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

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! The top-level routing/network map tracking logic lives here.
  11 //!
  12 //! You probably want to create a NetGraphMsgHandler and use that as your RoutingMessageHandler and then
  13 //! interrogate it to get routes for your own payments.
  14
  15 use bitcoin::secp256k1::key::PublicKey;
  16
  17 use ln::channelmanager::ChannelDetails;
  18 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
  19 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
  20 use routing::network_graph::{NetworkGraph, RoutingFees};
  21 use util::ser::{Writeable, Readable};
  22 use util::logger::Logger;
  23
  24 use prelude::*;
  25 use alloc::collections::BinaryHeap;
  26 use core::cmp;
  27 use core::ops::Deref;
  28
  29 /// A hop in a route
  30 #[derive(Clone, PartialEq)]
  31 pub struct RouteHop {
  32         /// The node_id of the node at this hop.
  33         pub pubkey: PublicKey,
  34         /// The node_announcement features of the node at this hop. For the last hop, these may be
  35         /// amended to match the features present in the invoice this node generated.
  36         pub node_features: NodeFeatures,
  37         /// The channel that should be used from the previous hop to reach this node.
  38         pub short_channel_id: u64,
  39         /// The channel_announcement features of the channel that should be used from the previous hop
  40         /// to reach this node.
  41         pub channel_features: ChannelFeatures,
  42         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  43         /// For the last hop, this should be the full value of the payment (might be more than
  44         /// requested if we had to match htlc_minimum_msat).
  45         pub fee_msat: u64,
  46         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  47         /// expected at the destination, in excess of the current block height.
  48         pub cltv_expiry_delta: u32,
  49 }
  50
  51 impl_writeable_tlv_based!(RouteHop, {
  52         (0, pubkey, required),
  53         (2, node_features, required),
  54         (4, short_channel_id, required),
  55         (6, channel_features, required),
  56         (8, fee_msat, required),
  57         (10, cltv_expiry_delta, required),
  58 });
  59
  60 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  61 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  62 #[derive(Clone, PartialEq)]
  63 pub struct Route {
  64         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  65         /// last RouteHop in each path must be the same.
  66         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  67         /// destination. Thus, this must always be at least length one. While the maximum length of any
  68         /// given path is variable, keeping the length of any path to less than 20 should currently
  69         /// ensure it is viable.
  70         pub paths: Vec<Vec<RouteHop>>,
  71 }
  72
  73 const SERIALIZATION_VERSION: u8 = 1;
  74 const MIN_SERIALIZATION_VERSION: u8 = 1;
  75
  76 impl Writeable for Route {
  77         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
  78                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
  79                 (self.paths.len() as u64).write(writer)?;
  80                 for hops in self.paths.iter() {
  81                         (hops.len() as u8).write(writer)?;
  82                         for hop in hops.iter() {
  83                                 hop.write(writer)?;
  84                         }
  85                 }
  86                 write_tlv_fields!(writer, {});
  87                 Ok(())
  88         }
  89 }
  90
  91 impl Readable for Route {
  92         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
  93                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
  94                 let path_count: u64 = Readable::read(reader)?;
  95                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
  96                 for _ in 0..path_count {
  97                         let hop_count: u8 = Readable::read(reader)?;
  98                         let mut hops = Vec::with_capacity(hop_count as usize);
  99                         for _ in 0..hop_count {
 100                                 hops.push(Readable::read(reader)?);
 101                         }
 102                         paths.push(hops);
 103                 }
 104                 read_tlv_fields!(reader, {});
 105                 Ok(Route { paths })
 106         }
 107 }
 108
 109 /// A list of hops along a payment path terminating with a channel to the recipient.
 110 #[derive(Eq, PartialEq, Debug, Clone)]
 111 pub struct RouteHint(pub Vec<RouteHintHop>);
 112
 113 /// A channel descriptor for a hop along a payment path.
 114 #[derive(Eq, PartialEq, Debug, Clone)]
 115 pub struct RouteHintHop {
 116         /// The node_id of the non-target end of the route
 117         pub src_node_id: PublicKey,
 118         /// The short_channel_id of this channel
 119         pub short_channel_id: u64,
 120         /// The fees which must be paid to use this channel
 121         pub fees: RoutingFees,
 122         /// The difference in CLTV values between this node and the next node.
 123         pub cltv_expiry_delta: u16,
 124         /// The minimum value, in msat, which must be relayed to the next hop.
 125         pub htlc_minimum_msat: Option<u64>,
 126         /// The maximum value in msat available for routing with a single HTLC.
 127         pub htlc_maximum_msat: Option<u64>,
 128 }
 129
 130 #[derive(Eq, PartialEq)]
 131 struct RouteGraphNode {
 132         pubkey: PublicKey,
 133         lowest_fee_to_peer_through_node: u64,
 134         lowest_fee_to_node: u64,
 135         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 136         // This value is upper-bounded by us by:
 137         // - how much is needed for a path being constructed
 138         // - how much value can channels following this node (up to the destination) can contribute,
 139         //   considering their capacity and fees
 140         value_contribution_msat: u64,
 141         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 142         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 143         path_htlc_minimum_msat: u64,
 144 }
 145
 146 impl cmp::Ord for RouteGraphNode {
 147         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 148                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 149                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 150                 other_score.cmp(&self_score).then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 151         }
 152 }
 153
 154 impl cmp::PartialOrd for RouteGraphNode {
 155         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 156                 Some(self.cmp(other))
 157         }
 158 }
 159
 160 struct DummyDirectionalChannelInfo {
 161         cltv_expiry_delta: u32,
 162         htlc_minimum_msat: u64,
 163         htlc_maximum_msat: Option<u64>,
 164         fees: RoutingFees,
 165 }
 166
 167 /// It's useful to keep track of the hops associated with the fees required to use them,
 168 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 169 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 170 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 171 #[derive(Clone)]
 172 struct PathBuildingHop<'a> {
 173         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 174         // Note that node_features is calculated separately after our initial graph walk.
 175         pubkey: PublicKey,
 176         short_channel_id: u64,
 177         channel_features: &'a ChannelFeatures,
 178         fee_msat: u64,
 179         cltv_expiry_delta: u32,
 180
 181         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 182         src_lowest_inbound_fees: RoutingFees,
 183         /// Fees of the channel used in this hop.
 184         channel_fees: RoutingFees,
 185         /// All the fees paid *after* this channel on the way to the destination
 186         next_hops_fee_msat: u64,
 187         /// Fee paid for the use of the current channel (see channel_fees).
 188         /// The value will be actually deducted from the counterparty balance on the previous link.
 189         hop_use_fee_msat: u64,
 190         /// Used to compare channels when choosing the for routing.
 191         /// Includes paying for the use of a hop and the following hops, as well as
 192         /// an estimated cost of reaching this hop.
 193         /// Might get stale when fees are recomputed. Primarily for internal use.
 194         total_fee_msat: u64,
 195         /// This is useful for update_value_and_recompute_fees to make sure
 196         /// we don't fall below the minimum. Should not be updated manually and
 197         /// generally should not be accessed.
 198         htlc_minimum_msat: u64,
 199         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 200         /// walk and may be invalid thereafter.
 201         path_htlc_minimum_msat: u64,
 202         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 203         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 204         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 205         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 206         /// avoid processing them again.
 207         was_processed: bool,
 208         #[cfg(any(test, feature = "fuzztarget"))]
 209         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 210         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 211         // value_contribution_msat, which requires tracking it here. See comments below where it is
 212         // used for more info.
 213         value_contribution_msat: u64,
 214 }
 215
 216 // Instantiated with a list of hops with correct data in them collected during path finding,
 217 // an instance of this struct should be further modified only via given methods.
 218 #[derive(Clone)]
 219 struct PaymentPath<'a> {
 220         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 221 }
 222
 223 impl<'a> PaymentPath<'a> {
 224         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 225         fn get_value_msat(&self) -> u64 {
 226                 self.hops.last().unwrap().0.fee_msat
 227         }
 228
 229         fn get_total_fee_paid_msat(&self) -> u64 {
 230                 if self.hops.len() < 1 {
 231                         return 0;
 232                 }
 233                 let mut result = 0;
 234                 // Can't use next_hops_fee_msat because it gets outdated.
 235                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 236                         if i != self.hops.len() - 1 {
 237                                 result += hop.fee_msat;
 238                         }
 239                 }
 240                 return result;
 241         }
 242
 243         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 244         // to change fees may result in an inconsistency.
 245         //
 246         // Sometimes we call this function right after constructing a path which is inconsistent in
 247         // that it the value being transferred has decreased while we were doing path finding, leading
 248         // to the fees being paid not lining up with the actual limits.
 249         //
 250         // Note that this function is not aware of the available_liquidity limit, and thus does not
 251         // support increasing the value being transferred.
 252         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 253                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 254
 255                 let mut total_fee_paid_msat = 0 as u64;
 256                 for i in (0..self.hops.len()).rev() {
 257                         let last_hop = i == self.hops.len() - 1;
 258
 259                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 260                         // will consist of the fees for the use of the next hop, and extra fees to match
 261                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 262                         let mut cur_hop_fees_msat = 0;
 263                         if !last_hop {
 264                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 265                         }
 266
 267                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 268                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 269                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 270                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 271                         // set it too high just to maliciously take more fees by exploiting this
 272                         // match htlc_minimum_msat logic.
 273                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 274                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 275                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 276                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 277                                 //
 278                                 // This might make us end up with a broken route, although this should be super-rare
 279                                 // in practice, both because of how healthy channels look like, and how we pick
 280                                 // channels in add_entry.
 281                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 282                                 // all payments*.
 283                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 284                                 total_fee_paid_msat += extra_fees_msat;
 285                                 cur_hop_fees_msat += extra_fees_msat;
 286                         }
 287
 288                         if last_hop {
 289                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 290                                 // it still could overpay for the htlc_minimum_msat.
 291                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 292                         } else {
 293                                 // Propagate updated fees for the use of the channels to one hop back, where they
 294                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 295                                 cur_hop.fee_msat = cur_hop_fees_msat;
 296                         }
 297
 298                         // Fee for the use of the current hop which will be deducted on the previous hop.
 299                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 300                         // this channel is free for us.
 301                         if i != 0 {
 302                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 303                                         cur_hop.hop_use_fee_msat = new_fee;
 304                                         total_fee_paid_msat += new_fee;
 305                                 } else {
 306                                         // It should not be possible because this function is called only to reduce the
 307                                         // value. In that case, compute_fee was already called with the same fees for
 308                                         // larger amount and there was no overflow.
 309                                         unreachable!();
 310                                 }
 311                         }
 312                 }
 313         }
 314 }
 315
 316 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 317         let proportional_fee_millions =
 318                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 319         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 320                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 321
 322                 Some(new_fee)
 323         } else {
 324                 // This function may be (indirectly) called without any verification,
 325                 // with channel_fees provided by a caller. We should handle it gracefully.
 326                 None
 327         }
 328 }
 329
 330 /// Gets a route from us (payer) to the given target node (payee).
 331 ///
 332 /// If the payee provided features in their invoice, they should be provided via payee_features.
 333 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 334 ///
 335 /// Private routing paths between a public node and the target may be included in `last_hops`.
 336 /// Currently, only the last hop in each path is considered.
 337 ///
 338 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 339 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 340 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 341 /// in first_hops will be used.
 342 ///
 343 /// Panics if first_hops contains channels without short_channel_ids
 344 /// (ChannelManager::list_usable_channels will never include such channels).
 345 ///
 346 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 347 /// equal), however the enabled/disabled bit on such channels as well as the
 348 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 349 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 350         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 351         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 352         // uptime/success in using a node in the past.
 353         if *payee == *our_node_id {
 354                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 355         }
 356
 357         if final_value_msat > MAX_VALUE_MSAT {
 358                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 359         }
 360
 361         if final_value_msat == 0 {
 362                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 363         }
 364
 365         let last_hops = last_hops.iter().filter_map(|hops| hops.0.last()).collect::<Vec<_>>();
 366         for last_hop in last_hops.iter() {
 367                 if last_hop.src_node_id == *payee {
 368                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 369                 }
 370         }
 371
 372         // The general routing idea is the following:
 373         // 1. Fill first/last hops communicated by the caller.
 374         // 2. Attempt to construct a path from payer to payee for transferring
 375         //    any ~sufficient (described later) value.
 376         //    If succeed, remember which channels were used and how much liquidity they have available,
 377         //    so that future paths don't rely on the same liquidity.
 378         // 3. Prooceed to the next step if:
 379         //    - we hit the recommended target value;
 380         //    - OR if we could not construct a new path. Any next attempt will fail too.
 381         //    Otherwise, repeat step 2.
 382         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 383         //    (not recommended value). If yes, proceed. If not, fail routing.
 384         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 385         // 6. Of all the found paths, select only those with the lowest total fee.
 386         // 7. The last path in every selected route is likely to be more than we need.
 387         //    Reduce its value-to-transfer and recompute fees.
 388         // 8. Choose the best route by the lowest total fee.
 389
 390         // As for the actual search algorithm,
 391         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 392         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 393         //
 394         // We are not a faithful Dijkstra's implementation because we can change values which impact
 395         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 396         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 397         // the value we are currently attempting to send over a path, we simply reduce the value being
 398         // sent along the path for any hops after that channel. This may imply that later fees (which
 399         // we've already tabulated) are lower because a smaller value is passing through the channels
 400         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 401         // channels which were selected earlier (and which may still be used for other paths without a
 402         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 403         // de-preferenced.
 404         //
 405         // One potentially problematic case for this algorithm would be if there are many
 406         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 407         // graph walking), we may never find a path which is not liquidity-limited and has lower
 408         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 409         // Because we only consider paths with at least 5% of the total value being sent, the damage
 410         // from such a case should be limited, however this could be further reduced in the future by
 411         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 412         // limits for the purposes of fee calculation.
 413         //
 414         // Alternatively, we could store more detailed path information in the heap (targets, below)
 415         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 416         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 417         // and practically (as we would need to store dynamically-allocated path information in heap
 418         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 419         // results of such an algorithm would likely be biased towards lower-value paths.
 420         //
 421         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 422         // outside of our current search value, running a path search more times to gather candidate
 423         // paths at different values. While this may be acceptable, further path searches may increase
 424         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 425         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 426         // the same time, remaining generic across different payment values.
 427         //
 428         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 429         // to use as the A* heuristic beyond just the cost to get one node further than the current
 430         // one.
 431
 432         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 433                 cltv_expiry_delta: 0,
 434                 htlc_minimum_msat: 0,
 435                 htlc_maximum_msat: None,
 436                 fees: RoutingFees {
 437                         base_msat: 0,
 438                         proportional_millionths: 0,
 439                 }
 440         };
 441
 442         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 443         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 444         // work reliably.
 445         let allow_mpp = if let Some(features) = &payee_features {
 446                 features.supports_basic_mpp()
 447         } else if let Some(node) = network.get_nodes().get(&payee) {
 448                 if let Some(node_info) = node.announcement_info.as_ref() {
 449                         node_info.features.supports_basic_mpp()
 450                 } else { false }
 451         } else { false };
 452
 453         // Step (1).
 454         // Prepare the data we'll use for payee-to-payer search by
 455         // inserting first hops suggested by the caller as targets.
 456         // Our search will then attempt to reach them while traversing from the payee node.
 457         let mut first_hop_targets: HashMap<_, (_, ChannelFeatures, _, NodeFeatures)> =
 458                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 459         if let Some(hops) = first_hops {
 460                 for chan in hops {
 461                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 462                         if chan.remote_network_id == *our_node_id {
 463                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 464                         }
 465                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.to_context(), chan.outbound_capacity_msat, chan.counterparty_features.to_context()));
 466                 }
 467                 if first_hop_targets.is_empty() {
 468                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 469                 }
 470         }
 471
 472         let empty_channel_features = ChannelFeatures::empty();
 473
 474         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 475         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 476         // adding duplicate entries when we find a better path to a given node.
 477         let mut targets = BinaryHeap::new();
 478
 479         // Map from node_id to information about the best current path to that node, including feerate
 480         // information.
 481         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 482
 483         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 484         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 485         // htlc_minimum with extra fees while still finding a cheaper path.
 486         let mut hit_minimum_limit;
 487
 488         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 489         // We start with a path_value of the exact amount we want, and if that generates a route we may
 490         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 491         // amount we want in total across paths, selecting the best subset at the end.
 492         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 493         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 494         let mut path_value_msat = final_value_msat;
 495
 496         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 497         // This map allows paths to be aware of the channel use by other paths in the same call.
 498         // This would help to make a better path finding decisions and not "overbook" channels.
 499         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 500         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network.get_nodes().len());
 501
 502         // Keeping track of how much value we already collected across other paths. Helps to decide:
 503         // - how much a new path should be transferring (upper bound);
 504         // - whether a channel should be disregarded because
 505         //   it's available liquidity is too small comparing to how much more we need to collect;
 506         // - when we want to stop looking for new paths.
 507         let mut already_collected_value_msat = 0;
 508
 509         macro_rules! add_entry {
 510                 // Adds entry which goes from $src_node_id to $dest_node_id
 511                 // over the channel with id $chan_id with fees described in
 512                 // $directional_info.
 513                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 514                 // since that value has to be transferred over this channel.
 515                 ( $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,
 516                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 517                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 518                         // practice these cases should be caught earlier:
 519                         // - for regular channels at channel announcement (TODO)
 520                         // - for first and last hops early in get_route
 521                         if $src_node_id != $dest_node_id.clone() {
 522                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 523                                         let mut initial_liquidity_available_msat = None;
 524                                         if let Some(capacity_sats) = $capacity_sats {
 525                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 526                                         }
 527
 528                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 529                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 530                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 531                                                 } else {
 532                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 533                                                 }
 534                                         }
 535
 536                                         match initial_liquidity_available_msat {
 537                                                 Some(available_msat) => available_msat,
 538                                                 // We assume channels with unknown balance have
 539                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 540                                                 None => 250_000 * 1000
 541                                         }
 542                                 });
 543
 544                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 545                                 // It may be misleading because we might later choose to reduce the value transferred
 546                                 // over these channels, and the channel which was insufficient might become sufficient.
 547                                 // Worst case: we drop a good channel here because it can't cover the high following
 548                                 // fees caused by one expensive channel, but then this channel could have been used
 549                                 // if the amount being transferred over this path is lower.
 550                                 // We do this for now, but this is a subject for removal.
 551                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 552
 553                                         // Routing Fragmentation Mitigation heuristic:
 554                                         //
 555                                         // Routing fragmentation across many payment paths increases the overall routing
 556                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 557                                         // Taking too many smaller paths also increases the chance of payment failure.
 558                                         // Thus to avoid this effect, we require from our collected links to provide
 559                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 560                                         //
 561                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 562                                         // This means as we successfully advance in our collection,
 563                                         // the absolute liquidity contribution is lowered,
 564                                         // thus increasing the number of potential channels to be selected.
 565
 566                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 567                                         // or 100% if we're not allowed to do multipath payments.
 568                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 569                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 570                                         } else {
 571                                                 final_value_msat
 572                                         };
 573                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 574                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 575
 576                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 577                                         // Includes paying fees for the use of the following channels.
 578                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 579                                                 Some(result) => result,
 580                                                 // Can't overflow due to how the values were computed right above.
 581                                                 None => unreachable!(),
 582                                         };
 583                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 584                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 585                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 586
 587                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 588                                         // bother considering this channel.
 589                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 590                                         // be only reduced later (not increased), so this channel should just be skipped
 591                                         // as not sufficient.
 592                                         if !over_path_minimum_msat {
 593                                                 hit_minimum_limit = true;
 594                                         } else if contributes_sufficient_value {
 595                                                 // Note that low contribution here (limited by available_liquidity_msat)
 596                                                 // might violate htlc_minimum_msat on the hops which are next along the
 597                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 598                                                 // path fees knowing the final path contribution after constructing it.
 599                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 600                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 601                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 602                                                         _ => u64::max_value()
 603                                                 };
 604                                                 let hm_entry = dist.entry(&$src_node_id);
 605                                                 let old_entry = hm_entry.or_insert_with(|| {
 606                                                         // If there was previously no known way to access
 607                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 608                                                         // a semi-dummy record just to compute the fees to reach the source node.
 609                                                         // This will affect our decision on selecting $chan_id
 610                                                         // as a way to reach the $dest_node_id.
 611                                                         let mut fee_base_msat = u32::max_value();
 612                                                         let mut fee_proportional_millionths = u32::max_value();
 613                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 614                                                                 fee_base_msat = fees.base_msat;
 615                                                                 fee_proportional_millionths = fees.proportional_millionths;
 616                                                         }
 617                                                         PathBuildingHop {
 618                                                                 pubkey: $dest_node_id.clone(),
 619                                                                 short_channel_id: 0,
 620                                                                 channel_features: $chan_features,
 621                                                                 fee_msat: 0,
 622                                                                 cltv_expiry_delta: 0,
 623                                                                 src_lowest_inbound_fees: RoutingFees {
 624                                                                         base_msat: fee_base_msat,
 625                                                                         proportional_millionths: fee_proportional_millionths,
 626                                                                 },
 627                                                                 channel_fees: $directional_info.fees,
 628                                                                 next_hops_fee_msat: u64::max_value(),
 629                                                                 hop_use_fee_msat: u64::max_value(),
 630                                                                 total_fee_msat: u64::max_value(),
 631                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 632                                                                 path_htlc_minimum_msat,
 633                                                                 was_processed: false,
 634                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 635                                                                 value_contribution_msat,
 636                                                         }
 637                                                 });
 638
 639                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 640                                                 let mut should_process = !old_entry.was_processed;
 641                                                 #[cfg(any(test, feature = "fuzztarget"))]
 642                                                 {
 643                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 644                                                         // of already-seen nodes only happens in cases we expect (see below).
 645                                                         if !should_process { should_process = true; }
 646                                                 }
 647
 648                                                 if should_process {
 649                                                         let mut hop_use_fee_msat = 0;
 650                                                         let mut total_fee_msat = $next_hops_fee_msat;
 651
 652                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 653                                                         // will have the same effective-fee
 654                                                         if $src_node_id != *our_node_id {
 655                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 656                                                                         // max_value means we'll always fail
 657                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 658                                                                         None => total_fee_msat = u64::max_value(),
 659                                                                         Some(fee_msat) => {
 660                                                                                 hop_use_fee_msat = fee_msat;
 661                                                                                 total_fee_msat += hop_use_fee_msat;
 662                                                                                 // When calculating the lowest inbound fees to a node, we
 663                                                                                 // calculate fees here not based on the actual value we think
 664                                                                                 // will flow over this channel, but on the minimum value that
 665                                                                                 // we'll accept flowing over it. The minimum accepted value
 666                                                                                 // is a constant through each path collection run, ensuring
 667                                                                                 // consistent basis. Otherwise we may later find a
 668                                                                                 // different path to the source node that is more expensive,
 669                                                                                 // but which we consider to be cheaper because we are capacity
 670                                                                                 // constrained and the relative fee becomes lower.
 671                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 672                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 673                                                                                         Some(Some(v)) => {
 674                                                                                                 total_fee_msat = v;
 675                                                                                         },
 676                                                                                         _ => {
 677                                                                                                 total_fee_msat = u64::max_value();
 678                                                                                         }
 679                                                                                 };
 680                                                                         }
 681                                                                 }
 682                                                         }
 683
 684                                                         let new_graph_node = RouteGraphNode {
 685                                                                 pubkey: $src_node_id,
 686                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 687                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 688                                                                 value_contribution_msat: value_contribution_msat,
 689                                                                 path_htlc_minimum_msat,
 690                                                         };
 691
 692                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 693                                                         // if this way is cheaper than the already known
 694                                                         // (considering the cost to "reach" this channel from the route destination,
 695                                                         // the cost of using this channel,
 696                                                         // and the cost of routing to the source node of this channel).
 697                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 698                                                         // paying it. Consider the following exploit:
 699                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 700                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 701                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 702                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 703                                                         // to this channel.
 704                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 705                                                         // but it may require additional tracking - we don't want to double-count
 706                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 707                                                         // can't use something that may decrease on future hops.
 708                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 709                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 710
 711                                                         if !old_entry.was_processed && new_cost < old_cost {
 712                                                                 targets.push(new_graph_node);
 713                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 714                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 715                                                                 old_entry.total_fee_msat = total_fee_msat;
 716                                                                 old_entry.pubkey = $dest_node_id.clone();
 717                                                                 old_entry.short_channel_id = $chan_id.clone();
 718                                                                 old_entry.channel_features = $chan_features;
 719                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 720                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 721                                                                 old_entry.channel_fees = $directional_info.fees;
 722                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 723                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 724                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 725                                                                 {
 726                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 727                                                                 }
 728                                                         } else if old_entry.was_processed && new_cost < old_cost {
 729                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 730                                                                 {
 731                                                                         // If we're skipping processing a node which was previously
 732                                                                         // processed even though we found another path to it with a
 733                                                                         // cheaper fee, check that it was because the second path we
 734                                                                         // found (which we are processing now) has a lower value
 735                                                                         // contribution due to an HTLC minimum limit.
 736                                                                         //
 737                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 738                                                                         // through channel A, and one through channel B. Channel A and
 739                                                                         // B are both in the to-process heap, with their scores set by
 740                                                                         // a higher htlc_minimum than fee.
 741                                                                         // Channel A is processed first, and the channels onwards from
 742                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 743                                                                         // Channel B off of the heap, note that it has a much more
 744                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 745                                                                         // all of node 1's channels using the new, reduced, amount.
 746                                                                         //
 747                                                                         // This would be bogus - we'd be selecting a higher-fee path
 748                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 749                                                                         // already decided to use.
 750                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 751                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 752                                                                 }
 753                                                         }
 754                                                 }
 755                                         }
 756                                 }
 757                         }
 758                 };
 759         }
 760
 761         let empty_node_features = NodeFeatures::empty();
 762         // Find ways (channels with destination) to reach a given node and store them
 763         // in the corresponding data structures (routing graph etc).
 764         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 765         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 766         // This data can later be helpful to optimize routing (pay lower fees).
 767         macro_rules! add_entries_to_cheapest_to_target_node {
 768                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 769                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 770                                 let was_processed = elem.was_processed;
 771                                 elem.was_processed = true;
 772                                 was_processed
 773                         } else {
 774                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 775                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 776                                 // If we're processing any other node, it is always be the result of a channel from it.
 777                                 assert_eq!($node_id, payee);
 778                                 false
 779                         };
 780
 781                         if !skip_node {
 782                                 if first_hops.is_some() {
 783                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&$node_id) {
 784                                                 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);
 785                                         }
 786                                 }
 787
 788                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 789                                         &node_info.features
 790                                 } else {
 791                                         &empty_node_features
 792                                 };
 793
 794                                 if !features.requires_unknown_bits() {
 795                                         for chan_id in $node.channels.iter() {
 796                                                 let chan = network.get_channels().get(chan_id).unwrap();
 797                                                 if !chan.features.requires_unknown_bits() {
 798                                                         if chan.node_one == *$node_id {
 799                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 800                                                                 if first_hops.is_none() || chan.node_two != *our_node_id {
 801                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 802                                                                                 if two_to_one.enabled {
 803                                                                                         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);
 804                                                                                 }
 805                                                                         }
 806                                                                 }
 807                                                         } else {
 808                                                                 if first_hops.is_none() || chan.node_one != *our_node_id {
 809                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 810                                                                                 if one_to_two.enabled {
 811                                                                                         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);
 812                                                                                 }
 813                                                                         }
 814                                                                 }
 815                                                         }
 816                                                 }
 817                                         }
 818                                 }
 819                         }
 820                 };
 821         }
 822
 823         let mut payment_paths = Vec::<PaymentPath>::new();
 824
 825         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 826         'paths_collection: loop {
 827                 // For every new path, start from scratch, except
 828                 // bookkeeped_channels_liquidity_available_msat, which will improve
 829                 // the further iterations of path finding. Also don't erase first_hop_targets.
 830                 targets.clear();
 831                 dist.clear();
 832                 hit_minimum_limit = false;
 833
 834                 // If first hop is a private channel and the only way to reach the payee, this is the only
 835                 // place where it could be added.
 836                 if first_hops.is_some() {
 837                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&payee) {
 838                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 839                         }
 840                 }
 841
 842                 // Add the payee as a target, so that the payee-to-payer
 843                 // search algorithm knows what to start with.
 844                 match network.get_nodes().get(payee) {
 845                         // The payee is not in our network graph, so nothing to add here.
 846                         // There is still a chance of reaching them via last_hops though,
 847                         // so don't yet fail the payment here.
 848                         // If not, targets.pop() will not even let us enter the loop in step 2.
 849                         None => {},
 850                         Some(node) => {
 851                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 852                         },
 853                 }
 854
 855                 // Step (1).
 856                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 857                 // earlier than general path finding, they will be somewhat prioritized, although currently
 858                 // it matters only if the fees are exactly the same.
 859                 for hop in last_hops.iter() {
 860                         let have_hop_src_in_graph =
 861                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
 862                                         // If this hop connects to a node with which we have a direct channel, ignore
 863                                         // the network graph and add both the hop and our direct channel to
 864                                         // the candidate set.
 865                                         //
 866                                         // Currently there are no channel-context features defined, so we are a
 867                                         // bit lazy here. In the future, we should pull them out via our
 868                                         // ChannelManager, but there's no reason to waste the space until we
 869                                         // need them.
 870                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 871                                         true
 872                                 } else {
 873                                         // In any other case, only add the hop if the source is in the regular network
 874                                         // graph:
 875                                         network.get_nodes().get(&hop.src_node_id).is_some()
 876                                 };
 877                         if have_hop_src_in_graph {
 878                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 879                                 // really sucks, cause we're gonna need that eventually.
 880                                 let last_hop_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 881                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 882                                         None => 0
 883                                 };
 884                                 let directional_info = DummyDirectionalChannelInfo {
 885                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 886                                         htlc_minimum_msat: last_hop_htlc_minimum_msat,
 887                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 888                                         fees: hop.fees,
 889                                 };
 890                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, &empty_channel_features, 0, path_value_msat, 0);
 891                         }
 892                 }
 893
 894                 // At this point, targets are filled with the data from first and
 895                 // last hops communicated by the caller, and the payment receiver.
 896                 let mut found_new_path = false;
 897
 898                 // Step (2).
 899                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 900                 // - not enough outgoing liquidity:
 901                 //   0 < already_collected_value_msat < final_value_msat
 902                 // - enough outgoing liquidity:
 903                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 904                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 905                 // paths_collection will be stopped because found_new_path==false.
 906                 // This is not necessarily a routing failure.
 907                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 908
 909                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 910                         // traversing the graph and arrange the path out of what we found.
 911                         if pubkey == *our_node_id {
 912                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 913                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
 914
 915                                 'path_walk: loop {
 916                                         if let Some(&(_, _, _, ref features)) = first_hop_targets.get(&ordered_hops.last().unwrap().0.pubkey) {
 917                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
 918                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().0.pubkey) {
 919                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 920                                                         ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
 921                                                 } else {
 922                                                         ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
 923                                                 }
 924                                         } else {
 925                                                 // We should be able to fill in features for everything except the last
 926                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 927                                                 // should be able to extend it further as BOLT 11 does have feature
 928                                                 // flags for the last hop node itself).
 929                                                 assert!(ordered_hops.last().unwrap().0.pubkey == *payee);
 930                                         }
 931
 932                                         // Means we succesfully traversed from the payer to the payee, now
 933                                         // save this path for the payment route. Also, update the liquidity
 934                                         // remaining on the used hops, so that we take them into account
 935                                         // while looking for more paths.
 936                                         if ordered_hops.last().unwrap().0.pubkey == *payee {
 937                                                 break 'path_walk;
 938                                         }
 939
 940                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.pubkey) {
 941                                                 Some(payment_hop) => payment_hop,
 942                                                 // We can't arrive at None because, if we ever add an entry to targets,
 943                                                 // we also fill in the entry in dist (see add_entry!).
 944                                                 None => unreachable!(),
 945                                         };
 946                                         // We "propagate" the fees one hop backward (topologically) here,
 947                                         // so that fees paid for a HTLC forwarding on the current channel are
 948                                         // associated with the previous channel (where they will be subtracted).
 949                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
 950                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
 951                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
 952                                 }
 953                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
 954                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
 955                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
 956
 957                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 958
 959                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 960                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 961                                 // on some channels we already passed (assuming dest->source direction). Here, we
 962                                 // recompute the fees again, so that if that's the case, we match the currently
 963                                 // underpaid htlc_minimum_msat with fees.
 964                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
 965
 966                                 // Since a path allows to transfer as much value as
 967                                 // the smallest channel it has ("bottleneck"), we should recompute
 968                                 // the fees so sender HTLC don't overpay fees when traversing
 969                                 // larger channels than the bottleneck. This may happen because
 970                                 // when we were selecting those channels we were not aware how much value
 971                                 // this path will transfer, and the relative fee for them
 972                                 // might have been computed considering a larger value.
 973                                 // Remember that we used these channels so that we don't rely
 974                                 // on the same liquidity in future paths.
 975                                 let mut prevented_redundant_path_selection = false;
 976                                 for (payment_hop, _) in payment_path.hops.iter() {
 977                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
 978                                         let mut spent_on_hop_msat = value_contribution_msat;
 979                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 980                                         spent_on_hop_msat += next_hops_fee_msat;
 981                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
 982                                                 // If this path used all of this channel's available liquidity, we know
 983                                                 // this path will not be selected again in the next loop iteration.
 984                                                 prevented_redundant_path_selection = true;
 985                                         }
 986                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 987                                 }
 988                                 if !prevented_redundant_path_selection {
 989                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
 990                                         // we'll probably end up picking the same path again on the next iteration.
 991                                         // Decrease the available liquidity of a hop in the middle of the path.
 992                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(
 993                                                 &payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id).unwrap();
 994                                         *victim_liquidity = 0;
 995                                 }
 996
 997                                 // Track the total amount all our collected paths allow to send so that we:
 998                                 // - know when to stop looking for more paths
 999                                 // - know which of the hops are useless considering how much more sats we need
1000                                 //   (contributes_sufficient_value)
1001                                 already_collected_value_msat += value_contribution_msat;
1002
1003                                 payment_paths.push(payment_path);
1004                                 found_new_path = true;
1005                                 break 'path_construction;
1006                         }
1007
1008                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1009                         // the equivalent of the `elem.was_processed` check in
1010                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1011                         if pubkey == *payee { continue 'path_construction; }
1012
1013                         // Otherwise, since the current target node is not us,
1014                         // keep "unrolling" the payment graph from payee to payer by
1015                         // finding a way to reach the current target from the payer side.
1016                         match network.get_nodes().get(&pubkey) {
1017                                 None => {},
1018                                 Some(node) => {
1019                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1020                                 },
1021                         }
1022                 }
1023
1024                 if !allow_mpp {
1025                         // If we don't support MPP, no use trying to gather more value ever.
1026                         break 'paths_collection;
1027                 }
1028
1029                 // Step (3).
1030                 // Stop either when the recommended value is reached or if no new path was found in this
1031                 // iteration.
1032                 // In the latter case, making another path finding attempt won't help,
1033                 // because we deterministically terminated the search due to low liquidity.
1034                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1035                         break 'paths_collection;
1036                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1037                         // Further, if this was our first walk of the graph, and we weren't limited by an
1038                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1039                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1040                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1041                         // still keeping a lower total fee than this path.
1042                         if !hit_minimum_limit {
1043                                 break 'paths_collection;
1044                         }
1045                         path_value_msat = recommended_value_msat;
1046                 }
1047         }
1048
1049         // Step (4).
1050         if payment_paths.len() == 0 {
1051                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1052         }
1053
1054         if already_collected_value_msat < final_value_msat {
1055                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1056         }
1057
1058         // Sort by total fees and take the best paths.
1059         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1060         if payment_paths.len() > 50 {
1061                 payment_paths.truncate(50);
1062         }
1063
1064         // Draw multiple sufficient routes by randomly combining the selected paths.
1065         let mut drawn_routes = Vec::new();
1066         for i in 0..payment_paths.len() {
1067                 let mut cur_route = Vec::<PaymentPath>::new();
1068                 let mut aggregate_route_value_msat = 0;
1069
1070                 // Step (5).
1071                 // TODO: real random shuffle
1072                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1073                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1074
1075                 // Step (6).
1076                 for payment_path in cur_payment_paths {
1077                         cur_route.push(payment_path.clone());
1078                         aggregate_route_value_msat += payment_path.get_value_msat();
1079                         if aggregate_route_value_msat > final_value_msat {
1080                                 // Last path likely overpaid. Substract it from the most expensive
1081                                 // (in terms of proportional fee) path in this route and recompute fees.
1082                                 // This might be not the most economically efficient way, but fewer paths
1083                                 // also makes routing more reliable.
1084                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1085
1086                                 // First, drop some expensive low-value paths entirely if possible.
1087                                 // Sort by value so that we drop many really-low values first, since
1088                                 // fewer paths is better: the payment is less likely to fail.
1089                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1090                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1091                                 cur_route.sort_by_key(|path| path.get_value_msat());
1092                                 // We should make sure that at least 1 path left.
1093                                 let mut paths_left = cur_route.len();
1094                                 cur_route.retain(|path| {
1095                                         if paths_left == 1 {
1096                                                 return true
1097                                         }
1098                                         let mut keep = true;
1099                                         let path_value_msat = path.get_value_msat();
1100                                         if path_value_msat <= overpaid_value_msat {
1101                                                 keep = false;
1102                                                 overpaid_value_msat -= path_value_msat;
1103                                                 paths_left -= 1;
1104                                         }
1105                                         keep
1106                                 });
1107
1108                                 if overpaid_value_msat == 0 {
1109                                         break;
1110                                 }
1111
1112                                 assert!(cur_route.len() > 0);
1113
1114                                 // Step (7).
1115                                 // Now, substract the overpaid value from the most-expensive path.
1116                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1117                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1118                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1119                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1120                                 // We already dropped all the small channels above, meaning all the
1121                                 // remaining channels are larger than remaining overpaid_value_msat.
1122                                 // Thus, this can't be negative.
1123                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1124                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1125                                 break;
1126                         }
1127                 }
1128                 drawn_routes.push(cur_route);
1129         }
1130
1131         // Step (8).
1132         // Select the best route by lowest total fee.
1133         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1134         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1135         for payment_path in drawn_routes.first().unwrap() {
1136                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1137                         RouteHop {
1138                                 pubkey: payment_hop.pubkey,
1139                                 node_features: node_features.clone(),
1140                                 short_channel_id: payment_hop.short_channel_id,
1141                                 channel_features: payment_hop.channel_features.clone(),
1142                                 fee_msat: payment_hop.fee_msat,
1143                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1144                         }
1145                 }).collect());
1146         }
1147
1148         if let Some(features) = &payee_features {
1149                 for path in selected_paths.iter_mut() {
1150                         path.last_mut().unwrap().node_features = features.to_context();
1151                 }
1152         }
1153
1154         let route = Route { paths: selected_paths };
1155         log_trace!(logger, "Got route: {}", log_route!(route));
1156         Ok(route)
1157 }
1158
1159 #[cfg(test)]
1160 mod tests {
1161         use routing::router::{get_route, RouteHint, RouteHintHop, RoutingFees};
1162         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1163         use chain::transaction::OutPoint;
1164         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1165         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1166            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1167         use ln::channelmanager;
1168         use util::test_utils;
1169         use util::ser::Writeable;
1170
1171         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1172         use bitcoin::hashes::Hash;
1173         use bitcoin::network::constants::Network;
1174         use bitcoin::blockdata::constants::genesis_block;
1175         use bitcoin::blockdata::script::Builder;
1176         use bitcoin::blockdata::opcodes;
1177         use bitcoin::blockdata::transaction::TxOut;
1178
1179         use hex;
1180
1181         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1182         use bitcoin::secp256k1::{Secp256k1, All};
1183
1184         use prelude::*;
1185         use std::sync::Arc;
1186
1187         // Using the same keys for LN and BTC ids
1188         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1189            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1190                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1191                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1192
1193                 let unsigned_announcement = UnsignedChannelAnnouncement {
1194                         features,
1195                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1196                         short_channel_id,
1197                         node_id_1,
1198                         node_id_2,
1199                         bitcoin_key_1: node_id_1,
1200                         bitcoin_key_2: node_id_2,
1201                         excess_data: Vec::new(),
1202                 };
1203
1204                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1205                 let valid_announcement = ChannelAnnouncement {
1206                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1207                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1208                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1209                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1210                         contents: unsigned_announcement.clone(),
1211                 };
1212                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1213                         Ok(res) => assert!(res),
1214                         _ => panic!()
1215                 };
1216         }
1217
1218         fn update_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate) {
1219                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1220                 let valid_channel_update = ChannelUpdate {
1221                         signature: secp_ctx.sign(&msghash, node_privkey),
1222                         contents: update.clone()
1223                 };
1224
1225                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1226                         Ok(res) => assert!(res),
1227                         Err(_) => panic!()
1228                 };
1229         }
1230
1231         fn add_or_update_node(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey,
1232            features: NodeFeatures, timestamp: u32) {
1233                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1234                 let unsigned_announcement = UnsignedNodeAnnouncement {
1235                         features,
1236                         timestamp,
1237                         node_id,
1238                         rgb: [0; 3],
1239                         alias: [0; 32],
1240                         addresses: Vec::new(),
1241                         excess_address_data: Vec::new(),
1242                         excess_data: Vec::new(),
1243                 };
1244                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1245                 let valid_announcement = NodeAnnouncement {
1246                         signature: secp_ctx.sign(&msghash, node_privkey),
1247                         contents: unsigned_announcement.clone()
1248                 };
1249
1250                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1251                         Ok(_) => (),
1252                         Err(_) => panic!()
1253                 };
1254         }
1255
1256         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1257                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1258                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1259                 }).collect();
1260
1261                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1262
1263                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1264                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1265
1266                 (our_privkey, our_id, privkeys, pubkeys)
1267         }
1268
1269         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1270                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1271                 // test for it later.
1272                 let idx = (id - 1) * 2 + 1;
1273                 if idx > 8*3 {
1274                         vec![1 << (idx - 8*3), 0, 0, 0]
1275                 } else if idx > 8*2 {
1276                         vec![1 << (idx - 8*2), 0, 0]
1277                 } else if idx > 8*1 {
1278                         vec![1 << (idx - 8*1), 0]
1279                 } else {
1280                         vec![1 << idx]
1281                 }
1282         }
1283
1284         fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<crate::util::test_utils::TestLogger>>, std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<test_utils::TestLogger>) {
1285                 let secp_ctx = Secp256k1::new();
1286                 let logger = Arc::new(test_utils::TestLogger::new());
1287                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1288                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1289                 // Build network from our_id to node7:
1290                 //
1291                 //        -1(1)2-  node0  -1(3)2-
1292                 //       /                       \
1293                 // our_id -1(12)2- node7 -1(13)2--- node2
1294                 //       \                       /
1295                 //        -1(2)2-  node1  -1(4)2-
1296                 //
1297                 //
1298                 // chan1  1-to-2: disabled
1299                 // chan1  2-to-1: enabled, 0 fee
1300                 //
1301                 // chan2  1-to-2: enabled, ignored fee
1302                 // chan2  2-to-1: enabled, 0 fee
1303                 //
1304                 // chan3  1-to-2: enabled, 0 fee
1305                 // chan3  2-to-1: enabled, 100 msat fee
1306                 //
1307                 // chan4  1-to-2: enabled, 100% fee
1308                 // chan4  2-to-1: enabled, 0 fee
1309                 //
1310                 // chan12 1-to-2: enabled, ignored fee
1311                 // chan12 2-to-1: enabled, 0 fee
1312                 //
1313                 // chan13 1-to-2: enabled, 200% fee
1314                 // chan13 2-to-1: enabled, 0 fee
1315                 //
1316                 //
1317                 //       -1(5)2- node3 -1(8)2--
1318                 //       |         2          |
1319                 //       |       (11)         |
1320                 //      /          1           \
1321                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1322                 //      \                      /
1323                 //       -1(7)2- node5 -1(10)2-
1324                 //
1325                 // chan5  1-to-2: enabled, 100 msat fee
1326                 // chan5  2-to-1: enabled, 0 fee
1327                 //
1328                 // chan6  1-to-2: enabled, 0 fee
1329                 // chan6  2-to-1: enabled, 0 fee
1330                 //
1331                 // chan7  1-to-2: enabled, 100% fee
1332                 // chan7  2-to-1: enabled, 0 fee
1333                 //
1334                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1335                 // chan8  2-to-1: enabled, 0 fee
1336                 //
1337                 // chan9  1-to-2: enabled, 1001 msat fee
1338                 // chan9  2-to-1: enabled, 0 fee
1339                 //
1340                 // chan10 1-to-2: enabled, 0 fee
1341                 // chan10 2-to-1: enabled, 0 fee
1342                 //
1343                 // chan11 1-to-2: enabled, 0 fee
1344                 // chan11 2-to-1: enabled, 0 fee
1345
1346                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1347
1348                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1349                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1350                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1351                         short_channel_id: 1,
1352                         timestamp: 1,
1353                         flags: 1,
1354                         cltv_expiry_delta: 0,
1355                         htlc_minimum_msat: 0,
1356                         htlc_maximum_msat: OptionalField::Absent,
1357                         fee_base_msat: 0,
1358                         fee_proportional_millionths: 0,
1359                         excess_data: Vec::new()
1360                 });
1361
1362                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1363
1364                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1365                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1366                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1367                         short_channel_id: 2,
1368                         timestamp: 1,
1369                         flags: 0,
1370                         cltv_expiry_delta: u16::max_value(),
1371                         htlc_minimum_msat: 0,
1372                         htlc_maximum_msat: OptionalField::Absent,
1373                         fee_base_msat: u32::max_value(),
1374                         fee_proportional_millionths: u32::max_value(),
1375                         excess_data: Vec::new()
1376                 });
1377                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1378                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1379                         short_channel_id: 2,
1380                         timestamp: 1,
1381                         flags: 1,
1382                         cltv_expiry_delta: 0,
1383                         htlc_minimum_msat: 0,
1384                         htlc_maximum_msat: OptionalField::Absent,
1385                         fee_base_msat: 0,
1386                         fee_proportional_millionths: 0,
1387                         excess_data: Vec::new()
1388                 });
1389
1390                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1391
1392                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1393                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1394                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1395                         short_channel_id: 12,
1396                         timestamp: 1,
1397                         flags: 0,
1398                         cltv_expiry_delta: u16::max_value(),
1399                         htlc_minimum_msat: 0,
1400                         htlc_maximum_msat: OptionalField::Absent,
1401                         fee_base_msat: u32::max_value(),
1402                         fee_proportional_millionths: u32::max_value(),
1403                         excess_data: Vec::new()
1404                 });
1405                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1406                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1407                         short_channel_id: 12,
1408                         timestamp: 1,
1409                         flags: 1,
1410                         cltv_expiry_delta: 0,
1411                         htlc_minimum_msat: 0,
1412                         htlc_maximum_msat: OptionalField::Absent,
1413                         fee_base_msat: 0,
1414                         fee_proportional_millionths: 0,
1415                         excess_data: Vec::new()
1416                 });
1417
1418                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1419
1420                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1421                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1422                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1423                         short_channel_id: 3,
1424                         timestamp: 1,
1425                         flags: 0,
1426                         cltv_expiry_delta: (3 << 8) | 1,
1427                         htlc_minimum_msat: 0,
1428                         htlc_maximum_msat: OptionalField::Absent,
1429                         fee_base_msat: 0,
1430                         fee_proportional_millionths: 0,
1431                         excess_data: Vec::new()
1432                 });
1433                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1434                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1435                         short_channel_id: 3,
1436                         timestamp: 1,
1437                         flags: 1,
1438                         cltv_expiry_delta: (3 << 8) | 2,
1439                         htlc_minimum_msat: 0,
1440                         htlc_maximum_msat: OptionalField::Absent,
1441                         fee_base_msat: 100,
1442                         fee_proportional_millionths: 0,
1443                         excess_data: Vec::new()
1444                 });
1445
1446                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1447                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1448                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1449                         short_channel_id: 4,
1450                         timestamp: 1,
1451                         flags: 0,
1452                         cltv_expiry_delta: (4 << 8) | 1,
1453                         htlc_minimum_msat: 0,
1454                         htlc_maximum_msat: OptionalField::Absent,
1455                         fee_base_msat: 0,
1456                         fee_proportional_millionths: 1000000,
1457                         excess_data: Vec::new()
1458                 });
1459                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1460                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1461                         short_channel_id: 4,
1462                         timestamp: 1,
1463                         flags: 1,
1464                         cltv_expiry_delta: (4 << 8) | 2,
1465                         htlc_minimum_msat: 0,
1466                         htlc_maximum_msat: OptionalField::Absent,
1467                         fee_base_msat: 0,
1468                         fee_proportional_millionths: 0,
1469                         excess_data: Vec::new()
1470                 });
1471
1472                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1473                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1474                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1475                         short_channel_id: 13,
1476                         timestamp: 1,
1477                         flags: 0,
1478                         cltv_expiry_delta: (13 << 8) | 1,
1479                         htlc_minimum_msat: 0,
1480                         htlc_maximum_msat: OptionalField::Absent,
1481                         fee_base_msat: 0,
1482                         fee_proportional_millionths: 2000000,
1483                         excess_data: Vec::new()
1484                 });
1485                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1486                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1487                         short_channel_id: 13,
1488                         timestamp: 1,
1489                         flags: 1,
1490                         cltv_expiry_delta: (13 << 8) | 2,
1491                         htlc_minimum_msat: 0,
1492                         htlc_maximum_msat: OptionalField::Absent,
1493                         fee_base_msat: 0,
1494                         fee_proportional_millionths: 0,
1495                         excess_data: Vec::new()
1496                 });
1497
1498                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1499
1500                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1501                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1502                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1503                         short_channel_id: 6,
1504                         timestamp: 1,
1505                         flags: 0,
1506                         cltv_expiry_delta: (6 << 8) | 1,
1507                         htlc_minimum_msat: 0,
1508                         htlc_maximum_msat: OptionalField::Absent,
1509                         fee_base_msat: 0,
1510                         fee_proportional_millionths: 0,
1511                         excess_data: Vec::new()
1512                 });
1513                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1514                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1515                         short_channel_id: 6,
1516                         timestamp: 1,
1517                         flags: 1,
1518                         cltv_expiry_delta: (6 << 8) | 2,
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_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1527                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1528                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1529                         short_channel_id: 11,
1530                         timestamp: 1,
1531                         flags: 0,
1532                         cltv_expiry_delta: (11 << 8) | 1,
1533                         htlc_minimum_msat: 0,
1534                         htlc_maximum_msat: OptionalField::Absent,
1535                         fee_base_msat: 0,
1536                         fee_proportional_millionths: 0,
1537                         excess_data: Vec::new()
1538                 });
1539                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1540                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1541                         short_channel_id: 11,
1542                         timestamp: 1,
1543                         flags: 1,
1544                         cltv_expiry_delta: (11 << 8) | 2,
1545                         htlc_minimum_msat: 0,
1546                         htlc_maximum_msat: OptionalField::Absent,
1547                         fee_base_msat: 0,
1548                         fee_proportional_millionths: 0,
1549                         excess_data: Vec::new()
1550                 });
1551
1552                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1553
1554                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1555
1556                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1557                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1558                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1559                         short_channel_id: 7,
1560                         timestamp: 1,
1561                         flags: 0,
1562                         cltv_expiry_delta: (7 << 8) | 1,
1563                         htlc_minimum_msat: 0,
1564                         htlc_maximum_msat: OptionalField::Absent,
1565                         fee_base_msat: 0,
1566                         fee_proportional_millionths: 1000000,
1567                         excess_data: Vec::new()
1568                 });
1569                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1570                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1571                         short_channel_id: 7,
1572                         timestamp: 1,
1573                         flags: 1,
1574                         cltv_expiry_delta: (7 << 8) | 2,
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[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1583
1584                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1585         }
1586
1587         #[test]
1588         fn simple_route_test() {
1589                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1590                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1591
1592                 // Simple route to 2 via 1
1593
1594                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger)) {
1595                         assert_eq!(err, "Cannot send a payment of 0 msat");
1596                 } else { panic!(); }
1597
1598                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1599                 assert_eq!(route.paths[0].len(), 2);
1600
1601                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1602                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1603                 assert_eq!(route.paths[0][0].fee_msat, 100);
1604                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1605                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1606                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1607
1608                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1609                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1610                 assert_eq!(route.paths[0][1].fee_msat, 100);
1611                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1612                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1613                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1614         }
1615
1616         #[test]
1617         fn invalid_first_hop_test() {
1618                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1619                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1620
1621                 // Simple route to 2 via 1
1622
1623                 let our_chans = vec![channelmanager::ChannelDetails {
1624                         channel_id: [0; 32],
1625                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1626                         short_channel_id: Some(2),
1627                         remote_network_id: our_id,
1628                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1629                         channel_value_satoshis: 100000,
1630                         user_id: 0,
1631                         outbound_capacity_msat: 100000,
1632                         inbound_capacity_msat: 100000,
1633                         is_outbound: true, is_funding_locked: true,
1634                         is_usable: true, is_public: true,
1635                         counterparty_forwarding_info: None,
1636                 }];
1637
1638                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
1639                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1640                 } else { panic!(); }
1641
1642                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1643                 assert_eq!(route.paths[0].len(), 2);
1644         }
1645
1646         #[test]
1647         fn htlc_minimum_test() {
1648                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1649                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1650
1651                 // Simple route to 2 via 1
1652
1653                 // Disable other paths
1654                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1655                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1656                         short_channel_id: 12,
1657                         timestamp: 2,
1658                         flags: 2, // to disable
1659                         cltv_expiry_delta: 0,
1660                         htlc_minimum_msat: 0,
1661                         htlc_maximum_msat: OptionalField::Absent,
1662                         fee_base_msat: 0,
1663                         fee_proportional_millionths: 0,
1664                         excess_data: Vec::new()
1665                 });
1666                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1667                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1668                         short_channel_id: 3,
1669                         timestamp: 2,
1670                         flags: 2, // to disable
1671                         cltv_expiry_delta: 0,
1672                         htlc_minimum_msat: 0,
1673                         htlc_maximum_msat: OptionalField::Absent,
1674                         fee_base_msat: 0,
1675                         fee_proportional_millionths: 0,
1676                         excess_data: Vec::new()
1677                 });
1678                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1679                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1680                         short_channel_id: 13,
1681                         timestamp: 2,
1682                         flags: 2, // to disable
1683                         cltv_expiry_delta: 0,
1684                         htlc_minimum_msat: 0,
1685                         htlc_maximum_msat: OptionalField::Absent,
1686                         fee_base_msat: 0,
1687                         fee_proportional_millionths: 0,
1688                         excess_data: Vec::new()
1689                 });
1690                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1691                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1692                         short_channel_id: 6,
1693                         timestamp: 2,
1694                         flags: 2, // to disable
1695                         cltv_expiry_delta: 0,
1696                         htlc_minimum_msat: 0,
1697                         htlc_maximum_msat: OptionalField::Absent,
1698                         fee_base_msat: 0,
1699                         fee_proportional_millionths: 0,
1700                         excess_data: Vec::new()
1701                 });
1702                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1703                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1704                         short_channel_id: 7,
1705                         timestamp: 2,
1706                         flags: 2, // to disable
1707                         cltv_expiry_delta: 0,
1708                         htlc_minimum_msat: 0,
1709                         htlc_maximum_msat: OptionalField::Absent,
1710                         fee_base_msat: 0,
1711                         fee_proportional_millionths: 0,
1712                         excess_data: Vec::new()
1713                 });
1714
1715                 // Check against amount_to_transfer_over_msat.
1716                 // Set minimal HTLC of 200_000_000 msat.
1717                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1718                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1719                         short_channel_id: 2,
1720                         timestamp: 3,
1721                         flags: 0,
1722                         cltv_expiry_delta: 0,
1723                         htlc_minimum_msat: 200_000_000,
1724                         htlc_maximum_msat: OptionalField::Absent,
1725                         fee_base_msat: 0,
1726                         fee_proportional_millionths: 0,
1727                         excess_data: Vec::new()
1728                 });
1729
1730                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1731                 // be used.
1732                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1733                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1734                         short_channel_id: 4,
1735                         timestamp: 3,
1736                         flags: 0,
1737                         cltv_expiry_delta: 0,
1738                         htlc_minimum_msat: 0,
1739                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1740                         fee_base_msat: 0,
1741                         fee_proportional_millionths: 0,
1742                         excess_data: Vec::new()
1743                 });
1744
1745                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1746                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)) {
1747                         assert_eq!(err, "Failed to find a path to the given destination");
1748                 } else { panic!(); }
1749
1750                 // Lift the restriction on the first hop.
1751                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1752                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1753                         short_channel_id: 2,
1754                         timestamp: 4,
1755                         flags: 0,
1756                         cltv_expiry_delta: 0,
1757                         htlc_minimum_msat: 0,
1758                         htlc_maximum_msat: OptionalField::Absent,
1759                         fee_base_msat: 0,
1760                         fee_proportional_millionths: 0,
1761                         excess_data: Vec::new()
1762                 });
1763
1764                 // A payment above the minimum should pass
1765                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)).unwrap();
1766                 assert_eq!(route.paths[0].len(), 2);
1767         }
1768
1769         #[test]
1770         fn htlc_minimum_overpay_test() {
1771                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1772                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1773
1774                 // A route to node#2 via two paths.
1775                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1776                 // Thus, they can't send 60 without overpaying.
1777                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1778                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1779                         short_channel_id: 2,
1780                         timestamp: 2,
1781                         flags: 0,
1782                         cltv_expiry_delta: 0,
1783                         htlc_minimum_msat: 35_000,
1784                         htlc_maximum_msat: OptionalField::Present(40_000),
1785                         fee_base_msat: 0,
1786                         fee_proportional_millionths: 0,
1787                         excess_data: Vec::new()
1788                 });
1789                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1790                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1791                         short_channel_id: 12,
1792                         timestamp: 3,
1793                         flags: 0,
1794                         cltv_expiry_delta: 0,
1795                         htlc_minimum_msat: 35_000,
1796                         htlc_maximum_msat: OptionalField::Present(40_000),
1797                         fee_base_msat: 0,
1798                         fee_proportional_millionths: 0,
1799                         excess_data: Vec::new()
1800                 });
1801
1802                 // Make 0 fee.
1803                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1804                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1805                         short_channel_id: 13,
1806                         timestamp: 2,
1807                         flags: 0,
1808                         cltv_expiry_delta: 0,
1809                         htlc_minimum_msat: 0,
1810                         htlc_maximum_msat: OptionalField::Absent,
1811                         fee_base_msat: 0,
1812                         fee_proportional_millionths: 0,
1813                         excess_data: Vec::new()
1814                 });
1815                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1816                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1817                         short_channel_id: 4,
1818                         timestamp: 2,
1819                         flags: 0,
1820                         cltv_expiry_delta: 0,
1821                         htlc_minimum_msat: 0,
1822                         htlc_maximum_msat: OptionalField::Absent,
1823                         fee_base_msat: 0,
1824                         fee_proportional_millionths: 0,
1825                         excess_data: Vec::new()
1826                 });
1827
1828                 // Disable other paths
1829                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1830                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1831                         short_channel_id: 1,
1832                         timestamp: 3,
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
1842                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1843                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1844                 // Overpay fees to hit htlc_minimum_msat.
1845                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1846                 // TODO: this could be better balanced to overpay 10k and not 15k.
1847                 assert_eq!(overpaid_fees, 15_000);
1848
1849                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1850                 // while taking even more fee to match htlc_minimum_msat.
1851                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1852                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1853                         short_channel_id: 12,
1854                         timestamp: 4,
1855                         flags: 0,
1856                         cltv_expiry_delta: 0,
1857                         htlc_minimum_msat: 65_000,
1858                         htlc_maximum_msat: OptionalField::Present(80_000),
1859                         fee_base_msat: 0,
1860                         fee_proportional_millionths: 0,
1861                         excess_data: Vec::new()
1862                 });
1863                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1864                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1865                         short_channel_id: 2,
1866                         timestamp: 3,
1867                         flags: 0,
1868                         cltv_expiry_delta: 0,
1869                         htlc_minimum_msat: 0,
1870                         htlc_maximum_msat: OptionalField::Absent,
1871                         fee_base_msat: 0,
1872                         fee_proportional_millionths: 0,
1873                         excess_data: Vec::new()
1874                 });
1875                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1876                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1877                         short_channel_id: 4,
1878                         timestamp: 4,
1879                         flags: 0,
1880                         cltv_expiry_delta: 0,
1881                         htlc_minimum_msat: 0,
1882                         htlc_maximum_msat: OptionalField::Absent,
1883                         fee_base_msat: 0,
1884                         fee_proportional_millionths: 100_000,
1885                         excess_data: Vec::new()
1886                 });
1887
1888                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1889                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1890                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1891                 assert_eq!(route.paths.len(), 1);
1892                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1893                 let fees = route.paths[0][0].fee_msat;
1894                 assert_eq!(fees, 5_000);
1895
1896                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1897                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1898                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1899                 // the other channel.
1900                 assert_eq!(route.paths.len(), 1);
1901                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1902                 let fees = route.paths[0][0].fee_msat;
1903                 assert_eq!(fees, 5_000);
1904         }
1905
1906         #[test]
1907         fn disable_channels_test() {
1908                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1909                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1910
1911                 // // Disable channels 4 and 12 by flags=2
1912                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1913                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1914                         short_channel_id: 4,
1915                         timestamp: 2,
1916                         flags: 2, // to disable
1917                         cltv_expiry_delta: 0,
1918                         htlc_minimum_msat: 0,
1919                         htlc_maximum_msat: OptionalField::Absent,
1920                         fee_base_msat: 0,
1921                         fee_proportional_millionths: 0,
1922                         excess_data: Vec::new()
1923                 });
1924                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1925                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1926                         short_channel_id: 12,
1927                         timestamp: 2,
1928                         flags: 2, // to disable
1929                         cltv_expiry_delta: 0,
1930                         htlc_minimum_msat: 0,
1931                         htlc_maximum_msat: OptionalField::Absent,
1932                         fee_base_msat: 0,
1933                         fee_proportional_millionths: 0,
1934                         excess_data: Vec::new()
1935                 });
1936
1937                 // If all the channels require some features we don't understand, route should fail
1938                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1939                         assert_eq!(err, "Failed to find a path to the given destination");
1940                 } else { panic!(); }
1941
1942                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1943                 let our_chans = vec![channelmanager::ChannelDetails {
1944                         channel_id: [0; 32],
1945                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1946                         short_channel_id: Some(42),
1947                         remote_network_id: nodes[7].clone(),
1948                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1949                         channel_value_satoshis: 0,
1950                         user_id: 0,
1951                         outbound_capacity_msat: 250_000_000,
1952                         inbound_capacity_msat: 0,
1953                         is_outbound: true, is_funding_locked: true,
1954                         is_usable: true, is_public: true,
1955                         counterparty_forwarding_info: None,
1956                 }];
1957                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1958                 assert_eq!(route.paths[0].len(), 2);
1959
1960                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1961                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1962                 assert_eq!(route.paths[0][0].fee_msat, 200);
1963                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1964                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1965                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1966
1967                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1968                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1969                 assert_eq!(route.paths[0][1].fee_msat, 100);
1970                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1971                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1972                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1973         }
1974
1975         #[test]
1976         fn disable_node_test() {
1977                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1978                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1979
1980                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1981                 let mut unknown_features = NodeFeatures::known();
1982                 unknown_features.set_required_unknown_bits();
1983                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1984                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1985                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1986
1987                 // If all nodes require some features we don't understand, route should fail
1988                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1989                         assert_eq!(err, "Failed to find a path to the given destination");
1990                 } else { panic!(); }
1991
1992                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1993                 let our_chans = vec![channelmanager::ChannelDetails {
1994                         channel_id: [0; 32],
1995                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1996                         short_channel_id: Some(42),
1997                         remote_network_id: nodes[7].clone(),
1998                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1999                         channel_value_satoshis: 0,
2000                         user_id: 0,
2001                         outbound_capacity_msat: 250_000_000,
2002                         inbound_capacity_msat: 0,
2003                         is_outbound: true, is_funding_locked: true,
2004                         is_usable: true, is_public: true,
2005                         counterparty_forwarding_info: None,
2006                 }];
2007                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2008                 assert_eq!(route.paths[0].len(), 2);
2009
2010                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2011                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2012                 assert_eq!(route.paths[0][0].fee_msat, 200);
2013                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2014                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2015                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2016
2017                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2018                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2019                 assert_eq!(route.paths[0][1].fee_msat, 100);
2020                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2021                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2022                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2023
2024                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2025                 // naively) assume that the user checked the feature bits on the invoice, which override
2026                 // the node_announcement.
2027         }
2028
2029         #[test]
2030         fn our_chans_test() {
2031                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2032                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2033
2034                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2035                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2036                 assert_eq!(route.paths[0].len(), 3);
2037
2038                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2039                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2040                 assert_eq!(route.paths[0][0].fee_msat, 200);
2041                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2042                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2043                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2044
2045                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2046                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2047                 assert_eq!(route.paths[0][1].fee_msat, 100);
2048                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2049                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2050                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2051
2052                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2053                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2054                 assert_eq!(route.paths[0][2].fee_msat, 100);
2055                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2056                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2057                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2058
2059                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2060                 let our_chans = vec![channelmanager::ChannelDetails {
2061                         channel_id: [0; 32],
2062                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2063                         short_channel_id: Some(42),
2064                         remote_network_id: nodes[7].clone(),
2065                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2066                         channel_value_satoshis: 0,
2067                         user_id: 0,
2068                         outbound_capacity_msat: 250_000_000,
2069                         inbound_capacity_msat: 0,
2070                         is_outbound: true, is_funding_locked: true,
2071                         is_usable: true, is_public: true,
2072                         counterparty_forwarding_info: None,
2073                 }];
2074                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2075                 assert_eq!(route.paths[0].len(), 2);
2076
2077                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2078                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2079                 assert_eq!(route.paths[0][0].fee_msat, 200);
2080                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2081                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2082                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2083
2084                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2085                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2086                 assert_eq!(route.paths[0][1].fee_msat, 100);
2087                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2088                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2089                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2090         }
2091
2092         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2093                 let zero_fees = RoutingFees {
2094                         base_msat: 0,
2095                         proportional_millionths: 0,
2096                 };
2097                 vec![RouteHint(vec![RouteHintHop {
2098                         src_node_id: nodes[3].clone(),
2099                         short_channel_id: 8,
2100                         fees: zero_fees,
2101                         cltv_expiry_delta: (8 << 8) | 1,
2102                         htlc_minimum_msat: None,
2103                         htlc_maximum_msat: None,
2104                 }]), RouteHint(vec![RouteHintHop {
2105                         src_node_id: nodes[4].clone(),
2106                         short_channel_id: 9,
2107                         fees: RoutingFees {
2108                                 base_msat: 1001,
2109                                 proportional_millionths: 0,
2110                         },
2111                         cltv_expiry_delta: (9 << 8) | 1,
2112                         htlc_minimum_msat: None,
2113                         htlc_maximum_msat: None,
2114                 }]), RouteHint(vec![RouteHintHop {
2115                         src_node_id: nodes[5].clone(),
2116                         short_channel_id: 10,
2117                         fees: zero_fees,
2118                         cltv_expiry_delta: (10 << 8) | 1,
2119                         htlc_minimum_msat: None,
2120                         htlc_maximum_msat: None,
2121                 }])]
2122         }
2123
2124         #[test]
2125         fn last_hops_test() {
2126                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2127                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2128
2129                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2130
2131                 // First check that last hop can't have its source as the payee.
2132                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2133                         src_node_id: nodes[6],
2134                         short_channel_id: 8,
2135                         fees: RoutingFees {
2136                                 base_msat: 1000,
2137                                 proportional_millionths: 0,
2138                         },
2139                         cltv_expiry_delta: (8 << 8) | 1,
2140                         htlc_minimum_msat: None,
2141                         htlc_maximum_msat: None,
2142                 }]);
2143
2144                 let mut invalid_last_hops = last_hops(&nodes);
2145                 invalid_last_hops.push(invalid_last_hop);
2146                 {
2147                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)) {
2148                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2149                         } else { panic!(); }
2150                 }
2151
2152                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2153                 assert_eq!(route.paths[0].len(), 5);
2154
2155                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2156                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2157                 assert_eq!(route.paths[0][0].fee_msat, 100);
2158                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2159                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2160                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2161
2162                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2163                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2164                 assert_eq!(route.paths[0][1].fee_msat, 0);
2165                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2166                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2167                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2168
2169                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2170                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2171                 assert_eq!(route.paths[0][2].fee_msat, 0);
2172                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2173                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2174                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2175
2176                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2177                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2178                 assert_eq!(route.paths[0][3].fee_msat, 0);
2179                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2180                 // If we have a peer in the node map, we'll use their features here since we don't have
2181                 // a way of figuring out their features from the invoice:
2182                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2183                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2184
2185                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2186                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2187                 assert_eq!(route.paths[0][4].fee_msat, 100);
2188                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2189                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2190                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2191         }
2192
2193         #[test]
2194         fn our_chans_last_hop_connect_test() {
2195                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2196                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2197
2198                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2199                 let our_chans = vec![channelmanager::ChannelDetails {
2200                         channel_id: [0; 32],
2201                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2202                         short_channel_id: Some(42),
2203                         remote_network_id: nodes[3].clone(),
2204                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2205                         channel_value_satoshis: 0,
2206                         user_id: 0,
2207                         outbound_capacity_msat: 250_000_000,
2208                         inbound_capacity_msat: 0,
2209                         is_outbound: true, is_funding_locked: true,
2210                         is_usable: true, is_public: true,
2211                         counterparty_forwarding_info: None,
2212                 }];
2213                 let mut last_hops = last_hops(&nodes);
2214                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2215                 assert_eq!(route.paths[0].len(), 2);
2216
2217                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2218                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2219                 assert_eq!(route.paths[0][0].fee_msat, 0);
2220                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2221                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2222                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2223
2224                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2225                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2226                 assert_eq!(route.paths[0][1].fee_msat, 100);
2227                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2228                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2229                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2230
2231                 last_hops[0].0[0].fees.base_msat = 1000;
2232
2233                 // Revert to via 6 as the fee on 8 goes up
2234                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2235                 assert_eq!(route.paths[0].len(), 4);
2236
2237                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2238                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2239                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2240                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2241                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2242                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2243
2244                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2245                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2246                 assert_eq!(route.paths[0][1].fee_msat, 100);
2247                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2248                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2249                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2250
2251                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2252                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2253                 assert_eq!(route.paths[0][2].fee_msat, 0);
2254                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2255                 // If we have a peer in the node map, we'll use their features here since we don't have
2256                 // a way of figuring out their features from the invoice:
2257                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2258                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2259
2260                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2261                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2262                 assert_eq!(route.paths[0][3].fee_msat, 100);
2263                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2264                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2265                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2266
2267                 // ...but still use 8 for larger payments as 6 has a variable feerate
2268                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger)).unwrap();
2269                 assert_eq!(route.paths[0].len(), 5);
2270
2271                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2272                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2273                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2274                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2275                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2276                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2277
2278                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2279                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2280                 assert_eq!(route.paths[0][1].fee_msat, 0);
2281                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2282                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2283                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2284
2285                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2286                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2287                 assert_eq!(route.paths[0][2].fee_msat, 0);
2288                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2289                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2290                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2291
2292                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2293                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2294                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2295                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2296                 // If we have a peer in the node map, we'll use their features here since we don't have
2297                 // a way of figuring out their features from the invoice:
2298                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2299                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2300
2301                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2302                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2303                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2304                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2305                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2306                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2307         }
2308
2309         #[test]
2310         fn unannounced_path_test() {
2311                 // We should be able to send a payment to a destination without any help of a routing graph
2312                 // if we have a channel with a common counterparty that appears in the first and last hop
2313                 // hints.
2314                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2315                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2316                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2317
2318                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2319                 let last_hops = RouteHint(vec![RouteHintHop {
2320                         src_node_id: middle_node_id,
2321                         short_channel_id: 8,
2322                         fees: RoutingFees {
2323                                 base_msat: 1000,
2324                                 proportional_millionths: 0,
2325                         },
2326                         cltv_expiry_delta: (8 << 8) | 1,
2327                         htlc_minimum_msat: None,
2328                         htlc_maximum_msat: None,
2329                 }]);
2330                 let our_chans = vec![channelmanager::ChannelDetails {
2331                         channel_id: [0; 32],
2332                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2333                         short_channel_id: Some(42),
2334                         remote_network_id: middle_node_id,
2335                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2336                         channel_value_satoshis: 100000,
2337                         user_id: 0,
2338                         outbound_capacity_msat: 100000,
2339                         inbound_capacity_msat: 100000,
2340                         is_outbound: true, is_funding_locked: true,
2341                         is_usable: true, is_public: true,
2342                         counterparty_forwarding_info: None,
2343                 }];
2344                 let route = get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &vec![&last_hops], 100, 42, Arc::new(test_utils::TestLogger::new())).unwrap();
2345
2346                 assert_eq!(route.paths[0].len(), 2);
2347
2348                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2349                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2350                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2351                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2352                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2353                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2354
2355                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2356                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2357                 assert_eq!(route.paths[0][1].fee_msat, 100);
2358                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2359                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2360                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2361         }
2362
2363         #[test]
2364         fn available_amount_while_routing_test() {
2365                 // Tests whether we choose the correct available channel amount while routing.
2366
2367                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2368                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2369
2370                 // We will use a simple single-path route from
2371                 // our node to node2 via node0: channels {1, 3}.
2372
2373                 // First disable all other paths.
2374                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2375                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2376                         short_channel_id: 2,
2377                         timestamp: 2,
2378                         flags: 2,
2379                         cltv_expiry_delta: 0,
2380                         htlc_minimum_msat: 0,
2381                         htlc_maximum_msat: OptionalField::Present(100_000),
2382                         fee_base_msat: 0,
2383                         fee_proportional_millionths: 0,
2384                         excess_data: Vec::new()
2385                 });
2386                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2387                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2388                         short_channel_id: 12,
2389                         timestamp: 2,
2390                         flags: 2,
2391                         cltv_expiry_delta: 0,
2392                         htlc_minimum_msat: 0,
2393                         htlc_maximum_msat: OptionalField::Present(100_000),
2394                         fee_base_msat: 0,
2395                         fee_proportional_millionths: 0,
2396                         excess_data: Vec::new()
2397                 });
2398
2399                 // Make the first channel (#1) very permissive,
2400                 // and we will be testing all limits on the second channel.
2401                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2402                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2403                         short_channel_id: 1,
2404                         timestamp: 2,
2405                         flags: 0,
2406                         cltv_expiry_delta: 0,
2407                         htlc_minimum_msat: 0,
2408                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2409                         fee_base_msat: 0,
2410                         fee_proportional_millionths: 0,
2411                         excess_data: Vec::new()
2412                 });
2413
2414                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2415                 // In this case, it should be set to 250_000 sats.
2416                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2417                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2418                         short_channel_id: 3,
2419                         timestamp: 2,
2420                         flags: 0,
2421                         cltv_expiry_delta: 0,
2422                         htlc_minimum_msat: 0,
2423                         htlc_maximum_msat: OptionalField::Absent,
2424                         fee_base_msat: 0,
2425                         fee_proportional_millionths: 0,
2426                         excess_data: Vec::new()
2427                 });
2428
2429                 {
2430                         // Attempt to route more than available results in a failure.
2431                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2432                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2433                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2434                         } else { panic!(); }
2435                 }
2436
2437                 {
2438                         // Now, attempt to route an exact amount we have should be fine.
2439                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2440                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2441                         assert_eq!(route.paths.len(), 1);
2442                         let path = route.paths.last().unwrap();
2443                         assert_eq!(path.len(), 2);
2444                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2445                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2446                 }
2447
2448                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2449                 // Disable channel #1 and use another first hop.
2450                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2451                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2452                         short_channel_id: 1,
2453                         timestamp: 3,
2454                         flags: 2,
2455                         cltv_expiry_delta: 0,
2456                         htlc_minimum_msat: 0,
2457                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2458                         fee_base_msat: 0,
2459                         fee_proportional_millionths: 0,
2460                         excess_data: Vec::new()
2461                 });
2462
2463                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2464                 let our_chans = vec![channelmanager::ChannelDetails {
2465                         channel_id: [0; 32],
2466                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
2467                         short_channel_id: Some(42),
2468                         remote_network_id: nodes[0].clone(),
2469                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2470                         channel_value_satoshis: 0,
2471                         user_id: 0,
2472                         outbound_capacity_msat: 200_000_000,
2473                         inbound_capacity_msat: 0,
2474                         is_outbound: true, is_funding_locked: true,
2475                         is_usable: true, is_public: true,
2476                         counterparty_forwarding_info: None,
2477                 }];
2478
2479                 {
2480                         // Attempt to route more than available results in a failure.
2481                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2482                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2483                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2484                         } else { panic!(); }
2485                 }
2486
2487                 {
2488                         // Now, attempt to route an exact amount we have should be fine.
2489                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2490                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2491                         assert_eq!(route.paths.len(), 1);
2492                         let path = route.paths.last().unwrap();
2493                         assert_eq!(path.len(), 2);
2494                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2495                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2496                 }
2497
2498                 // Enable channel #1 back.
2499                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2500                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2501                         short_channel_id: 1,
2502                         timestamp: 4,
2503                         flags: 0,
2504                         cltv_expiry_delta: 0,
2505                         htlc_minimum_msat: 0,
2506                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2507                         fee_base_msat: 0,
2508                         fee_proportional_millionths: 0,
2509                         excess_data: Vec::new()
2510                 });
2511
2512
2513                 // Now let's see if routing works if we know only htlc_maximum_msat.
2514                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2515                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2516                         short_channel_id: 3,
2517                         timestamp: 3,
2518                         flags: 0,
2519                         cltv_expiry_delta: 0,
2520                         htlc_minimum_msat: 0,
2521                         htlc_maximum_msat: OptionalField::Present(15_000),
2522                         fee_base_msat: 0,
2523                         fee_proportional_millionths: 0,
2524                         excess_data: Vec::new()
2525                 });
2526
2527                 {
2528                         // Attempt to route more than available results in a failure.
2529                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2530                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2531                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2532                         } else { panic!(); }
2533                 }
2534
2535                 {
2536                         // Now, attempt to route an exact amount we have should be fine.
2537                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2538                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2539                         assert_eq!(route.paths.len(), 1);
2540                         let path = route.paths.last().unwrap();
2541                         assert_eq!(path.len(), 2);
2542                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2543                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2544                 }
2545
2546                 // Now let's see if routing works if we know only capacity from the UTXO.
2547
2548                 // We can't change UTXO capacity on the fly, so we'll disable
2549                 // the existing channel and add another one with the capacity we need.
2550                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2551                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2552                         short_channel_id: 3,
2553                         timestamp: 4,
2554                         flags: 2,
2555                         cltv_expiry_delta: 0,
2556                         htlc_minimum_msat: 0,
2557                         htlc_maximum_msat: OptionalField::Absent,
2558                         fee_base_msat: 0,
2559                         fee_proportional_millionths: 0,
2560                         excess_data: Vec::new()
2561                 });
2562
2563                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2564                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2565                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2566                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2567                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2568
2569                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2570                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2571
2572                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2573                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2574                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2575                         short_channel_id: 333,
2576                         timestamp: 1,
2577                         flags: 0,
2578                         cltv_expiry_delta: (3 << 8) | 1,
2579                         htlc_minimum_msat: 0,
2580                         htlc_maximum_msat: OptionalField::Absent,
2581                         fee_base_msat: 0,
2582                         fee_proportional_millionths: 0,
2583                         excess_data: Vec::new()
2584                 });
2585                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2586                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2587                         short_channel_id: 333,
2588                         timestamp: 1,
2589                         flags: 1,
2590                         cltv_expiry_delta: (3 << 8) | 2,
2591                         htlc_minimum_msat: 0,
2592                         htlc_maximum_msat: OptionalField::Absent,
2593                         fee_base_msat: 100,
2594                         fee_proportional_millionths: 0,
2595                         excess_data: Vec::new()
2596                 });
2597
2598                 {
2599                         // Attempt to route more than available results in a failure.
2600                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2601                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2602                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2603                         } else { panic!(); }
2604                 }
2605
2606                 {
2607                         // Now, attempt to route an exact amount we have should be fine.
2608                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2609                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2610                         assert_eq!(route.paths.len(), 1);
2611                         let path = route.paths.last().unwrap();
2612                         assert_eq!(path.len(), 2);
2613                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2614                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2615                 }
2616
2617                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2618                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2619                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2620                         short_channel_id: 333,
2621                         timestamp: 6,
2622                         flags: 0,
2623                         cltv_expiry_delta: 0,
2624                         htlc_minimum_msat: 0,
2625                         htlc_maximum_msat: OptionalField::Present(10_000),
2626                         fee_base_msat: 0,
2627                         fee_proportional_millionths: 0,
2628                         excess_data: Vec::new()
2629                 });
2630
2631                 {
2632                         // Attempt to route more than available results in a failure.
2633                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2634                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2635                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2636                         } else { panic!(); }
2637                 }
2638
2639                 {
2640                         // Now, attempt to route an exact amount we have should be fine.
2641                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2642                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2643                         assert_eq!(route.paths.len(), 1);
2644                         let path = route.paths.last().unwrap();
2645                         assert_eq!(path.len(), 2);
2646                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2647                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2648                 }
2649         }
2650
2651         #[test]
2652         fn available_liquidity_last_hop_test() {
2653                 // Check that available liquidity properly limits the path even when only
2654                 // one of the latter hops is limited.
2655                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2656                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2657
2658                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2659                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2660                 // Total capacity: 50 sats.
2661
2662                 // Disable other potential paths.
2663                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2664                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2665                         short_channel_id: 2,
2666                         timestamp: 2,
2667                         flags: 2,
2668                         cltv_expiry_delta: 0,
2669                         htlc_minimum_msat: 0,
2670                         htlc_maximum_msat: OptionalField::Present(100_000),
2671                         fee_base_msat: 0,
2672                         fee_proportional_millionths: 0,
2673                         excess_data: Vec::new()
2674                 });
2675                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2676                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2677                         short_channel_id: 7,
2678                         timestamp: 2,
2679                         flags: 2,
2680                         cltv_expiry_delta: 0,
2681                         htlc_minimum_msat: 0,
2682                         htlc_maximum_msat: OptionalField::Present(100_000),
2683                         fee_base_msat: 0,
2684                         fee_proportional_millionths: 0,
2685                         excess_data: Vec::new()
2686                 });
2687
2688                 // Limit capacities
2689
2690                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2691                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2692                         short_channel_id: 12,
2693                         timestamp: 2,
2694                         flags: 0,
2695                         cltv_expiry_delta: 0,
2696                         htlc_minimum_msat: 0,
2697                         htlc_maximum_msat: OptionalField::Present(100_000),
2698                         fee_base_msat: 0,
2699                         fee_proportional_millionths: 0,
2700                         excess_data: Vec::new()
2701                 });
2702                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2703                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2704                         short_channel_id: 13,
2705                         timestamp: 2,
2706                         flags: 0,
2707                         cltv_expiry_delta: 0,
2708                         htlc_minimum_msat: 0,
2709                         htlc_maximum_msat: OptionalField::Present(100_000),
2710                         fee_base_msat: 0,
2711                         fee_proportional_millionths: 0,
2712                         excess_data: Vec::new()
2713                 });
2714
2715                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2716                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2717                         short_channel_id: 6,
2718                         timestamp: 2,
2719                         flags: 0,
2720                         cltv_expiry_delta: 0,
2721                         htlc_minimum_msat: 0,
2722                         htlc_maximum_msat: OptionalField::Present(50_000),
2723                         fee_base_msat: 0,
2724                         fee_proportional_millionths: 0,
2725                         excess_data: Vec::new()
2726                 });
2727                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2728                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2729                         short_channel_id: 11,
2730                         timestamp: 2,
2731                         flags: 0,
2732                         cltv_expiry_delta: 0,
2733                         htlc_minimum_msat: 0,
2734                         htlc_maximum_msat: OptionalField::Present(100_000),
2735                         fee_base_msat: 0,
2736                         fee_proportional_millionths: 0,
2737                         excess_data: Vec::new()
2738                 });
2739                 {
2740                         // Attempt to route more than available results in a failure.
2741                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2742                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2743                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2744                         } else { panic!(); }
2745                 }
2746
2747                 {
2748                         // Now, attempt to route 49 sats (just a bit below the capacity).
2749                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2750                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2751                         assert_eq!(route.paths.len(), 1);
2752                         let mut total_amount_paid_msat = 0;
2753                         for path in &route.paths {
2754                                 assert_eq!(path.len(), 4);
2755                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2756                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2757                         }
2758                         assert_eq!(total_amount_paid_msat, 49_000);
2759                 }
2760
2761                 {
2762                         // Attempt to route an exact amount is also fine
2763                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2764                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2765                         assert_eq!(route.paths.len(), 1);
2766                         let mut total_amount_paid_msat = 0;
2767                         for path in &route.paths {
2768                                 assert_eq!(path.len(), 4);
2769                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2770                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2771                         }
2772                         assert_eq!(total_amount_paid_msat, 50_000);
2773                 }
2774         }
2775
2776         #[test]
2777         fn ignore_fee_first_hop_test() {
2778                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2779                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2780
2781                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2782                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2783                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2784                         short_channel_id: 1,
2785                         timestamp: 2,
2786                         flags: 0,
2787                         cltv_expiry_delta: 0,
2788                         htlc_minimum_msat: 0,
2789                         htlc_maximum_msat: OptionalField::Present(100_000),
2790                         fee_base_msat: 1_000_000,
2791                         fee_proportional_millionths: 0,
2792                         excess_data: Vec::new()
2793                 });
2794                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2795                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2796                         short_channel_id: 3,
2797                         timestamp: 2,
2798                         flags: 0,
2799                         cltv_expiry_delta: 0,
2800                         htlc_minimum_msat: 0,
2801                         htlc_maximum_msat: OptionalField::Present(50_000),
2802                         fee_base_msat: 0,
2803                         fee_proportional_millionths: 0,
2804                         excess_data: Vec::new()
2805                 });
2806
2807                 {
2808                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2809                         assert_eq!(route.paths.len(), 1);
2810                         let mut total_amount_paid_msat = 0;
2811                         for path in &route.paths {
2812                                 assert_eq!(path.len(), 2);
2813                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2814                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2815                         }
2816                         assert_eq!(total_amount_paid_msat, 50_000);
2817                 }
2818         }
2819
2820         #[test]
2821         fn simple_mpp_route_test() {
2822                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2823                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2824
2825                 // We need a route consisting of 3 paths:
2826                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2827                 // To achieve this, the amount being transferred should be around
2828                 // the total capacity of these 3 paths.
2829
2830                 // First, we set limits on these (previously unlimited) channels.
2831                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2832
2833                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2834                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2835                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2836                         short_channel_id: 1,
2837                         timestamp: 2,
2838                         flags: 0,
2839                         cltv_expiry_delta: 0,
2840                         htlc_minimum_msat: 0,
2841                         htlc_maximum_msat: OptionalField::Present(100_000),
2842                         fee_base_msat: 0,
2843                         fee_proportional_millionths: 0,
2844                         excess_data: Vec::new()
2845                 });
2846                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2847                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2848                         short_channel_id: 3,
2849                         timestamp: 2,
2850                         flags: 0,
2851                         cltv_expiry_delta: 0,
2852                         htlc_minimum_msat: 0,
2853                         htlc_maximum_msat: OptionalField::Present(50_000),
2854                         fee_base_msat: 0,
2855                         fee_proportional_millionths: 0,
2856                         excess_data: Vec::new()
2857                 });
2858
2859                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2860                 // (total limit 60).
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: 12,
2864                         timestamp: 2,
2865                         flags: 0,
2866                         cltv_expiry_delta: 0,
2867                         htlc_minimum_msat: 0,
2868                         htlc_maximum_msat: OptionalField::Present(60_000),
2869                         fee_base_msat: 0,
2870                         fee_proportional_millionths: 0,
2871                         excess_data: Vec::new()
2872                 });
2873                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2874                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2875                         short_channel_id: 13,
2876                         timestamp: 2,
2877                         flags: 0,
2878                         cltv_expiry_delta: 0,
2879                         htlc_minimum_msat: 0,
2880                         htlc_maximum_msat: OptionalField::Present(60_000),
2881                         fee_base_msat: 0,
2882                         fee_proportional_millionths: 0,
2883                         excess_data: Vec::new()
2884                 });
2885
2886                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2887                 // (total capacity 180 sats).
2888                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2889                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2890                         short_channel_id: 2,
2891                         timestamp: 2,
2892                         flags: 0,
2893                         cltv_expiry_delta: 0,
2894                         htlc_minimum_msat: 0,
2895                         htlc_maximum_msat: OptionalField::Present(200_000),
2896                         fee_base_msat: 0,
2897                         fee_proportional_millionths: 0,
2898                         excess_data: Vec::new()
2899                 });
2900                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2901                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2902                         short_channel_id: 4,
2903                         timestamp: 2,
2904                         flags: 0,
2905                         cltv_expiry_delta: 0,
2906                         htlc_minimum_msat: 0,
2907                         htlc_maximum_msat: OptionalField::Present(180_000),
2908                         fee_base_msat: 0,
2909                         fee_proportional_millionths: 0,
2910                         excess_data: Vec::new()
2911                 });
2912
2913                 {
2914                         // Attempt to route more than available results in a failure.
2915                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2916                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2917                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2918                         } else { panic!(); }
2919                 }
2920
2921                 {
2922                         // Now, attempt to route 250 sats (just a bit below the capacity).
2923                         // Our algorithm should provide us with these 3 paths.
2924                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2925                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2926                         assert_eq!(route.paths.len(), 3);
2927                         let mut total_amount_paid_msat = 0;
2928                         for path in &route.paths {
2929                                 assert_eq!(path.len(), 2);
2930                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2931                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2932                         }
2933                         assert_eq!(total_amount_paid_msat, 250_000);
2934                 }
2935
2936                 {
2937                         // Attempt to route an exact amount is also fine
2938                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2939                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2940                         assert_eq!(route.paths.len(), 3);
2941                         let mut total_amount_paid_msat = 0;
2942                         for path in &route.paths {
2943                                 assert_eq!(path.len(), 2);
2944                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2945                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2946                         }
2947                         assert_eq!(total_amount_paid_msat, 290_000);
2948                 }
2949         }
2950
2951         #[test]
2952         fn long_mpp_route_test() {
2953                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2954                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2955
2956                 // We need a route consisting of 3 paths:
2957                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2958                 // Note that these paths overlap (channels 5, 12, 13).
2959                 // We will route 300 sats.
2960                 // Each path will have 100 sats capacity, those channels which
2961                 // are used twice will have 200 sats capacity.
2962
2963                 // Disable other potential paths.
2964                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2965                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2966                         short_channel_id: 2,
2967                         timestamp: 2,
2968                         flags: 2,
2969                         cltv_expiry_delta: 0,
2970                         htlc_minimum_msat: 0,
2971                         htlc_maximum_msat: OptionalField::Present(100_000),
2972                         fee_base_msat: 0,
2973                         fee_proportional_millionths: 0,
2974                         excess_data: Vec::new()
2975                 });
2976                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2977                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2978                         short_channel_id: 7,
2979                         timestamp: 2,
2980                         flags: 2,
2981                         cltv_expiry_delta: 0,
2982                         htlc_minimum_msat: 0,
2983                         htlc_maximum_msat: OptionalField::Present(100_000),
2984                         fee_base_msat: 0,
2985                         fee_proportional_millionths: 0,
2986                         excess_data: Vec::new()
2987                 });
2988
2989                 // Path via {node0, node2} is channels {1, 3, 5}.
2990                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2991                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2992                         short_channel_id: 1,
2993                         timestamp: 2,
2994                         flags: 0,
2995                         cltv_expiry_delta: 0,
2996                         htlc_minimum_msat: 0,
2997                         htlc_maximum_msat: OptionalField::Present(100_000),
2998                         fee_base_msat: 0,
2999                         fee_proportional_millionths: 0,
3000                         excess_data: Vec::new()
3001                 });
3002                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3003                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3004                         short_channel_id: 3,
3005                         timestamp: 2,
3006                         flags: 0,
3007                         cltv_expiry_delta: 0,
3008                         htlc_minimum_msat: 0,
3009                         htlc_maximum_msat: OptionalField::Present(100_000),
3010                         fee_base_msat: 0,
3011                         fee_proportional_millionths: 0,
3012                         excess_data: Vec::new()
3013                 });
3014
3015                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3016                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3017                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3018                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3019                         short_channel_id: 5,
3020                         timestamp: 2,
3021                         flags: 0,
3022                         cltv_expiry_delta: 0,
3023                         htlc_minimum_msat: 0,
3024                         htlc_maximum_msat: OptionalField::Present(200_000),
3025                         fee_base_msat: 0,
3026                         fee_proportional_millionths: 0,
3027                         excess_data: Vec::new()
3028                 });
3029
3030                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3031                 // Add 100 sats to the capacities of {12, 13}, because these channels
3032                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3033                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3034                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3035                         short_channel_id: 12,
3036                         timestamp: 2,
3037                         flags: 0,
3038                         cltv_expiry_delta: 0,
3039                         htlc_minimum_msat: 0,
3040                         htlc_maximum_msat: OptionalField::Present(200_000),
3041                         fee_base_msat: 0,
3042                         fee_proportional_millionths: 0,
3043                         excess_data: Vec::new()
3044                 });
3045                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3046                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3047                         short_channel_id: 13,
3048                         timestamp: 2,
3049                         flags: 0,
3050                         cltv_expiry_delta: 0,
3051                         htlc_minimum_msat: 0,
3052                         htlc_maximum_msat: OptionalField::Present(200_000),
3053                         fee_base_msat: 0,
3054                         fee_proportional_millionths: 0,
3055                         excess_data: Vec::new()
3056                 });
3057
3058                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3059                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3060                         short_channel_id: 6,
3061                         timestamp: 2,
3062                         flags: 0,
3063                         cltv_expiry_delta: 0,
3064                         htlc_minimum_msat: 0,
3065                         htlc_maximum_msat: OptionalField::Present(100_000),
3066                         fee_base_msat: 0,
3067                         fee_proportional_millionths: 0,
3068                         excess_data: Vec::new()
3069                 });
3070                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3071                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3072                         short_channel_id: 11,
3073                         timestamp: 2,
3074                         flags: 0,
3075                         cltv_expiry_delta: 0,
3076                         htlc_minimum_msat: 0,
3077                         htlc_maximum_msat: OptionalField::Present(100_000),
3078                         fee_base_msat: 0,
3079                         fee_proportional_millionths: 0,
3080                         excess_data: Vec::new()
3081                 });
3082
3083                 // Path via {node7, node2} is channels {12, 13, 5}.
3084                 // We already limited them to 200 sats (they are used twice for 100 sats).
3085                 // Nothing to do here.
3086
3087                 {
3088                         // Attempt to route more than available results in a failure.
3089                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3090                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3091                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3092                         } else { panic!(); }
3093                 }
3094
3095                 {
3096                         // Now, attempt to route 300 sats (exact amount we can route).
3097                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3098                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3099                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3100                         assert_eq!(route.paths.len(), 3);
3101
3102                         let mut total_amount_paid_msat = 0;
3103                         for path in &route.paths {
3104                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3105                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3106                         }
3107                         assert_eq!(total_amount_paid_msat, 300_000);
3108                 }
3109
3110         }
3111
3112         #[test]
3113         fn mpp_cheaper_route_test() {
3114                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3115                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3116
3117                 // This test checks that if we have two cheaper paths and one more expensive path,
3118                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3119                 // two cheaper paths will be taken.
3120                 // These paths have equal available liquidity.
3121
3122                 // We need a combination of 3 paths:
3123                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3124                 // Note that these paths overlap (channels 5, 12, 13).
3125                 // Each path will have 100 sats capacity, those channels which
3126                 // are used twice will have 200 sats capacity.
3127
3128                 // Disable other potential paths.
3129                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3130                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3131                         short_channel_id: 2,
3132                         timestamp: 2,
3133                         flags: 2,
3134                         cltv_expiry_delta: 0,
3135                         htlc_minimum_msat: 0,
3136                         htlc_maximum_msat: OptionalField::Present(100_000),
3137                         fee_base_msat: 0,
3138                         fee_proportional_millionths: 0,
3139                         excess_data: Vec::new()
3140                 });
3141                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3142                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3143                         short_channel_id: 7,
3144                         timestamp: 2,
3145                         flags: 2,
3146                         cltv_expiry_delta: 0,
3147                         htlc_minimum_msat: 0,
3148                         htlc_maximum_msat: OptionalField::Present(100_000),
3149                         fee_base_msat: 0,
3150                         fee_proportional_millionths: 0,
3151                         excess_data: Vec::new()
3152                 });
3153
3154                 // Path via {node0, node2} is channels {1, 3, 5}.
3155                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3156                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3157                         short_channel_id: 1,
3158                         timestamp: 2,
3159                         flags: 0,
3160                         cltv_expiry_delta: 0,
3161                         htlc_minimum_msat: 0,
3162                         htlc_maximum_msat: OptionalField::Present(100_000),
3163                         fee_base_msat: 0,
3164                         fee_proportional_millionths: 0,
3165                         excess_data: Vec::new()
3166                 });
3167                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3168                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3169                         short_channel_id: 3,
3170                         timestamp: 2,
3171                         flags: 0,
3172                         cltv_expiry_delta: 0,
3173                         htlc_minimum_msat: 0,
3174                         htlc_maximum_msat: OptionalField::Present(100_000),
3175                         fee_base_msat: 0,
3176                         fee_proportional_millionths: 0,
3177                         excess_data: Vec::new()
3178                 });
3179
3180                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3181                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3182                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3183                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3184                         short_channel_id: 5,
3185                         timestamp: 2,
3186                         flags: 0,
3187                         cltv_expiry_delta: 0,
3188                         htlc_minimum_msat: 0,
3189                         htlc_maximum_msat: OptionalField::Present(200_000),
3190                         fee_base_msat: 0,
3191                         fee_proportional_millionths: 0,
3192                         excess_data: Vec::new()
3193                 });
3194
3195                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3196                 // Add 100 sats to the capacities of {12, 13}, because these channels
3197                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3198                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3199                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3200                         short_channel_id: 12,
3201                         timestamp: 2,
3202                         flags: 0,
3203                         cltv_expiry_delta: 0,
3204                         htlc_minimum_msat: 0,
3205                         htlc_maximum_msat: OptionalField::Present(200_000),
3206                         fee_base_msat: 0,
3207                         fee_proportional_millionths: 0,
3208                         excess_data: Vec::new()
3209                 });
3210                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3211                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3212                         short_channel_id: 13,
3213                         timestamp: 2,
3214                         flags: 0,
3215                         cltv_expiry_delta: 0,
3216                         htlc_minimum_msat: 0,
3217                         htlc_maximum_msat: OptionalField::Present(200_000),
3218                         fee_base_msat: 0,
3219                         fee_proportional_millionths: 0,
3220                         excess_data: Vec::new()
3221                 });
3222
3223                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3224                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3225                         short_channel_id: 6,
3226                         timestamp: 2,
3227                         flags: 0,
3228                         cltv_expiry_delta: 0,
3229                         htlc_minimum_msat: 0,
3230                         htlc_maximum_msat: OptionalField::Present(100_000),
3231                         fee_base_msat: 1_000,
3232                         fee_proportional_millionths: 0,
3233                         excess_data: Vec::new()
3234                 });
3235                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3236                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3237                         short_channel_id: 11,
3238                         timestamp: 2,
3239                         flags: 0,
3240                         cltv_expiry_delta: 0,
3241                         htlc_minimum_msat: 0,
3242                         htlc_maximum_msat: OptionalField::Present(100_000),
3243                         fee_base_msat: 0,
3244                         fee_proportional_millionths: 0,
3245                         excess_data: Vec::new()
3246                 });
3247
3248                 // Path via {node7, node2} is channels {12, 13, 5}.
3249                 // We already limited them to 200 sats (they are used twice for 100 sats).
3250                 // Nothing to do here.
3251
3252                 {
3253                         // Now, attempt to route 180 sats.
3254                         // Our algorithm should provide us with these 2 paths.
3255                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3256                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3257                         assert_eq!(route.paths.len(), 2);
3258
3259                         let mut total_value_transferred_msat = 0;
3260                         let mut total_paid_msat = 0;
3261                         for path in &route.paths {
3262                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3263                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3264                                 for hop in path {
3265                                         total_paid_msat += hop.fee_msat;
3266                                 }
3267                         }
3268                         // If we paid fee, this would be higher.
3269                         assert_eq!(total_value_transferred_msat, 180_000);
3270                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3271                         assert_eq!(total_fees_paid, 0);
3272                 }
3273         }
3274
3275         #[test]
3276         fn fees_on_mpp_route_test() {
3277                 // This test makes sure that MPP algorithm properly takes into account
3278                 // fees charged on the channels, by making the fees impactful:
3279                 // if the fee is not properly accounted for, the behavior is different.
3280                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3281                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3282
3283                 // We need a route consisting of 2 paths:
3284                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3285                 // We will route 200 sats, Each path will have 100 sats capacity.
3286
3287                 // This test is not particularly stable: e.g.,
3288                 // there's a way to route via {node0, node2, node4}.
3289                 // It works while pathfinding is deterministic, but can be broken otherwise.
3290                 // It's fine to ignore this concern for now.
3291
3292                 // Disable other potential paths.
3293                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3294                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3295                         short_channel_id: 2,
3296                         timestamp: 2,
3297                         flags: 2,
3298                         cltv_expiry_delta: 0,
3299                         htlc_minimum_msat: 0,
3300                         htlc_maximum_msat: OptionalField::Present(100_000),
3301                         fee_base_msat: 0,
3302                         fee_proportional_millionths: 0,
3303                         excess_data: Vec::new()
3304                 });
3305
3306                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3307                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3308                         short_channel_id: 7,
3309                         timestamp: 2,
3310                         flags: 2,
3311                         cltv_expiry_delta: 0,
3312                         htlc_minimum_msat: 0,
3313                         htlc_maximum_msat: OptionalField::Present(100_000),
3314                         fee_base_msat: 0,
3315                         fee_proportional_millionths: 0,
3316                         excess_data: Vec::new()
3317                 });
3318
3319                 // Path via {node0, node2} is channels {1, 3, 5}.
3320                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3321                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3322                         short_channel_id: 1,
3323                         timestamp: 2,
3324                         flags: 0,
3325                         cltv_expiry_delta: 0,
3326                         htlc_minimum_msat: 0,
3327                         htlc_maximum_msat: OptionalField::Present(100_000),
3328                         fee_base_msat: 0,
3329                         fee_proportional_millionths: 0,
3330                         excess_data: Vec::new()
3331                 });
3332                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3333                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3334                         short_channel_id: 3,
3335                         timestamp: 2,
3336                         flags: 0,
3337                         cltv_expiry_delta: 0,
3338                         htlc_minimum_msat: 0,
3339                         htlc_maximum_msat: OptionalField::Present(100_000),
3340                         fee_base_msat: 0,
3341                         fee_proportional_millionths: 0,
3342                         excess_data: Vec::new()
3343                 });
3344
3345                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3346                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3347                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3348                         short_channel_id: 5,
3349                         timestamp: 2,
3350                         flags: 0,
3351                         cltv_expiry_delta: 0,
3352                         htlc_minimum_msat: 0,
3353                         htlc_maximum_msat: OptionalField::Present(100_000),
3354                         fee_base_msat: 0,
3355                         fee_proportional_millionths: 0,
3356                         excess_data: Vec::new()
3357                 });
3358
3359                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3360                 // All channels should be 100 sats capacity. But for the fee experiment,
3361                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3362                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3363                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3364                 // so no matter how large are other channels,
3365                 // the whole path will be limited by 100 sats with just these 2 conditions:
3366                 // - channel 12 capacity is 250 sats
3367                 // - fee for channel 6 is 150 sats
3368                 // Let's test this by enforcing these 2 conditions and removing other limits.
3369                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3370                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3371                         short_channel_id: 12,
3372                         timestamp: 2,
3373                         flags: 0,
3374                         cltv_expiry_delta: 0,
3375                         htlc_minimum_msat: 0,
3376                         htlc_maximum_msat: OptionalField::Present(250_000),
3377                         fee_base_msat: 0,
3378                         fee_proportional_millionths: 0,
3379                         excess_data: Vec::new()
3380                 });
3381                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3382                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3383                         short_channel_id: 13,
3384                         timestamp: 2,
3385                         flags: 0,
3386                         cltv_expiry_delta: 0,
3387                         htlc_minimum_msat: 0,
3388                         htlc_maximum_msat: OptionalField::Absent,
3389                         fee_base_msat: 0,
3390                         fee_proportional_millionths: 0,
3391                         excess_data: Vec::new()
3392                 });
3393
3394                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3395                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3396                         short_channel_id: 6,
3397                         timestamp: 2,
3398                         flags: 0,
3399                         cltv_expiry_delta: 0,
3400                         htlc_minimum_msat: 0,
3401                         htlc_maximum_msat: OptionalField::Absent,
3402                         fee_base_msat: 150_000,
3403                         fee_proportional_millionths: 0,
3404                         excess_data: Vec::new()
3405                 });
3406                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3407                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3408                         short_channel_id: 11,
3409                         timestamp: 2,
3410                         flags: 0,
3411                         cltv_expiry_delta: 0,
3412                         htlc_minimum_msat: 0,
3413                         htlc_maximum_msat: OptionalField::Absent,
3414                         fee_base_msat: 0,
3415                         fee_proportional_millionths: 0,
3416                         excess_data: Vec::new()
3417                 });
3418
3419                 {
3420                         // Attempt to route more than available results in a failure.
3421                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3422                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3423                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3424                         } else { panic!(); }
3425                 }
3426
3427                 {
3428                         // Now, attempt to route 200 sats (exact amount we can route).
3429                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3430                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3431                         assert_eq!(route.paths.len(), 2);
3432
3433                         let mut total_amount_paid_msat = 0;
3434                         for path in &route.paths {
3435                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3436                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3437                         }
3438                         assert_eq!(total_amount_paid_msat, 200_000);
3439                 }
3440
3441         }
3442
3443         #[test]
3444         fn drop_lowest_channel_mpp_route_test() {
3445                 // This test checks that low-capacity channel is dropped when after
3446                 // path finding we realize that we found more capacity than we need.
3447                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3448                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3449
3450                 // We need a route consisting of 3 paths:
3451                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3452
3453                 // The first and the second paths should be sufficient, but the third should be
3454                 // cheaper, so that we select it but drop later.
3455
3456                 // First, we set limits on these (previously unlimited) channels.
3457                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3458
3459                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3460                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3461                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3462                         short_channel_id: 1,
3463                         timestamp: 2,
3464                         flags: 0,
3465                         cltv_expiry_delta: 0,
3466                         htlc_minimum_msat: 0,
3467                         htlc_maximum_msat: OptionalField::Present(100_000),
3468                         fee_base_msat: 0,
3469                         fee_proportional_millionths: 0,
3470                         excess_data: Vec::new()
3471                 });
3472                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3473                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3474                         short_channel_id: 3,
3475                         timestamp: 2,
3476                         flags: 0,
3477                         cltv_expiry_delta: 0,
3478                         htlc_minimum_msat: 0,
3479                         htlc_maximum_msat: OptionalField::Present(50_000),
3480                         fee_base_msat: 100,
3481                         fee_proportional_millionths: 0,
3482                         excess_data: Vec::new()
3483                 });
3484
3485                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3486                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3487                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3488                         short_channel_id: 12,
3489                         timestamp: 2,
3490                         flags: 0,
3491                         cltv_expiry_delta: 0,
3492                         htlc_minimum_msat: 0,
3493                         htlc_maximum_msat: OptionalField::Present(60_000),
3494                         fee_base_msat: 100,
3495                         fee_proportional_millionths: 0,
3496                         excess_data: Vec::new()
3497                 });
3498                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3499                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3500                         short_channel_id: 13,
3501                         timestamp: 2,
3502                         flags: 0,
3503                         cltv_expiry_delta: 0,
3504                         htlc_minimum_msat: 0,
3505                         htlc_maximum_msat: OptionalField::Present(60_000),
3506                         fee_base_msat: 0,
3507                         fee_proportional_millionths: 0,
3508                         excess_data: Vec::new()
3509                 });
3510
3511                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3512                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3513                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3514                         short_channel_id: 2,
3515                         timestamp: 2,
3516                         flags: 0,
3517                         cltv_expiry_delta: 0,
3518                         htlc_minimum_msat: 0,
3519                         htlc_maximum_msat: OptionalField::Present(20_000),
3520                         fee_base_msat: 0,
3521                         fee_proportional_millionths: 0,
3522                         excess_data: Vec::new()
3523                 });
3524                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3525                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3526                         short_channel_id: 4,
3527                         timestamp: 2,
3528                         flags: 0,
3529                         cltv_expiry_delta: 0,
3530                         htlc_minimum_msat: 0,
3531                         htlc_maximum_msat: OptionalField::Present(20_000),
3532                         fee_base_msat: 0,
3533                         fee_proportional_millionths: 0,
3534                         excess_data: Vec::new()
3535                 });
3536
3537                 {
3538                         // Attempt to route more than available results in a failure.
3539                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3540                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3541                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3542                         } else { panic!(); }
3543                 }
3544
3545                 {
3546                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3547                         // Our algorithm should provide us with these 3 paths.
3548                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3549                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3550                         assert_eq!(route.paths.len(), 3);
3551                         let mut total_amount_paid_msat = 0;
3552                         for path in &route.paths {
3553                                 assert_eq!(path.len(), 2);
3554                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3555                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3556                         }
3557                         assert_eq!(total_amount_paid_msat, 125_000);
3558                 }
3559
3560                 {
3561                         // Attempt to route without the last small cheap channel
3562                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3563                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3564                         assert_eq!(route.paths.len(), 2);
3565                         let mut total_amount_paid_msat = 0;
3566                         for path in &route.paths {
3567                                 assert_eq!(path.len(), 2);
3568                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3569                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3570                         }
3571                         assert_eq!(total_amount_paid_msat, 90_000);
3572                 }
3573         }
3574
3575         #[test]
3576         fn min_criteria_consistency() {
3577                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3578                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3579                 // was updated with a different criterion from the heap sorting, resulting in loops in
3580                 // calculated paths. We test for that specific case here.
3581
3582                 // We construct a network that looks like this:
3583                 //
3584                 //            node2 -1(3)2- node3
3585                 //              2          2
3586                 //               (2)     (4)
3587                 //                  1   1
3588                 //    node1 -1(5)2- node4 -1(1)2- node6
3589                 //    2
3590                 //   (6)
3591                 //        1
3592                 // our_node
3593                 //
3594                 // We create a loop on the side of our real path - our destination is node 6, with a
3595                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3596                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3597                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3598                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3599                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3600                 // "previous hop" being set to node 3, creating a loop in the path.
3601                 let secp_ctx = Secp256k1::new();
3602                 let logger = Arc::new(test_utils::TestLogger::new());
3603                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3604                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3605
3606                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3607                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3608                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3609                         short_channel_id: 6,
3610                         timestamp: 1,
3611                         flags: 0,
3612                         cltv_expiry_delta: (6 << 8) | 0,
3613                         htlc_minimum_msat: 0,
3614                         htlc_maximum_msat: OptionalField::Absent,
3615                         fee_base_msat: 0,
3616                         fee_proportional_millionths: 0,
3617                         excess_data: Vec::new()
3618                 });
3619                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3620
3621                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3622                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3623                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3624                         short_channel_id: 5,
3625                         timestamp: 1,
3626                         flags: 0,
3627                         cltv_expiry_delta: (5 << 8) | 0,
3628                         htlc_minimum_msat: 0,
3629                         htlc_maximum_msat: OptionalField::Absent,
3630                         fee_base_msat: 100,
3631                         fee_proportional_millionths: 0,
3632                         excess_data: Vec::new()
3633                 });
3634                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3635
3636                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3637                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3638                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3639                         short_channel_id: 4,
3640                         timestamp: 1,
3641                         flags: 0,
3642                         cltv_expiry_delta: (4 << 8) | 0,
3643                         htlc_minimum_msat: 0,
3644                         htlc_maximum_msat: OptionalField::Absent,
3645                         fee_base_msat: 0,
3646                         fee_proportional_millionths: 0,
3647                         excess_data: Vec::new()
3648                 });
3649                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3650
3651                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3652                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3653                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3654                         short_channel_id: 3,
3655                         timestamp: 1,
3656                         flags: 0,
3657                         cltv_expiry_delta: (3 << 8) | 0,
3658                         htlc_minimum_msat: 0,
3659                         htlc_maximum_msat: OptionalField::Absent,
3660                         fee_base_msat: 0,
3661                         fee_proportional_millionths: 0,
3662                         excess_data: Vec::new()
3663                 });
3664                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
3665
3666                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
3667                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3668                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3669                         short_channel_id: 2,
3670                         timestamp: 1,
3671                         flags: 0,
3672                         cltv_expiry_delta: (2 << 8) | 0,
3673                         htlc_minimum_msat: 0,
3674                         htlc_maximum_msat: OptionalField::Absent,
3675                         fee_base_msat: 0,
3676                         fee_proportional_millionths: 0,
3677                         excess_data: Vec::new()
3678                 });
3679
3680                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
3681                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3682                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3683                         short_channel_id: 1,
3684                         timestamp: 1,
3685                         flags: 0,
3686                         cltv_expiry_delta: (1 << 8) | 0,
3687                         htlc_minimum_msat: 100,
3688                         htlc_maximum_msat: OptionalField::Absent,
3689                         fee_base_msat: 0,
3690                         fee_proportional_millionths: 0,
3691                         excess_data: Vec::new()
3692                 });
3693                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
3694
3695                 {
3696                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
3697                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
3698                         assert_eq!(route.paths.len(), 1);
3699                         assert_eq!(route.paths[0].len(), 3);
3700
3701                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
3702                         assert_eq!(route.paths[0][0].short_channel_id, 6);
3703                         assert_eq!(route.paths[0][0].fee_msat, 100);
3704                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
3705                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
3706                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
3707
3708                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
3709                         assert_eq!(route.paths[0][1].short_channel_id, 5);
3710                         assert_eq!(route.paths[0][1].fee_msat, 0);
3711                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
3712                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
3713                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
3714
3715                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
3716                         assert_eq!(route.paths[0][2].short_channel_id, 1);
3717                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
3718                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
3719                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
3720                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
3721                 }
3722         }
3723
3724
3725         #[test]
3726         fn exact_fee_liquidity_limit() {
3727                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
3728                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
3729                 // we calculated fees on a higher value, resulting in us ignoring such paths.
3730                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3731                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
3732
3733                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
3734                 // send.
3735                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3736                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3737                         short_channel_id: 2,
3738                         timestamp: 2,
3739                         flags: 0,
3740                         cltv_expiry_delta: 0,
3741                         htlc_minimum_msat: 0,
3742                         htlc_maximum_msat: OptionalField::Present(85_000),
3743                         fee_base_msat: 0,
3744                         fee_proportional_millionths: 0,
3745                         excess_data: Vec::new()
3746                 });
3747
3748                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3749                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3750                         short_channel_id: 12,
3751                         timestamp: 2,
3752                         flags: 0,
3753                         cltv_expiry_delta: (4 << 8) | 1,
3754                         htlc_minimum_msat: 0,
3755                         htlc_maximum_msat: OptionalField::Present(270_000),
3756                         fee_base_msat: 0,
3757                         fee_proportional_millionths: 1000000,
3758                         excess_data: Vec::new()
3759                 });
3760
3761                 {
3762                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
3763                         // 200% fee charged channel 13 in the 1-to-2 direction.
3764                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3765                         assert_eq!(route.paths.len(), 1);
3766                         assert_eq!(route.paths[0].len(), 2);
3767
3768                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3769                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3770                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3771                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3772                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3773                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3774
3775                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3776                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3777                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3778                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3779                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
3780                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3781                 }
3782         }
3783
3784         #[test]
3785         fn htlc_max_reduction_below_min() {
3786                 // Test that if, while walking the graph, we reduce the value being sent to meet an
3787                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
3788                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
3789                 // resulting in us thinking there is no possible path, even if other paths exist.
3790                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3791                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3792
3793                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
3794                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
3795                 // then try to send 90_000.
3796                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3797                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3798                         short_channel_id: 2,
3799                         timestamp: 2,
3800                         flags: 0,
3801                         cltv_expiry_delta: 0,
3802                         htlc_minimum_msat: 0,
3803                         htlc_maximum_msat: OptionalField::Present(80_000),
3804                         fee_base_msat: 0,
3805                         fee_proportional_millionths: 0,
3806                         excess_data: Vec::new()
3807                 });
3808                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3809                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3810                         short_channel_id: 4,
3811                         timestamp: 2,
3812                         flags: 0,
3813                         cltv_expiry_delta: (4 << 8) | 1,
3814                         htlc_minimum_msat: 90_000,
3815                         htlc_maximum_msat: OptionalField::Absent,
3816                         fee_base_msat: 0,
3817                         fee_proportional_millionths: 0,
3818                         excess_data: Vec::new()
3819                 });
3820
3821                 {
3822                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
3823                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
3824                         // expensive) channels 12-13 path.
3825                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3826                         assert_eq!(route.paths.len(), 1);
3827                         assert_eq!(route.paths[0].len(), 2);
3828
3829                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3830                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3831                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3832                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3833                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3834                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3835
3836                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3837                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3838                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3839                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3840                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
3841                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3842                 }
3843         }
3844
3845         #[cfg(not(feature = "no_std"))]
3846         pub(super) fn random_init_seed() -> u64 {
3847                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
3848                 use core::hash::{BuildHasher, Hasher};
3849                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
3850                 println!("Using seed of {}", seed);
3851                 seed
3852         }
3853         #[cfg(not(feature = "no_std"))]
3854         use util::ser::Readable;
3855
3856         #[test]
3857         #[cfg(not(feature = "no_std"))]
3858         fn generate_routes() {
3859                 let mut d = match super::test_utils::get_route_file() {
3860                         Ok(f) => f,
3861                         Err(e) => {
3862                                 eprintln!("{}", e);
3863                                 return;
3864                         },
3865                 };
3866                 let graph = NetworkGraph::read(&mut d).unwrap();
3867
3868                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3869                 let mut seed = random_init_seed() as usize;
3870                 'load_endpoints: for _ in 0..10 {
3871                         loop {
3872                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3873                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3874                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3875                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3876                                 let amt = seed as u64 % 200_000_000;
3877                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3878                                         continue 'load_endpoints;
3879                                 }
3880                         }
3881                 }
3882         }
3883
3884         #[test]
3885         #[cfg(not(feature = "no_std"))]
3886         fn generate_routes_mpp() {
3887                 let mut d = match super::test_utils::get_route_file() {
3888                         Ok(f) => f,
3889                         Err(e) => {
3890                                 eprintln!("{}", e);
3891                                 return;
3892                         },
3893                 };
3894                 let graph = NetworkGraph::read(&mut d).unwrap();
3895
3896                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3897                 let mut seed = random_init_seed() as usize;
3898                 'load_endpoints: for _ in 0..10 {
3899                         loop {
3900                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3901                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3902                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3903                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3904                                 let amt = seed as u64 % 200_000_000;
3905                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3906                                         continue 'load_endpoints;
3907                                 }
3908                         }
3909                 }
3910         }
3911 }
3912
3913 #[cfg(all(test, not(feature = "no_std")))]
3914 pub(crate) mod test_utils {
3915         use std::fs::File;
3916         /// Tries to open a network graph file, or panics with a URL to fetch it.
3917         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
3918                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
3919                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
3920                         .or_else(|_| { // Fall back to guessing based on the binary location
3921                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
3922                                 let mut path = std::env::current_exe().unwrap();
3923                                 path.pop(); // lightning-...
3924                                 path.pop(); // deps
3925                                 path.pop(); // debug
3926                                 path.pop(); // target
3927                                 path.push("lightning");
3928                                 path.push("net_graph-2021-05-31.bin");
3929                                 eprintln!("{}", path.to_str().unwrap());
3930                                 File::open(path)
3931                         })
3932                 .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");
3933                 #[cfg(require_route_graph_test)]
3934                 return Ok(res.unwrap());
3935                 #[cfg(not(require_route_graph_test))]
3936                 return res;
3937         }
3938 }
3939
3940 #[cfg(all(test, feature = "unstable", not(feature = "no_std")))]
3941 mod benches {
3942         use super::*;
3943         use util::logger::{Logger, Record};
3944
3945         use test::Bencher;
3946
3947         struct DummyLogger {}
3948         impl Logger for DummyLogger {
3949                 fn log(&self, _record: &Record) {}
3950         }
3951
3952         #[bench]
3953         fn generate_routes(bench: &mut Bencher) {
3954                 let mut d = test_utils::get_route_file().unwrap();
3955                 let graph = NetworkGraph::read(&mut d).unwrap();
3956
3957                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3958                 let mut path_endpoints = Vec::new();
3959                 let mut seed: usize = 0xdeadbeef;
3960                 'load_endpoints: for _ in 0..100 {
3961                         loop {
3962                                 seed *= 0xdeadbeef;
3963                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3964                                 seed *= 0xdeadbeef;
3965                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3966                                 let amt = seed as u64 % 1_000_000;
3967                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3968                                         path_endpoints.push((src, dst, amt));
3969                                         continue 'load_endpoints;
3970                                 }
3971                         }
3972                 }
3973
3974                 // ...then benchmark finding paths between the nodes we learned.
3975                 let mut idx = 0;
3976                 bench.iter(|| {
3977                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3978                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3979                         idx += 1;
3980                 });
3981         }
3982
3983         #[bench]
3984         fn generate_mpp_routes(bench: &mut Bencher) {
3985                 let mut d = test_utils::get_route_file().unwrap();
3986                 let graph = NetworkGraph::read(&mut d).unwrap();
3987
3988                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3989                 let mut path_endpoints = Vec::new();
3990                 let mut seed: usize = 0xdeadbeef;
3991                 'load_endpoints: for _ in 0..100 {
3992                         loop {
3993                                 seed *= 0xdeadbeef;
3994                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3995                                 seed *= 0xdeadbeef;
3996                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3997                                 let amt = seed as u64 % 1_000_000;
3998                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3999                                         path_endpoints.push((src, dst, amt));
4000                                         continue 'load_endpoints;
4001                                 }
4002                         }
4003                 }
4004
4005                 // ...then benchmark finding paths between the nodes we learned.
4006                 let mut idx = 0;
4007                 bench.iter(|| {
4008                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4009                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
4010                         idx += 1;
4011                 });
4012         }
4013 }