_proportional_millionths: 0,
3777                         excess_data: Vec::new()
3778                 });
3779                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3780                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3781                         short_channel_id: 13,
3782                         timestamp: 2,
3783                         flags: 0,
3784                         cltv_expiry_delta: 0,
3785                         htlc_minimum_msat: 0,
3786                         htlc_maximum_msat: OptionalField::Absent,
3787                         fee_base_msat: 0,
3788                         fee_proportional_millionths: 0,
3789                         excess_data: Vec::new()
3790                 });
3791
3792                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3793                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3794                         short_channel_id: 6,
3795                         timestamp: 2,
3796                         flags: 0,
3797                         cltv_expiry_delta: 0,
3798                         htlc_minimum_msat: 0,
3799                         htlc_maximum_msat: OptionalField::Absent,
3800                         fee_base_msat: 150_000,
3801                         fee_proportional_millionths: 0,
3802                         excess_data: Vec::new()
3803                 });
3804                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3805                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3806                         short_channel_id: 11,
3807                         timestamp: 2,
3808                         flags: 0,
3809                         cltv_expiry_delta: 0,
3810                         htlc_minimum_msat: 0,
3811                         htlc_maximum_msat: OptionalField::Absent,
3812                         fee_base_msat: 0,
3813                         fee_proportional_millionths: 0,
3814                         excess_data: Vec::new()
3815                 });
3816
3817                 {
3818                         // Attempt to route more than available results in a failure.
3819                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3820                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3821                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3822                         } else { panic!(); }
3823                 }
3824
3825                 {
3826                         // Now, attempt to route 200 sats (exact amount we can route).
3827                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3828                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3829                         assert_eq!(route.paths.len(), 2);
3830
3831                         let mut total_amount_paid_msat = 0;
3832                         for path in &route.paths {
3833                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3834                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3835                         }
3836                         assert_eq!(total_amount_paid_msat, 200_000);
3837                         assert_eq!(route.get_total_fees(), 150_000);
3838                 }
3839
3840         }
3841
3842         #[test]
3843         fn drop_lowest_channel_mpp_route_test() {
3844                 // This test checks that low-capacity channel is dropped when after
3845                 // path finding we realize that we found more capacity than we need.
3846                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3847                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3848
3849                 // We need a route consisting of 3 paths:
3850                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3851
3852                 // The first and the second paths should be sufficient, but the third should be
3853                 // cheaper, so that we select it but drop later.
3854
3855                 // First, we set limits on these (previously unlimited) channels.
3856                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3857
3858                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3859                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3860                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3861                         short_channel_id: 1,
3862                         timestamp: 2,
3863                         flags: 0,
3864                         cltv_expiry_delta: 0,
3865                         htlc_minimum_msat: 0,
3866                         htlc_maximum_msat: OptionalField::Present(100_000),
3867                         fee_base_msat: 0,
3868                         fee_proportional_millionths: 0,
3869                         excess_data: Vec::new()
3870                 });
3871                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3872                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3873                         short_channel_id: 3,
3874                         timestamp: 2,
3875                         flags: 0,
3876                         cltv_expiry_delta: 0,
3877                         htlc_minimum_msat: 0,
3878                         htlc_maximum_msat: OptionalField::Present(50_000),
3879                         fee_base_msat: 100,
3880                         fee_proportional_millionths: 0,
3881                         excess_data: Vec::new()
3882                 });
3883
3884                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3885                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3886                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3887                         short_channel_id: 12,
3888                         timestamp: 2,
3889                         flags: 0,
3890                         cltv_expiry_delta: 0,
3891                         htlc_minimum_msat: 0,
3892                         htlc_maximum_msat: OptionalField::Present(60_000),
3893                         fee_base_msat: 100,
3894                         fee_proportional_millionths: 0,
3895                         excess_data: Vec::new()
3896                 });
3897                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3898                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3899                         short_channel_id: 13,
3900                         timestamp: 2,
3901                         flags: 0,
3902                         cltv_expiry_delta: 0,
3903                         htlc_minimum_msat: 0,
3904                         htlc_maximum_msat: OptionalField::Present(60_000),
3905                         fee_base_msat: 0,
3906                         fee_proportional_millionths: 0,
3907                         excess_data: Vec::new()
3908                 });
3909
3910                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3911                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3912                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3913                         short_channel_id: 2,
3914                         timestamp: 2,
3915                         flags: 0,
3916                         cltv_expiry_delta: 0,
3917                         htlc_minimum_msat: 0,
3918                         htlc_maximum_msat: OptionalField::Present(20_000),
3919                         fee_base_msat: 0,
3920                         fee_proportional_millionths: 0,
3921                         excess_data: Vec::new()
3922                 });
3923                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3924                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3925                         short_channel_id: 4,
3926                         timestamp: 2,
3927                         flags: 0,
3928                         cltv_expiry_delta: 0,
3929                         htlc_minimum_msat: 0,
3930                         htlc_maximum_msat: OptionalField::Present(20_000),
3931                         fee_base_msat: 0,
3932                         fee_proportional_millionths: 0,
3933                         excess_data: Vec::new()
3934                 });
3935
3936                 {
3937                         // Attempt to route more than available results in a failure.
3938                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3939                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3940                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3941                         } else { panic!(); }
3942                 }
3943
3944                 {
3945                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3946                         // Our algorithm should provide us with these 3 paths.
3947                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3948                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3949                         assert_eq!(route.paths.len(), 3);
3950                         let mut total_amount_paid_msat = 0;
3951                         for path in &route.paths {
3952                                 assert_eq!(path.len(), 2);
3953                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3954                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3955                         }
3956                         assert_eq!(total_amount_paid_msat, 125_000);
3957                 }
3958
3959                 {
3960                         // Attempt to route without the last small cheap channel
3961                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3962                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3963                         assert_eq!(route.paths.len(), 2);
3964                         let mut total_amount_paid_msat = 0;
3965                         for path in &route.paths {
3966                                 assert_eq!(path.len(), 2);
3967                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3968                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3969                         }
3970                         assert_eq!(total_amount_paid_msat, 90_000);
3971                 }
3972         }
3973
3974         #[test]
3975         fn min_criteria_consistency() {
3976                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3977                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3978                 // was updated with a different criterion from the heap sorting, resulting in loops in
3979                 // calculated paths. We test for that specific case here.
3980
3981                 // We construct a network that looks like this:
3982                 //
3983                 //            node2 -1(3)2- node3
3984                 //              2          2
3985                 //               (2)     (4)
3986                 //                  1   1
3987                 //    node1 -1(5)2- node4 -1(1)2- node6
3988                 //    2
3989                 //   (6)
3990                 //        1
3991                 // our_node
3992                 //
3993                 // We create a loop on the side of our real path - our destination is node 6, with a
3994                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3995                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3996                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3997                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3998                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3999                 // "previous hop" being set to node 3, creating a loop in the path.
4000                 let secp_ctx = Secp256k1::new();
4001                 let logger = Arc::new(test_utils::TestLogger::new());
4002                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4003                 let net_graph_msg_handler = NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger));
4004                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4005
4006                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
4007                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4008                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4009                         short_channel_id: 6,
4010                         timestamp: 1,
4011                         flags: 0,
4012                         cltv_expiry_delta: (6 << 8) | 0,
4013                         htlc_minimum_msat: 0,
4014                         htlc_maximum_msat: OptionalField::Absent,
4015                         fee_base_msat: 0,
4016                         fee_proportional_millionths: 0,
4017                         excess_data: Vec::new()
4018                 });
4019                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
4020
4021                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4022                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4023                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4024                         short_channel_id: 5,
4025                         timestamp: 1,
4026                         flags: 0,
4027                         cltv_expiry_delta: (5 << 8) | 0,
4028                         htlc_minimum_msat: 0,
4029                         htlc_maximum_msat: OptionalField::Absent,
4030                         fee_base_msat: 100,
4031                         fee_proportional_millionths: 0,
4032                         excess_data: Vec::new()
4033                 });
4034                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
4035
4036                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
4037                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4038                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4039                         short_channel_id: 4,
4040                         timestamp: 1,
4041                         flags: 0,
4042                         cltv_expiry_delta: (4 << 8) | 0,
4043                         htlc_minimum_msat: 0,
4044                         htlc_maximum_msat: OptionalField::Absent,
4045                         fee_base_msat: 0,
4046                         fee_proportional_millionths: 0,
4047                         excess_data: Vec::new()
4048                 });
4049                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
4050
4051                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
4052                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
4053                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4054                         short_channel_id: 3,
4055                         timestamp: 1,
4056                         flags: 0,
4057                         cltv_expiry_delta: (3 << 8) | 0,
4058                         htlc_minimum_msat: 0,
4059                         htlc_maximum_msat: OptionalField::Absent,
4060                         fee_base_msat: 0,
4061                         fee_proportional_millionths: 0,
4062                         excess_data: Vec::new()
4063                 });
4064                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
4065
4066                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
4067                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4068                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4069                         short_channel_id: 2,
4070                         timestamp: 1,
4071                         flags: 0,
4072                         cltv_expiry_delta: (2 << 8) | 0,
4073                         htlc_minimum_msat: 0,
4074                         htlc_maximum_msat: OptionalField::Absent,
4075                         fee_base_msat: 0,
4076                         fee_proportional_millionths: 0,
4077                         excess_data: Vec::new()
4078                 });
4079
4080                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
4081                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4082                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4083                         short_channel_id: 1,
4084                         timestamp: 1,
4085                         flags: 0,
4086                         cltv_expiry_delta: (1 << 8) | 0,
4087                         htlc_minimum_msat: 100,
4088                         htlc_maximum_msat: OptionalField::Absent,
4089                         fee_base_msat: 0,
4090                         fee_proportional_millionths: 0,
4091                         excess_data: Vec::new()
4092                 });
4093                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
4094
4095                 {
4096                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
4097                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
4098                         assert_eq!(route.paths.len(), 1);
4099                         assert_eq!(route.paths[0].len(), 3);
4100
4101                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
4102                         assert_eq!(route.paths[0][0].short_channel_id, 6);
4103                         assert_eq!(route.paths[0][0].fee_msat, 100);
4104                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
4105                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
4106                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
4107
4108                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
4109                         assert_eq!(route.paths[0][1].short_channel_id, 5);
4110                         assert_eq!(route.paths[0][1].fee_msat, 0);
4111                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
4112                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
4113                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
4114
4115                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
4116                         assert_eq!(route.paths[0][2].short_channel_id, 1);
4117                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
4118                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
4119                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
4120                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
4121                 }
4122         }
4123
4124
4125         #[test]
4126         fn exact_fee_liquidity_limit() {
4127                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
4128                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
4129                 // we calculated fees on a higher value, resulting in us ignoring such paths.
4130                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4131                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
4132
4133                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
4134                 // send.
4135                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4136                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4137                         short_channel_id: 2,
4138                         timestamp: 2,
4139                         flags: 0,
4140                         cltv_expiry_delta: 0,
4141                         htlc_minimum_msat: 0,
4142                         htlc_maximum_msat: OptionalField::Present(85_000),
4143                         fee_base_msat: 0,
4144                         fee_proportional_millionths: 0,
4145                         excess_data: Vec::new()
4146                 });
4147
4148                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4149                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4150                         short_channel_id: 12,
4151                         timestamp: 2,
4152                         flags: 0,
4153                         cltv_expiry_delta: (4 << 8) | 1,
4154                         htlc_minimum_msat: 0,
4155                         htlc_maximum_msat: OptionalField::Present(270_000),
4156                         fee_base_msat: 0,
4157                         fee_proportional_millionths: 1000000,
4158                         excess_data: Vec::new()
4159                 });
4160
4161                 {
4162                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
4163                         // 200% fee charged channel 13 in the 1-to-2 direction.
4164                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
4165                         assert_eq!(route.paths.len(), 1);
4166                         assert_eq!(route.paths[0].len(), 2);
4167
4168                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4169                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4170                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4171                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4172                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4173                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4174
4175                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4176                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4177                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4178                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4179                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
4180                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4181                 }
4182         }
4183
4184         #[test]
4185         fn htlc_max_reduction_below_min() {
4186                 // Test that if, while walking the graph, we reduce the value being sent to meet an
4187                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
4188                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
4189                 // resulting in us thinking there is no possible path, even if other paths exist.
4190                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4191                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4192
4193                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
4194                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
4195                 // then try to send 90_000.
4196                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4197                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4198                         short_channel_id: 2,
4199                         timestamp: 2,
4200                         flags: 0,
4201                         cltv_expiry_delta: 0,
4202                         htlc_minimum_msat: 0,
4203                         htlc_maximum_msat: OptionalField::Present(80_000),
4204                         fee_base_msat: 0,
4205                         fee_proportional_millionths: 0,
4206                         excess_data: Vec::new()
4207                 });
4208                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4209                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4210                         short_channel_id: 4,
4211                         timestamp: 2,
4212                         flags: 0,
4213                         cltv_expiry_delta: (4 << 8) | 1,
4214                         htlc_minimum_msat: 90_000,
4215                         htlc_maximum_msat: OptionalField::Absent,
4216                         fee_base_msat: 0,
4217                         fee_proportional_millionths: 0,
4218                         excess_data: Vec::new()
4219                 });
4220
4221                 {
4222                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
4223                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
4224                         // expensive) channels 12-13 path.
4225                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
4226                         assert_eq!(route.paths.len(), 1);
4227                         assert_eq!(route.paths[0].len(), 2);
4228
4229                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4230                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4231                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4232                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4233                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4234                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4235
4236                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4237                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4238                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4239                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4240                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
4241                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4242                 }
4243         }
4244
4245         #[test]
4246         fn multiple_direct_first_hops() {
4247                 // Previously we'd only ever considered one first hop path per counterparty.
4248                 // However, as we don't restrict users to one channel per peer, we really need to support
4249                 // looking at all first hop paths.
4250                 // Here we test that we do not ignore all-but-the-last first hop paths per counterparty (as
4251                 // we used to do by overwriting the `first_hop_targets` hashmap entry) and that we can MPP
4252                 // route over multiple channels with the same first hop.
4253                 let secp_ctx = Secp256k1::new();
4254                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4255                 let logger = Arc::new(test_utils::TestLogger::new());
4256                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4257
4258                 {
4259                         let route = get_route(&our_id, &network_graph, &nodes[0], Some(InvoiceFeatures::known()), Some(&[
4260                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 200_000),
4261                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 10_000),
4262                         ]), &[], 100_000, 42, Arc::clone(&logger)).unwrap();
4263                         assert_eq!(route.paths.len(), 1);
4264                         assert_eq!(route.paths[0].len(), 1);
4265
4266                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4267                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4268                         assert_eq!(route.paths[0][0].fee_msat, 100_000);
4269                 }
4270                 {
4271                         let route = get_route(&our_id, &network_graph, &nodes[0], Some(InvoiceFeatures::known()), Some(&[
4272                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 50_000),
4273                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 50_000),
4274                         ]), &[], 100_000, 42, Arc::clone(&logger)).unwrap();
4275                         assert_eq!(route.paths.len(), 2);
4276                         assert_eq!(route.paths[0].len(), 1);
4277                         assert_eq!(route.paths[1].len(), 1);
4278
4279                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4280                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4281                         assert_eq!(route.paths[0][0].fee_msat, 50_000);
4282
4283                         assert_eq!(route.paths[1][0].pubkey, nodes[0]);
4284                         assert_eq!(route.paths[1][0].short_channel_id, 2);
4285                         assert_eq!(route.paths[1][0].fee_msat, 50_000);
4286                 }
4287         }
4288
4289         #[test]
4290         fn total_fees_single_path() {
4291                 let route = Route {
4292                         paths: vec![vec![
4293                                 RouteHop {
4294                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4295                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4296                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4297                                 },
4298                                 RouteHop {
4299                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4300                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4301                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4302                                 },
4303                                 RouteHop {
4304                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
4305                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4306                                         short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0
4307                                 },
4308                         ]],
4309                 };
4310
4311                 assert_eq!(route.get_total_fees(), 250);
4312                 assert_eq!(route.get_total_amount(), 225);
4313         }
4314
4315         #[test]
4316         fn total_fees_multi_path() {
4317                 let route = Route {
4318                         paths: vec![vec![
4319                                 RouteHop {
4320                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4321                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4322                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4323                                 },
4324                                 RouteHop {
4325                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4326                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4327                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4328                                 },
4329                         ],vec![
4330                                 RouteHop {
4331                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4332                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4333                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4334                                 },
4335                                 RouteHop {
4336                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4337                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4338                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4339                                 },
4340                         ]],
4341                 };
4342
4343                 assert_eq!(route.get_total_fees(), 200);
4344                 assert_eq!(route.get_total_amount(), 300);
4345         }
4346
4347         #[test]
4348         fn total_empty_route_no_panic() {
4349                 // In an earlier version of `Route::get_total_fees` and `Route::get_total_amount`, they
4350                 // would both panic if the route was completely empty. We test to ensure they return 0
4351                 // here, even though its somewhat nonsensical as a route.
4352                 let route = Route { paths: Vec::new() };
4353
4354                 assert_eq!(route.get_total_fees(), 0);
4355                 assert_eq!(route.get_total_amount(), 0);
4356         }
4357
4358         #[cfg(not(feature = "no-std"))]
4359         pub(super) fn random_init_seed() -> u64 {
4360                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
4361                 use core::hash::{BuildHasher, Hasher};
4362                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
4363                 println!("Using seed of {}", seed);
4364                 seed
4365         }
4366         #[cfg(not(feature = "no-std"))]
4367         use util::ser::Readable;
4368
4369         #[test]
4370         #[cfg(not(feature = "no-std"))]
4371         fn generate_routes() {
4372                 let mut d = match super::test_utils::get_route_file() {
4373                         Ok(f) => f,
4374                         Err(e) => {
4375                                 eprintln!("{}", e);
4376                                 return;
4377                         },
4378                 };
4379                 let graph = NetworkGraph::read(&mut d).unwrap();
4380
4381                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4382                 let mut seed = random_init_seed() as usize;
4383                 let nodes = graph.read_only().nodes().clone();
4384                 'load_endpoints: for _ in 0..10 {
4385                         loop {
4386                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4387                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4388                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4389                                 let dst = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4390                                 let amt = seed as u64 % 200_000_000;
4391                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
4392                                         continue 'load_endpoints;
4393                                 }
4394                         }
4395                 }
4396         }
4397
4398         #[test]
4399         #[cfg(not(feature = "no-std"))]
4400         fn generate_routes_mpp() {
4401                 let mut d = match super::test_utils::get_route_file() {
4402                         Ok(f) => f,
4403                         Err(e) => {
4404                                 eprintln!("{}", e);
4405                                 return;
4406                         },
4407                 };
4408                 let graph = NetworkGraph::read(&mut d).unwrap();
4409
4410                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4411                 let mut seed = random_init_seed() as usize;
4412                 let nodes = graph.read_only().nodes().clone();
4413                 'load_endpoints: for _ in 0..10 {
4414                         loop {
4415                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4416                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4417                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4418                                 let dst = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4419                                 let amt = seed as u64 % 200_000_000;
4420                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
4421                                         continue 'load_endpoints;
4422                                 }
4423                         }
4424                 }
4425         }
4426 }
4427
4428 #[cfg(all(test, not(feature = "no-std")))]
4429 pub(crate) mod test_utils {
4430         use std::fs::File;
4431         /// Tries to open a network graph file, or panics with a URL to fetch it.
4432         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
4433                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
4434                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
4435                         .or_else(|_| { // Fall back to guessing based on the binary location
4436                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
4437                                 let mut path = std::env::current_exe().unwrap();
4438                                 path.pop(); // lightning-...
4439                                 path.pop(); // deps
4440                                 path.pop(); // debug
4441                                 path.pop(); // target
4442                                 path.push("lightning");
4443                                 path.push("net_graph-2021-05-31.bin");
4444                                 eprintln!("{}", path.to_str().unwrap());
4445                                 File::open(path)
4446                         })
4447                 .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");
4448                 #[cfg(require_route_graph_test)]
4449                 return Ok(res.unwrap());
4450                 #[cfg(not(require_route_graph_test))]
4451                 return res;
4452         }
4453 }
4454
4455 #[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
4456 mod benches {
4457         use super::*;
4458         use util::logger::{Logger, Record};
4459
4460         use test::Bencher;
4461
4462         struct DummyLogger {}
4463         impl Logger for DummyLogger {
4464                 fn log(&self, _record: &Record) {}
4465         }
4466
4467         #[bench]
4468         fn generate_routes(bench: &mut Bencher) {
4469                 let mut d = test_utils::get_route_file().unwrap();
4470                 let graph = NetworkGraph::read(&mut d).unwrap();
4471                 let nodes = graph.read_only().nodes().clone();
4472
4473                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4474                 let mut path_endpoints = Vec::new();
4475                 let mut seed: usize = 0xdeadbeef;
4476                 'load_endpoints: for _ in 0..100 {
4477                         loop {
4478                                 seed *= 0xdeadbeef;
4479                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4480                                 seed *= 0xdeadbeef;
4481                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4482                                 let amt = seed as u64 % 1_000_000;
4483                                 if get_route(&src, &graph, &dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
4484                                         path_endpoints.push((src, dst, amt));
4485                                         continue 'load_endpoints;
4486                                 }
4487                         }
4488                 }
4489
4490                 // ...then benchmark finding paths between the nodes we learned.
4491                 let mut idx = 0;
4492                 bench.iter(|| {
4493                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4494                         assert!(get_route(&src, &graph, &dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
4495                         idx += 1;
4496                 });
4497         }
4498
4499         #[bench]
4500         fn generate_mpp_routes(bench: &mut Bencher) {
4501                 let mut d = test_utils::get_route_file().unwrap();
4502                 let graph = NetworkGraph::read(&mut d).unwrap();
4503                 let nodes = graph.read_only().nodes().clone();
4504
4505                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4506                 let mut path_endpoints = Vec::new();
4507                 let mut seed: usize = 0xdeadbeef;
4508                 'load_endpoints: for _ in 0..100 {
4509                         loop {
4510                                 seed *= 0xdeadbeef;
4511                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4512                                 seed *= 0xdeadbeef;
4513                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4514                                 let amt = seed as u64 % 1_000_000;
4515                                 if get_route(&src, &graph, &dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
4516                                         path_endpoints.push((src, dst, amt));
4517                                         continue 'load_endpoints;
4518                                 }
4519                         }
4520                 }
4521
4522                 // ...then benchmark finding paths between the nodes we learned.
4523                 let mut idx = 0;
4524                 bench.iter(|| {
4525                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4526                         assert!(get_route(&src, &graph, &dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
4527                         idx += 1;
4528                 });
4529         }
4530 }