_ 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 io;
  25 use prelude::*;
  26 use alloc::collections::BinaryHeap;
  27 use core::cmp;
  28 use core::ops::Deref;
  29
  30 /// A hop in a route
  31 #[derive(Clone, Hash, PartialEq, Eq)]
  32 pub struct RouteHop {
  33         /// The node_id of the node at this hop.
  34         pub pubkey: PublicKey,
  35         /// The node_announcement features of the node at this hop. For the last hop, these may be
  36         /// amended to match the features present in the invoice this node generated.
  37         pub node_features: NodeFeatures,
  38         /// The channel that should be used from the previous hop to reach this node.
  39         pub short_channel_id: u64,
  40         /// The channel_announcement features of the channel that should be used from the previous hop
  41         /// to reach this node.
  42         pub channel_features: ChannelFeatures,
  43         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  44         /// For the last hop, this should be the full value of the payment (might be more than
  45         /// requested if we had to match htlc_minimum_msat).
  46         pub fee_msat: u64,
  47         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  48         /// expected at the destination, in excess of the current block height.
  49         pub cltv_expiry_delta: u32,
  50 }
  51
  52 impl_writeable_tlv_based!(RouteHop, {
  53         (0, pubkey, required),
  54         (2, node_features, required),
  55         (4, short_channel_id, required),
  56         (6, channel_features, required),
  57         (8, fee_msat, required),
  58         (10, cltv_expiry_delta, required),
  59 });
  60
  61 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  62 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  63 #[derive(Clone, Hash, PartialEq, Eq)]
  64 pub struct Route {
  65         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  66         /// last RouteHop in each path must be the same.
  67         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  68         /// destination. Thus, this must always be at least length one. While the maximum length of any
  69         /// given path is variable, keeping the length of any path to less than 20 should currently
  70         /// ensure it is viable.
  71         pub paths: Vec<Vec<RouteHop>>,
  72 }
  73
  74 const SERIALIZATION_VERSION: u8 = 1;
  75 const MIN_SERIALIZATION_VERSION: u8 = 1;
  76
  77 impl Writeable for Route {
  78         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
  79                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
  80                 (self.paths.len() as u64).write(writer)?;
  81                 for hops in self.paths.iter() {
  82                         (hops.len() as u8).write(writer)?;
  83                         for hop in hops.iter() {
  84                                 hop.write(writer)?;
  85                         }
  86                 }
  87                 write_tlv_fields!(writer, {});
  88                 Ok(())
  89         }
  90 }
  91
  92 impl Readable for Route {
  93         fn read<R: io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
  94                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
  95                 let path_count: u64 = Readable::read(reader)?;
  96                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
  97                 for _ in 0..path_count {
  98                         let hop_count: u8 = Readable::read(reader)?;
  99                         let mut hops = Vec::with_capacity(hop_count as usize);
 100                         for _ in 0..hop_count {
 101                                 hops.push(Readable::read(reader)?);
 102                         }
 103                         paths.push(hops);
 104                 }
 105                 read_tlv_fields!(reader, {});
 106                 Ok(Route { paths })
 107         }
 108 }
 109
 110 /// A list of hops along a payment path terminating with a channel to the recipient.
 111 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 112 pub struct RouteHint(pub Vec<RouteHintHop>);
 113
 114 /// A channel descriptor for a hop along a payment path.
 115 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 116 pub struct RouteHintHop {
 117         /// The node_id of the non-target end of the route
 118         pub src_node_id: PublicKey,
 119         /// The short_channel_id of this channel
 120         pub short_channel_id: u64,
 121         /// The fees which must be paid to use this channel
 122         pub fees: RoutingFees,
 123         /// The difference in CLTV values between this node and the next node.
 124         pub cltv_expiry_delta: u16,
 125         /// The minimum value, in msat, which must be relayed to the next hop.
 126         pub htlc_minimum_msat: Option<u64>,
 127         /// The maximum value in msat available for routing with a single HTLC.
 128         pub htlc_maximum_msat: Option<u64>,
 129 }
 130
 131 #[derive(Eq, PartialEq)]
 132 struct RouteGraphNode {
 133         pubkey: PublicKey,
 134         lowest_fee_to_peer_through_node: u64,
 135         lowest_fee_to_node: u64,
 136         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 137         // This value is upper-bounded by us by:
 138         // - how much is needed for a path being constructed
 139         // - how much value can channels following this node (up to the destination) can contribute,
 140         //   considering their capacity and fees
 141         value_contribution_msat: u64,
 142         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 143         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 144         path_htlc_minimum_msat: u64,
 145 }
 146
 147 impl cmp::Ord for RouteGraphNode {
 148         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 149                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 150                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 151                 other_score.cmp(&self_score).then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 152         }
 153 }
 154
 155 impl cmp::PartialOrd for RouteGraphNode {
 156         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 157                 Some(self.cmp(other))
 158         }
 159 }
 160
 161 struct DummyDirectionalChannelInfo {
 162         cltv_expiry_delta: u32,
 163         htlc_minimum_msat: u64,
 164         htlc_maximum_msat: Option<u64>,
 165         fees: RoutingFees,
 166 }
 167
 168 /// It's useful to keep track of the hops associated with the fees required to use them,
 169 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 170 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 171 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 172 #[derive(Clone, Debug)]
 173 struct PathBuildingHop<'a> {
 174         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 175         // Note that node_features is calculated separately after our initial graph walk.
 176         pubkey: PublicKey,
 177         short_channel_id: u64,
 178         channel_features: &'a ChannelFeatures,
 179         fee_msat: u64,
 180         cltv_expiry_delta: u32,
 181
 182         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 183         src_lowest_inbound_fees: RoutingFees,
 184         /// Fees of the channel used in this hop.
 185         channel_fees: RoutingFees,
 186         /// All the fees paid *after* this channel on the way to the destination
 187         next_hops_fee_msat: u64,
 188         /// Fee paid for the use of the current channel (see channel_fees).
 189         /// The value will be actually deducted from the counterparty balance on the previous link.
 190         hop_use_fee_msat: u64,
 191         /// Used to compare channels when choosing the for routing.
 192         /// Includes paying for the use of a hop and the following hops, as well as
 193         /// an estimated cost of reaching this hop.
 194         /// Might get stale when fees are recomputed. Primarily for internal use.
 195         total_fee_msat: u64,
 196         /// This is useful for update_value_and_recompute_fees to make sure
 197         /// we don't fall below the minimum. Should not be updated manually and
 198         /// generally should not be accessed.
 199         htlc_minimum_msat: u64,
 200         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 201         /// walk and may be invalid thereafter.
 202         path_htlc_minimum_msat: u64,
 203         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 204         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 205         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 206         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 207         /// avoid processing them again.
 208         was_processed: bool,
 209         #[cfg(any(test, feature = "fuzztarget"))]
 210         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 211         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 212         // value_contribution_msat, which requires tracking it here. See comments below where it is
 213         // used for more info.
 214         value_contribution_msat: u64,
 215 }
 216
 217 // Instantiated with a list of hops with correct data in them collected during path finding,
 218 // an instance of this struct should be further modified only via given methods.
 219 #[derive(Clone)]
 220 struct PaymentPath<'a> {
 221         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 222 }
 223
 224 impl<'a> PaymentPath<'a> {
 225         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 226         fn get_value_msat(&self) -> u64 {
 227                 self.hops.last().unwrap().0.fee_msat
 228         }
 229
 230         fn get_total_fee_paid_msat(&self) -> u64 {
 231                 if self.hops.len() < 1 {
 232                         return 0;
 233                 }
 234                 let mut result = 0;
 235                 // Can't use next_hops_fee_msat because it gets outdated.
 236                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 237                         if i != self.hops.len() - 1 {
 238                                 result += hop.fee_msat;
 239                         }
 240                 }
 241                 return result;
 242         }
 243
 244         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 245         // to change fees may result in an inconsistency.
 246         //
 247         // Sometimes we call this function right after constructing a path which is inconsistent in
 248         // that it the value being transferred has decreased while we were doing path finding, leading
 249         // to the fees being paid not lining up with the actual limits.
 250         //
 251         // Note that this function is not aware of the available_liquidity limit, and thus does not
 252         // support increasing the value being transferred.
 253         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 254                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 255
 256                 let mut total_fee_paid_msat = 0 as u64;
 257                 for i in (0..self.hops.len()).rev() {
 258                         let last_hop = i == self.hops.len() - 1;
 259
 260                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 261                         // will consist of the fees for the use of the next hop, and extra fees to match
 262                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 263                         let mut cur_hop_fees_msat = 0;
 264                         if !last_hop {
 265                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 266                         }
 267
 268                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 269                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 270                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 271                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 272                         // set it too high just to maliciously take more fees by exploiting this
 273                         // match htlc_minimum_msat logic.
 274                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 275                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 276                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 277                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 278                                 //
 279                                 // This might make us end up with a broken route, although this should be super-rare
 280                                 // in practice, both because of how healthy channels look like, and how we pick
 281                                 // channels in add_entry.
 282                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 283                                 // all payments*.
 284                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 285                                 total_fee_paid_msat += extra_fees_msat;
 286                                 cur_hop_fees_msat += extra_fees_msat;
 287                         }
 288
 289                         if last_hop {
 290                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 291                                 // it still could overpay for the htlc_minimum_msat.
 292                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 293                         } else {
 294                                 // Propagate updated fees for the use of the channels to one hop back, where they
 295                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 296                                 cur_hop.fee_msat = cur_hop_fees_msat;
 297                         }
 298
 299                         // Fee for the use of the current hop which will be deducted on the previous hop.
 300                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 301                         // this channel is free for us.
 302                         if i != 0 {
 303                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 304                                         cur_hop.hop_use_fee_msat = new_fee;
 305                                         total_fee_paid_msat += new_fee;
 306                                 } else {
 307                                         // It should not be possible because this function is called only to reduce the
 308                                         // value. In that case, compute_fee was already called with the same fees for
 309                                         // larger amount and there was no overflow.
 310                                         unreachable!();
 311                                 }
 312                         }
 313                 }
 314         }
 315 }
 316
 317 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 318         let proportional_fee_millions =
 319                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 320         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 321                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 322
 323                 Some(new_fee)
 324         } else {
 325                 // This function may be (indirectly) called without any verification,
 326                 // with channel_fees provided by a caller. We should handle it gracefully.
 327                 None
 328         }
 329 }
 330
 331 /// Gets a keysend route from us (payer) to the given target node (payee). This is needed because
 332 /// keysend payments do not have an invoice from which to pull the payee's supported features, which
 333 /// makes it tricky to otherwise supply the `payee_features` parameter of `get_route`.
 334 pub fn get_keysend_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee:
 335                        &PublicKey, first_hops: Option<&[&ChannelDetails]>, last_hops: &[&RouteHint],
 336                        final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route,
 337                        LightningError> where L::Target: Logger {
 338         let invoice_features = InvoiceFeatures::for_keysend();
 339         get_route(our_node_id, network, payee, Some(invoice_features), first_hops, last_hops,
 340             final_value_msat, final_cltv, logger)
 341 }
 342
 343 /// Gets a route from us (payer) to the given target node (payee).
 344 ///
 345 /// If the payee provided features in their invoice, they should be provided via payee_features.
 346 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 347 ///
 348 /// Private routing paths between a public node and the target may be included in `last_hops`.
 349 /// Currently, only the last hop in each path is considered.
 350 ///
 351 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 352 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 353 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 354 /// in first_hops will be used.
 355 ///
 356 /// Panics if first_hops contains channels without short_channel_ids
 357 /// (ChannelManager::list_usable_channels will never include such channels).
 358 ///
 359 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 360 /// equal), however the enabled/disabled bit on such channels as well as the
 361 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 362 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 363         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 364         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 365         // uptime/success in using a node in the past.
 366         if *payee == *our_node_id {
 367                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 368         }
 369
 370         if final_value_msat > MAX_VALUE_MSAT {
 371                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 372         }
 373
 374         if final_value_msat == 0 {
 375                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 376         }
 377
 378         for route in last_hops.iter() {
 379                 for hop in &route.0 {
 380                         if hop.src_node_id == *payee {
 381                                 return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 382                         }
 383                 }
 384         }
 385
 386         // The general routing idea is the following:
 387         // 1. Fill first/last hops communicated by the caller.
 388         // 2. Attempt to construct a path from payer to payee for transferring
 389         //    any ~sufficient (described later) value.
 390         //    If succeed, remember which channels were used and how much liquidity they have available,
 391         //    so that future paths don't rely on the same liquidity.
 392         // 3. Prooceed to the next step if:
 393         //    - we hit the recommended target value;
 394         //    - OR if we could not construct a new path. Any next attempt will fail too.
 395         //    Otherwise, repeat step 2.
 396         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 397         //    (not recommended value). If yes, proceed. If not, fail routing.
 398         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 399         // 6. Of all the found paths, select only those with the lowest total fee.
 400         // 7. The last path in every selected route is likely to be more than we need.
 401         //    Reduce its value-to-transfer and recompute fees.
 402         // 8. Choose the best route by the lowest total fee.
 403
 404         // As for the actual search algorithm,
 405         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 406         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 407         //
 408         // We are not a faithful Dijkstra's implementation because we can change values which impact
 409         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 410         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 411         // the value we are currently attempting to send over a path, we simply reduce the value being
 412         // sent along the path for any hops after that channel. This may imply that later fees (which
 413         // we've already tabulated) are lower because a smaller value is passing through the channels
 414         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 415         // channels which were selected earlier (and which may still be used for other paths without a
 416         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 417         // de-preferenced.
 418         //
 419         // One potentially problematic case for this algorithm would be if there are many
 420         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 421         // graph walking), we may never find a path which is not liquidity-limited and has lower
 422         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 423         // Because we only consider paths with at least 5% of the total value being sent, the damage
 424         // from such a case should be limited, however this could be further reduced in the future by
 425         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 426         // limits for the purposes of fee calculation.
 427         //
 428         // Alternatively, we could store more detailed path information in the heap (targets, below)
 429         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 430         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 431         // and practically (as we would need to store dynamically-allocated path information in heap
 432         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 433         // results of such an algorithm would likely be biased towards lower-value paths.
 434         //
 435         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 436         // outside of our current search value, running a path search more times to gather candidate
 437         // paths at different values. While this may be acceptable, further path searches may increase
 438         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 439         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 440         // the same time, remaining generic across different payment values.
 441         //
 442         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 443         // to use as the A* heuristic beyond just the cost to get one node further than the current
 444         // one.
 445
 446         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 447                 cltv_expiry_delta: 0,
 448                 htlc_minimum_msat: 0,
 449                 htlc_maximum_msat: None,
 450                 fees: RoutingFees {
 451                         base_msat: 0,
 452                         proportional_millionths: 0,
 453                 }
 454         };
 455
 456         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 457         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 458         // work reliably.
 459         let allow_mpp = if let Some(features) = &payee_features {
 460                 features.supports_basic_mpp()
 461         } else if let Some(node) = network.get_nodes().get(&payee) {
 462                 if let Some(node_info) = node.announcement_info.as_ref() {
 463                         node_info.features.supports_basic_mpp()
 464                 } else { false }
 465         } else { false };
 466
 467         // Step (1).
 468         // Prepare the data we'll use for payee-to-payer search by
 469         // inserting first hops suggested by the caller as targets.
 470         // Our search will then attempt to reach them while traversing from the payee node.
 471         let mut first_hop_targets: HashMap<_, (_, ChannelFeatures, _, NodeFeatures)> =
 472                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 473         if let Some(hops) = first_hops {
 474                 for chan in hops {
 475                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 476                         if chan.counterparty.node_id == *our_node_id {
 477                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 478                         }
 479                         first_hop_targets.insert(chan.counterparty.node_id, (short_channel_id, chan.counterparty.features.to_context(), chan.outbound_capacity_msat, chan.counterparty.features.to_context()));
 480                 }
 481                 if first_hop_targets.is_empty() {
 482                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 483                 }
 484         }
 485
 486         let empty_channel_features = ChannelFeatures::empty();
 487
 488         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 489         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 490         // adding duplicate entries when we find a better path to a given node.
 491         let mut targets = BinaryHeap::new();
 492
 493         // Map from node_id to information about the best current path to that node, including feerate
 494         // information.
 495         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 496
 497         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 498         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 499         // htlc_minimum with extra fees while still finding a cheaper path.
 500         let mut hit_minimum_limit;
 501
 502         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 503         // We start with a path_value of the exact amount we want, and if that generates a route we may
 504         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 505         // amount we want in total across paths, selecting the best subset at the end.
 506         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 507         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 508         let mut path_value_msat = final_value_msat;
 509
 510         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 511         // This map allows paths to be aware of the channel use by other paths in the same call.
 512         // This would help to make a better path finding decisions and not "overbook" channels.
 513         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 514         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network.get_nodes().len());
 515
 516         // Keeping track of how much value we already collected across other paths. Helps to decide:
 517         // - how much a new path should be transferring (upper bound);
 518         // - whether a channel should be disregarded because
 519         //   it's available liquidity is too small comparing to how much more we need to collect;
 520         // - when we want to stop looking for new paths.
 521         let mut already_collected_value_msat = 0;
 522
 523         log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payee, our_node_id, final_value_msat);
 524
 525         macro_rules! add_entry {
 526                 // Adds entry which goes from $src_node_id to $dest_node_id
 527                 // over the channel with id $chan_id with fees described in
 528                 // $directional_info.
 529                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 530                 // since that value has to be transferred over this channel.
 531                 // Returns whether this channel caused an update to `targets`.
 532                 ( $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,
 533                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => { {
 534                         // We "return" whether we updated the path at the end, via this:
 535                         let mut did_add_update_path_to_src_node = false;
 536                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 537                         // practice these cases should be caught earlier:
 538                         // - for regular channels at channel announcement (TODO)
 539                         // - for first and last hops early in get_route
 540                         if $src_node_id != $dest_node_id.clone() {
 541                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 542                                         let mut initial_liquidity_available_msat = None;
 543                                         if let Some(capacity_sats) = $capacity_sats {
 544                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 545                                         }
 546
 547                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 548                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 549                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 550                                                 } else {
 551                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 552                                                 }
 553                                         }
 554
 555                                         match initial_liquidity_available_msat {
 556                                                 Some(available_msat) => available_msat,
 557                                                 // We assume channels with unknown balance have
 558                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 559                                                 None => 250_000 * 1000
 560                                         }
 561                                 });
 562
 563                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 564                                 // It may be misleading because we might later choose to reduce the value transferred
 565                                 // over these channels, and the channel which was insufficient might become sufficient.
 566                                 // Worst case: we drop a good channel here because it can't cover the high following
 567                                 // fees caused by one expensive channel, but then this channel could have been used
 568                                 // if the amount being transferred over this path is lower.
 569                                 // We do this for now, but this is a subject for removal.
 570                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 571
 572                                         // Routing Fragmentation Mitigation heuristic:
 573                                         //
 574                                         // Routing fragmentation across many payment paths increases the overall routing
 575                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 576                                         // Taking too many smaller paths also increases the chance of payment failure.
 577                                         // Thus to avoid this effect, we require from our collected links to provide
 578                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 579                                         //
 580                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 581                                         // This means as we successfully advance in our collection,
 582                                         // the absolute liquidity contribution is lowered,
 583                                         // thus increasing the number of potential channels to be selected.
 584
 585                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 586                                         // or 100% if we're not allowed to do multipath payments.
 587                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 588                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 589                                         } else {
 590                                                 final_value_msat
 591                                         };
 592                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 593                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 594
 595                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 596                                         // Includes paying fees for the use of the following channels.
 597                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 598                                                 Some(result) => result,
 599                                                 // Can't overflow due to how the values were computed right above.
 600                                                 None => unreachable!(),
 601                                         };
 602                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 603                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 604                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 605
 606                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 607                                         // bother considering this channel.
 608                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 609                                         // be only reduced later (not increased), so this channel should just be skipped
 610                                         // as not sufficient.
 611                                         if !over_path_minimum_msat {
 612                                                 hit_minimum_limit = true;
 613                                         } else if contributes_sufficient_value {
 614                                                 // Note that low contribution here (limited by available_liquidity_msat)
 615                                                 // might violate htlc_minimum_msat on the hops which are next along the
 616                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 617                                                 // path fees knowing the final path contribution after constructing it.
 618                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 619                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 620                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 621                                                         _ => u64::max_value()
 622                                                 };
 623                                                 let hm_entry = dist.entry(&$src_node_id);
 624                                                 let old_entry = hm_entry.or_insert_with(|| {
 625                                                         // If there was previously no known way to access
 626                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 627                                                         // a semi-dummy record just to compute the fees to reach the source node.
 628                                                         // This will affect our decision on selecting $chan_id
 629                                                         // as a way to reach the $dest_node_id.
 630                                                         let mut fee_base_msat = u32::max_value();
 631                                                         let mut fee_proportional_millionths = u32::max_value();
 632                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 633                                                                 fee_base_msat = fees.base_msat;
 634                                                                 fee_proportional_millionths = fees.proportional_millionths;
 635                                                         }
 636                                                         PathBuildingHop {
 637                                                                 pubkey: $dest_node_id.clone(),
 638                                                                 short_channel_id: 0,
 639                                                                 channel_features: $chan_features,
 640                                                                 fee_msat: 0,
 641                                                                 cltv_expiry_delta: 0,
 642                                                                 src_lowest_inbound_fees: RoutingFees {
 643                                                                         base_msat: fee_base_msat,
 644                                                                         proportional_millionths: fee_proportional_millionths,
 645                                                                 },
 646                                                                 channel_fees: $directional_info.fees,
 647                                                                 next_hops_fee_msat: u64::max_value(),
 648                                                                 hop_use_fee_msat: u64::max_value(),
 649                                                                 total_fee_msat: u64::max_value(),
 650                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 651                                                                 path_htlc_minimum_msat,
 652                                                                 was_processed: false,
 653                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 654                                                                 value_contribution_msat,
 655                                                         }
 656                                                 });
 657
 658                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 659                                                 let mut should_process = !old_entry.was_processed;
 660                                                 #[cfg(any(test, feature = "fuzztarget"))]
 661                                                 {
 662                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 663                                                         // of already-seen nodes only happens in cases we expect (see below).
 664                                                         if !should_process { should_process = true; }
 665                                                 }
 666
 667                                                 if should_process {
 668                                                         let mut hop_use_fee_msat = 0;
 669                                                         let mut total_fee_msat = $next_hops_fee_msat;
 670
 671                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 672                                                         // will have the same effective-fee
 673                                                         if $src_node_id != *our_node_id {
 674                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 675                                                                         // max_value means we'll always fail
 676                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 677                                                                         None => total_fee_msat = u64::max_value(),
 678                                                                         Some(fee_msat) => {
 679                                                                                 hop_use_fee_msat = fee_msat;
 680                                                                                 total_fee_msat += hop_use_fee_msat;
 681                                                                                 // When calculating the lowest inbound fees to a node, we
 682                                                                                 // calculate fees here not based on the actual value we think
 683                                                                                 // will flow over this channel, but on the minimum value that
 684                                                                                 // we'll accept flowing over it. The minimum accepted value
 685                                                                                 // is a constant through each path collection run, ensuring
 686                                                                                 // consistent basis. Otherwise we may later find a
 687                                                                                 // different path to the source node that is more expensive,
 688                                                                                 // but which we consider to be cheaper because we are capacity
 689                                                                                 // constrained and the relative fee becomes lower.
 690                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 691                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 692                                                                                         Some(Some(v)) => {
 693                                                                                                 total_fee_msat = v;
 694                                                                                         },
 695                                                                                         _ => {
 696                                                                                                 total_fee_msat = u64::max_value();
 697                                                                                         }
 698                                                                                 };
 699                                                                         }
 700                                                                 }
 701                                                         }
 702
 703                                                         let new_graph_node = RouteGraphNode {
 704                                                                 pubkey: $src_node_id,
 705                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 706                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 707                                                                 value_contribution_msat: value_contribution_msat,
 708                                                                 path_htlc_minimum_msat,
 709                                                         };
 710
 711                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 712                                                         // if this way is cheaper than the already known
 713                                                         // (considering the cost to "reach" this channel from the route destination,
 714                                                         // the cost of using this channel,
 715                                                         // and the cost of routing to the source node of this channel).
 716                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 717                                                         // paying it. Consider the following exploit:
 718                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 719                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 720                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 721                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 722                                                         // to this channel.
 723                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 724                                                         // but it may require additional tracking - we don't want to double-count
 725                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 726                                                         // can't use something that may decrease on future hops.
 727                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 728                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 729
 730                                                         if !old_entry.was_processed && new_cost < old_cost {
 731                                                                 targets.push(new_graph_node);
 732                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 733                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 734                                                                 old_entry.total_fee_msat = total_fee_msat;
 735                                                                 old_entry.pubkey = $dest_node_id.clone();
 736                                                                 old_entry.short_channel_id = $chan_id.clone();
 737                                                                 old_entry.channel_features = $chan_features;
 738                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 739                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 740                                                                 old_entry.channel_fees = $directional_info.fees;
 741                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 742                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 743                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 744                                                                 {
 745                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 746                                                                 }
 747                                                                 did_add_update_path_to_src_node = true;
 748                                                         } else if old_entry.was_processed && new_cost < old_cost {
 749                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 750                                                                 {
 751                                                                         // If we're skipping processing a node which was previously
 752                                                                         // processed even though we found another path to it with a
 753                                                                         // cheaper fee, check that it was because the second path we
 754                                                                         // found (which we are processing now) has a lower value
 755                                                                         // contribution due to an HTLC minimum limit.
 756                                                                         //
 757                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 758                                                                         // through channel A, and one through channel B. Channel A and
 759                                                                         // B are both in the to-process heap, with their scores set by
 760                                                                         // a higher htlc_minimum than fee.
 761                                                                         // Channel A is processed first, and the channels onwards from
 762                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 763                                                                         // Channel B off of the heap, note that it has a much more
 764                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 765                                                                         // all of node 1's channels using the new, reduced, amount.
 766                                                                         //
 767                                                                         // This would be bogus - we'd be selecting a higher-fee path
 768                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 769                                                                         // already decided to use.
 770                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 771                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 772                                                                 }
 773                                                         }
 774                                                 }
 775                                         }
 776                                 }
 777                         }
 778                         did_add_update_path_to_src_node
 779                 } }
 780         }
 781
 782         let empty_node_features = NodeFeatures::empty();
 783         // Find ways (channels with destination) to reach a given node and store them
 784         // in the corresponding data structures (routing graph etc).
 785         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 786         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 787         // This data can later be helpful to optimize routing (pay lower fees).
 788         macro_rules! add_entries_to_cheapest_to_target_node {
 789                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 790                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 791                                 let was_processed = elem.was_processed;
 792                                 elem.was_processed = true;
 793                                 was_processed
 794                         } else {
 795                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 796                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 797                                 // If we're processing any other node, it is always be the result of a channel from it.
 798                                 assert_eq!($node_id, payee);
 799                                 false
 800                         };
 801
 802                         if !skip_node {
 803                                 if first_hops.is_some() {
 804                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&$node_id) {
 805                                                 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);
 806                                         }
 807                                 }
 808
 809                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 810                                         &node_info.features
 811                                 } else {
 812                                         &empty_node_features
 813                                 };
 814
 815                                 if !features.requires_unknown_bits() {
 816                                         for chan_id in $node.channels.iter() {
 817                                                 let chan = network.get_channels().get(chan_id).unwrap();
 818                                                 if !chan.features.requires_unknown_bits() {
 819                                                         if chan.node_one == *$node_id {
 820                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 821                                                                 if first_hops.is_none() || chan.node_two != *our_node_id {
 822                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 823                                                                                 if two_to_one.enabled {
 824                                                                                         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);
 825                                                                                 }
 826                                                                         }
 827                                                                 }
 828                                                         } else {
 829                                                                 if first_hops.is_none() || chan.node_one != *our_node_id {
 830                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 831                                                                                 if one_to_two.enabled {
 832                                                                                         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);
 833                                                                                 }
 834                                                                         }
 835                                                                 }
 836                                                         }
 837                                                 }
 838                                         }
 839                                 }
 840                         }
 841                 };
 842         }
 843
 844         let mut payment_paths = Vec::<PaymentPath>::new();
 845
 846         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 847         'paths_collection: loop {
 848                 // For every new path, start from scratch, except
 849                 // bookkeeped_channels_liquidity_available_msat, which will improve
 850                 // the further iterations of path finding. Also don't erase first_hop_targets.
 851                 targets.clear();
 852                 dist.clear();
 853                 hit_minimum_limit = false;
 854
 855                 // If first hop is a private channel and the only way to reach the payee, this is the only
 856                 // place where it could be added.
 857                 if first_hops.is_some() {
 858                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&payee) {
 859                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 860                         }
 861                 }
 862
 863                 // Add the payee as a target, so that the payee-to-payer
 864                 // search algorithm knows what to start with.
 865                 match network.get_nodes().get(payee) {
 866                         // The payee is not in our network graph, so nothing to add here.
 867                         // There is still a chance of reaching them via last_hops though,
 868                         // so don't yet fail the payment here.
 869                         // If not, targets.pop() will not even let us enter the loop in step 2.
 870                         None => {},
 871                         Some(node) => {
 872                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 873                         },
 874                 }
 875
 876                 // Step (1).
 877                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 878                 // earlier than general path finding, they will be somewhat prioritized, although currently
 879                 // it matters only if the fees are exactly the same.
 880                 for route in last_hops.iter().filter(|route| !route.0.is_empty()) {
 881                         let first_hop_in_route = &(route.0)[0];
 882                         let have_hop_src_in_graph =
 883                                 // Only add the hops in this route to our candidate set if either
 884                                 // we have a direct channel to the first hop or the first hop is
 885                                 // in the regular network graph.
 886                                 first_hop_targets.get(&first_hop_in_route.src_node_id).is_some() ||
 887                                 network.get_nodes().get(&first_hop_in_route.src_node_id).is_some();
 888                         if have_hop_src_in_graph {
 889                                 // We start building the path from reverse, i.e., from payee
 890                                 // to the first RouteHintHop in the path.
 891                                 let hop_iter = route.0.iter().rev();
 892                                 let prev_hop_iter = core::iter::once(payee).chain(
 893                                         route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
 894                                 let mut hop_used = true;
 895                                 let mut aggregate_next_hops_fee_msat: u64 = 0;
 896                                 let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
 897
 898                                 for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
 899                                         // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 900                                         // really sucks, cause we're gonna need that eventually.
 901                                         let hop_htlc_minimum_msat: u64 = hop.htlc_minimum_msat.unwrap_or(0);
 902
 903                                         let directional_info = DummyDirectionalChannelInfo {
 904                                                 cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 905                                                 htlc_minimum_msat: hop_htlc_minimum_msat,
 906                                                 htlc_maximum_msat: hop.htlc_maximum_msat,
 907                                                 fees: hop.fees,
 908                                         };
 909
 910                                         let reqd_channel_cap = if let Some (val) = final_value_msat.checked_add(match idx {
 911                                                 0 => 999,
 912                                                 _ => aggregate_next_hops_fee_msat.checked_add(999).unwrap_or(u64::max_value())
 913                                         }) { Some( val / 1000 ) } else { break; }; // converting from msat or breaking if max ~ infinity
 914
 915
 916                                         // We assume that the recipient only included route hints for routes which had
 917                                         // sufficient value to route `final_value_msat`. Note that in the case of "0-value"
 918                                         // invoices where the invoice does not specify value this may not be the case, but
 919                                         // better to include the hints than not.
 920                                         if !add_entry!(hop.short_channel_id, hop.src_node_id, prev_hop_id, directional_info, reqd_channel_cap, &empty_channel_features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat) {
 921                                                 // If this hop was not used then there is no use checking the preceding hops
 922                                                 // in the RouteHint. We can break by just searching for a direct channel between
 923                                                 // last checked hop and first_hop_targets
 924                                                 hop_used = false;
 925                                         }
 926
 927                                         // Searching for a direct channel between last checked hop and first_hop_targets
 928                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&prev_hop_id) {
 929                                                 add_entry!(first_hop, *our_node_id , prev_hop_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat);
 930                                         }
 931
 932                                         if !hop_used {
 933                                                 break;
 934                                         }
 935
 936                                         // In the next values of the iterator, the aggregate fees already reflects
 937                                         // the sum of value sent from payer (final_value_msat) and routing fees
 938                                         // for the last node in the RouteHint. We need to just add the fees to
 939                                         // route through the current node so that the preceeding node (next iteration)
 940                                         // can use it.
 941                                         let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
 942                                                 .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
 943                                         aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
 944
 945                                         let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
 946                                         let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
 947                                                 .checked_add(hop_htlc_minimum_msat_inc);
 948                                         aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
 949
 950                                         if idx == route.0.len() - 1 {
 951                                                 // The last hop in this iterator is the first hop in
 952                                                 // overall RouteHint.
 953                                                 // If this hop connects to a node with which we have a direct channel,
 954                                                 // ignore the network graph and, if the last hop was added, add our
 955                                                 // direct channel to the candidate set.
 956                                                 //
 957                                                 // Note that we *must* check if the last hop was added as `add_entry`
 958                                                 // always assumes that the third argument is a node to which we have a
 959                                                 // path.
 960                                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
 961                                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat);
 962                                                 }
 963                                         }
 964                                 }
 965                         }
 966                 }
 967
 968                 log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
 969
 970                 // At this point, targets are filled with the data from first and
 971                 // last hops communicated by the caller, and the payment receiver.
 972                 let mut found_new_path = false;
 973
 974                 // Step (2).
 975                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 976                 // - not enough outgoing liquidity:
 977                 //   0 < already_collected_value_msat < final_value_msat
 978                 // - enough outgoing liquidity:
 979                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 980                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 981                 // paths_collection will be stopped because found_new_path==false.
 982                 // This is not necessarily a routing failure.
 983                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 984
 985                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 986                         // traversing the graph and arrange the path out of what we found.
 987                         if pubkey == *our_node_id {
 988                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 989                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
 990
 991                                 'path_walk: loop {
 992                                         if let Some(&(_, _, _, ref features)) = first_hop_targets.get(&ordered_hops.last().unwrap().0.pubkey) {
 993                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
 994                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().0.pubkey) {
 995                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 996                                                         ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
 997                                                 } else {
 998                                                         ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
 999                                                 }
1000                                         } else {
1001                                                 // We should be able to fill in features for everything except the last
1002                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
1003                                                 // should be able to extend it further as BOLT 11 does have feature
1004                                                 // flags for the last hop node itself).
1005                                                 assert!(ordered_hops.last().unwrap().0.pubkey == *payee);
1006                                         }
1007
1008                                         // Means we succesfully traversed from the payer to the payee, now
1009                                         // save this path for the payment route. Also, update the liquidity
1010                                         // remaining on the used hops, so that we take them into account
1011                                         // while looking for more paths.
1012                                         if ordered_hops.last().unwrap().0.pubkey == *payee {
1013                                                 break 'path_walk;
1014                                         }
1015
1016                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.pubkey) {
1017                                                 Some(payment_hop) => payment_hop,
1018                                                 // We can't arrive at None because, if we ever add an entry to targets,
1019                                                 // we also fill in the entry in dist (see add_entry!).
1020                                                 None => unreachable!(),
1021                                         };
1022                                         // We "propagate" the fees one hop backward (topologically) here,
1023                                         // so that fees paid for a HTLC forwarding on the current channel are
1024                                         // associated with the previous channel (where they will be subtracted).
1025                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
1026                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
1027                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
1028                                 }
1029                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
1030                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
1031                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
1032
1033                                 log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
1034                                         ordered_hops.len(), value_contribution_msat, ordered_hops);
1035
1036                                 let mut payment_path = PaymentPath {hops: ordered_hops};
1037
1038                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
1039                                 // value being transferred along the way, we could have violated htlc_minimum_msat
1040                                 // on some channels we already passed (assuming dest->source direction). Here, we
1041                                 // recompute the fees again, so that if that's the case, we match the currently
1042                                 // underpaid htlc_minimum_msat with fees.
1043                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
1044
1045                                 // Since a path allows to transfer as much value as
1046                                 // the smallest channel it has ("bottleneck"), we should recompute
1047                                 // the fees so sender HTLC don't overpay fees when traversing
1048                                 // larger channels than the bottleneck. This may happen because
1049                                 // when we were selecting those channels we were not aware how much value
1050                                 // this path will transfer, and the relative fee for them
1051                                 // might have been computed considering a larger value.
1052                                 // Remember that we used these channels so that we don't rely
1053                                 // on the same liquidity in future paths.
1054                                 let mut prevented_redundant_path_selection = false;
1055                                 for (payment_hop, _) in payment_path.hops.iter() {
1056                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
1057                                         let mut spent_on_hop_msat = value_contribution_msat;
1058                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
1059                                         spent_on_hop_msat += next_hops_fee_msat;
1060                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
1061                                                 // If this path used all of this channel's available liquidity, we know
1062                                                 // this path will not be selected again in the next loop iteration.
1063                                                 prevented_redundant_path_selection = true;
1064                                         }
1065                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
1066                                 }
1067                                 if !prevented_redundant_path_selection {
1068                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
1069                                         // we'll probably end up picking the same path again on the next iteration.
1070                                         // Decrease the available liquidity of a hop in the middle of the path.
1071                                         let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
1072                                         log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
1073                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
1074                                         *victim_liquidity = 0;
1075                                 }
1076
1077                                 // Track the total amount all our collected paths allow to send so that we:
1078                                 // - know when to stop looking for more paths
1079                                 // - know which of the hops are useless considering how much more sats we need
1080                                 //   (contributes_sufficient_value)
1081                                 already_collected_value_msat += value_contribution_msat;
1082
1083                                 payment_paths.push(payment_path);
1084                                 found_new_path = true;
1085                                 break 'path_construction;
1086                         }
1087
1088                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1089                         // the equivalent of the `elem.was_processed` check in
1090                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1091                         if pubkey == *payee { continue 'path_construction; }
1092
1093                         // Otherwise, since the current target node is not us,
1094                         // keep "unrolling" the payment graph from payee to payer by
1095                         // finding a way to reach the current target from the payer side.
1096                         match network.get_nodes().get(&pubkey) {
1097                                 None => {},
1098                                 Some(node) => {
1099                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1100                                 },
1101                         }
1102                 }
1103
1104                 if !allow_mpp {
1105                         // If we don't support MPP, no use trying to gather more value ever.
1106                         break 'paths_collection;
1107                 }
1108
1109                 // Step (3).
1110                 // Stop either when the recommended value is reached or if no new path was found in this
1111                 // iteration.
1112                 // In the latter case, making another path finding attempt won't help,
1113                 // because we deterministically terminated the search due to low liquidity.
1114                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1115                         log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
1116                                 already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
1117                         break 'paths_collection;
1118                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1119                         // Further, if this was our first walk of the graph, and we weren't limited by an
1120                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1121                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1122                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1123                         // still keeping a lower total fee than this path.
1124                         if !hit_minimum_limit {
1125                                 log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
1126                                 break 'paths_collection;
1127                         }
1128                         log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
1129                         path_value_msat = recommended_value_msat;
1130                 }
1131         }
1132
1133         // Step (4).
1134         if payment_paths.len() == 0 {
1135                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1136         }
1137
1138         if already_collected_value_msat < final_value_msat {
1139                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1140         }
1141
1142         // Sort by total fees and take the best paths.
1143         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1144         if payment_paths.len() > 50 {
1145                 payment_paths.truncate(50);
1146         }
1147
1148         // Draw multiple sufficient routes by randomly combining the selected paths.
1149         let mut drawn_routes = Vec::new();
1150         for i in 0..payment_paths.len() {
1151                 let mut cur_route = Vec::<PaymentPath>::new();
1152                 let mut aggregate_route_value_msat = 0;
1153
1154                 // Step (5).
1155                 // TODO: real random shuffle
1156                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1157                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1158
1159                 // Step (6).
1160                 for payment_path in cur_payment_paths {
1161                         cur_route.push(payment_path.clone());
1162                         aggregate_route_value_msat += payment_path.get_value_msat();
1163                         if aggregate_route_value_msat > final_value_msat {
1164                                 // Last path likely overpaid. Substract it from the most expensive
1165                                 // (in terms of proportional fee) path in this route and recompute fees.
1166                                 // This might be not the most economically efficient way, but fewer paths
1167                                 // also makes routing more reliable.
1168                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1169
1170                                 // First, drop some expensive low-value paths entirely if possible.
1171                                 // Sort by value so that we drop many really-low values first, since
1172                                 // fewer paths is better: the payment is less likely to fail.
1173                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1174                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1175                                 cur_route.sort_by_key(|path| path.get_value_msat());
1176                                 // We should make sure that at least 1 path left.
1177                                 let mut paths_left = cur_route.len();
1178                                 cur_route.retain(|path| {
1179                                         if paths_left == 1 {
1180                                                 return true
1181                                         }
1182                                         let mut keep = true;
1183                                         let path_value_msat = path.get_value_msat();
1184                                         if path_value_msat <= overpaid_value_msat {
1185                                                 keep = false;
1186                                                 overpaid_value_msat -= path_value_msat;
1187                                                 paths_left -= 1;
1188                                         }
1189                                         keep
1190                                 });
1191
1192                                 if overpaid_value_msat == 0 {
1193                                         break;
1194                                 }
1195
1196                                 assert!(cur_route.len() > 0);
1197
1198                                 // Step (7).
1199                                 // Now, substract the overpaid value from the most-expensive path.
1200                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1201                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1202                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1203                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1204                                 // We already dropped all the small channels above, meaning all the
1205                                 // remaining channels are larger than remaining overpaid_value_msat.
1206                                 // Thus, this can't be negative.
1207                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1208                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1209                                 break;
1210                         }
1211                 }
1212                 drawn_routes.push(cur_route);
1213         }
1214
1215         // Step (8).
1216         // Select the best route by lowest total fee.
1217         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1218         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1219         for payment_path in drawn_routes.first().unwrap() {
1220                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1221                         RouteHop {
1222                                 pubkey: payment_hop.pubkey,
1223                                 node_features: node_features.clone(),
1224                                 short_channel_id: payment_hop.short_channel_id,
1225                                 channel_features: payment_hop.channel_features.clone(),
1226                                 fee_msat: payment_hop.fee_msat,
1227                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1228                         }
1229                 }).collect());
1230         }
1231
1232         if let Some(features) = &payee_features {
1233                 for path in selected_paths.iter_mut() {
1234                         path.last_mut().unwrap().node_features = features.to_context();
1235                 }
1236         }
1237
1238         let route = Route { paths: selected_paths };
1239         log_info!(logger, "Got route to {}: {}", payee, log_route!(route));
1240         Ok(route)
1241 }
1242
1243 #[cfg(test)]
1244 mod tests {
1245         use routing::router::{get_route, Route, RouteHint, RouteHintHop, RoutingFees};
1246         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1247         use chain::transaction::OutPoint;
1248         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1249         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1250            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1251         use ln::channelmanager;
1252         use util::test_utils;
1253         use util::ser::Writeable;
1254
1255         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1256         use bitcoin::hashes::Hash;
1257         use bitcoin::network::constants::Network;
1258         use bitcoin::blockdata::constants::genesis_block;
1259         use bitcoin::blockdata::script::Builder;
1260         use bitcoin::blockdata::opcodes;
1261         use bitcoin::blockdata::transaction::TxOut;
1262
1263         use hex;
1264
1265         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1266         use bitcoin::secp256k1::{Secp256k1, All};
1267
1268         use prelude::*;
1269         use sync::{self, Arc};
1270
1271         fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
1272                         features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
1273                 channelmanager::ChannelDetails {
1274                         channel_id: [0; 32],
1275                         counterparty: channelmanager::ChannelCounterparty {
1276                                 features,
1277                                 node_id,
1278                                 unspendable_punishment_reserve: 0,
1279                                 forwarding_info: None,
1280                         },
1281                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1282                         short_channel_id,
1283                         channel_value_satoshis: 0,
1284                         user_id: 0,
1285                         outbound_capacity_msat,
1286                         inbound_capacity_msat: 42,
1287                         unspendable_punishment_reserve: None,
1288                         confirmations_required: None,
1289                         force_close_spend_delay: None,
1290                         is_outbound: true, is_funding_locked: true,
1291                         is_usable: true, is_public: true,
1292                 }
1293         }
1294
1295         // Using the same keys for LN and BTC ids
1296         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1297            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1298                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1299                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1300
1301                 let unsigned_announcement = UnsignedChannelAnnouncement {
1302                         features,
1303                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1304                         short_channel_id,
1305                         node_id_1,
1306                         node_id_2,
1307                         bitcoin_key_1: node_id_1,
1308                         bitcoin_key_2: node_id_2,
1309                         excess_data: Vec::new(),
1310                 };
1311
1312                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1313                 let valid_announcement = ChannelAnnouncement {
1314                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1315                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1316                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1317                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1318                         contents: unsigned_announcement.clone(),
1319                 };
1320                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1321                         Ok(res) => assert!(res),
1322                         _ => panic!()
1323                 };
1324         }
1325
1326         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) {
1327                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1328                 let valid_channel_update = ChannelUpdate {
1329                         signature: secp_ctx.sign(&msghash, node_privkey),
1330                         contents: update.clone()
1331                 };
1332
1333                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1334                         Ok(res) => assert!(res),
1335                         Err(_) => panic!()
1336                 };
1337         }
1338
1339         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,
1340            features: NodeFeatures, timestamp: u32) {
1341                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1342                 let unsigned_announcement = UnsignedNodeAnnouncement {
1343                         features,
1344                         timestamp,
1345                         node_id,
1346                         rgb: [0; 3],
1347                         alias: [0; 32],
1348                         addresses: Vec::new(),
1349                         excess_address_data: Vec::new(),
1350                         excess_data: Vec::new(),
1351                 };
1352                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1353                 let valid_announcement = NodeAnnouncement {
1354                         signature: secp_ctx.sign(&msghash, node_privkey),
1355                         contents: unsigned_announcement.clone()
1356                 };
1357
1358                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1359                         Ok(_) => (),
1360                         Err(_) => panic!()
1361                 };
1362         }
1363
1364         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1365                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1366                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1367                 }).collect();
1368
1369                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1370
1371                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1372                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1373
1374                 (our_privkey, our_id, privkeys, pubkeys)
1375         }
1376
1377         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1378                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1379                 // test for it later.
1380                 let idx = (id - 1) * 2 + 1;
1381                 if idx > 8*3 {
1382                         vec![1 << (idx - 8*3), 0, 0, 0]
1383                 } else if idx > 8*2 {
1384                         vec![1 << (idx - 8*2), 0, 0]
1385                 } else if idx > 8*1 {
1386                         vec![1 << (idx - 8*1), 0]
1387                 } else {
1388                         vec![1 << idx]
1389                 }
1390         }
1391
1392         fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>, sync::Arc<test_utils::TestChainSource>, sync::Arc<test_utils::TestLogger>) {
1393                 let secp_ctx = Secp256k1::new();
1394                 let logger = Arc::new(test_utils::TestLogger::new());
1395                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1396                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1397                 // Build network from our_id to node6:
1398                 //
1399                 //        -1(1)2-  node0  -1(3)2-
1400                 //       /                       \
1401                 // our_id -1(12)2- node7 -1(13)2--- node2
1402                 //       \                       /
1403                 //        -1(2)2-  node1  -1(4)2-
1404                 //
1405                 //
1406                 // chan1  1-to-2: disabled
1407                 // chan1  2-to-1: enabled, 0 fee
1408                 //
1409                 // chan2  1-to-2: enabled, ignored fee
1410                 // chan2  2-to-1: enabled, 0 fee
1411                 //
1412                 // chan3  1-to-2: enabled, 0 fee
1413                 // chan3  2-to-1: enabled, 100 msat fee
1414                 //
1415                 // chan4  1-to-2: enabled, 100% fee
1416                 // chan4  2-to-1: enabled, 0 fee
1417                 //
1418                 // chan12 1-to-2: enabled, ignored fee
1419                 // chan12 2-to-1: enabled, 0 fee
1420                 //
1421                 // chan13 1-to-2: enabled, 200% fee
1422                 // chan13 2-to-1: enabled, 0 fee
1423                 //
1424                 //
1425                 //       -1(5)2- node3 -1(8)2--
1426                 //       |         2          |
1427                 //       |       (11)         |
1428                 //      /          1           \
1429                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1430                 //      \                      /
1431                 //       -1(7)2- node5 -1(10)2-
1432                 //
1433                 // Channels 5, 8, 9 and 10 are private channels.
1434                 //
1435                 // chan5  1-to-2: enabled, 100 msat fee
1436                 // chan5  2-to-1: enabled, 0 fee
1437                 //
1438                 // chan6  1-to-2: enabled, 0 fee
1439                 // chan6  2-to-1: enabled, 0 fee
1440                 //
1441                 // chan7  1-to-2: enabled, 100% fee
1442                 // chan7  2-to-1: enabled, 0 fee
1443                 //
1444                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1445                 // chan8  2-to-1: enabled, 0 fee
1446                 //
1447                 // chan9  1-to-2: enabled, 1001 msat fee
1448                 // chan9  2-to-1: enabled, 0 fee
1449                 //
1450                 // chan10 1-to-2: enabled, 0 fee
1451                 // chan10 2-to-1: enabled, 0 fee
1452                 //
1453                 // chan11 1-to-2: enabled, 0 fee
1454                 // chan11 2-to-1: enabled, 0 fee
1455
1456                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1457
1458                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1459                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1460                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1461                         short_channel_id: 1,
1462                         timestamp: 1,
1463                         flags: 1,
1464                         cltv_expiry_delta: 0,
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_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1473
1474                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1475                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1476                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1477                         short_channel_id: 2,
1478                         timestamp: 1,
1479                         flags: 0,
1480                         cltv_expiry_delta: u16::max_value(),
1481                         htlc_minimum_msat: 0,
1482                         htlc_maximum_msat: OptionalField::Absent,
1483                         fee_base_msat: u32::max_value(),
1484                         fee_proportional_millionths: u32::max_value(),
1485                         excess_data: Vec::new()
1486                 });
1487                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1488                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1489                         short_channel_id: 2,
1490                         timestamp: 1,
1491                         flags: 1,
1492                         cltv_expiry_delta: 0,
1493                         htlc_minimum_msat: 0,
1494                         htlc_maximum_msat: OptionalField::Absent,
1495                         fee_base_msat: 0,
1496                         fee_proportional_millionths: 0,
1497                         excess_data: Vec::new()
1498                 });
1499
1500                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1501
1502                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1503                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1504                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1505                         short_channel_id: 12,
1506                         timestamp: 1,
1507                         flags: 0,
1508                         cltv_expiry_delta: u16::max_value(),
1509                         htlc_minimum_msat: 0,
1510                         htlc_maximum_msat: OptionalField::Absent,
1511                         fee_base_msat: u32::max_value(),
1512                         fee_proportional_millionths: u32::max_value(),
1513                         excess_data: Vec::new()
1514                 });
1515                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1516                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1517                         short_channel_id: 12,
1518                         timestamp: 1,
1519                         flags: 1,
1520                         cltv_expiry_delta: 0,
1521                         htlc_minimum_msat: 0,
1522                         htlc_maximum_msat: OptionalField::Absent,
1523                         fee_base_msat: 0,
1524                         fee_proportional_millionths: 0,
1525                         excess_data: Vec::new()
1526                 });
1527
1528                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1529
1530                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1531                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1532                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1533                         short_channel_id: 3,
1534                         timestamp: 1,
1535                         flags: 0,
1536                         cltv_expiry_delta: (3 << 8) | 1,
1537                         htlc_minimum_msat: 0,
1538                         htlc_maximum_msat: OptionalField::Absent,
1539                         fee_base_msat: 0,
1540                         fee_proportional_millionths: 0,
1541                         excess_data: Vec::new()
1542                 });
1543                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1544                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1545                         short_channel_id: 3,
1546                         timestamp: 1,
1547                         flags: 1,
1548                         cltv_expiry_delta: (3 << 8) | 2,
1549                         htlc_minimum_msat: 0,
1550                         htlc_maximum_msat: OptionalField::Absent,
1551                         fee_base_msat: 100,
1552                         fee_proportional_millionths: 0,
1553                         excess_data: Vec::new()
1554                 });
1555
1556                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1557                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1558                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1559                         short_channel_id: 4,
1560                         timestamp: 1,
1561                         flags: 0,
1562                         cltv_expiry_delta: (4 << 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[2], UnsignedChannelUpdate {
1570                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1571                         short_channel_id: 4,
1572                         timestamp: 1,
1573                         flags: 1,
1574                         cltv_expiry_delta: (4 << 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_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1583                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1584                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1585                         short_channel_id: 13,
1586                         timestamp: 1,
1587                         flags: 0,
1588                         cltv_expiry_delta: (13 << 8) | 1,
1589                         htlc_minimum_msat: 0,
1590                         htlc_maximum_msat: OptionalField::Absent,
1591                         fee_base_msat: 0,
1592                         fee_proportional_millionths: 2000000,
1593                         excess_data: Vec::new()
1594                 });
1595                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1596                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1597                         short_channel_id: 13,
1598                         timestamp: 1,
1599                         flags: 1,
1600                         cltv_expiry_delta: (13 << 8) | 2,
1601                         htlc_minimum_msat: 0,
1602                         htlc_maximum_msat: OptionalField::Absent,
1603                         fee_base_msat: 0,
1604                         fee_proportional_millionths: 0,
1605                         excess_data: Vec::new()
1606                 });
1607
1608                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1609
1610                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1611                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1612                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1613                         short_channel_id: 6,
1614                         timestamp: 1,
1615                         flags: 0,
1616                         cltv_expiry_delta: (6 << 8) | 1,
1617                         htlc_minimum_msat: 0,
1618                         htlc_maximum_msat: OptionalField::Absent,
1619                         fee_base_msat: 0,
1620                         fee_proportional_millionths: 0,
1621                         excess_data: Vec::new()
1622                 });
1623                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1624                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1625                         short_channel_id: 6,
1626                         timestamp: 1,
1627                         flags: 1,
1628                         cltv_expiry_delta: (6 << 8) | 2,
1629                         htlc_minimum_msat: 0,
1630                         htlc_maximum_msat: OptionalField::Absent,
1631                         fee_base_msat: 0,
1632                         fee_proportional_millionths: 0,
1633                         excess_data: Vec::new(),
1634                 });
1635
1636                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1637                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1638                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1639                         short_channel_id: 11,
1640                         timestamp: 1,
1641                         flags: 0,
1642                         cltv_expiry_delta: (11 << 8) | 1,
1643                         htlc_minimum_msat: 0,
1644                         htlc_maximum_msat: OptionalField::Absent,
1645                         fee_base_msat: 0,
1646                         fee_proportional_millionths: 0,
1647                         excess_data: Vec::new()
1648                 });
1649                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1650                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1651                         short_channel_id: 11,
1652                         timestamp: 1,
1653                         flags: 1,
1654                         cltv_expiry_delta: (11 << 8) | 2,
1655                         htlc_minimum_msat: 0,
1656                         htlc_maximum_msat: OptionalField::Absent,
1657                         fee_base_msat: 0,
1658                         fee_proportional_millionths: 0,
1659                         excess_data: Vec::new()
1660                 });
1661
1662                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1663
1664                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1665
1666                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1667                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1668                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1669                         short_channel_id: 7,
1670                         timestamp: 1,
1671                         flags: 0,
1672                         cltv_expiry_delta: (7 << 8) | 1,
1673                         htlc_minimum_msat: 0,
1674                         htlc_maximum_msat: OptionalField::Absent,
1675                         fee_base_msat: 0,
1676                         fee_proportional_millionths: 1000000,
1677                         excess_data: Vec::new()
1678                 });
1679                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1680                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1681                         short_channel_id: 7,
1682                         timestamp: 1,
1683                         flags: 1,
1684                         cltv_expiry_delta: (7 << 8) | 2,
1685                         htlc_minimum_msat: 0,
1686                         htlc_maximum_msat: OptionalField::Absent,
1687                         fee_base_msat: 0,
1688                         fee_proportional_millionths: 0,
1689                         excess_data: Vec::new()
1690                 });
1691
1692                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1693
1694                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1695         }
1696
1697         #[test]
1698         fn simple_route_test() {
1699                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1700                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1701
1702                 // Simple route to 2 via 1
1703
1704                 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)) {
1705                         assert_eq!(err, "Cannot send a payment of 0 msat");
1706                 } else { panic!(); }
1707
1708                 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();
1709                 assert_eq!(route.paths[0].len(), 2);
1710
1711                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1712                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1713                 assert_eq!(route.paths[0][0].fee_msat, 100);
1714                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1715                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1716                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1717
1718                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1719                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1720                 assert_eq!(route.paths[0][1].fee_msat, 100);
1721                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1722                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1723                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1724         }
1725
1726         #[test]
1727         fn invalid_first_hop_test() {
1728                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1729                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1730
1731                 // Simple route to 2 via 1
1732
1733                 let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
1734
1735                 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)) {
1736                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1737                 } else { panic!(); }
1738
1739                 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();
1740                 assert_eq!(route.paths[0].len(), 2);
1741         }
1742
1743         #[test]
1744         fn htlc_minimum_test() {
1745                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1746                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1747
1748                 // Simple route to 2 via 1
1749
1750                 // Disable other paths
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: 12,
1754                         timestamp: 2,
1755                         flags: 2, // to disable
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                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1764                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1765                         short_channel_id: 3,
1766                         timestamp: 2,
1767                         flags: 2, // to disable
1768                         cltv_expiry_delta: 0,
1769                         htlc_minimum_msat: 0,
1770                         htlc_maximum_msat: OptionalField::Absent,
1771                         fee_base_msat: 0,
1772                         fee_proportional_millionths: 0,
1773                         excess_data: Vec::new()
1774                 });
1775                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1776                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1777                         short_channel_id: 13,
1778                         timestamp: 2,
1779                         flags: 2, // to disable
1780                         cltv_expiry_delta: 0,
1781                         htlc_minimum_msat: 0,
1782                         htlc_maximum_msat: OptionalField::Absent,
1783                         fee_base_msat: 0,
1784                         fee_proportional_millionths: 0,
1785                         excess_data: Vec::new()
1786                 });
1787                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1788                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1789                         short_channel_id: 6,
1790                         timestamp: 2,
1791                         flags: 2, // to disable
1792                         cltv_expiry_delta: 0,
1793                         htlc_minimum_msat: 0,
1794                         htlc_maximum_msat: OptionalField::Absent,
1795                         fee_base_msat: 0,
1796                         fee_proportional_millionths: 0,
1797                         excess_data: Vec::new()
1798                 });
1799                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1800                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1801                         short_channel_id: 7,
1802                         timestamp: 2,
1803                         flags: 2, // to disable
1804                         cltv_expiry_delta: 0,
1805                         htlc_minimum_msat: 0,
1806                         htlc_maximum_msat: OptionalField::Absent,
1807                         fee_base_msat: 0,
1808                         fee_proportional_millionths: 0,
1809                         excess_data: Vec::new()
1810                 });
1811
1812                 // Check against amount_to_transfer_over_msat.
1813                 // Set minimal HTLC of 200_000_000 msat.
1814                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1815                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1816                         short_channel_id: 2,
1817                         timestamp: 3,
1818                         flags: 0,
1819                         cltv_expiry_delta: 0,
1820                         htlc_minimum_msat: 200_000_000,
1821                         htlc_maximum_msat: OptionalField::Absent,
1822                         fee_base_msat: 0,
1823                         fee_proportional_millionths: 0,
1824                         excess_data: Vec::new()
1825                 });
1826
1827                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1828                 // be used.
1829                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1830                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1831                         short_channel_id: 4,
1832                         timestamp: 3,
1833                         flags: 0,
1834                         cltv_expiry_delta: 0,
1835                         htlc_minimum_msat: 0,
1836                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1837                         fee_base_msat: 0,
1838                         fee_proportional_millionths: 0,
1839                         excess_data: Vec::new()
1840                 });
1841
1842                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1843                 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)) {
1844                         assert_eq!(err, "Failed to find a path to the given destination");
1845                 } else { panic!(); }
1846
1847                 // Lift the restriction on the first hop.
1848                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1849                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1850                         short_channel_id: 2,
1851                         timestamp: 4,
1852                         flags: 0,
1853                         cltv_expiry_delta: 0,
1854                         htlc_minimum_msat: 0,
1855                         htlc_maximum_msat: OptionalField::Absent,
1856                         fee_base_msat: 0,
1857                         fee_proportional_millionths: 0,
1858                         excess_data: Vec::new()
1859                 });
1860
1861                 // A payment above the minimum should pass
1862                 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();
1863                 assert_eq!(route.paths[0].len(), 2);
1864         }
1865
1866         #[test]
1867         fn htlc_minimum_overpay_test() {
1868                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1869                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1870
1871                 // A route to node#2 via two paths.
1872                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1873                 // Thus, they can't send 60 without overpaying.
1874                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1875                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1876                         short_channel_id: 2,
1877                         timestamp: 2,
1878                         flags: 0,
1879                         cltv_expiry_delta: 0,
1880                         htlc_minimum_msat: 35_000,
1881                         htlc_maximum_msat: OptionalField::Present(40_000),
1882                         fee_base_msat: 0,
1883                         fee_proportional_millionths: 0,
1884                         excess_data: Vec::new()
1885                 });
1886                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1887                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1888                         short_channel_id: 12,
1889                         timestamp: 3,
1890                         flags: 0,
1891                         cltv_expiry_delta: 0,
1892                         htlc_minimum_msat: 35_000,
1893                         htlc_maximum_msat: OptionalField::Present(40_000),
1894                         fee_base_msat: 0,
1895                         fee_proportional_millionths: 0,
1896                         excess_data: Vec::new()
1897                 });
1898
1899                 // Make 0 fee.
1900                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1901                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1902                         short_channel_id: 13,
1903                         timestamp: 2,
1904                         flags: 0,
1905                         cltv_expiry_delta: 0,
1906                         htlc_minimum_msat: 0,
1907                         htlc_maximum_msat: OptionalField::Absent,
1908                         fee_base_msat: 0,
1909                         fee_proportional_millionths: 0,
1910                         excess_data: Vec::new()
1911                 });
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: 0,
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
1925                 // Disable other paths
1926                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1927                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1928                         short_channel_id: 1,
1929                         timestamp: 3,
1930                         flags: 2, // to disable
1931                         cltv_expiry_delta: 0,
1932                         htlc_minimum_msat: 0,
1933                         htlc_maximum_msat: OptionalField::Absent,
1934                         fee_base_msat: 0,
1935                         fee_proportional_millionths: 0,
1936                         excess_data: Vec::new()
1937                 });
1938
1939                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1940                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1941                 // Overpay fees to hit htlc_minimum_msat.
1942                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1943                 // TODO: this could be better balanced to overpay 10k and not 15k.
1944                 assert_eq!(overpaid_fees, 15_000);
1945
1946                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1947                 // while taking even more fee to match htlc_minimum_msat.
1948                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1949                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1950                         short_channel_id: 12,
1951                         timestamp: 4,
1952                         flags: 0,
1953                         cltv_expiry_delta: 0,
1954                         htlc_minimum_msat: 65_000,
1955                         htlc_maximum_msat: OptionalField::Present(80_000),
1956                         fee_base_msat: 0,
1957                         fee_proportional_millionths: 0,
1958                         excess_data: Vec::new()
1959                 });
1960                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1961                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1962                         short_channel_id: 2,
1963                         timestamp: 3,
1964                         flags: 0,
1965                         cltv_expiry_delta: 0,
1966                         htlc_minimum_msat: 0,
1967                         htlc_maximum_msat: OptionalField::Absent,
1968                         fee_base_msat: 0,
1969                         fee_proportional_millionths: 0,
1970                         excess_data: Vec::new()
1971                 });
1972                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1973                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1974                         short_channel_id: 4,
1975                         timestamp: 4,
1976                         flags: 0,
1977                         cltv_expiry_delta: 0,
1978                         htlc_minimum_msat: 0,
1979                         htlc_maximum_msat: OptionalField::Absent,
1980                         fee_base_msat: 0,
1981                         fee_proportional_millionths: 100_000,
1982                         excess_data: Vec::new()
1983                 });
1984
1985                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1986                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1987                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1988                 assert_eq!(route.paths.len(), 1);
1989                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1990                 let fees = route.paths[0][0].fee_msat;
1991                 assert_eq!(fees, 5_000);
1992
1993                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1994                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1995                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1996                 // the other channel.
1997                 assert_eq!(route.paths.len(), 1);
1998                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1999                 let fees = route.paths[0][0].fee_msat;
2000                 assert_eq!(fees, 5_000);
2001         }
2002
2003         #[test]
2004         fn disable_channels_test() {
2005                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2006                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2007
2008                 // // Disable channels 4 and 12 by flags=2
2009                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2010                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2011                         short_channel_id: 4,
2012                         timestamp: 2,
2013                         flags: 2, // to disable
2014                         cltv_expiry_delta: 0,
2015                         htlc_minimum_msat: 0,
2016                         htlc_maximum_msat: OptionalField::Absent,
2017                         fee_base_msat: 0,
2018                         fee_proportional_millionths: 0,
2019                         excess_data: Vec::new()
2020                 });
2021                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2022                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2023                         short_channel_id: 12,
2024                         timestamp: 2,
2025                         flags: 2, // to disable
2026                         cltv_expiry_delta: 0,
2027                         htlc_minimum_msat: 0,
2028                         htlc_maximum_msat: OptionalField::Absent,
2029                         fee_base_msat: 0,
2030                         fee_proportional_millionths: 0,
2031                         excess_data: Vec::new()
2032                 });
2033
2034                 // If all the channels require some features we don't understand, route should fail
2035                 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)) {
2036                         assert_eq!(err, "Failed to find a path to the given destination");
2037                 } else { panic!(); }
2038
2039                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2040                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2041                 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();
2042                 assert_eq!(route.paths[0].len(), 2);
2043
2044                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2045                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2046                 assert_eq!(route.paths[0][0].fee_msat, 200);
2047                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2048                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2049                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2050
2051                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2052                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2053                 assert_eq!(route.paths[0][1].fee_msat, 100);
2054                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2055                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2056                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2057         }
2058
2059         #[test]
2060         fn disable_node_test() {
2061                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2062                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2063
2064                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
2065                 let unknown_features = NodeFeatures::known().set_unknown_feature_required();
2066                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
2067                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
2068                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
2069
2070                 // If all nodes require some features we don't understand, route should fail
2071                 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)) {
2072                         assert_eq!(err, "Failed to find a path to the given destination");
2073                 } else { panic!(); }
2074
2075                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2076                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2077                 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();
2078                 assert_eq!(route.paths[0].len(), 2);
2079
2080                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2081                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2082                 assert_eq!(route.paths[0][0].fee_msat, 200);
2083                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2084                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2085                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2086
2087                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2088                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2089                 assert_eq!(route.paths[0][1].fee_msat, 100);
2090                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2091                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2092                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2093
2094                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2095                 // naively) assume that the user checked the feature bits on the invoice, which override
2096                 // the node_announcement.
2097         }
2098
2099         #[test]
2100         fn our_chans_test() {
2101                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2102                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2103
2104                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2105                 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();
2106                 assert_eq!(route.paths[0].len(), 3);
2107
2108                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2109                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2110                 assert_eq!(route.paths[0][0].fee_msat, 200);
2111                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2112                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2113                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2114
2115                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2116                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2117                 assert_eq!(route.paths[0][1].fee_msat, 100);
2118                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2119                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2120                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2121
2122                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2123                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2124                 assert_eq!(route.paths[0][2].fee_msat, 100);
2125                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2126                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2127                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2128
2129                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2130                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2131                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2132                 assert_eq!(route.paths[0].len(), 2);
2133
2134                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2135                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2136                 assert_eq!(route.paths[0][0].fee_msat, 200);
2137                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2138                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2139                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2140
2141                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2142                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2143                 assert_eq!(route.paths[0][1].fee_msat, 100);
2144                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2145                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2146                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2147         }
2148
2149         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2150                 let zero_fees = RoutingFees {
2151                         base_msat: 0,
2152                         proportional_millionths: 0,
2153                 };
2154                 vec![RouteHint(vec![RouteHintHop {
2155                         src_node_id: nodes[3].clone(),
2156                         short_channel_id: 8,
2157                         fees: zero_fees,
2158                         cltv_expiry_delta: (8 << 8) | 1,
2159                         htlc_minimum_msat: None,
2160                         htlc_maximum_msat: None,
2161                 }
2162                 ]), RouteHint(vec![RouteHintHop {
2163                         src_node_id: nodes[4].clone(),
2164                         short_channel_id: 9,
2165                         fees: RoutingFees {
2166                                 base_msat: 1001,
2167                                 proportional_millionths: 0,
2168                         },
2169                         cltv_expiry_delta: (9 << 8) | 1,
2170                         htlc_minimum_msat: None,
2171                         htlc_maximum_msat: None,
2172                 }]), RouteHint(vec![RouteHintHop {
2173                         src_node_id: nodes[5].clone(),
2174                         short_channel_id: 10,
2175                         fees: zero_fees,
2176                         cltv_expiry_delta: (10 << 8) | 1,
2177                         htlc_minimum_msat: None,
2178                         htlc_maximum_msat: None,
2179                 }])]
2180         }
2181
2182         fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2183                 let zero_fees = RoutingFees {
2184                         base_msat: 0,
2185                         proportional_millionths: 0,
2186                 };
2187                 vec![RouteHint(vec![RouteHintHop {
2188                         src_node_id: nodes[2].clone(),
2189                         short_channel_id: 5,
2190                         fees: RoutingFees {
2191                                 base_msat: 100,
2192                                 proportional_millionths: 0,
2193                         },
2194                         cltv_expiry_delta: (5 << 8) | 1,
2195                         htlc_minimum_msat: None,
2196                         htlc_maximum_msat: None,
2197                 }, RouteHintHop {
2198                         src_node_id: nodes[3].clone(),
2199                         short_channel_id: 8,
2200                         fees: zero_fees,
2201                         cltv_expiry_delta: (8 << 8) | 1,
2202                         htlc_minimum_msat: None,
2203                         htlc_maximum_msat: None,
2204                 }
2205                 ]), RouteHint(vec![RouteHintHop {
2206                         src_node_id: nodes[4].clone(),
2207                         short_channel_id: 9,
2208                         fees: RoutingFees {
2209                                 base_msat: 1001,
2210                                 proportional_millionths: 0,
2211                         },
2212                         cltv_expiry_delta: (9 << 8) | 1,
2213                         htlc_minimum_msat: None,
2214                         htlc_maximum_msat: None,
2215                 }]), RouteHint(vec![RouteHintHop {
2216                         src_node_id: nodes[5].clone(),
2217                         short_channel_id: 10,
2218                         fees: zero_fees,
2219                         cltv_expiry_delta: (10 << 8) | 1,
2220                         htlc_minimum_msat: None,
2221                         htlc_maximum_msat: None,
2222                 }])]
2223         }
2224
2225         #[test]
2226         fn partial_route_hint_test() {
2227                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2228                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2229
2230                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2231                 // Tests the behaviour when the RouteHint contains a suboptimal hop.
2232                 // RouteHint may be partially used by the algo to build the best path.
2233
2234                 // First check that last hop can't have its source as the payee.
2235                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2236                         src_node_id: nodes[6],
2237                         short_channel_id: 8,
2238                         fees: RoutingFees {
2239                                 base_msat: 1000,
2240                                 proportional_millionths: 0,
2241                         },
2242                         cltv_expiry_delta: (8 << 8) | 1,
2243                         htlc_minimum_msat: None,
2244                         htlc_maximum_msat: None,
2245                 }]);
2246
2247                 let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
2248                 invalid_last_hops.push(invalid_last_hop);
2249                 {
2250                         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)) {
2251                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2252                         } else { panic!(); }
2253                 }
2254
2255                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops_multi_private_channels(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2256                 assert_eq!(route.paths[0].len(), 5);
2257
2258                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2259                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2260                 assert_eq!(route.paths[0][0].fee_msat, 100);
2261                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2262                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2263                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2264
2265                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2266                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2267                 assert_eq!(route.paths[0][1].fee_msat, 0);
2268                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2269                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2270                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2271
2272                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2273                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2274                 assert_eq!(route.paths[0][2].fee_msat, 0);
2275                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2276                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2277                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2278
2279                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2280                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2281                 assert_eq!(route.paths[0][3].fee_msat, 0);
2282                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2283                 // If we have a peer in the node map, we'll use their features here since we don't have
2284                 // a way of figuring out their features from the invoice:
2285                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2286                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2287
2288                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2289                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2290                 assert_eq!(route.paths[0][4].fee_msat, 100);
2291                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2292                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2293                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2294         }
2295
2296         fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2297                 let zero_fees = RoutingFees {
2298                         base_msat: 0,
2299                         proportional_millionths: 0,
2300                 };
2301                 vec![RouteHint(vec![RouteHintHop {
2302                         src_node_id: nodes[3].clone(),
2303                         short_channel_id: 8,
2304                         fees: zero_fees,
2305                         cltv_expiry_delta: (8 << 8) | 1,
2306                         htlc_minimum_msat: None,
2307                         htlc_maximum_msat: None,
2308                 }]), RouteHint(vec![
2309
2310                 ]), RouteHint(vec![RouteHintHop {
2311                         src_node_id: nodes[5].clone(),
2312                         short_channel_id: 10,
2313                         fees: zero_fees,
2314                         cltv_expiry_delta: (10 << 8) | 1,
2315                         htlc_minimum_msat: None,
2316                         htlc_maximum_msat: None,
2317                 }])]
2318         }
2319
2320         #[test]
2321         fn ignores_empty_last_hops_test() {
2322                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2323                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2324
2325                 // Test handling of an empty RouteHint passed in Invoice.
2326
2327                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &empty_last_hop(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2328                 assert_eq!(route.paths[0].len(), 5);
2329
2330                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2331                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2332                 assert_eq!(route.paths[0][0].fee_msat, 100);
2333                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2334                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2335                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2336
2337                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2338                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2339                 assert_eq!(route.paths[0][1].fee_msat, 0);
2340                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2341                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2342                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2343
2344                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2345                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2346                 assert_eq!(route.paths[0][2].fee_msat, 0);
2347                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2348                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2349                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2350
2351                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2352                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2353                 assert_eq!(route.paths[0][3].fee_msat, 0);
2354                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2355                 // If we have a peer in the node map, we'll use their features here since we don't have
2356                 // a way of figuring out their features from the invoice:
2357                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2358                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2359
2360                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2361                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2362                 assert_eq!(route.paths[0][4].fee_msat, 100);
2363                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2364                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2365                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2366         }
2367
2368         fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2369                 let zero_fees = RoutingFees {
2370                         base_msat: 0,
2371                         proportional_millionths: 0,
2372                 };
2373                 vec![RouteHint(vec![RouteHintHop {
2374                         src_node_id: nodes[2].clone(),
2375                         short_channel_id: 5,
2376                         fees: RoutingFees {
2377                                 base_msat: 100,
2378                                 proportional_millionths: 0,
2379                         },
2380                         cltv_expiry_delta: (5 << 8) | 1,
2381                         htlc_minimum_msat: None,
2382                         htlc_maximum_msat: None,
2383                 }, RouteHintHop {
2384                         src_node_id: nodes[3].clone(),
2385                         short_channel_id: 8,
2386                         fees: zero_fees,
2387                         cltv_expiry_delta: (8 << 8) | 1,
2388                         htlc_minimum_msat: None,
2389                         htlc_maximum_msat: None,
2390                 }]), RouteHint(vec![RouteHintHop {
2391                         src_node_id: nodes[5].clone(),
2392                         short_channel_id: 10,
2393                         fees: zero_fees,
2394                         cltv_expiry_delta: (10 << 8) | 1,
2395                         htlc_minimum_msat: None,
2396                         htlc_maximum_msat: None,
2397                 }])]
2398         }
2399
2400         #[test]
2401         fn multi_hint_last_hops_test() {
2402                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2403                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2404                 // Test through channels 2, 3, 5, 8.
2405                 // Test shows that multiple hop hints are considered.
2406
2407                 // Disabling channels 6 & 7 by flags=2
2408                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2409                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2410                         short_channel_id: 6,
2411                         timestamp: 2,
2412                         flags: 2, // to disable
2413                         cltv_expiry_delta: 0,
2414                         htlc_minimum_msat: 0,
2415                         htlc_maximum_msat: OptionalField::Absent,
2416                         fee_base_msat: 0,
2417                         fee_proportional_millionths: 0,
2418                         excess_data: Vec::new()
2419                 });
2420                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2421                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2422                         short_channel_id: 7,
2423                         timestamp: 2,
2424                         flags: 2, // to disable
2425                         cltv_expiry_delta: 0,
2426                         htlc_minimum_msat: 0,
2427                         htlc_maximum_msat: OptionalField::Absent,
2428                         fee_base_msat: 0,
2429                         fee_proportional_millionths: 0,
2430                         excess_data: Vec::new()
2431                 });
2432
2433                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &multi_hint_last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2434                 assert_eq!(route.paths[0].len(), 4);
2435
2436                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2437                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2438                 assert_eq!(route.paths[0][0].fee_msat, 200);
2439                 assert_eq!(route.paths[0][0].cltv_expiry_delta, 1025);
2440                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2441                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2442
2443                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2444                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2445                 assert_eq!(route.paths[0][1].fee_msat, 100);
2446                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 1281);
2447                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2448                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2449
2450                 assert_eq!(route.paths[0][2].pubkey, nodes[3]);
2451                 assert_eq!(route.paths[0][2].short_channel_id, 5);
2452                 assert_eq!(route.paths[0][2].fee_msat, 0);
2453                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 2049);
2454                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
2455                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
2456
2457                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2458                 assert_eq!(route.paths[0][3].short_channel_id, 8);
2459                 assert_eq!(route.paths[0][3].fee_msat, 100);
2460                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2461                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2462                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2463         }
2464
2465         fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2466                 let zero_fees = RoutingFees {
2467                         base_msat: 0,
2468                         proportional_millionths: 0,
2469                 };
2470                 vec![RouteHint(vec![RouteHintHop {
2471                         src_node_id: nodes[4].clone(),
2472                         short_channel_id: 11,
2473                         fees: zero_fees,
2474                         cltv_expiry_delta: (11 << 8) | 1,
2475                         htlc_minimum_msat: None,
2476                         htlc_maximum_msat: None,
2477                 }, RouteHintHop {
2478                         src_node_id: nodes[3].clone(),
2479                         short_channel_id: 8,
2480                         fees: zero_fees,
2481                         cltv_expiry_delta: (8 << 8) | 1,
2482                         htlc_minimum_msat: None,
2483                         htlc_maximum_msat: None,
2484                 }]), RouteHint(vec![RouteHintHop {
2485                         src_node_id: nodes[4].clone(),
2486                         short_channel_id: 9,
2487                         fees: RoutingFees {
2488                                 base_msat: 1001,
2489                                 proportional_millionths: 0,
2490                         },
2491                         cltv_expiry_delta: (9 << 8) | 1,
2492                         htlc_minimum_msat: None,
2493                         htlc_maximum_msat: None,
2494                 }]), RouteHint(vec![RouteHintHop {
2495                         src_node_id: nodes[5].clone(),
2496                         short_channel_id: 10,
2497                         fees: zero_fees,
2498                         cltv_expiry_delta: (10 << 8) | 1,
2499                         htlc_minimum_msat: None,
2500                         htlc_maximum_msat: None,
2501                 }])]
2502         }
2503
2504         #[test]
2505         fn last_hops_with_public_channel_test() {
2506                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2507                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2508                 // This test shows that public routes can be present in the invoice
2509                 // which would be handled in the same manner.
2510
2511                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops_with_public_channel(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2512                 assert_eq!(route.paths[0].len(), 5);
2513
2514                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2515                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2516                 assert_eq!(route.paths[0][0].fee_msat, 100);
2517                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2518                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2519                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2520
2521                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2522                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2523                 assert_eq!(route.paths[0][1].fee_msat, 0);
2524                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2525                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2526                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2527
2528                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2529                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2530                 assert_eq!(route.paths[0][2].fee_msat, 0);
2531                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2532                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2533                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2534
2535                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2536                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2537                 assert_eq!(route.paths[0][3].fee_msat, 0);
2538                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2539                 // If we have a peer in the node map, we'll use their features here since we don't have
2540                 // a way of figuring out their features from the invoice:
2541                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2542                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new());
2543
2544                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2545                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2546                 assert_eq!(route.paths[0][4].fee_msat, 100);
2547                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2548                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2549                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2550         }
2551
2552         #[test]
2553         fn our_chans_last_hop_connect_test() {
2554                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2555                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2556
2557                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2558                 let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2559                 let mut last_hops = last_hops(&nodes);
2560                 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();
2561                 assert_eq!(route.paths[0].len(), 2);
2562
2563                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2564                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2565                 assert_eq!(route.paths[0][0].fee_msat, 0);
2566                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2567                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2568                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2569
2570                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2571                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2572                 assert_eq!(route.paths[0][1].fee_msat, 100);
2573                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2574                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2575                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2576
2577                 last_hops[0].0[0].fees.base_msat = 1000;
2578
2579                 // Revert to via 6 as the fee on 8 goes up
2580                 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();
2581                 assert_eq!(route.paths[0].len(), 4);
2582
2583                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2584                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2585                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2586                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2587                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2588                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2589
2590                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2591                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2592                 assert_eq!(route.paths[0][1].fee_msat, 100);
2593                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2594                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2595                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2596
2597                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2598                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2599                 assert_eq!(route.paths[0][2].fee_msat, 0);
2600                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2601                 // If we have a peer in the node map, we'll use their features here since we don't have
2602                 // a way of figuring out their features from the invoice:
2603                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2604                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2605
2606                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2607                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2608                 assert_eq!(route.paths[0][3].fee_msat, 100);
2609                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2610                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2611                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2612
2613                 // ...but still use 8 for larger payments as 6 has a variable feerate
2614                 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();
2615                 assert_eq!(route.paths[0].len(), 5);
2616
2617                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2618                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2619                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2620                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2621                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2622                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2623
2624                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2625                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2626                 assert_eq!(route.paths[0][1].fee_msat, 0);
2627                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2628                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2629                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2630
2631                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2632                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2633                 assert_eq!(route.paths[0][2].fee_msat, 0);
2634                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2635                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2636                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2637
2638                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2639                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2640                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2641                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2642                 // If we have a peer in the node map, we'll use their features here since we don't have
2643                 // a way of figuring out their features from the invoice:
2644                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2645                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2646
2647                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2648                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2649                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2650                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2651                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2652                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2653         }
2654
2655         fn do_unannounced_path_test(last_hop_htlc_max: Option<u64>, last_hop_fee_prop: u32, outbound_capacity_msat: u64, route_val: u64) -> Result<Route, LightningError> {
2656                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2657                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2658                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2659
2660                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2661                 let last_hops = RouteHint(vec![RouteHintHop {
2662                         src_node_id: middle_node_id,
2663                         short_channel_id: 8,
2664                         fees: RoutingFees {
2665                                 base_msat: 1000,
2666                                 proportional_millionths: last_hop_fee_prop,
2667                         },
2668                         cltv_expiry_delta: (8 << 8) | 1,
2669                         htlc_minimum_msat: None,
2670                         htlc_maximum_msat: last_hop_htlc_max,
2671                 }]);
2672                 let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
2673                 get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &vec![&last_hops], route_val, 42, Arc::new(test_utils::TestLogger::new()))
2674         }
2675
2676         #[test]
2677         fn unannounced_path_test() {
2678                 // We should be able to send a payment to a destination without any help of a routing graph
2679                 // if we have a channel with a common counterparty that appears in the first and last hop
2680                 // hints.
2681                 let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
2682
2683                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2684                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2685                 assert_eq!(route.paths[0].len(), 2);
2686
2687                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2688                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2689                 assert_eq!(route.paths[0][0].fee_msat, 1001);
2690                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2691                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2692                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2693
2694                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2695                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2696                 assert_eq!(route.paths[0][1].fee_msat, 1000000);
2697                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2698                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2699                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2700         }
2701
2702         #[test]
2703         fn overflow_unannounced_path_test_liquidity_underflow() {
2704                 // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
2705                 // the last-hop had a fee which overflowed a u64, we'd panic.
2706                 // This was due to us adding the first-hop from us unconditionally, causing us to think
2707                 // we'd built a path (as our node is in the "best candidate" set), when we had not.
2708                 // In this test, we previously hit a subtraction underflow due to having less available
2709                 // liquidity at the last hop than 0.
2710                 assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 0, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
2711         }
2712
2713         #[test]
2714         fn overflow_unannounced_path_test_feerate_overflow() {
2715                 // This tests for the same case as above, except instead of hitting a subtraction
2716                 // underflow, we hit a case where the fee charged at a hop overflowed.
2717                 assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 50000, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
2718         }
2719
2720         #[test]
2721         fn available_amount_while_routing_test() {
2722                 // Tests whether we choose the correct available channel amount while routing.
2723
2724                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2725                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2726
2727                 // We will use a simple single-path route from
2728                 // our node to node2 via node0: channels {1, 3}.
2729
2730                 // First disable all other paths.
2731                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2732                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2733                         short_channel_id: 2,
2734                         timestamp: 2,
2735                         flags: 2,
2736                         cltv_expiry_delta: 0,
2737                         htlc_minimum_msat: 0,
2738                         htlc_maximum_msat: OptionalField::Present(100_000),
2739                         fee_base_msat: 0,
2740                         fee_proportional_millionths: 0,
2741                         excess_data: Vec::new()
2742                 });
2743                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2744                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2745                         short_channel_id: 12,
2746                         timestamp: 2,
2747                         flags: 2,
2748                         cltv_expiry_delta: 0,
2749                         htlc_minimum_msat: 0,
2750                         htlc_maximum_msat: OptionalField::Present(100_000),
2751                         fee_base_msat: 0,
2752                         fee_proportional_millionths: 0,
2753                         excess_data: Vec::new()
2754                 });
2755
2756                 // Make the first channel (#1) very permissive,
2757                 // and we will be testing all limits on the second channel.
2758                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2759                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2760                         short_channel_id: 1,
2761                         timestamp: 2,
2762                         flags: 0,
2763                         cltv_expiry_delta: 0,
2764                         htlc_minimum_msat: 0,
2765                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2766                         fee_base_msat: 0,
2767                         fee_proportional_millionths: 0,
2768                         excess_data: Vec::new()
2769                 });
2770
2771                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2772                 // In this case, it should be set to 250_000 sats.
2773                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2774                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2775                         short_channel_id: 3,
2776                         timestamp: 2,
2777                         flags: 0,
2778                         cltv_expiry_delta: 0,
2779                         htlc_minimum_msat: 0,
2780                         htlc_maximum_msat: OptionalField::Absent,
2781                         fee_base_msat: 0,
2782                         fee_proportional_millionths: 0,
2783                         excess_data: Vec::new()
2784                 });
2785
2786                 {
2787                         // Attempt to route more than available results in a failure.
2788                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2789                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2790                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2791                         } else { panic!(); }
2792                 }
2793
2794                 {
2795                         // Now, attempt to route an exact amount we have should be fine.
2796                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2797                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2798                         assert_eq!(route.paths.len(), 1);
2799                         let path = route.paths.last().unwrap();
2800                         assert_eq!(path.len(), 2);
2801                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2802                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2803                 }
2804
2805                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2806                 // Disable channel #1 and use another first hop.
2807                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2808                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2809                         short_channel_id: 1,
2810                         timestamp: 3,
2811                         flags: 2,
2812                         cltv_expiry_delta: 0,
2813                         htlc_minimum_msat: 0,
2814                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2815                         fee_base_msat: 0,
2816                         fee_proportional_millionths: 0,
2817                         excess_data: Vec::new()
2818                 });
2819
2820                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2821                 let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
2822
2823                 {
2824                         // Attempt to route more than available results in a failure.
2825                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2826                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2827                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2828                         } else { panic!(); }
2829                 }
2830
2831                 {
2832                         // Now, attempt to route an exact amount we have should be fine.
2833                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2834                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2835                         assert_eq!(route.paths.len(), 1);
2836                         let path = route.paths.last().unwrap();
2837                         assert_eq!(path.len(), 2);
2838                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2839                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2840                 }
2841
2842                 // Enable channel #1 back.
2843                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2844                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2845                         short_channel_id: 1,
2846                         timestamp: 4,
2847                         flags: 0,
2848                         cltv_expiry_delta: 0,
2849                         htlc_minimum_msat: 0,
2850                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2851                         fee_base_msat: 0,
2852                         fee_proportional_millionths: 0,
2853                         excess_data: Vec::new()
2854                 });
2855
2856
2857                 // Now let's see if routing works if we know only htlc_maximum_msat.
2858                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2859                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2860                         short_channel_id: 3,
2861                         timestamp: 3,
2862                         flags: 0,
2863                         cltv_expiry_delta: 0,
2864                         htlc_minimum_msat: 0,
2865                         htlc_maximum_msat: OptionalField::Present(15_000),
2866                         fee_base_msat: 0,
2867                         fee_proportional_millionths: 0,
2868                         excess_data: Vec::new()
2869                 });
2870
2871                 {
2872                         // Attempt to route more than available results in a failure.
2873                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2874                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2875                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2876                         } else { panic!(); }
2877                 }
2878
2879                 {
2880                         // Now, attempt to route an exact amount we have should be fine.
2881                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2882                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2883                         assert_eq!(route.paths.len(), 1);
2884                         let path = route.paths.last().unwrap();
2885                         assert_eq!(path.len(), 2);
2886                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2887                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2888                 }
2889
2890                 // Now let's see if routing works if we know only capacity from the UTXO.
2891
2892                 // We can't change UTXO capacity on the fly, so we'll disable
2893                 // the existing channel and add another one with the capacity we need.
2894                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2895                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2896                         short_channel_id: 3,
2897                         timestamp: 4,
2898                         flags: 2,
2899                         cltv_expiry_delta: 0,
2900                         htlc_minimum_msat: 0,
2901                         htlc_maximum_msat: OptionalField::Absent,
2902                         fee_base_msat: 0,
2903                         fee_proportional_millionths: 0,
2904                         excess_data: Vec::new()
2905                 });
2906
2907                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2908                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2909                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2910                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2911                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2912
2913                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2914                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2915
2916                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2917                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2918                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2919                         short_channel_id: 333,
2920                         timestamp: 1,
2921                         flags: 0,
2922                         cltv_expiry_delta: (3 << 8) | 1,
2923                         htlc_minimum_msat: 0,
2924                         htlc_maximum_msat: OptionalField::Absent,
2925                         fee_base_msat: 0,
2926                         fee_proportional_millionths: 0,
2927                         excess_data: Vec::new()
2928                 });
2929                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2930                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2931                         short_channel_id: 333,
2932                         timestamp: 1,
2933                         flags: 1,
2934                         cltv_expiry_delta: (3 << 8) | 2,
2935                         htlc_minimum_msat: 0,
2936                         htlc_maximum_msat: OptionalField::Absent,
2937                         fee_base_msat: 100,
2938                         fee_proportional_millionths: 0,
2939                         excess_data: Vec::new()
2940                 });
2941
2942                 {
2943                         // Attempt to route more than available results in a failure.
2944                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2945                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2946                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2947                         } else { panic!(); }
2948                 }
2949
2950                 {
2951                         // Now, attempt to route an exact amount we have should be fine.
2952                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2953                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2954                         assert_eq!(route.paths.len(), 1);
2955                         let path = route.paths.last().unwrap();
2956                         assert_eq!(path.len(), 2);
2957                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2958                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2959                 }
2960
2961                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2962                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2963                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2964                         short_channel_id: 333,
2965                         timestamp: 6,
2966                         flags: 0,
2967                         cltv_expiry_delta: 0,
2968                         htlc_minimum_msat: 0,
2969                         htlc_maximum_msat: OptionalField::Present(10_000),
2970                         fee_base_msat: 0,
2971                         fee_proportional_millionths: 0,
2972                         excess_data: Vec::new()
2973                 });
2974
2975                 {
2976                         // Attempt to route more than available results in a failure.
2977                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2978                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2979                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2980                         } else { panic!(); }
2981                 }
2982
2983                 {
2984                         // Now, attempt to route an exact amount we have should be fine.
2985                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2986                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2987                         assert_eq!(route.paths.len(), 1);
2988                         let path = route.paths.last().unwrap();
2989                         assert_eq!(path.len(), 2);
2990                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2991                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2992                 }
2993         }
2994
2995         #[test]
2996         fn available_liquidity_last_hop_test() {
2997                 // Check that available liquidity properly limits the path even when only
2998                 // one of the latter hops is limited.
2999                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3000                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3001
3002                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3003                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
3004                 // Total capacity: 50 sats.
3005
3006                 // Disable other potential paths.
3007                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3008                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3009                         short_channel_id: 2,
3010                         timestamp: 2,
3011                         flags: 2,
3012                         cltv_expiry_delta: 0,
3013                         htlc_minimum_msat: 0,
3014                         htlc_maximum_msat: OptionalField::Present(100_000),
3015                         fee_base_msat: 0,
3016                         fee_proportional_millionths: 0,
3017                         excess_data: Vec::new()
3018                 });
3019                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3020                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3021                         short_channel_id: 7,
3022                         timestamp: 2,
3023                         flags: 2,
3024                         cltv_expiry_delta: 0,
3025                         htlc_minimum_msat: 0,
3026                         htlc_maximum_msat: OptionalField::Present(100_000),
3027                         fee_base_msat: 0,
3028                         fee_proportional_millionths: 0,
3029                         excess_data: Vec::new()
3030                 });
3031
3032                 // Limit capacities
3033
3034                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3035                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3036                         short_channel_id: 12,
3037                         timestamp: 2,
3038                         flags: 0,
3039                         cltv_expiry_delta: 0,
3040                         htlc_minimum_msat: 0,
3041                         htlc_maximum_msat: OptionalField::Present(100_000),
3042                         fee_base_msat: 0,
3043                         fee_proportional_millionths: 0,
3044                         excess_data: Vec::new()
3045                 });
3046                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3047                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3048                         short_channel_id: 13,
3049                         timestamp: 2,
3050                         flags: 0,
3051                         cltv_expiry_delta: 0,
3052                         htlc_minimum_msat: 0,
3053                         htlc_maximum_msat: OptionalField::Present(100_000),
3054                         fee_base_msat: 0,
3055                         fee_proportional_millionths: 0,
3056                         excess_data: Vec::new()
3057                 });
3058
3059                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3060                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3061                         short_channel_id: 6,
3062                         timestamp: 2,
3063                         flags: 0,
3064                         cltv_expiry_delta: 0,
3065                         htlc_minimum_msat: 0,
3066                         htlc_maximum_msat: OptionalField::Present(50_000),
3067                         fee_base_msat: 0,
3068                         fee_proportional_millionths: 0,
3069                         excess_data: Vec::new()
3070                 });
3071                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3072                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3073                         short_channel_id: 11,
3074                         timestamp: 2,
3075                         flags: 0,
3076                         cltv_expiry_delta: 0,
3077                         htlc_minimum_msat: 0,
3078                         htlc_maximum_msat: OptionalField::Present(100_000),
3079                         fee_base_msat: 0,
3080                         fee_proportional_millionths: 0,
3081                         excess_data: Vec::new()
3082                 });
3083                 {
3084                         // Attempt to route more than available results in a failure.
3085                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3086                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
3087                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3088                         } else { panic!(); }
3089                 }
3090
3091                 {
3092                         // Now, attempt to route 49 sats (just a bit below the capacity).
3093                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3094                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
3095                         assert_eq!(route.paths.len(), 1);
3096                         let mut total_amount_paid_msat = 0;
3097                         for path in &route.paths {
3098                                 assert_eq!(path.len(), 4);
3099                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3100                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3101                         }
3102                         assert_eq!(total_amount_paid_msat, 49_000);
3103                 }
3104
3105                 {
3106                         // Attempt to route an exact amount is also fine
3107                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3108                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
3109                         assert_eq!(route.paths.len(), 1);
3110                         let mut total_amount_paid_msat = 0;
3111                         for path in &route.paths {
3112                                 assert_eq!(path.len(), 4);
3113                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3114                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3115                         }
3116                         assert_eq!(total_amount_paid_msat, 50_000);
3117                 }
3118         }
3119
3120         #[test]
3121         fn ignore_fee_first_hop_test() {
3122                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3123                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3124
3125                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3126                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3127                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3128                         short_channel_id: 1,
3129                         timestamp: 2,
3130                         flags: 0,
3131                         cltv_expiry_delta: 0,
3132                         htlc_minimum_msat: 0,
3133                         htlc_maximum_msat: OptionalField::Present(100_000),
3134                         fee_base_msat: 1_000_000,
3135                         fee_proportional_millionths: 0,
3136                         excess_data: Vec::new()
3137                 });
3138                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3139                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3140                         short_channel_id: 3,
3141                         timestamp: 2,
3142                         flags: 0,
3143                         cltv_expiry_delta: 0,
3144                         htlc_minimum_msat: 0,
3145                         htlc_maximum_msat: OptionalField::Present(50_000),
3146                         fee_base_msat: 0,
3147                         fee_proportional_millionths: 0,
3148                         excess_data: Vec::new()
3149                 });
3150
3151                 {
3152                         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();
3153                         assert_eq!(route.paths.len(), 1);
3154                         let mut total_amount_paid_msat = 0;
3155                         for path in &route.paths {
3156                                 assert_eq!(path.len(), 2);
3157                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3158                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3159                         }
3160                         assert_eq!(total_amount_paid_msat, 50_000);
3161                 }
3162         }
3163
3164         #[test]
3165         fn simple_mpp_route_test() {
3166                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3167                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3168
3169                 // We need a route consisting of 3 paths:
3170                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3171                 // To achieve this, the amount being transferred should be around
3172                 // the total capacity of these 3 paths.
3173
3174                 // First, we set limits on these (previously unlimited) channels.
3175                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
3176
3177                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3178                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3179                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3180                         short_channel_id: 1,
3181                         timestamp: 2,
3182                         flags: 0,
3183                         cltv_expiry_delta: 0,
3184                         htlc_minimum_msat: 0,
3185                         htlc_maximum_msat: OptionalField::Present(100_000),
3186                         fee_base_msat: 0,
3187                         fee_proportional_millionths: 0,
3188                         excess_data: Vec::new()
3189                 });
3190                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3191                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3192                         short_channel_id: 3,
3193                         timestamp: 2,
3194                         flags: 0,
3195                         cltv_expiry_delta: 0,
3196                         htlc_minimum_msat: 0,
3197                         htlc_maximum_msat: OptionalField::Present(50_000),
3198                         fee_base_msat: 0,
3199                         fee_proportional_millionths: 0,
3200                         excess_data: Vec::new()
3201                 });
3202
3203                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
3204                 // (total limit 60).
3205                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3206                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3207                         short_channel_id: 12,
3208                         timestamp: 2,
3209                         flags: 0,
3210                         cltv_expiry_delta: 0,
3211                         htlc_minimum_msat: 0,
3212                         htlc_maximum_msat: OptionalField::Present(60_000),
3213                         fee_base_msat: 0,
3214                         fee_proportional_millionths: 0,
3215                         excess_data: Vec::new()
3216                 });
3217                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3218                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3219                         short_channel_id: 13,
3220                         timestamp: 2,
3221                         flags: 0,
3222                         cltv_expiry_delta: 0,
3223                         htlc_minimum_msat: 0,
3224                         htlc_maximum_msat: OptionalField::Present(60_000),
3225                         fee_base_msat: 0,
3226                         fee_proportional_millionths: 0,
3227                         excess_data: Vec::new()
3228                 });
3229
3230                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
3231                 // (total capacity 180 sats).
3232                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3233                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3234                         short_channel_id: 2,
3235                         timestamp: 2,
3236                         flags: 0,
3237                         cltv_expiry_delta: 0,
3238                         htlc_minimum_msat: 0,
3239                         htlc_maximum_msat: OptionalField::Present(200_000),
3240                         fee_base_msat: 0,
3241                         fee_proportional_millionths: 0,
3242                         excess_data: Vec::new()
3243                 });
3244                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3245                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3246                         short_channel_id: 4,
3247                         timestamp: 2,
3248                         flags: 0,
3249                         cltv_expiry_delta: 0,
3250                         htlc_minimum_msat: 0,
3251                         htlc_maximum_msat: OptionalField::Present(180_000),
3252                         fee_base_msat: 0,
3253                         fee_proportional_millionths: 0,
3254                         excess_data: Vec::new()
3255                 });
3256
3257                 {
3258                         // Attempt to route more than available results in a failure.
3259                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
3260                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
3261                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3262                         } else { panic!(); }
3263                 }
3264
3265                 {
3266                         // Now, attempt to route 250 sats (just a bit below the capacity).
3267                         // Our algorithm should provide us with these 3 paths.
3268                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3269                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
3270                         assert_eq!(route.paths.len(), 3);
3271                         let mut total_amount_paid_msat = 0;
3272                         for path in &route.paths {
3273                                 assert_eq!(path.len(), 2);
3274                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3275                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3276                         }
3277                         assert_eq!(total_amount_paid_msat, 250_000);
3278                 }
3279
3280                 {
3281                         // Attempt to route an exact amount is also fine
3282                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3283                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
3284                         assert_eq!(route.paths.len(), 3);
3285                         let mut total_amount_paid_msat = 0;
3286                         for path in &route.paths {
3287                                 assert_eq!(path.len(), 2);
3288                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3289                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3290                         }
3291                         assert_eq!(total_amount_paid_msat, 290_000);
3292                 }
3293         }
3294
3295         #[test]
3296         fn long_mpp_route_test() {
3297                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3298                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3299
3300                 // We need a route consisting of 3 paths:
3301                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3302                 // Note that these paths overlap (channels 5, 12, 13).
3303                 // We will route 300 sats.
3304                 // Each path will have 100 sats capacity, those channels which
3305                 // are used twice will have 200 sats capacity.
3306
3307                 // Disable other potential paths.
3308                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3309                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3310                         short_channel_id: 2,
3311                         timestamp: 2,
3312                         flags: 2,
3313                         cltv_expiry_delta: 0,
3314                         htlc_minimum_msat: 0,
3315                         htlc_maximum_msat: OptionalField::Present(100_000),
3316                         fee_base_msat: 0,
3317                         fee_proportional_millionths: 0,
3318                         excess_data: Vec::new()
3319                 });
3320                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3321                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3322                         short_channel_id: 7,
3323                         timestamp: 2,
3324                         flags: 2,
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
3333                 // Path via {node0, node2} is channels {1, 3, 5}.
3334                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3335                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3336                         short_channel_id: 1,
3337                         timestamp: 2,
3338                         flags: 0,
3339                         cltv_expiry_delta: 0,
3340                         htlc_minimum_msat: 0,
3341                         htlc_maximum_msat: OptionalField::Present(100_000),
3342                         fee_base_msat: 0,
3343                         fee_proportional_millionths: 0,
3344                         excess_data: Vec::new()
3345                 });
3346                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3347                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3348                         short_channel_id: 3,
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                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3360                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3361                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3362                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3363                         short_channel_id: 5,
3364                         timestamp: 2,
3365                         flags: 0,
3366                         cltv_expiry_delta: 0,
3367                         htlc_minimum_msat: 0,
3368                         htlc_maximum_msat: OptionalField::Present(200_000),
3369                         fee_base_msat: 0,
3370                         fee_proportional_millionths: 0,
3371                         excess_data: Vec::new()
3372                 });
3373
3374                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3375                 // Add 100 sats to the capacities of {12, 13}, because these channels
3376                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3377                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3378                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3379                         short_channel_id: 12,
3380                         timestamp: 2,
3381                         flags: 0,
3382                         cltv_expiry_delta: 0,
3383                         htlc_minimum_msat: 0,
3384                         htlc_maximum_msat: OptionalField::Present(200_000),
3385                         fee_base_msat: 0,
3386                         fee_proportional_millionths: 0,
3387                         excess_data: Vec::new()
3388                 });
3389                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3390                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3391                         short_channel_id: 13,
3392                         timestamp: 2,
3393                         flags: 0,
3394                         cltv_expiry_delta: 0,
3395                         htlc_minimum_msat: 0,
3396                         htlc_maximum_msat: OptionalField::Present(200_000),
3397                         fee_base_msat: 0,
3398                         fee_proportional_millionths: 0,
3399                         excess_data: Vec::new()
3400                 });
3401
3402                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3403                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3404                         short_channel_id: 6,
3405                         timestamp: 2,
3406                         flags: 0,
3407                         cltv_expiry_delta: 0,
3408                         htlc_minimum_msat: 0,
3409                         htlc_maximum_msat: OptionalField::Present(100_000),
3410                         fee_base_msat: 0,
3411                         fee_proportional_millionths: 0,
3412                         excess_data: Vec::new()
3413                 });
3414                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3415                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3416                         short_channel_id: 11,
3417                         timestamp: 2,
3418                         flags: 0,
3419                         cltv_expiry_delta: 0,
3420                         htlc_minimum_msat: 0,
3421                         htlc_maximum_msat: OptionalField::Present(100_000),
3422                         fee_base_msat: 0,
3423                         fee_proportional_millionths: 0,
3424                         excess_data: Vec::new()
3425                 });
3426
3427                 // Path via {node7, node2} is channels {12, 13, 5}.
3428                 // We already limited them to 200 sats (they are used twice for 100 sats).
3429                 // Nothing to do here.
3430
3431                 {
3432                         // Attempt to route more than available results in a failure.
3433                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3434                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3435                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3436                         } else { panic!(); }
3437                 }
3438
3439                 {
3440                         // Now, attempt to route 300 sats (exact amount we can route).
3441                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3442                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3443                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3444                         assert_eq!(route.paths.len(), 3);
3445
3446                         let mut total_amount_paid_msat = 0;
3447                         for path in &route.paths {
3448                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3449                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3450                         }
3451                         assert_eq!(total_amount_paid_msat, 300_000);
3452                 }
3453
3454         }
3455
3456         #[test]
3457         fn mpp_cheaper_route_test() {
3458                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3459                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3460
3461                 // This test checks that if we have two cheaper paths and one more expensive path,
3462                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3463                 // two cheaper paths will be taken.
3464                 // These paths have equal available liquidity.
3465
3466                 // We need a combination of 3 paths:
3467                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3468                 // Note that these paths overlap (channels 5, 12, 13).
3469                 // Each path will have 100 sats capacity, those channels which
3470                 // are used twice will have 200 sats capacity.
3471
3472                 // Disable other potential paths.
3473                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3474                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3475                         short_channel_id: 2,
3476                         timestamp: 2,
3477                         flags: 2,
3478                         cltv_expiry_delta: 0,
3479                         htlc_minimum_msat: 0,
3480                         htlc_maximum_msat: OptionalField::Present(100_000),
3481                         fee_base_msat: 0,
3482                         fee_proportional_millionths: 0,
3483                         excess_data: Vec::new()
3484                 });
3485                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3486                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3487                         short_channel_id: 7,
3488                         timestamp: 2,
3489                         flags: 2,
3490                         cltv_expiry_delta: 0,
3491                         htlc_minimum_msat: 0,
3492                         htlc_maximum_msat: OptionalField::Present(100_000),
3493                         fee_base_msat: 0,
3494                         fee_proportional_millionths: 0,
3495                         excess_data: Vec::new()
3496                 });
3497
3498                 // Path via {node0, node2} is channels {1, 3, 5}.
3499                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3500                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3501                         short_channel_id: 1,
3502                         timestamp: 2,
3503                         flags: 0,
3504                         cltv_expiry_delta: 0,
3505                         htlc_minimum_msat: 0,
3506                         htlc_maximum_msat: OptionalField::Present(100_000),
3507                         fee_base_msat: 0,
3508                         fee_proportional_millionths: 0,
3509                         excess_data: Vec::new()
3510                 });
3511                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3512                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3513                         short_channel_id: 3,
3514                         timestamp: 2,
3515                         flags: 0,
3516                         cltv_expiry_delta: 0,
3517                         htlc_minimum_msat: 0,
3518                         htlc_maximum_msat: OptionalField::Present(100_000),
3519                         fee_base_msat: 0,
3520                         fee_proportional_millionths: 0,
3521                         excess_data: Vec::new()
3522                 });
3523
3524                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3525                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3526                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3527                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3528                         short_channel_id: 5,
3529                         timestamp: 2,
3530                         flags: 0,
3531                         cltv_expiry_delta: 0,
3532                         htlc_minimum_msat: 0,
3533                         htlc_maximum_msat: OptionalField::Present(200_000),
3534                         fee_base_msat: 0,
3535                         fee_proportional_millionths: 0,
3536                         excess_data: Vec::new()
3537                 });
3538
3539                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3540                 // Add 100 sats to the capacities of {12, 13}, because these channels
3541                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3542                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3543                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3544                         short_channel_id: 12,
3545                         timestamp: 2,
3546                         flags: 0,
3547                         cltv_expiry_delta: 0,
3548                         htlc_minimum_msat: 0,
3549                         htlc_maximum_msat: OptionalField::Present(200_000),
3550                         fee_base_msat: 0,
3551                         fee_proportional_millionths: 0,
3552                         excess_data: Vec::new()
3553                 });
3554                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3555                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3556                         short_channel_id: 13,
3557                         timestamp: 2,
3558                         flags: 0,
3559                         cltv_expiry_delta: 0,
3560                         htlc_minimum_msat: 0,
3561                         htlc_maximum_msat: OptionalField::Present(200_000),
3562                         fee_base_msat: 0,
3563                         fee_proportional_millionths: 0,
3564                         excess_data: Vec::new()
3565                 });
3566
3567                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3568                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3569                         short_channel_id: 6,
3570                         timestamp: 2,
3571                         flags: 0,
3572                         cltv_expiry_delta: 0,
3573                         htlc_minimum_msat: 0,
3574                         htlc_maximum_msat: OptionalField::Present(100_000),
3575                         fee_base_msat: 1_000,
3576                         fee_proportional_millionths: 0,
3577                         excess_data: Vec::new()
3578                 });
3579                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3580                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3581                         short_channel_id: 11,
3582                         timestamp: 2,
3583                         flags: 0,
3584                         cltv_expiry_delta: 0,
3585                         htlc_minimum_msat: 0,
3586                         htlc_maximum_msat: OptionalField::Present(100_000),
3587                         fee_base_msat: 0,
3588                         fee_proportional_millionths: 0,
3589                         excess_data: Vec::new()
3590                 });
3591
3592                 // Path via {node7, node2} is channels {12, 13, 5}.
3593                 // We already limited them to 200 sats (they are used twice for 100 sats).
3594                 // Nothing to do here.
3595
3596                 {
3597                         // Now, attempt to route 180 sats.
3598                         // Our algorithm should provide us with these 2 paths.
3599                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3600                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3601                         assert_eq!(route.paths.len(), 2);
3602
3603                         let mut total_value_transferred_msat = 0;
3604                         let mut total_paid_msat = 0;
3605                         for path in &route.paths {
3606                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3607                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3608                                 for hop in path {
3609                                         total_paid_msat += hop.fee_msat;
3610                                 }
3611                         }
3612                         // If we paid fee, this would be higher.
3613                         assert_eq!(total_value_transferred_msat, 180_000);
3614                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3615                         assert_eq!(total_fees_paid, 0);
3616                 }
3617         }
3618
3619         #[test]
3620         fn fees_on_mpp_route_test() {
3621                 // This test makes sure that MPP algorithm properly takes into account
3622                 // fees charged on the channels, by making the fees impactful:
3623                 // if the fee is not properly accounted for, the behavior is different.
3624                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3625                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3626
3627                 // We need a route consisting of 2 paths:
3628                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3629                 // We will route 200 sats, Each path will have 100 sats capacity.
3630
3631                 // This test is not particularly stable: e.g.,
3632                 // there's a way to route via {node0, node2, node4}.
3633                 // It works while pathfinding is deterministic, but can be broken otherwise.
3634                 // It's fine to ignore this concern for now.
3635
3636                 // Disable other potential paths.
3637                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3638                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3639                         short_channel_id: 2,
3640                         timestamp: 2,
3641                         flags: 2,
3642                         cltv_expiry_delta: 0,
3643                         htlc_minimum_msat: 0,
3644                         htlc_maximum_msat: OptionalField::Present(100_000),
3645                         fee_base_msat: 0,
3646                         fee_proportional_millionths: 0,
3647                         excess_data: Vec::new()
3648                 });
3649
3650                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3651                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3652                         short_channel_id: 7,
3653                         timestamp: 2,
3654                         flags: 2,
3655                         cltv_expiry_delta: 0,
3656                         htlc_minimum_msat: 0,
3657                         htlc_maximum_msat: OptionalField::Present(100_000),
3658                         fee_base_msat: 0,
3659                         fee_proportional_millionths: 0,
3660                         excess_data: Vec::new()
3661                 });
3662
3663                 // Path via {node0, node2} is channels {1, 3, 5}.
3664                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3665                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3666                         short_channel_id: 1,
3667                         timestamp: 2,
3668                         flags: 0,
3669                         cltv_expiry_delta: 0,
3670                         htlc_minimum_msat: 0,
3671                         htlc_maximum_msat: OptionalField::Present(100_000),
3672                         fee_base_msat: 0,
3673                         fee_proportional_millionths: 0,
3674                         excess_data: Vec::new()
3675                 });
3676                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3677                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3678                         short_channel_id: 3,
3679                         timestamp: 2,
3680                         flags: 0,
3681                         cltv_expiry_delta: 0,
3682                         htlc_minimum_msat: 0,
3683                         htlc_maximum_msat: OptionalField::Present(100_000),
3684                         fee_base_msat: 0,
3685                         fee_proportional_millionths: 0,
3686                         excess_data: Vec::new()
3687                 });
3688
3689                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3690                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3691                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3692                         short_channel_id: 5,
3693                         timestamp: 2,
3694                         flags: 0,
3695                         cltv_expiry_delta: 0,
3696                         htlc_minimum_msat: 0,
3697                         htlc_maximum_msat: OptionalField::Present(100_000),
3698                         fee_base_msat: 0,
3699                         fee_proportional_millionths: 0,
3700                         excess_data: Vec::new()
3701                 });
3702
3703                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3704                 // All channels should be 100 sats capacity. But for the fee experiment,
3705                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3706                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3707                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3708                 // so no matter how large are other channels,
3709                 // the whole path will be limited by 100 sats with just these 2 conditions:
3710                 // - channel 12 capacity is 250 sats
3711                 // - fee for channel 6 is 150 sats
3712                 // Let's test this by enforcing these 2 conditions and removing other limits.
3713                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3714                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3715                         short_channel_id: 12,
3716                         timestamp: 2,
3717                         flags: 0,
3718                         cltv_expiry_delta: 0,
3719                         htlc_minimum_msat: 0,
3720                         htlc_maximum_msat: OptionalField::Present(250_000),
3721                         fee_base_msat: 0,
3722                         fee_proportional_millionths: 0,
3723                         excess_data: Vec::new()
3724                 });
3725                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3726                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3727                         short_channel_id: 13,
3728                         timestamp: 2,
3729                         flags: 0,
3730                         cltv_expiry_delta: 0,
3731                         htlc_minimum_msat: 0,
3732                         htlc_maximum_msat: OptionalField::Absent,
3733                         fee_base_msat: 0,
3734                         fee_proportional_millionths: 0,
3735                         excess_data: Vec::new()
3736                 });
3737
3738                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3739                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3740                         short_channel_id: 6,
3741                         timestamp: 2,
3742                         flags: 0,
3743                         cltv_expiry_delta: 0,
3744                         htlc_minimum_msat: 0,
3745                         htlc_maximum_msat: OptionalField::Absent,
3746                         fee_base_msat: 150_000,
3747                         fee_proportional_millionths: 0,
3748                         excess_data: Vec::new()
3749                 });
3750                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3751                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3752                         short_channel_id: 11,
3753                         timestamp: 2,
3754                         flags: 0,
3755                         cltv_expiry_delta: 0,
3756                         htlc_minimum_msat: 0,
3757                         htlc_maximum_msat: OptionalField::Absent,
3758                         fee_base_msat: 0,
3759                         fee_proportional_millionths: 0,
3760                         excess_data: Vec::new()
3761                 });
3762
3763                 {
3764                         // Attempt to route more than available results in a failure.
3765                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3766                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3767                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3768                         } else { panic!(); }
3769                 }
3770
3771                 {
3772                         // Now, attempt to route 200 sats (exact amount we can route).
3773                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3774                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3775                         assert_eq!(route.paths.len(), 2);
3776
3777                         let mut total_amount_paid_msat = 0;
3778                         for path in &route.paths {
3779                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3780                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3781                         }
3782                         assert_eq!(total_amount_paid_msat, 200_000);
3783                 }
3784
3785         }
3786
3787         #[test]
3788         fn drop_lowest_channel_mpp_route_test() {
3789                 // This test checks that low-capacity channel is dropped when after
3790                 // path finding we realize that we found more capacity than we need.
3791                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3792                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3793
3794                 // We need a route consisting of 3 paths:
3795                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3796
3797                 // The first and the second paths should be sufficient, but the third should be
3798                 // cheaper, so that we select it but drop later.
3799
3800                 // First, we set limits on these (previously unlimited) channels.
3801                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3802
3803                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3804                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3805                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3806                         short_channel_id: 1,
3807                         timestamp: 2,
3808                         flags: 0,
3809                         cltv_expiry_delta: 0,
3810                         htlc_minimum_msat: 0,
3811                         htlc_maximum_msat: OptionalField::Present(100_000),
3812                         fee_base_msat: 0,
3813                         fee_proportional_millionths: 0,
3814                         excess_data: Vec::new()
3815                 });
3816                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3817                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3818                         short_channel_id: 3,
3819                         timestamp: 2,
3820                         flags: 0,
3821                         cltv_expiry_delta: 0,
3822                         htlc_minimum_msat: 0,
3823                         htlc_maximum_msat: OptionalField::Present(50_000),
3824                         fee_base_msat: 100,
3825                         fee_proportional_millionths: 0,
3826                         excess_data: Vec::new()
3827                 });
3828
3829                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3830                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3831                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3832                         short_channel_id: 12,
3833                         timestamp: 2,
3834                         flags: 0,
3835                         cltv_expiry_delta: 0,
3836                         htlc_minimum_msat: 0,
3837                         htlc_maximum_msat: OptionalField::Present(60_000),
3838                         fee_base_msat: 100,
3839                         fee_proportional_millionths: 0,
3840                         excess_data: Vec::new()
3841                 });
3842                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3843                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3844                         short_channel_id: 13,
3845                         timestamp: 2,
3846                         flags: 0,
3847                         cltv_expiry_delta: 0,
3848                         htlc_minimum_msat: 0,
3849                         htlc_maximum_msat: OptionalField::Present(60_000),
3850                         fee_base_msat: 0,
3851                         fee_proportional_millionths: 0,
3852                         excess_data: Vec::new()
3853                 });
3854
3855                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3856                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3857                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3858                         short_channel_id: 2,
3859                         timestamp: 2,
3860                         flags: 0,
3861                         cltv_expiry_delta: 0,
3862                         htlc_minimum_msat: 0,
3863                         htlc_maximum_msat: OptionalField::Present(20_000),
3864                         fee_base_msat: 0,
3865                         fee_proportional_millionths: 0,
3866                         excess_data: Vec::new()
3867                 });
3868                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3869                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3870                         short_channel_id: 4,
3871                         timestamp: 2,
3872                         flags: 0,
3873                         cltv_expiry_delta: 0,
3874                         htlc_minimum_msat: 0,
3875                         htlc_maximum_msat: OptionalField::Present(20_000),
3876                         fee_base_msat: 0,
3877                         fee_proportional_millionths: 0,
3878                         excess_data: Vec::new()
3879                 });
3880
3881                 {
3882                         // Attempt to route more than available results in a failure.
3883                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3884                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3885                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3886                         } else { panic!(); }
3887                 }
3888
3889                 {
3890                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3891                         // Our algorithm should provide us with these 3 paths.
3892                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3893                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3894                         assert_eq!(route.paths.len(), 3);
3895                         let mut total_amount_paid_msat = 0;
3896                         for path in &route.paths {
3897                                 assert_eq!(path.len(), 2);
3898                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3899                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3900                         }
3901                         assert_eq!(total_amount_paid_msat, 125_000);
3902                 }
3903
3904                 {
3905                         // Attempt to route without the last small cheap channel
3906                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3907                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3908                         assert_eq!(route.paths.len(), 2);
3909                         let mut total_amount_paid_msat = 0;
3910                         for path in &route.paths {
3911                                 assert_eq!(path.len(), 2);
3912                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3913                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3914                         }
3915                         assert_eq!(total_amount_paid_msat, 90_000);
3916                 }
3917         }
3918
3919         #[test]
3920         fn min_criteria_consistency() {
3921                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3922                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3923                 // was updated with a different criterion from the heap sorting, resulting in loops in
3924                 // calculated paths. We test for that specific case here.
3925
3926                 // We construct a network that looks like this:
3927                 //
3928                 //            node2 -1(3)2- node3
3929                 //              2          2
3930                 //               (2)     (4)
3931                 //                  1   1
3932                 //    node1 -1(5)2- node4 -1(1)2- node6
3933                 //    2
3934                 //   (6)
3935                 //        1
3936                 // our_node
3937                 //
3938                 // We create a loop on the side of our real path - our destination is node 6, with a
3939                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3940                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3941                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3942                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3943                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3944                 // "previous hop" being set to node 3, creating a loop in the path.
3945                 let secp_ctx = Secp256k1::new();
3946                 let logger = Arc::new(test_utils::TestLogger::new());
3947                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3948                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3949
3950                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3951                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3952                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3953                         short_channel_id: 6,
3954                         timestamp: 1,
3955                         flags: 0,
3956                         cltv_expiry_delta: (6 << 8) | 0,
3957                         htlc_minimum_msat: 0,
3958                         htlc_maximum_msat: OptionalField::Absent,
3959                         fee_base_msat: 0,
3960                         fee_proportional_millionths: 0,
3961                         excess_data: Vec::new()
3962                 });
3963                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3964
3965                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3966                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3967                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3968                         short_channel_id: 5,
3969                         timestamp: 1,
3970                         flags: 0,
3971                         cltv_expiry_delta: (5 << 8) | 0,
3972                         htlc_minimum_msat: 0,
3973                         htlc_maximum_msat: OptionalField::Absent,
3974                         fee_base_msat: 100,
3975                         fee_proportional_millionths: 0,
3976                         excess_data: Vec::new()
3977                 });
3978                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3979
3980                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3981                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3982                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3983                         short_channel_id: 4,
3984                         timestamp: 1,
3985                         flags: 0,
3986                         cltv_expiry_delta: (4 << 8) | 0,
3987                         htlc_minimum_msat: 0,
3988                         htlc_maximum_msat: OptionalField::Absent,
3989                         fee_base_msat: 0,
3990                         fee_proportional_millionths: 0,
3991                         excess_data: Vec::new()
3992                 });
3993                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3994
3995                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3996                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3997                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3998                         short_channel_id: 3,
3999                         timestamp: 1,
4000                         flags: 0,
4001                         cltv_expiry_delta: (3 << 8) | 0,
4002                         htlc_minimum_msat: 0,
4003                         htlc_maximum_msat: OptionalField::Absent,
4004                         fee_base_msat: 0,
4005                         fee_proportional_millionths: 0,
4006                         excess_data: Vec::new()
4007                 });
4008                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
4009
4010                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
4011                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4012                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4013                         short_channel_id: 2,
4014                         timestamp: 1,
4015                         flags: 0,
4016                         cltv_expiry_delta: (2 << 8) | 0,
4017                         htlc_minimum_msat: 0,
4018                         htlc_maximum_msat: OptionalField::Absent,
4019                         fee_base_msat: 0,
4020                         fee_proportional_millionths: 0,
4021                         excess_data: Vec::new()
4022                 });
4023
4024                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
4025                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4026                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4027                         short_channel_id: 1,
4028                         timestamp: 1,
4029                         flags: 0,
4030                         cltv_expiry_delta: (1 << 8) | 0,
4031                         htlc_minimum_msat: 100,
4032                         htlc_maximum_msat: OptionalField::Absent,
4033                         fee_base_msat: 0,
4034                         fee_proportional_millionths: 0,
4035                         excess_data: Vec::new()
4036                 });
4037                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
4038
4039                 {
4040                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
4041                         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();
4042                         assert_eq!(route.paths.len(), 1);
4043                         assert_eq!(route.paths[0].len(), 3);
4044
4045                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
4046                         assert_eq!(route.paths[0][0].short_channel_id, 6);
4047                         assert_eq!(route.paths[0][0].fee_msat, 100);
4048                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
4049                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
4050                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
4051
4052                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
4053                         assert_eq!(route.paths[0][1].short_channel_id, 5);
4054                         assert_eq!(route.paths[0][1].fee_msat, 0);
4055                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
4056                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
4057                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
4058
4059                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
4060                         assert_eq!(route.paths[0][2].short_channel_id, 1);
4061                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
4062                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
4063                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
4064                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
4065                 }
4066         }
4067
4068
4069         #[test]
4070         fn exact_fee_liquidity_limit() {
4071                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
4072                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
4073                 // we calculated fees on a higher value, resulting in us ignoring such paths.
4074                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4075                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
4076
4077                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
4078                 // send.
4079                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4080                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4081                         short_channel_id: 2,
4082                         timestamp: 2,
4083                         flags: 0,
4084                         cltv_expiry_delta: 0,
4085                         htlc_minimum_msat: 0,
4086                         htlc_maximum_msat: OptionalField::Present(85_000),
4087                         fee_base_msat: 0,
4088                         fee_proportional_millionths: 0,
4089                         excess_data: Vec::new()
4090                 });
4091
4092                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4093                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4094                         short_channel_id: 12,
4095                         timestamp: 2,
4096                         flags: 0,
4097                         cltv_expiry_delta: (4 << 8) | 1,
4098                         htlc_minimum_msat: 0,
4099                         htlc_maximum_msat: OptionalField::Present(270_000),
4100                         fee_base_msat: 0,
4101                         fee_proportional_millionths: 1000000,
4102                         excess_data: Vec::new()
4103                 });
4104
4105                 {
4106                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
4107                         // 200% fee charged channel 13 in the 1-to-2 direction.
4108                         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();
4109                         assert_eq!(route.paths.len(), 1);
4110                         assert_eq!(route.paths[0].len(), 2);
4111
4112                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4113                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4114                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4115                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4116                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4117                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4118
4119                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4120                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4121                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4122                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4123                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
4124                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4125                 }
4126         }
4127
4128         #[test]
4129         fn htlc_max_reduction_below_min() {
4130                 // Test that if, while walking the graph, we reduce the value being sent to meet an
4131                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
4132                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
4133                 // resulting in us thinking there is no possible path, even if other paths exist.
4134                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4135                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4136
4137                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
4138                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
4139                 // then try to send 90_000.
4140                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4141                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4142                         short_channel_id: 2,
4143                         timestamp: 2,
4144                         flags: 0,
4145                         cltv_expiry_delta: 0,
4146                         htlc_minimum_msat: 0,
4147                         htlc_maximum_msat: OptionalField::Present(80_000),
4148                         fee_base_msat: 0,
4149                         fee_proportional_millionths: 0,
4150                         excess_data: Vec::new()
4151                 });
4152                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4153                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4154                         short_channel_id: 4,
4155                         timestamp: 2,
4156                         flags: 0,
4157                         cltv_expiry_delta: (4 << 8) | 1,
4158                         htlc_minimum_msat: 90_000,
4159                         htlc_maximum_msat: OptionalField::Absent,
4160                         fee_base_msat: 0,
4161                         fee_proportional_millionths: 0,
4162                         excess_data: Vec::new()
4163                 });
4164
4165                 {
4166                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
4167                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
4168                         // expensive) channels 12-13 path.
4169                         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();
4170                         assert_eq!(route.paths.len(), 1);
4171                         assert_eq!(route.paths[0].len(), 2);
4172
4173                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4174                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4175                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4176                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4177                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4178                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4179
4180                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4181                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4182                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4183                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4184                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
4185                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4186                 }
4187         }
4188
4189         #[cfg(not(feature = "no-std"))]
4190         pub(super) fn random_init_seed() -> u64 {
4191                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
4192                 use core::hash::{BuildHasher, Hasher};
4193                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
4194                 println!("Using seed of {}", seed);
4195                 seed
4196         }
4197         #[cfg(not(feature = "no-std"))]
4198         use util::ser::Readable;
4199
4200         #[test]
4201         #[cfg(not(feature = "no-std"))]
4202         fn generate_routes() {
4203                 let mut d = match super::test_utils::get_route_file() {
4204                         Ok(f) => f,
4205                         Err(e) => {
4206                                 eprintln!("{}", e);
4207                                 return;
4208                         },
4209                 };
4210                 let graph = NetworkGraph::read(&mut d).unwrap();
4211
4212                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4213                 let mut seed = random_init_seed() as usize;
4214                 'load_endpoints: for _ in 0..10 {
4215                         loop {
4216                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4217                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
4218                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4219                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
4220                                 let amt = seed as u64 % 200_000_000;
4221                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
4222                                         continue 'load_endpoints;
4223                                 }
4224                         }
4225                 }
4226         }
4227
4228         #[test]
4229         #[cfg(not(feature = "no-std"))]
4230         fn generate_routes_mpp() {
4231                 let mut d = match super::test_utils::get_route_file() {
4232                         Ok(f) => f,
4233                         Err(e) => {
4234                                 eprintln!("{}", e);
4235                                 return;
4236                         },
4237                 };
4238                 let graph = NetworkGraph::read(&mut d).unwrap();
4239
4240                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4241                 let mut seed = random_init_seed() as usize;
4242                 'load_endpoints: for _ in 0..10 {
4243                         loop {
4244                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4245                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
4246                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4247                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
4248                                 let amt = seed as u64 % 200_000_000;
4249                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
4250                                         continue 'load_endpoints;
4251                                 }
4252                         }
4253                 }
4254         }
4255 }
4256
4257 #[cfg(all(test, not(feature = "no-std")))]
4258 pub(crate) mod test_utils {
4259         use std::fs::File;
4260         /// Tries to open a network graph file, or panics with a URL to fetch it.
4261         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
4262                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
4263                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
4264                         .or_else(|_| { // Fall back to guessing based on the binary location
4265                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
4266                                 let mut path = std::env::current_exe().unwrap();
4267                                 path.pop(); // lightning-...
4268                                 path.pop(); // deps
4269                                 path.pop(); // debug
4270                                 path.pop(); // target
4271                                 path.push("lightning");
4272                                 path.push("net_graph-2021-05-31.bin");
4273                                 eprintln!("{}", path.to_str().unwrap());
4274                                 File::open(path)
4275                         })
4276                 .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");
4277                 #[cfg(require_route_graph_test)]
4278                 return Ok(res.unwrap());
4279                 #[cfg(not(require_route_graph_test))]
4280                 return res;
4281         }
4282 }
4283
4284 #[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
4285 mod benches {
4286         use super::*;
4287         use util::logger::{Logger, Record};
4288
4289         use test::Bencher;
4290
4291         struct DummyLogger {}
4292         impl Logger for DummyLogger {
4293                 fn log(&self, _record: &Record) {}
4294         }
4295
4296         #[bench]
4297         fn generate_routes(bench: &mut Bencher) {
4298                 let mut d = test_utils::get_route_file().unwrap();
4299                 let graph = NetworkGraph::read(&mut d).unwrap();
4300
4301                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4302                 let mut path_endpoints = Vec::new();
4303                 let mut seed: usize = 0xdeadbeef;
4304                 'load_endpoints: for _ in 0..100 {
4305                         loop {
4306                                 seed *= 0xdeadbeef;
4307                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
4308                                 seed *= 0xdeadbeef;
4309                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
4310                                 let amt = seed as u64 % 1_000_000;
4311                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
4312                                         path_endpoints.push((src, dst, amt));
4313                                         continue 'load_endpoints;
4314                                 }
4315                         }
4316                 }
4317
4318                 // ...then benchmark finding paths between the nodes we learned.
4319                 let mut idx = 0;
4320                 bench.iter(|| {
4321                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4322                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
4323                         idx += 1;
4324                 });
4325         }
4326
4327         #[bench]
4328         fn generate_mpp_routes(bench: &mut Bencher) {
4329                 let mut d = test_utils::get_route_file().unwrap();
4330                 let graph = NetworkGraph::read(&mut d).unwrap();
4331
4332                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4333                 let mut path_endpoints = Vec::new();
4334                 let mut seed: usize = 0xdeadbeef;
4335                 'load_endpoints: for _ in 0..100 {
4336                         loop {
4337                                 seed *= 0xdeadbeef;
4338                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
4339                                 seed *= 0xdeadbeef;
4340                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
4341                                 let amt = seed as u64 % 1_000_000;
4342                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
4343                                         path_endpoints.push((src, dst, amt));
4344                                         continue 'load_endpoints;
4345                                 }
4346                         }
4347                 }
4348
4349                 // ...then benchmark finding paths between the nodes we learned.
4350                 let mut idx = 0;
4351                 bench.iter(|| {
4352                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4353                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
4354                         idx += 1;
4355                 });
4356         }
4357 }