_ Git - rust-lightning/blob - lightning-invoice/src/payment.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 //! A module for paying Lightning invoices and sending spontaneous payments.
  11 //!
  12 //! Defines an [`InvoicePayer`] utility for sending payments, parameterized by [`Payer`] and
  13 //! [`Router`] traits. Implementations of [`Payer`] provide the payer's node id, channels, and means
  14 //! to send a payment over a [`Route`]. Implementations of [`Router`] find a [`Route`] between payer
  15 //! and payee using information provided by the payer and from the payee's [`Invoice`], when
  16 //! applicable.
  17 //!
  18 //! [`InvoicePayer`] is parameterized by a [`LockableScore`], which it uses for scoring failed and
  19 //! successful payment paths upon receiving [`Event::PaymentPathFailed`] and
  20 //! [`Event::PaymentPathSuccessful`] events, respectively.
  21 //!
  22 //! [`InvoicePayer`] is capable of retrying failed payments. It accomplishes this by implementing
  23 //! [`EventHandler`] which decorates a user-provided handler. It will intercept any
  24 //! [`Event::PaymentPathFailed`] events and retry the failed paths for a fixed number of total
  25 //! attempts or until retry is no longer possible. In such a situation, [`InvoicePayer`] will pass
  26 //! along the events to the user-provided handler.
  27 //!
  28 //! # Example
  29 //!
  30 //! ```
  31 //! # extern crate lightning;
  32 //! # extern crate lightning_invoice;
  33 //! # extern crate secp256k1;
  34 //! #
  35 //! # use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
  36 //! # use lightning::ln::channelmanager::{ChannelDetails, PaymentId, PaymentSendFailure};
  37 //! # use lightning::ln::msgs::LightningError;
  38 //! # use lightning::routing::scoring::Score;
  39 //! # use lightning::routing::network_graph::NodeId;
  40 //! # use lightning::routing::router::{Route, RouteHop, RouteParameters};
  41 //! # use lightning::util::events::{Event, EventHandler, EventsProvider};
  42 //! # use lightning::util::logger::{Logger, Record};
  43 //! # use lightning::util::ser::{Writeable, Writer};
  44 //! # use lightning_invoice::Invoice;
  45 //! # use lightning_invoice::payment::{InvoicePayer, Payer, RetryAttempts, Router};
  46 //! # use secp256k1::key::PublicKey;
  47 //! # use std::cell::RefCell;
  48 //! # use std::ops::Deref;
  49 //! #
  50 //! # struct FakeEventProvider {}
  51 //! # impl EventsProvider for FakeEventProvider {
  52 //! #     fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {}
  53 //! # }
  54 //! #
  55 //! # struct FakePayer {}
  56 //! # impl Payer for FakePayer {
  57 //! #     fn node_id(&self) -> PublicKey { unimplemented!() }
  58 //! #     fn first_hops(&self) -> Vec<ChannelDetails> { unimplemented!() }
  59 //! #     fn send_payment(
  60 //! #         &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>
  61 //! #     ) -> Result<PaymentId, PaymentSendFailure> { unimplemented!() }
  62 //! #     fn send_spontaneous_payment(
  63 //! #         &self, route: &Route, payment_preimage: PaymentPreimage
  64 //! #     ) -> Result<PaymentId, PaymentSendFailure> { unimplemented!() }
  65 //! #     fn retry_payment(
  66 //! #         &self, route: &Route, payment_id: PaymentId
  67 //! #     ) -> Result<(), PaymentSendFailure> { unimplemented!() }
  68 //! # }
  69 //! #
  70 //! # struct FakeRouter {}
  71 //! # impl<S: Score> Router<S> for FakeRouter {
  72 //! #     fn find_route(
  73 //! #         &self, payer: &PublicKey, params: &RouteParameters, payment_hash: &PaymentHash,
  74 //! #         first_hops: Option<&[&ChannelDetails]>, scorer: &S
  75 //! #     ) -> Result<Route, LightningError> { unimplemented!() }
  76 //! # }
  77 //! #
  78 //! # struct FakeScorer {}
  79 //! # impl Writeable for FakeScorer {
  80 //! #     fn write<W: Writer>(&self, w: &mut W) -> Result<(), std::io::Error> { unimplemented!(); }
  81 //! # }
  82 //! # impl Score for FakeScorer {
  83 //! #     fn channel_penalty_msat(
  84 //! #         &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, _target: &NodeId
  85 //! #     ) -> u64 { 0 }
  86 //! #     fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
  87 //! #     fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
  88 //! # }
  89 //! #
  90 //! # struct FakeLogger {}
  91 //! # impl Logger for FakeLogger {
  92 //! #     fn log(&self, record: &Record) { unimplemented!() }
  93 //! # }
  94 //! #
  95 //! # fn main() {
  96 //! let event_handler = |event: &Event| {
  97 //!     match event {
  98 //!         Event::PaymentPathFailed { .. } => println!("payment failed after retries"),
  99 //!         Event::PaymentSent { .. } => println!("payment successful"),
 100 //!         _ => {},
 101 //!     }
 102 //! };
 103 //! # let payer = FakePayer {};
 104 //! # let router = FakeRouter {};
 105 //! # let scorer = RefCell::new(FakeScorer {});
 106 //! # let logger = FakeLogger {};
 107 //! let invoice_payer = InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 108 //!
 109 //! let invoice = "...";
 110 //! if let Ok(invoice) = invoice.parse::<Invoice>() {
 111 //!     invoice_payer.pay_invoice(&invoice).unwrap();
 112 //!
 113 //! # let event_provider = FakeEventProvider {};
 114 //!     loop {
 115 //!         event_provider.process_pending_events(&invoice_payer);
 116 //!     }
 117 //! }
 118 //! # }
 119 //! ```
 120 //!
 121 //! # Note
 122 //!
 123 //! The [`Route`] is computed before each payment attempt. Any updates affecting path finding such
 124 //! as updates to the network graph or changes to channel scores should be applied prior to
 125 //! retries, typically by way of composing [`EventHandler`]s accordingly.
 126
 127 use crate::Invoice;
 128
 129 use bitcoin_hashes::Hash;
 130 use bitcoin_hashes::sha256::Hash as Sha256;
 131
 132 use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 133 use lightning::ln::channelmanager::{ChannelDetails, PaymentId, PaymentSendFailure};
 134 use lightning::ln::msgs::LightningError;
 135 use lightning::routing::scoring::{LockableScore, Score};
 136 use lightning::routing::router::{Payee, Route, RouteParameters};
 137 use lightning::util::events::{Event, EventHandler};
 138 use lightning::util::logger::Logger;
 139
 140 use secp256k1::key::PublicKey;
 141
 142 use std::collections::hash_map::{self, HashMap};
 143 use std::ops::Deref;
 144 use std::sync::Mutex;
 145 use std::time::{Duration, SystemTime};
 146
 147 /// A utility for paying [`Invoice`]s and sending spontaneous payments.
 148 ///
 149 /// See [module-level documentation] for details.
 150 ///
 151 /// [module-level documentation]: crate::payment
 152 pub struct InvoicePayer<P: Deref, R, S: Deref, L: Deref, E>
 153 where
 154         P::Target: Payer,
 155         R: for <'a> Router<<<S as Deref>::Target as LockableScore<'a>>::Locked>,
 156         S::Target: for <'a> LockableScore<'a>,
 157         L::Target: Logger,
 158         E: EventHandler,
 159 {
 160         payer: P,
 161         router: R,
 162         scorer: S,
 163         logger: L,
 164         event_handler: E,
 165         /// Caches the overall attempts at making a payment, which is updated prior to retrying.
 166         payment_cache: Mutex<HashMap<PaymentHash, usize>>,
 167         retry_attempts: RetryAttempts,
 168 }
 169
 170 /// A trait defining behavior of an [`Invoice`] payer.
 171 pub trait Payer {
 172         /// Returns the payer's node id.
 173         fn node_id(&self) -> PublicKey;
 174
 175         /// Returns the payer's channels.
 176         fn first_hops(&self) -> Vec<ChannelDetails>;
 177
 178         /// Sends a payment over the Lightning Network using the given [`Route`].
 179         fn send_payment(
 180                 &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>
 181         ) -> Result<PaymentId, PaymentSendFailure>;
 182
 183         /// Sends a spontaneous payment over the Lightning Network using the given [`Route`].
 184         fn send_spontaneous_payment(
 185                 &self, route: &Route, payment_preimage: PaymentPreimage
 186         ) -> Result<PaymentId, PaymentSendFailure>;
 187
 188         /// Retries a failed payment path for the [`PaymentId`] using the given [`Route`].
 189         fn retry_payment(&self, route: &Route, payment_id: PaymentId) -> Result<(), PaymentSendFailure>;
 190 }
 191
 192 /// A trait defining behavior for routing an [`Invoice`] payment.
 193 pub trait Router<S: Score> {
 194         /// Finds a [`Route`] between `payer` and `payee` for a payment with the given values.
 195         fn find_route(
 196                 &self, payer: &PublicKey, params: &RouteParameters, payment_hash: &PaymentHash,
 197                 first_hops: Option<&[&ChannelDetails]>, scorer: &S
 198         ) -> Result<Route, LightningError>;
 199 }
 200
 201 /// Number of attempts to retry payment path failures for an [`Invoice`].
 202 ///
 203 /// Note that this is the number of *path* failures, not full payment retries. For multi-path
 204 /// payments, if this is less than the total number of paths, we will never even retry all of the
 205 /// payment's paths.
 206 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 207 pub struct RetryAttempts(pub usize);
 208
 209 /// An error that may occur when making a payment.
 210 #[derive(Clone, Debug)]
 211 pub enum PaymentError {
 212         /// An error resulting from the provided [`Invoice`] or payment hash.
 213         Invoice(&'static str),
 214         /// An error occurring when finding a route.
 215         Routing(LightningError),
 216         /// An error occurring when sending a payment.
 217         Sending(PaymentSendFailure),
 218 }
 219
 220 impl<P: Deref, R, S: Deref, L: Deref, E> InvoicePayer<P, R, S, L, E>
 221 where
 222         P::Target: Payer,
 223         R: for <'a> Router<<<S as Deref>::Target as LockableScore<'a>>::Locked>,
 224         S::Target: for <'a> LockableScore<'a>,
 225         L::Target: Logger,
 226         E: EventHandler,
 227 {
 228         /// Creates an invoice payer that retries failed payment paths.
 229         ///
 230         /// Will forward any [`Event::PaymentPathFailed`] events to the decorated `event_handler` once
 231         /// `retry_attempts` has been exceeded for a given [`Invoice`].
 232         pub fn new(
 233                 payer: P, router: R, scorer: S, logger: L, event_handler: E, retry_attempts: RetryAttempts
 234         ) -> Self {
 235                 Self {
 236                         payer,
 237                         router,
 238                         scorer,
 239                         logger,
 240                         event_handler,
 241                         payment_cache: Mutex::new(HashMap::new()),
 242                         retry_attempts,
 243                 }
 244         }
 245
 246         /// Pays the given [`Invoice`], caching it for later use in case a retry is needed.
 247         ///
 248         /// You should ensure that the `invoice.payment_hash()` is unique and the same payment_hash has
 249         /// never been paid before. Because [`InvoicePayer`] is stateless no effort is made to do so
 250         /// for you.
 251         pub fn pay_invoice(&self, invoice: &Invoice) -> Result<PaymentId, PaymentError> {
 252                 if invoice.amount_milli_satoshis().is_none() {
 253                         Err(PaymentError::Invoice("amount missing"))
 254                 } else {
 255                         self.pay_invoice_using_amount(invoice, None)
 256                 }
 257         }
 258
 259         /// Pays the given zero-value [`Invoice`] using the given amount, caching it for later use in
 260         /// case a retry is needed.
 261         ///
 262         /// You should ensure that the `invoice.payment_hash()` is unique and the same payment_hash has
 263         /// never been paid before. Because [`InvoicePayer`] is stateless no effort is made to do so
 264         /// for you.
 265         pub fn pay_zero_value_invoice(
 266                 &self, invoice: &Invoice, amount_msats: u64
 267         ) -> Result<PaymentId, PaymentError> {
 268                 if invoice.amount_milli_satoshis().is_some() {
 269                         Err(PaymentError::Invoice("amount unexpected"))
 270                 } else {
 271                         self.pay_invoice_using_amount(invoice, Some(amount_msats))
 272                 }
 273         }
 274
 275         fn pay_invoice_using_amount(
 276                 &self, invoice: &Invoice, amount_msats: Option<u64>
 277         ) -> Result<PaymentId, PaymentError> {
 278                 debug_assert!(invoice.amount_milli_satoshis().is_some() ^ amount_msats.is_some());
 279
 280                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 281                 match self.payment_cache.lock().unwrap().entry(payment_hash) {
 282                         hash_map::Entry::Occupied(_) => return Err(PaymentError::Invoice("payment pending")),
 283                         hash_map::Entry::Vacant(entry) => entry.insert(0),
 284                 };
 285
 286                 let payment_secret = Some(invoice.payment_secret().clone());
 287                 let mut payee = Payee::from_node_id(invoice.recover_payee_pub_key())
 288                         .with_expiry_time(expiry_time_from_unix_epoch(&invoice).as_secs())
 289                         .with_route_hints(invoice.route_hints());
 290                 if let Some(features) = invoice.features() {
 291                         payee = payee.with_features(features.clone());
 292                 }
 293                 let params = RouteParameters {
 294                         payee,
 295                         final_value_msat: invoice.amount_milli_satoshis().or(amount_msats).unwrap(),
 296                         final_cltv_expiry_delta: invoice.min_final_cltv_expiry() as u32,
 297                 };
 298
 299                 let send_payment = |route: &Route| {
 300                         self.payer.send_payment(route, payment_hash, &payment_secret)
 301                 };
 302                 self.pay_internal(&params, payment_hash, send_payment)
 303                         .map_err(|e| { self.payment_cache.lock().unwrap().remove(&payment_hash); e })
 304         }
 305
 306         /// Pays `pubkey` an amount using the hash of the given preimage, caching it for later use in
 307         /// case a retry is needed.
 308         ///
 309         /// You should ensure that `payment_preimage` is unique and that its `payment_hash` has never
 310         /// been paid before. Because [`InvoicePayer`] is stateless no effort is made to do so for you.
 311         pub fn pay_pubkey(
 312                 &self, pubkey: PublicKey, payment_preimage: PaymentPreimage, amount_msats: u64,
 313                 final_cltv_expiry_delta: u32
 314         ) -> Result<PaymentId, PaymentError> {
 315                 let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
 316                 match self.payment_cache.lock().unwrap().entry(payment_hash) {
 317                         hash_map::Entry::Occupied(_) => return Err(PaymentError::Invoice("payment pending")),
 318                         hash_map::Entry::Vacant(entry) => entry.insert(0),
 319                 };
 320
 321                 let params = RouteParameters {
 322                         payee: Payee::for_keysend(pubkey),
 323                         final_value_msat: amount_msats,
 324                         final_cltv_expiry_delta,
 325                 };
 326
 327                 let send_payment = |route: &Route| {
 328                         self.payer.send_spontaneous_payment(route, payment_preimage)
 329                 };
 330                 self.pay_internal(&params, payment_hash, send_payment)
 331                         .map_err(|e| { self.payment_cache.lock().unwrap().remove(&payment_hash); e })
 332         }
 333
 334         fn pay_internal<F: FnOnce(&Route) -> Result<PaymentId, PaymentSendFailure> + Copy>(
 335                 &self, params: &RouteParameters, payment_hash: PaymentHash, send_payment: F,
 336         ) -> Result<PaymentId, PaymentError> {
 337                 if has_expired(params) {
 338                         log_trace!(self.logger, "Invoice expired prior to send for payment {}", log_bytes!(payment_hash.0));
 339                         return Err(PaymentError::Invoice("Invoice expired prior to send"));
 340                 }
 341
 342                 let payer = self.payer.node_id();
 343                 let first_hops = self.payer.first_hops();
 344                 let route = self.router.find_route(
 345                         &payer, params, &payment_hash, Some(&first_hops.iter().collect::<Vec<_>>()),
 346                         &self.scorer.lock()
 347                 ).map_err(|e| PaymentError::Routing(e))?;
 348
 349                 match send_payment(&route) {
 350                         Ok(payment_id) => Ok(payment_id),
 351                         Err(e) => match e {
 352                                 PaymentSendFailure::ParameterError(_) => Err(e),
 353                                 PaymentSendFailure::PathParameterError(_) => Err(e),
 354                                 PaymentSendFailure::AllFailedRetrySafe(_) => {
 355                                         let mut payment_cache = self.payment_cache.lock().unwrap();
 356                                         let retry_count = payment_cache.get_mut(&payment_hash).unwrap();
 357                                         if *retry_count >= self.retry_attempts.0 {
 358                                                 Err(e)
 359                                         } else {
 360                                                 *retry_count += 1;
 361                                                 std::mem::drop(payment_cache);
 362                                                 Ok(self.pay_internal(params, payment_hash, send_payment)?)
 363                                         }
 364                                 },
 365                                 PaymentSendFailure::PartialFailure { failed_paths_retry, payment_id, .. } => {
 366                                         if let Some(retry_data) = failed_paths_retry {
 367                                                 // Some paths were sent, even if we failed to send the full MPP value our
 368                                                 // recipient may misbehave and claim the funds, at which point we have to
 369                                                 // consider the payment sent, so return `Ok()` here, ignoring any retry
 370                                                 // errors.
 371                                                 let _ = self.retry_payment(payment_id, payment_hash, &retry_data);
 372                                                 Ok(payment_id)
 373                                         } else {
 374                                                 // This may happen if we send a payment and some paths fail, but
 375                                                 // only due to a temporary monitor failure or the like, implying
 376                                                 // they're really in-flight, but we haven't sent the initial
 377                                                 // HTLC-Add messages yet.
 378                                                 Ok(payment_id)
 379                                         }
 380                                 },
 381                         },
 382                 }.map_err(|e| PaymentError::Sending(e))
 383         }
 384
 385         fn retry_payment(
 386                 &self, payment_id: PaymentId, payment_hash: PaymentHash, params: &RouteParameters
 387         ) -> Result<(), ()> {
 388                 let max_payment_attempts = self.retry_attempts.0 + 1;
 389                 let attempts = *self.payment_cache.lock().unwrap()
 390                         .entry(payment_hash)
 391                         .and_modify(|attempts| *attempts += 1)
 392                         .or_insert(1);
 393
 394                 if attempts >= max_payment_attempts {
 395                         log_trace!(self.logger, "Payment {} exceeded maximum attempts; not retrying (attempts: {})", log_bytes!(payment_hash.0), attempts);
 396                         return Err(());
 397                 }
 398
 399                 if has_expired(params) {
 400                         log_trace!(self.logger, "Invoice expired for payment {}; not retrying (attempts: {})", log_bytes!(payment_hash.0), attempts);
 401                         return Err(());
 402                 }
 403
 404                 let payer = self.payer.node_id();
 405                 let first_hops = self.payer.first_hops();
 406                 let route = self.router.find_route(
 407                         &payer, &params, &payment_hash, Some(&first_hops.iter().collect::<Vec<_>>()),
 408                         &self.scorer.lock()
 409                 );
 410                 if route.is_err() {
 411                         log_trace!(self.logger, "Failed to find a route for payment {}; not retrying (attempts: {})", log_bytes!(payment_hash.0), attempts);
 412                         return Err(());
 413                 }
 414
 415                 match self.payer.retry_payment(&route.unwrap(), payment_id) {
 416                         Ok(()) => Ok(()),
 417                         Err(PaymentSendFailure::ParameterError(_)) |
 418                         Err(PaymentSendFailure::PathParameterError(_)) => {
 419                                 log_trace!(self.logger, "Failed to retry for payment {} due to bogus route/payment data, not retrying.", log_bytes!(payment_hash.0));
 420                                 Err(())
 421                         },
 422                         Err(PaymentSendFailure::AllFailedRetrySafe(_)) => {
 423                                 self.retry_payment(payment_id, payment_hash, params)
 424                         },
 425                         Err(PaymentSendFailure::PartialFailure { failed_paths_retry, .. }) => {
 426                                 if let Some(retry) = failed_paths_retry {
 427                                         // Always return Ok for the same reason as noted in pay_internal.
 428                                         let _ = self.retry_payment(payment_id, payment_hash, &retry);
 429                                 }
 430                                 Ok(())
 431                         },
 432                 }
 433         }
 434
 435         /// Removes the payment cached by the given payment hash.
 436         ///
 437         /// Should be called once a payment has failed or succeeded if not using [`InvoicePayer`] as an
 438         /// [`EventHandler`]. Otherwise, calling this method is unnecessary.
 439         pub fn remove_cached_payment(&self, payment_hash: &PaymentHash) {
 440                 self.payment_cache.lock().unwrap().remove(payment_hash);
 441         }
 442 }
 443
 444 fn expiry_time_from_unix_epoch(invoice: &Invoice) -> Duration {
 445         invoice.timestamp().duration_since(SystemTime::UNIX_EPOCH).unwrap() + invoice.expiry_time()
 446 }
 447
 448 fn has_expired(params: &RouteParameters) -> bool {
 449         if let Some(expiry_time) = params.payee.expiry_time {
 450                 Invoice::is_expired_from_epoch(&SystemTime::UNIX_EPOCH, Duration::from_secs(expiry_time))
 451         } else { false }
 452 }
 453
 454 impl<P: Deref, R, S: Deref, L: Deref, E> EventHandler for InvoicePayer<P, R, S, L, E>
 455 where
 456         P::Target: Payer,
 457         R: for <'a> Router<<<S as Deref>::Target as LockableScore<'a>>::Locked>,
 458         S::Target: for <'a> LockableScore<'a>,
 459         L::Target: Logger,
 460         E: EventHandler,
 461 {
 462         fn handle_event(&self, event: &Event) {
 463                 match event {
 464                         Event::PaymentPathFailed {
 465                                 all_paths_failed, payment_id, payment_hash, rejected_by_dest, path,
 466                                 short_channel_id, retry, ..
 467                         } => {
 468                                 if let Some(short_channel_id) = short_channel_id {
 469                                         let path = path.iter().collect::<Vec<_>>();
 470                                         self.scorer.lock().payment_path_failed(&path, *short_channel_id);
 471                                 }
 472
 473                                 if *rejected_by_dest {
 474                                         log_trace!(self.logger, "Payment {} rejected by destination; not retrying", log_bytes!(payment_hash.0));
 475                                 } else if payment_id.is_none() {
 476                                         log_trace!(self.logger, "Payment {} has no id; not retrying", log_bytes!(payment_hash.0));
 477                                 } else if retry.is_none() {
 478                                         log_trace!(self.logger, "Payment {} missing retry params; not retrying", log_bytes!(payment_hash.0));
 479                                 } else if self.retry_payment(payment_id.unwrap(), *payment_hash, retry.as_ref().unwrap()).is_ok() {
 480                                         // We retried at least somewhat, don't provide the PaymentPathFailed event to the user.
 481                                         return;
 482                                 }
 483
 484                                 if *all_paths_failed { self.payment_cache.lock().unwrap().remove(payment_hash); }
 485                         },
 486                         Event::PaymentPathSuccessful { path, .. } => {
 487                                 let path = path.iter().collect::<Vec<_>>();
 488                                 self.scorer.lock().payment_path_successful(&path);
 489                         },
 490                         Event::PaymentSent { payment_hash, .. } => {
 491                                 let mut payment_cache = self.payment_cache.lock().unwrap();
 492                                 let attempts = payment_cache
 493                                         .remove(payment_hash)
 494                                         .map_or(1, |attempts| attempts + 1);
 495                                 log_trace!(self.logger, "Payment {} succeeded (attempts: {})", log_bytes!(payment_hash.0), attempts);
 496                         },
 497                         _ => {},
 498                 }
 499
 500                 // Delegate to the decorated event handler unless the payment is retried.
 501                 self.event_handler.handle_event(event)
 502         }
 503 }
 504
 505 #[cfg(test)]
 506 mod tests {
 507         use super::*;
 508         use crate::{DEFAULT_EXPIRY_TIME, InvoiceBuilder, Currency};
 509         use utils::create_invoice_from_channelmanager;
 510         use bitcoin_hashes::sha256::Hash as Sha256;
 511         use lightning::ln::PaymentPreimage;
 512         use lightning::ln::features::{ChannelFeatures, NodeFeatures, InitFeatures};
 513         use lightning::ln::functional_test_utils::*;
 514         use lightning::ln::msgs::{ErrorAction, LightningError};
 515         use lightning::routing::network_graph::NodeId;
 516         use lightning::routing::router::{Payee, Route, RouteHop};
 517         use lightning::util::test_utils::TestLogger;
 518         use lightning::util::errors::APIError;
 519         use lightning::util::events::{Event, MessageSendEventsProvider};
 520         use secp256k1::{SecretKey, PublicKey, Secp256k1};
 521         use std::cell::RefCell;
 522         use std::collections::VecDeque;
 523         use std::time::{SystemTime, Duration};
 524
 525         fn invoice(payment_preimage: PaymentPreimage) -> Invoice {
 526                 let payment_hash = Sha256::hash(&payment_preimage.0);
 527                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 528                 InvoiceBuilder::new(Currency::Bitcoin)
 529                         .description("test".into())
 530                         .payment_hash(payment_hash)
 531                         .payment_secret(PaymentSecret([0; 32]))
 532                         .current_timestamp()
 533                         .min_final_cltv_expiry(144)
 534                         .amount_milli_satoshis(128)
 535                         .build_signed(|hash| {
 536                                 Secp256k1::new().sign_recoverable(hash, &private_key)
 537                         })
 538                         .unwrap()
 539         }
 540
 541         fn zero_value_invoice(payment_preimage: PaymentPreimage) -> Invoice {
 542                 let payment_hash = Sha256::hash(&payment_preimage.0);
 543                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 544                 InvoiceBuilder::new(Currency::Bitcoin)
 545                         .description("test".into())
 546                         .payment_hash(payment_hash)
 547                         .payment_secret(PaymentSecret([0; 32]))
 548                         .current_timestamp()
 549                         .min_final_cltv_expiry(144)
 550                         .build_signed(|hash| {
 551                                 Secp256k1::new().sign_recoverable(hash, &private_key)
 552                         })
 553                         .unwrap()
 554         }
 555
 556         fn expired_invoice(payment_preimage: PaymentPreimage) -> Invoice {
 557                 let payment_hash = Sha256::hash(&payment_preimage.0);
 558                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 559                 let timestamp = SystemTime::now()
 560                         .checked_sub(Duration::from_secs(DEFAULT_EXPIRY_TIME * 2))
 561                         .unwrap();
 562                 InvoiceBuilder::new(Currency::Bitcoin)
 563                         .description("test".into())
 564                         .payment_hash(payment_hash)
 565                         .payment_secret(PaymentSecret([0; 32]))
 566                         .timestamp(timestamp)
 567                         .min_final_cltv_expiry(144)
 568                         .amount_milli_satoshis(128)
 569                         .build_signed(|hash| {
 570                                 Secp256k1::new().sign_recoverable(hash, &private_key)
 571                         })
 572                         .unwrap()
 573         }
 574
 575         fn pubkey() -> PublicKey {
 576                 PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap()
 577         }
 578
 579         #[test]
 580         fn pays_invoice_on_first_attempt() {
 581                 let event_handled = core::cell::RefCell::new(false);
 582                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 583
 584                 let payment_preimage = PaymentPreimage([1; 32]);
 585                 let invoice = invoice(payment_preimage);
 586                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 587                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 588
 589                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
 590                 let router = TestRouter {};
 591                 let scorer = RefCell::new(TestScorer::new());
 592                 let logger = TestLogger::new();
 593                 let invoice_payer =
 594                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(0));
 595
 596                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 597                 assert_eq!(*payer.attempts.borrow(), 1);
 598
 599                 invoice_payer.handle_event(&Event::PaymentSent {
 600                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
 601                 });
 602                 assert_eq!(*event_handled.borrow(), true);
 603                 assert_eq!(*payer.attempts.borrow(), 1);
 604         }
 605
 606         #[test]
 607         fn pays_invoice_on_retry() {
 608                 let event_handled = core::cell::RefCell::new(false);
 609                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 610
 611                 let payment_preimage = PaymentPreimage([1; 32]);
 612                 let invoice = invoice(payment_preimage);
 613                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 614                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 615
 616                 let payer = TestPayer::new()
 617                         .expect_send(Amount::ForInvoice(final_value_msat))
 618                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 619                 let router = TestRouter {};
 620                 let scorer = RefCell::new(TestScorer::new());
 621                 let logger = TestLogger::new();
 622                 let invoice_payer =
 623                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 624
 625                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 626                 assert_eq!(*payer.attempts.borrow(), 1);
 627
 628                 let event = Event::PaymentPathFailed {
 629                         payment_id,
 630                         payment_hash,
 631                         network_update: None,
 632                         rejected_by_dest: false,
 633                         all_paths_failed: false,
 634                         path: TestRouter::path_for_value(final_value_msat),
 635                         short_channel_id: None,
 636                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 637                 };
 638                 invoice_payer.handle_event(&event);
 639                 assert_eq!(*event_handled.borrow(), false);
 640                 assert_eq!(*payer.attempts.borrow(), 2);
 641
 642                 invoice_payer.handle_event(&Event::PaymentSent {
 643                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
 644                 });
 645                 assert_eq!(*event_handled.borrow(), true);
 646                 assert_eq!(*payer.attempts.borrow(), 2);
 647         }
 648
 649         #[test]
 650         fn pays_invoice_on_partial_failure() {
 651                 let event_handler = |_: &_| { panic!() };
 652
 653                 let payment_preimage = PaymentPreimage([1; 32]);
 654                 let invoice = invoice(payment_preimage);
 655                 let retry = TestRouter::retry_for_invoice(&invoice);
 656                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 657
 658                 let payer = TestPayer::new()
 659                         .fails_with_partial_failure(retry.clone(), OnAttempt(1))
 660                         .fails_with_partial_failure(retry, OnAttempt(2))
 661                         .expect_send(Amount::ForInvoice(final_value_msat))
 662                         .expect_send(Amount::OnRetry(final_value_msat / 2))
 663                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 664                 let router = TestRouter {};
 665                 let scorer = RefCell::new(TestScorer::new());
 666                 let logger = TestLogger::new();
 667                 let invoice_payer =
 668                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 669
 670                 assert!(invoice_payer.pay_invoice(&invoice).is_ok());
 671         }
 672
 673         #[test]
 674         fn retries_payment_path_for_unknown_payment() {
 675                 let event_handled = core::cell::RefCell::new(false);
 676                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 677
 678                 let payment_preimage = PaymentPreimage([1; 32]);
 679                 let invoice = invoice(payment_preimage);
 680                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 681                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 682
 683                 let payer = TestPayer::new()
 684                         .expect_send(Amount::OnRetry(final_value_msat / 2))
 685                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 686                 let router = TestRouter {};
 687                 let scorer = RefCell::new(TestScorer::new());
 688                 let logger = TestLogger::new();
 689                 let invoice_payer =
 690                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 691
 692                 let payment_id = Some(PaymentId([1; 32]));
 693                 let event = Event::PaymentPathFailed {
 694                         payment_id,
 695                         payment_hash,
 696                         network_update: None,
 697                         rejected_by_dest: false,
 698                         all_paths_failed: false,
 699                         path: TestRouter::path_for_value(final_value_msat),
 700                         short_channel_id: None,
 701                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 702                 };
 703                 invoice_payer.handle_event(&event);
 704                 assert_eq!(*event_handled.borrow(), false);
 705                 assert_eq!(*payer.attempts.borrow(), 1);
 706
 707                 invoice_payer.handle_event(&event);
 708                 assert_eq!(*event_handled.borrow(), false);
 709                 assert_eq!(*payer.attempts.borrow(), 2);
 710
 711                 invoice_payer.handle_event(&Event::PaymentSent {
 712                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
 713                 });
 714                 assert_eq!(*event_handled.borrow(), true);
 715                 assert_eq!(*payer.attempts.borrow(), 2);
 716         }
 717
 718         #[test]
 719         fn fails_paying_invoice_after_max_retries() {
 720                 let event_handled = core::cell::RefCell::new(false);
 721                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 722
 723                 let payment_preimage = PaymentPreimage([1; 32]);
 724                 let invoice = invoice(payment_preimage);
 725                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 726
 727                 let payer = TestPayer::new()
 728                         .expect_send(Amount::ForInvoice(final_value_msat))
 729                         .expect_send(Amount::OnRetry(final_value_msat / 2))
 730                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 731                 let router = TestRouter {};
 732                 let scorer = RefCell::new(TestScorer::new());
 733                 let logger = TestLogger::new();
 734                 let invoice_payer =
 735                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 736
 737                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 738                 assert_eq!(*payer.attempts.borrow(), 1);
 739
 740                 let event = Event::PaymentPathFailed {
 741                         payment_id,
 742                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
 743                         network_update: None,
 744                         rejected_by_dest: false,
 745                         all_paths_failed: true,
 746                         path: TestRouter::path_for_value(final_value_msat),
 747                         short_channel_id: None,
 748                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 749                 };
 750                 invoice_payer.handle_event(&event);
 751                 assert_eq!(*event_handled.borrow(), false);
 752                 assert_eq!(*payer.attempts.borrow(), 2);
 753
 754                 let event = Event::PaymentPathFailed {
 755                         payment_id,
 756                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
 757                         network_update: None,
 758                         rejected_by_dest: false,
 759                         all_paths_failed: false,
 760                         path: TestRouter::path_for_value(final_value_msat / 2),
 761                         short_channel_id: None,
 762                         retry: Some(RouteParameters {
 763                                 final_value_msat: final_value_msat / 2, ..TestRouter::retry_for_invoice(&invoice)
 764                         }),
 765                 };
 766                 invoice_payer.handle_event(&event);
 767                 assert_eq!(*event_handled.borrow(), false);
 768                 assert_eq!(*payer.attempts.borrow(), 3);
 769
 770                 invoice_payer.handle_event(&event);
 771                 assert_eq!(*event_handled.borrow(), true);
 772                 assert_eq!(*payer.attempts.borrow(), 3);
 773         }
 774
 775         #[test]
 776         fn fails_paying_invoice_with_missing_retry_params() {
 777                 let event_handled = core::cell::RefCell::new(false);
 778                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 779
 780                 let payment_preimage = PaymentPreimage([1; 32]);
 781                 let invoice = invoice(payment_preimage);
 782                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 783
 784                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
 785                 let router = TestRouter {};
 786                 let scorer = RefCell::new(TestScorer::new());
 787                 let logger = TestLogger::new();
 788                 let invoice_payer =
 789                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 790
 791                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 792                 assert_eq!(*payer.attempts.borrow(), 1);
 793
 794                 let event = Event::PaymentPathFailed {
 795                         payment_id,
 796                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
 797                         network_update: None,
 798                         rejected_by_dest: false,
 799                         all_paths_failed: false,
 800                         path: vec![],
 801                         short_channel_id: None,
 802                         retry: None,
 803                 };
 804                 invoice_payer.handle_event(&event);
 805                 assert_eq!(*event_handled.borrow(), true);
 806                 assert_eq!(*payer.attempts.borrow(), 1);
 807         }
 808
 809         #[test]
 810         fn fails_paying_invoice_after_expiration() {
 811                 let event_handled = core::cell::RefCell::new(false);
 812                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 813
 814                 let payer = TestPayer::new();
 815                 let router = TestRouter {};
 816                 let scorer = RefCell::new(TestScorer::new());
 817                 let logger = TestLogger::new();
 818                 let invoice_payer =
 819                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 820
 821                 let payment_preimage = PaymentPreimage([1; 32]);
 822                 let invoice = expired_invoice(payment_preimage);
 823                 if let PaymentError::Invoice(msg) = invoice_payer.pay_invoice(&invoice).unwrap_err() {
 824                         assert_eq!(msg, "Invoice expired prior to send");
 825                 } else { panic!("Expected Invoice Error"); }
 826         }
 827
 828         #[test]
 829         fn fails_retrying_invoice_after_expiration() {
 830                 let event_handled = core::cell::RefCell::new(false);
 831                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 832
 833                 let payment_preimage = PaymentPreimage([1; 32]);
 834                 let invoice = invoice(payment_preimage);
 835                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 836
 837                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
 838                 let router = TestRouter {};
 839                 let scorer = RefCell::new(TestScorer::new());
 840                 let logger = TestLogger::new();
 841                 let invoice_payer =
 842                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 843
 844                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 845                 assert_eq!(*payer.attempts.borrow(), 1);
 846
 847                 let mut retry_data = TestRouter::retry_for_invoice(&invoice);
 848                 retry_data.payee.expiry_time = Some(SystemTime::now()
 849                         .checked_sub(Duration::from_secs(2)).unwrap()
 850                         .duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs());
 851                 let event = Event::PaymentPathFailed {
 852                         payment_id,
 853                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
 854                         network_update: None,
 855                         rejected_by_dest: false,
 856                         all_paths_failed: false,
 857                         path: vec![],
 858                         short_channel_id: None,
 859                         retry: Some(retry_data),
 860                 };
 861                 invoice_payer.handle_event(&event);
 862                 assert_eq!(*event_handled.borrow(), true);
 863                 assert_eq!(*payer.attempts.borrow(), 1);
 864         }
 865
 866         #[test]
 867         fn fails_paying_invoice_after_retry_error() {
 868                 let event_handled = core::cell::RefCell::new(false);
 869                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 870
 871                 let payment_preimage = PaymentPreimage([1; 32]);
 872                 let invoice = invoice(payment_preimage);
 873                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 874
 875                 let payer = TestPayer::new()
 876                         .fails_on_attempt(2)
 877                         .expect_send(Amount::ForInvoice(final_value_msat))
 878                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 879                 let router = TestRouter {};
 880                 let scorer = RefCell::new(TestScorer::new());
 881                 let logger = TestLogger::new();
 882                 let invoice_payer =
 883                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 884
 885                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 886                 assert_eq!(*payer.attempts.borrow(), 1);
 887
 888                 let event = Event::PaymentPathFailed {
 889                         payment_id,
 890                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
 891                         network_update: None,
 892                         rejected_by_dest: false,
 893                         all_paths_failed: false,
 894                         path: TestRouter::path_for_value(final_value_msat / 2),
 895                         short_channel_id: None,
 896                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 897                 };
 898                 invoice_payer.handle_event(&event);
 899                 assert_eq!(*event_handled.borrow(), true);
 900                 assert_eq!(*payer.attempts.borrow(), 2);
 901         }
 902
 903         #[test]
 904         fn fails_paying_invoice_after_rejected_by_payee() {
 905                 let event_handled = core::cell::RefCell::new(false);
 906                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 907
 908                 let payment_preimage = PaymentPreimage([1; 32]);
 909                 let invoice = invoice(payment_preimage);
 910                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 911
 912                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
 913                 let router = TestRouter {};
 914                 let scorer = RefCell::new(TestScorer::new());
 915                 let logger = TestLogger::new();
 916                 let invoice_payer =
 917                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
 918
 919                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 920                 assert_eq!(*payer.attempts.borrow(), 1);
 921
 922                 let event = Event::PaymentPathFailed {
 923                         payment_id,
 924                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
 925                         network_update: None,
 926                         rejected_by_dest: true,
 927                         all_paths_failed: false,
 928                         path: vec![],
 929                         short_channel_id: None,
 930                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 931                 };
 932                 invoice_payer.handle_event(&event);
 933                 assert_eq!(*event_handled.borrow(), true);
 934                 assert_eq!(*payer.attempts.borrow(), 1);
 935         }
 936
 937         #[test]
 938         fn fails_repaying_invoice_with_pending_payment() {
 939                 let event_handled = core::cell::RefCell::new(false);
 940                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 941
 942                 let payment_preimage = PaymentPreimage([1; 32]);
 943                 let invoice = invoice(payment_preimage);
 944                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 945
 946                 let payer = TestPayer::new()
 947                         .expect_send(Amount::ForInvoice(final_value_msat))
 948                         .expect_send(Amount::ForInvoice(final_value_msat));
 949                 let router = TestRouter {};
 950                 let scorer = RefCell::new(TestScorer::new());
 951                 let logger = TestLogger::new();
 952                 let invoice_payer =
 953                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(0));
 954
 955                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 956
 957                 // Cannot repay an invoice pending payment.
 958                 match invoice_payer.pay_invoice(&invoice) {
 959                         Err(PaymentError::Invoice("payment pending")) => {},
 960                         Err(_) => panic!("unexpected error"),
 961                         Ok(_) => panic!("expected invoice error"),
 962                 }
 963
 964                 // Can repay an invoice once cleared from cache.
 965                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 966                 invoice_payer.remove_cached_payment(&payment_hash);
 967                 assert!(invoice_payer.pay_invoice(&invoice).is_ok());
 968
 969                 // Cannot retry paying an invoice if cleared from cache.
 970                 invoice_payer.remove_cached_payment(&payment_hash);
 971                 let event = Event::PaymentPathFailed {
 972                         payment_id,
 973                         payment_hash,
 974                         network_update: None,
 975                         rejected_by_dest: false,
 976                         all_paths_failed: false,
 977                         path: vec![],
 978                         short_channel_id: None,
 979                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 980                 };
 981                 invoice_payer.handle_event(&event);
 982                 assert_eq!(*event_handled.borrow(), true);
 983         }
 984
 985         #[test]
 986         fn fails_paying_invoice_with_routing_errors() {
 987                 let payer = TestPayer::new();
 988                 let router = FailingRouter {};
 989                 let scorer = RefCell::new(TestScorer::new());
 990                 let logger = TestLogger::new();
 991                 let invoice_payer =
 992                         InvoicePayer::new(&payer, router, &scorer, &logger, |_: &_| {}, RetryAttempts(0));
 993
 994                 let payment_preimage = PaymentPreimage([1; 32]);
 995                 let invoice = invoice(payment_preimage);
 996                 match invoice_payer.pay_invoice(&invoice) {
 997                         Err(PaymentError::Routing(_)) => {},
 998                         Err(_) => panic!("unexpected error"),
 999                         Ok(_) => panic!("expected routing error"),
1000                 }
1001         }
1002
1003         #[test]
1004         fn fails_paying_invoice_with_sending_errors() {
1005                 let payment_preimage = PaymentPreimage([1; 32]);
1006                 let invoice = invoice(payment_preimage);
1007                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1008
1009                 let payer = TestPayer::new()
1010                         .fails_on_attempt(1)
1011                         .expect_send(Amount::ForInvoice(final_value_msat));
1012                 let router = TestRouter {};
1013                 let scorer = RefCell::new(TestScorer::new());
1014                 let logger = TestLogger::new();
1015                 let invoice_payer =
1016                         InvoicePayer::new(&payer, router, &scorer, &logger, |_: &_| {}, RetryAttempts(0));
1017
1018                 match invoice_payer.pay_invoice(&invoice) {
1019                         Err(PaymentError::Sending(_)) => {},
1020                         Err(_) => panic!("unexpected error"),
1021                         Ok(_) => panic!("expected sending error"),
1022                 }
1023         }
1024
1025         #[test]
1026         fn pays_zero_value_invoice_using_amount() {
1027                 let event_handled = core::cell::RefCell::new(false);
1028                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1029
1030                 let payment_preimage = PaymentPreimage([1; 32]);
1031                 let invoice = zero_value_invoice(payment_preimage);
1032                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1033                 let final_value_msat = 100;
1034
1035                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1036                 let router = TestRouter {};
1037                 let scorer = RefCell::new(TestScorer::new());
1038                 let logger = TestLogger::new();
1039                 let invoice_payer =
1040                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(0));
1041
1042                 let payment_id =
1043                         Some(invoice_payer.pay_zero_value_invoice(&invoice, final_value_msat).unwrap());
1044                 assert_eq!(*payer.attempts.borrow(), 1);
1045
1046                 invoice_payer.handle_event(&Event::PaymentSent {
1047                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
1048                 });
1049                 assert_eq!(*event_handled.borrow(), true);
1050                 assert_eq!(*payer.attempts.borrow(), 1);
1051         }
1052
1053         #[test]
1054         fn fails_paying_zero_value_invoice_with_amount() {
1055                 let event_handled = core::cell::RefCell::new(false);
1056                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1057
1058                 let payer = TestPayer::new();
1059                 let router = TestRouter {};
1060                 let scorer = RefCell::new(TestScorer::new());
1061                 let logger = TestLogger::new();
1062                 let invoice_payer =
1063                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(0));
1064
1065                 let payment_preimage = PaymentPreimage([1; 32]);
1066                 let invoice = invoice(payment_preimage);
1067
1068                 // Cannot repay an invoice pending payment.
1069                 match invoice_payer.pay_zero_value_invoice(&invoice, 100) {
1070                         Err(PaymentError::Invoice("amount unexpected")) => {},
1071                         Err(_) => panic!("unexpected error"),
1072                         Ok(_) => panic!("expected invoice error"),
1073                 }
1074         }
1075
1076         #[test]
1077         fn pays_pubkey_with_amount() {
1078                 let event_handled = core::cell::RefCell::new(false);
1079                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1080
1081                 let pubkey = pubkey();
1082                 let payment_preimage = PaymentPreimage([1; 32]);
1083                 let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
1084                 let final_value_msat = 100;
1085                 let final_cltv_expiry_delta = 42;
1086
1087                 let payer = TestPayer::new()
1088                         .expect_send(Amount::Spontaneous(final_value_msat))
1089                         .expect_send(Amount::OnRetry(final_value_msat));
1090                 let router = TestRouter {};
1091                 let scorer = RefCell::new(TestScorer::new());
1092                 let logger = TestLogger::new();
1093                 let invoice_payer =
1094                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
1095
1096                 let payment_id = Some(invoice_payer.pay_pubkey(
1097                                 pubkey, payment_preimage, final_value_msat, final_cltv_expiry_delta
1098                         ).unwrap());
1099                 assert_eq!(*payer.attempts.borrow(), 1);
1100
1101                 let retry = RouteParameters {
1102                         payee: Payee::for_keysend(pubkey),
1103                         final_value_msat,
1104                         final_cltv_expiry_delta,
1105                 };
1106                 let event = Event::PaymentPathFailed {
1107                         payment_id,
1108                         payment_hash,
1109                         network_update: None,
1110                         rejected_by_dest: false,
1111                         all_paths_failed: false,
1112                         path: vec![],
1113                         short_channel_id: None,
1114                         retry: Some(retry),
1115                 };
1116                 invoice_payer.handle_event(&event);
1117                 assert_eq!(*event_handled.borrow(), false);
1118                 assert_eq!(*payer.attempts.borrow(), 2);
1119
1120                 invoice_payer.handle_event(&Event::PaymentSent {
1121                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
1122                 });
1123                 assert_eq!(*event_handled.borrow(), true);
1124                 assert_eq!(*payer.attempts.borrow(), 2);
1125         }
1126
1127         #[test]
1128         fn scores_failed_channel() {
1129                 let event_handled = core::cell::RefCell::new(false);
1130                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1131
1132                 let payment_preimage = PaymentPreimage([1; 32]);
1133                 let invoice = invoice(payment_preimage);
1134                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1135                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1136                 let path = TestRouter::path_for_value(final_value_msat);
1137                 let short_channel_id = Some(path[0].short_channel_id);
1138
1139                 // Expect that scorer is given short_channel_id upon handling the event.
1140                 let payer = TestPayer::new()
1141                         .expect_send(Amount::ForInvoice(final_value_msat))
1142                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1143                 let router = TestRouter {};
1144                 let scorer = RefCell::new(TestScorer::new().expect(PaymentPath::Failure {
1145                         path: path.clone(), short_channel_id: path[0].short_channel_id,
1146                 }));
1147                 let logger = TestLogger::new();
1148                 let invoice_payer =
1149                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
1150
1151                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1152                 let event = Event::PaymentPathFailed {
1153                         payment_id,
1154                         payment_hash,
1155                         network_update: None,
1156                         rejected_by_dest: false,
1157                         all_paths_failed: false,
1158                         path,
1159                         short_channel_id,
1160                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1161                 };
1162                 invoice_payer.handle_event(&event);
1163         }
1164
1165         #[test]
1166         fn scores_successful_channels() {
1167                 let event_handled = core::cell::RefCell::new(false);
1168                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1169
1170                 let payment_preimage = PaymentPreimage([1; 32]);
1171                 let invoice = invoice(payment_preimage);
1172                 let payment_hash = Some(PaymentHash(invoice.payment_hash().clone().into_inner()));
1173                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1174                 let route = TestRouter::route_for_value(final_value_msat);
1175
1176                 // Expect that scorer is given short_channel_id upon handling the event.
1177                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1178                 let router = TestRouter {};
1179                 let scorer = RefCell::new(TestScorer::new()
1180                         .expect(PaymentPath::Success { path: route.paths[0].clone() })
1181                         .expect(PaymentPath::Success { path: route.paths[1].clone() })
1182                 );
1183                 let logger = TestLogger::new();
1184                 let invoice_payer =
1185                         InvoicePayer::new(&payer, router, &scorer, &logger, event_handler, RetryAttempts(2));
1186
1187                 let payment_id = invoice_payer.pay_invoice(&invoice).unwrap();
1188                 let event = Event::PaymentPathSuccessful {
1189                         payment_id, payment_hash, path: route.paths[0].clone()
1190                 };
1191                 invoice_payer.handle_event(&event);
1192                 let event = Event::PaymentPathSuccessful {
1193                         payment_id, payment_hash, path: route.paths[1].clone()
1194                 };
1195                 invoice_payer.handle_event(&event);
1196         }
1197
1198         struct TestRouter;
1199
1200         impl TestRouter {
1201                 fn route_for_value(final_value_msat: u64) -> Route {
1202                         Route {
1203                                 paths: vec![
1204                                         vec![RouteHop {
1205                                                 pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
1206                                                 channel_features: ChannelFeatures::empty(),
1207                                                 node_features: NodeFeatures::empty(),
1208                                                 short_channel_id: 0, fee_msat: final_value_msat / 2, cltv_expiry_delta: 144
1209                                         }],
1210                                         vec![RouteHop {
1211                                                 pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
1212                                                 channel_features: ChannelFeatures::empty(),
1213                                                 node_features: NodeFeatures::empty(),
1214                                                 short_channel_id: 1, fee_msat: final_value_msat / 2, cltv_expiry_delta: 144
1215                                         }],
1216                                 ],
1217                                 payee: None,
1218                         }
1219                 }
1220
1221                 fn path_for_value(final_value_msat: u64) -> Vec<RouteHop> {
1222                         TestRouter::route_for_value(final_value_msat).paths[0].clone()
1223                 }
1224
1225                 fn retry_for_invoice(invoice: &Invoice) -> RouteParameters {
1226                         let mut payee = Payee::from_node_id(invoice.recover_payee_pub_key())
1227                                 .with_expiry_time(expiry_time_from_unix_epoch(invoice).as_secs())
1228                                 .with_route_hints(invoice.route_hints());
1229                         if let Some(features) = invoice.features() {
1230                                 payee = payee.with_features(features.clone());
1231                         }
1232                         let final_value_msat = invoice.amount_milli_satoshis().unwrap() / 2;
1233                         RouteParameters {
1234                                 payee,
1235                                 final_value_msat,
1236                                 final_cltv_expiry_delta: invoice.min_final_cltv_expiry() as u32,
1237                         }
1238                 }
1239         }
1240
1241         impl<S: Score> Router<S> for TestRouter {
1242                 fn find_route(
1243                         &self, _payer: &PublicKey, params: &RouteParameters, _payment_hash: &PaymentHash,
1244                         _first_hops: Option<&[&ChannelDetails]>, _scorer: &S
1245                 ) -> Result<Route, LightningError> {
1246                         Ok(Route {
1247                                 payee: Some(params.payee.clone()), ..Self::route_for_value(params.final_value_msat)
1248                         })
1249                 }
1250         }
1251
1252         struct FailingRouter;
1253
1254         impl<S: Score> Router<S> for FailingRouter {
1255                 fn find_route(
1256                         &self, _payer: &PublicKey, _params: &RouteParameters, _payment_hash: &PaymentHash,
1257                         _first_hops: Option<&[&ChannelDetails]>, _scorer: &S
1258                 ) -> Result<Route, LightningError> {
1259                         Err(LightningError { err: String::new(), action: ErrorAction::IgnoreError })
1260                 }
1261         }
1262
1263         struct TestScorer {
1264                 expectations: Option<VecDeque<PaymentPath>>,
1265         }
1266
1267         #[derive(Debug)]
1268         enum PaymentPath {
1269                 Failure { path: Vec<RouteHop>, short_channel_id: u64 },
1270                 Success { path: Vec<RouteHop> },
1271         }
1272
1273         impl TestScorer {
1274                 fn new() -> Self {
1275                         Self {
1276                                 expectations: None,
1277                         }
1278                 }
1279
1280                 fn expect(mut self, expectation: PaymentPath) -> Self {
1281                         self.expectations.get_or_insert_with(|| VecDeque::new()).push_back(expectation);
1282                         self
1283                 }
1284         }
1285
1286         #[cfg(c_bindings)]
1287         impl lightning::util::ser::Writeable for TestScorer {
1288                 fn write<W: lightning::util::ser::Writer>(&self, _: &mut W) -> Result<(), std::io::Error> { unreachable!(); }
1289         }
1290
1291         impl Score for TestScorer {
1292                 fn channel_penalty_msat(
1293                         &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, _target: &NodeId
1294                 ) -> u64 { 0 }
1295
1296                 fn payment_path_failed(&mut self, actual_path: &[&RouteHop], actual_short_channel_id: u64) {
1297                         if let Some(expectations) = &mut self.expectations {
1298                                 match expectations.pop_front() {
1299                                         Some(PaymentPath::Failure { path, short_channel_id }) => {
1300                                                 assert_eq!(actual_path, &path.iter().collect::<Vec<_>>()[..]);
1301                                                 assert_eq!(actual_short_channel_id, short_channel_id);
1302                                         },
1303                                         Some(PaymentPath::Success { path }) => {
1304                                                 panic!("Unexpected successful payment path: {:?}", path)
1305                                         },
1306                                         None => panic!("Unexpected payment_path_failed call: {:?}", actual_path),
1307                                 }
1308                         }
1309                 }
1310
1311                 fn payment_path_successful(&mut self, actual_path: &[&RouteHop]) {
1312                         if let Some(expectations) = &mut self.expectations {
1313                                 match expectations.pop_front() {
1314                                         Some(PaymentPath::Failure { path, .. }) => {
1315                                                 panic!("Unexpected payment path failure: {:?}", path)
1316                                         },
1317                                         Some(PaymentPath::Success { path }) => {
1318                                                 assert_eq!(actual_path, &path.iter().collect::<Vec<_>>()[..]);
1319                                         },
1320                                         None => panic!("Unexpected payment_path_successful call: {:?}", actual_path),
1321                                 }
1322                         }
1323                 }
1324         }
1325
1326         impl Drop for TestScorer {
1327                 fn drop(&mut self) {
1328                         if std::thread::panicking() {
1329                                 return;
1330                         }
1331
1332                         if let Some(expectations) = &self.expectations {
1333                                 if !expectations.is_empty() {
1334                                         panic!("Unsatisfied scorer expectations: {:?}", expectations);
1335                                 }
1336                         }
1337                 }
1338         }
1339
1340         struct TestPayer {
1341                 expectations: core::cell::RefCell<VecDeque<Amount>>,
1342                 attempts: core::cell::RefCell<usize>,
1343                 failing_on_attempt: core::cell::RefCell<HashMap<usize, PaymentSendFailure>>,
1344         }
1345
1346         #[derive(Clone, Debug, PartialEq, Eq)]
1347         enum Amount {
1348                 ForInvoice(u64),
1349                 Spontaneous(u64),
1350                 OnRetry(u64),
1351         }
1352
1353         struct OnAttempt(usize);
1354
1355         impl TestPayer {
1356                 fn new() -> Self {
1357                         Self {
1358                                 expectations: core::cell::RefCell::new(VecDeque::new()),
1359                                 attempts: core::cell::RefCell::new(0),
1360                                 failing_on_attempt: core::cell::RefCell::new(HashMap::new()),
1361                         }
1362                 }
1363
1364                 fn expect_send(self, value_msat: Amount) -> Self {
1365                         self.expectations.borrow_mut().push_back(value_msat);
1366                         self
1367                 }
1368
1369                 fn fails_on_attempt(self, attempt: usize) -> Self {
1370                         let failure = PaymentSendFailure::ParameterError(APIError::MonitorUpdateFailed);
1371                         self.fails_with(failure, OnAttempt(attempt))
1372                 }
1373
1374                 fn fails_with_partial_failure(self, retry: RouteParameters, attempt: OnAttempt) -> Self {
1375                         self.fails_with(PaymentSendFailure::PartialFailure {
1376                                 results: vec![],
1377                                 failed_paths_retry: Some(retry),
1378                                 payment_id: PaymentId([1; 32]),
1379                         }, attempt)
1380                 }
1381
1382                 fn fails_with(self, failure: PaymentSendFailure, attempt: OnAttempt) -> Self {
1383                         self.failing_on_attempt.borrow_mut().insert(attempt.0, failure);
1384                         self
1385                 }
1386
1387                 fn check_attempts(&self) -> Result<PaymentId, PaymentSendFailure> {
1388                         let mut attempts = self.attempts.borrow_mut();
1389                         *attempts += 1;
1390
1391                         match self.failing_on_attempt.borrow_mut().remove(&*attempts) {
1392                                 Some(failure) => Err(failure),
1393                                 None => Ok(PaymentId([1; 32])),
1394                         }
1395                 }
1396
1397                 fn check_value_msats(&self, actual_value_msats: Amount) {
1398                         let expected_value_msats = self.expectations.borrow_mut().pop_front();
1399                         if let Some(expected_value_msats) = expected_value_msats {
1400                                 assert_eq!(actual_value_msats, expected_value_msats);
1401                         } else {
1402                                 panic!("Unexpected amount: {:?}", actual_value_msats);
1403                         }
1404                 }
1405         }
1406
1407         impl Drop for TestPayer {
1408                 fn drop(&mut self) {
1409                         if std::thread::panicking() {
1410                                 return;
1411                         }
1412
1413                         if !self.expectations.borrow().is_empty() {
1414                                 panic!("Unsatisfied payment expectations: {:?}", self.expectations.borrow());
1415                         }
1416                 }
1417         }
1418
1419         impl Payer for TestPayer {
1420                 fn node_id(&self) -> PublicKey {
1421                         let secp_ctx = Secp256k1::new();
1422                         PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap())
1423                 }
1424
1425                 fn first_hops(&self) -> Vec<ChannelDetails> {
1426                         Vec::new()
1427                 }
1428
1429                 fn send_payment(
1430                         &self, route: &Route, _payment_hash: PaymentHash,
1431                         _payment_secret: &Option<PaymentSecret>
1432                 ) -> Result<PaymentId, PaymentSendFailure> {
1433                         self.check_value_msats(Amount::ForInvoice(route.get_total_amount()));
1434                         self.check_attempts()
1435                 }
1436
1437                 fn send_spontaneous_payment(
1438                         &self, route: &Route, _payment_preimage: PaymentPreimage,
1439                 ) -> Result<PaymentId, PaymentSendFailure> {
1440                         self.check_value_msats(Amount::Spontaneous(route.get_total_amount()));
1441                         self.check_attempts()
1442                 }
1443
1444                 fn retry_payment(
1445                         &self, route: &Route, _payment_id: PaymentId
1446                 ) -> Result<(), PaymentSendFailure> {
1447                         self.check_value_msats(Amount::OnRetry(route.get_total_amount()));
1448                         self.check_attempts().map(|_| ())
1449                 }
1450         }
1451
1452         // *** Full Featured Functional Tests with a Real ChannelManager ***
1453         struct ManualRouter(RefCell<VecDeque<Result<Route, LightningError>>>);
1454
1455         impl<S: Score> Router<S> for ManualRouter {
1456                 fn find_route(
1457                         &self, _payer: &PublicKey, _params: &RouteParameters, _payment_hash: &PaymentHash,
1458                         _first_hops: Option<&[&ChannelDetails]>, _scorer: &S
1459                 ) -> Result<Route, LightningError> {
1460                         self.0.borrow_mut().pop_front().unwrap()
1461                 }
1462         }
1463         impl ManualRouter {
1464                 fn expect_find_route(&self, result: Result<Route, LightningError>) {
1465                         self.0.borrow_mut().push_back(result);
1466                 }
1467         }
1468         impl Drop for ManualRouter {
1469                 fn drop(&mut self) {
1470                         if std::thread::panicking() {
1471                                 return;
1472                         }
1473                         assert!(self.0.borrow_mut().is_empty());
1474                 }
1475         }
1476
1477         #[test]
1478         fn retry_multi_path_single_failed_payment() {
1479                 // Tests that we can/will retry after a single path of an MPP payment failed immediately
1480                 let chanmon_cfgs = create_chanmon_cfgs(2);
1481                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
1482                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None, None]);
1483                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
1484
1485                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
1486                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
1487                 let chans = nodes[0].node.list_usable_channels();
1488                 let mut route = Route {
1489                         paths: vec![
1490                                 vec![RouteHop {
1491                                         pubkey: nodes[1].node.get_our_node_id(),
1492                                         node_features: NodeFeatures::known(),
1493                                         short_channel_id: chans[0].short_channel_id.unwrap(),
1494                                         channel_features: ChannelFeatures::known(),
1495                                         fee_msat: 10_000,
1496                                         cltv_expiry_delta: 100,
1497                                 }],
1498                                 vec![RouteHop {
1499                                         pubkey: nodes[1].node.get_our_node_id(),
1500                                         node_features: NodeFeatures::known(),
1501                                         short_channel_id: chans[1].short_channel_id.unwrap(),
1502                                         channel_features: ChannelFeatures::known(),
1503                                         fee_msat: 100_000_001, // Our default max-HTLC-value is 10% of the channel value, which this is one more than
1504                                         cltv_expiry_delta: 100,
1505                                 }],
1506                         ],
1507                         payee: Some(Payee::from_node_id(nodes[1].node.get_our_node_id())),
1508                 };
1509                 let router = ManualRouter(RefCell::new(VecDeque::new()));
1510                 router.expect_find_route(Ok(route.clone()));
1511                 // On retry, split the payment across both channels.
1512                 route.paths[0][0].fee_msat = 50_000_001;
1513                 route.paths[1][0].fee_msat = 50_000_000;
1514                 router.expect_find_route(Ok(route.clone()));
1515
1516                 let event_handler = |_: &_| { panic!(); };
1517                 let scorer = RefCell::new(TestScorer::new());
1518                 let invoice_payer = InvoicePayer::new(nodes[0].node, router, &scorer, nodes[0].logger, event_handler, RetryAttempts(1));
1519
1520                 assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager(
1521                         &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string()).unwrap())
1522                         .is_ok());
1523                 let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
1524                 assert_eq!(htlc_msgs.len(), 2);
1525                 check_added_monitors!(nodes[0], 2);
1526         }
1527
1528         #[test]
1529         fn immediate_retry_on_failure() {
1530                 // Tests that we can/will retry immediately after a failure
1531                 let chanmon_cfgs = create_chanmon_cfgs(2);
1532                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
1533                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None, None]);
1534                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
1535
1536                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
1537                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
1538                 let chans = nodes[0].node.list_usable_channels();
1539                 let mut route = Route {
1540                         paths: vec![
1541                                 vec![RouteHop {
1542                                         pubkey: nodes[1].node.get_our_node_id(),
1543                                         node_features: NodeFeatures::known(),
1544                                         short_channel_id: chans[0].short_channel_id.unwrap(),
1545                                         channel_features: ChannelFeatures::known(),
1546                                         fee_msat: 100_000_001, // Our default max-HTLC-value is 10% of the channel value, which this is one more than
1547                                         cltv_expiry_delta: 100,
1548                                 }],
1549                         ],
1550                         payee: Some(Payee::from_node_id(nodes[1].node.get_our_node_id())),
1551                 };
1552                 let router = ManualRouter(RefCell::new(VecDeque::new()));
1553                 router.expect_find_route(Ok(route.clone()));
1554                 // On retry, split the payment across both channels.
1555                 route.paths.push(route.paths[0].clone());
1556                 route.paths[0][0].short_channel_id = chans[1].short_channel_id.unwrap();
1557                 route.paths[0][0].fee_msat = 50_000_000;
1558                 route.paths[1][0].fee_msat = 50_000_001;
1559                 router.expect_find_route(Ok(route.clone()));
1560
1561                 let event_handler = |_: &_| { panic!(); };
1562                 let scorer = RefCell::new(TestScorer::new());
1563                 let invoice_payer = InvoicePayer::new(nodes[0].node, router, &scorer, nodes[0].logger, event_handler, RetryAttempts(1));
1564
1565                 assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager(
1566                         &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string()).unwrap())
1567                         .is_ok());
1568                 let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
1569                 assert_eq!(htlc_msgs.len(), 2);
1570                 check_added_monitors!(nodes[0], 2);
1571         }
1572 }