_ 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`] uses its [`Router`] parameterization for optionally notifying scorers upon
  19 //! receiving the [`Event::PaymentPathFailed`] and [`Event::PaymentPathSuccessful`] events.
  20 //! It also does the same for payment probe failure and success events using [`Event::ProbeFailed`]
  21 //! and [`Event::ProbeSuccessful`].
  22 //!
  23 //! [`InvoicePayer`] is capable of retrying failed payments. It accomplishes this by implementing
  24 //! [`EventHandler`] which decorates a user-provided handler. It will intercept any
  25 //! [`Event::PaymentPathFailed`] events and retry the failed paths for a fixed number of total
  26 //! attempts or until retry is no longer possible. In such a situation, [`InvoicePayer`] will pass
  27 //! along the events to the user-provided handler.
  28 //!
  29 //! # Example
  30 //!
  31 //! ```
  32 //! # extern crate lightning;
  33 //! # extern crate lightning_invoice;
  34 //! # extern crate secp256k1;
  35 //! #
  36 //! # use lightning::io;
  37 //! # use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
  38 //! # use lightning::ln::channelmanager::{ChannelDetails, PaymentId, PaymentSendFailure};
  39 //! # use lightning::ln::msgs::LightningError;
  40 //! # use lightning::routing::gossip::NodeId;
  41 //! # use lightning::routing::router::{Route, RouteHop, RouteParameters};
  42 //! # use lightning::routing::scoring::{ChannelUsage, Score};
  43 //! # use lightning::util::events::{Event, EventHandler, EventsProvider};
  44 //! # use lightning::util::logger::{Logger, Record};
  45 //! # use lightning::util::ser::{Writeable, Writer};
  46 //! # use lightning_invoice::Invoice;
  47 //! # use lightning_invoice::payment::{InFlightHtlcs, InvoicePayer, Payer, Retry, Router};
  48 //! # use secp256k1::PublicKey;
  49 //! # use std::cell::RefCell;
  50 //! # use std::ops::Deref;
  51 //! #
  52 //! # struct FakeEventProvider {}
  53 //! # impl EventsProvider for FakeEventProvider {
  54 //! #     fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {}
  55 //! # }
  56 //! #
  57 //! # struct FakePayer {}
  58 //! # impl Payer for FakePayer {
  59 //! #     fn node_id(&self) -> PublicKey { unimplemented!() }
  60 //! #     fn first_hops(&self) -> Vec<ChannelDetails> { unimplemented!() }
  61 //! #     fn send_payment(
  62 //! #         &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>
  63 //! #     ) -> Result<PaymentId, PaymentSendFailure> { unimplemented!() }
  64 //! #     fn send_spontaneous_payment(
  65 //! #         &self, route: &Route, payment_preimage: PaymentPreimage
  66 //! #     ) -> Result<PaymentId, PaymentSendFailure> { unimplemented!() }
  67 //! #     fn retry_payment(
  68 //! #         &self, route: &Route, payment_id: PaymentId
  69 //! #     ) -> Result<(), PaymentSendFailure> { unimplemented!() }
  70 //! #     fn abandon_payment(&self, payment_id: PaymentId) { unimplemented!() }
  71 //! # }
  72 //! #
  73 //! # struct FakeRouter {}
  74 //! # impl Router for FakeRouter {
  75 //! #     fn find_route(
  76 //! #         &self, payer: &PublicKey, params: &RouteParameters, payment_hash: &PaymentHash,
  77 //! #         first_hops: Option<&[&ChannelDetails]>, _inflight_htlcs: InFlightHtlcs
  78 //! #     ) -> Result<Route, LightningError> { unimplemented!() }
  79 //! #
  80 //! #     fn notify_payment_path_failed(&self, path: Vec<&RouteHop>, short_channel_id: u64) {  unimplemented!() }
  81 //! #     fn notify_payment_path_successful(&self, path: Vec<&RouteHop>) {  unimplemented!() }
  82 //! #     fn notify_payment_probe_successful(&self, path: Vec<&RouteHop>) {  unimplemented!() }
  83 //! #     fn notify_payment_probe_failed(&self, path: Vec<&RouteHop>, short_channel_id: u64) { unimplemented!() }
  84 //! # }
  85 //! #
  86 //! # struct FakeScorer {}
  87 //! # impl Writeable for FakeScorer {
  88 //! #     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> { unimplemented!(); }
  89 //! # }
  90 //! # impl Score for FakeScorer {
  91 //! #     fn channel_penalty_msat(
  92 //! #         &self, _short_channel_id: u64, _source: &NodeId, _target: &NodeId, _usage: ChannelUsage
  93 //! #     ) -> u64 { 0 }
  94 //! #     fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
  95 //! #     fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
  96 //! #     fn probe_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
  97 //! #     fn probe_successful(&mut self, _path: &[&RouteHop]) {}
  98 //! # }
  99 //! #
 100 //! # struct FakeLogger {}
 101 //! # impl Logger for FakeLogger {
 102 //! #     fn log(&self, record: &Record) { unimplemented!() }
 103 //! # }
 104 //! #
 105 //! # fn main() {
 106 //! let event_handler = |event: &Event| {
 107 //!     match event {
 108 //!         Event::PaymentPathFailed { .. } => println!("payment failed after retries"),
 109 //!         Event::PaymentSent { .. } => println!("payment successful"),
 110 //!         _ => {},
 111 //!     }
 112 //! };
 113 //! # let payer = FakePayer {};
 114 //! # let router = FakeRouter {};
 115 //! # let scorer = RefCell::new(FakeScorer {});
 116 //! # let logger = FakeLogger {};
 117 //! let invoice_payer = InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
 118 //!
 119 //! let invoice = "...";
 120 //! if let Ok(invoice) = invoice.parse::<Invoice>() {
 121 //!     invoice_payer.pay_invoice(&invoice).unwrap();
 122 //!
 123 //! # let event_provider = FakeEventProvider {};
 124 //!     loop {
 125 //!         event_provider.process_pending_events(&invoice_payer);
 126 //!     }
 127 //! }
 128 //! # }
 129 //! ```
 130 //!
 131 //! # Note
 132 //!
 133 //! The [`Route`] is computed before each payment attempt. Any updates affecting path finding such
 134 //! as updates to the network graph or changes to channel scores should be applied prior to
 135 //! retries, typically by way of composing [`EventHandler`]s accordingly.
 136
 137 use crate::Invoice;
 138
 139 use bitcoin_hashes::Hash;
 140 use bitcoin_hashes::sha256::Hash as Sha256;
 141
 142 use crate::prelude::*;
 143 use lightning::io;
 144 use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 145 use lightning::ln::channelmanager::{ChannelDetails, PaymentId, PaymentSendFailure};
 146 use lightning::ln::msgs::LightningError;
 147 use lightning::routing::gossip::NodeId;
 148 use lightning::routing::router::{PaymentParameters, Route, RouteHop, RouteParameters};
 149 use lightning::util::errors::APIError;
 150 use lightning::util::events::{Event, EventHandler};
 151 use lightning::util::logger::Logger;
 152 use time_utils::Time;
 153 use crate::sync::Mutex;
 154
 155 use secp256k1::PublicKey;
 156
 157 use core::fmt;
 158 use core::fmt::{Debug, Display, Formatter};
 159 use core::ops::Deref;
 160 use core::time::Duration;
 161 #[cfg(feature = "std")]
 162 use std::time::SystemTime;
 163
 164 /// A utility for paying [`Invoice`]s and sending spontaneous payments.
 165 ///
 166 /// See [module-level documentation] for details.
 167 ///
 168 /// [module-level documentation]: crate::payment
 169 pub type InvoicePayer<P, R, L, E> = InvoicePayerUsingTime::<P, R, L, E, ConfiguredTime>;
 170
 171 #[cfg(not(feature = "no-std"))]
 172 type ConfiguredTime = std::time::Instant;
 173 #[cfg(feature = "no-std")]
 174 use time_utils;
 175 #[cfg(feature = "no-std")]
 176 type ConfiguredTime = time_utils::Eternity;
 177
 178 /// (C-not exported) generally all users should use the [`InvoicePayer`] type alias.
 179 pub struct InvoicePayerUsingTime<P: Deref, R: Router, L: Deref, E: EventHandler, T: Time>
 180 where
 181         P::Target: Payer,
 182         L::Target: Logger,
 183 {
 184         payer: P,
 185         router: R,
 186         logger: L,
 187         event_handler: E,
 188         /// Caches the overall attempts at making a payment, which is updated prior to retrying.
 189         payment_cache: Mutex<HashMap<PaymentHash, PaymentInfo<T>>>,
 190         retry: Retry,
 191 }
 192
 193 /// Used by [`InvoicePayerUsingTime::payment_cache`] to track the payments that are either
 194 /// currently being made, or have outstanding paths that need retrying.
 195 struct PaymentInfo<T: Time> {
 196         attempts: PaymentAttempts<T>,
 197         paths: Vec<Vec<RouteHop>>,
 198 }
 199
 200 impl<T: Time> PaymentInfo<T> {
 201         fn new() -> Self {
 202                 PaymentInfo {
 203                         attempts: PaymentAttempts::new(),
 204                         paths: vec![],
 205                 }
 206         }
 207 }
 208
 209 /// Storing minimal payment attempts information required for determining if a outbound payment can
 210 /// be retried.
 211 #[derive(Clone, Copy)]
 212 struct PaymentAttempts<T: Time> {
 213         /// This count will be incremented only after the result of the attempt is known. When it's 0,
 214         /// it means the result of the first attempt is now known yet.
 215         count: usize,
 216         /// This field is only used when retry is [`Retry::Timeout`] which is only build with feature std
 217         first_attempted_at: T
 218 }
 219
 220 impl<T: Time> PaymentAttempts<T> {
 221         fn new() -> Self {
 222                 PaymentAttempts {
 223                         count: 0,
 224                         first_attempted_at: T::now()
 225                 }
 226         }
 227 }
 228
 229 impl<T: Time> Display for PaymentAttempts<T> {
 230         fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
 231                 #[cfg(feature = "no-std")]
 232                 return write!( f, "attempts: {}", self.count);
 233                 #[cfg(not(feature = "no-std"))]
 234                 return write!(
 235                         f,
 236                         "attempts: {}, duration: {}s",
 237                         self.count,
 238                         T::now().duration_since(self.first_attempted_at).as_secs()
 239                 );
 240         }
 241 }
 242
 243 /// A trait defining behavior of an [`Invoice`] payer.
 244 pub trait Payer {
 245         /// Returns the payer's node id.
 246         fn node_id(&self) -> PublicKey;
 247
 248         /// Returns the payer's channels.
 249         fn first_hops(&self) -> Vec<ChannelDetails>;
 250
 251         /// Sends a payment over the Lightning Network using the given [`Route`].
 252         fn send_payment(
 253                 &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>
 254         ) -> Result<PaymentId, PaymentSendFailure>;
 255
 256         /// Sends a spontaneous payment over the Lightning Network using the given [`Route`].
 257         fn send_spontaneous_payment(
 258                 &self, route: &Route, payment_preimage: PaymentPreimage
 259         ) -> Result<PaymentId, PaymentSendFailure>;
 260
 261         /// Retries a failed payment path for the [`PaymentId`] using the given [`Route`].
 262         fn retry_payment(&self, route: &Route, payment_id: PaymentId) -> Result<(), PaymentSendFailure>;
 263
 264         /// Signals that no further retries for the given payment will occur.
 265         fn abandon_payment(&self, payment_id: PaymentId);
 266 }
 267
 268 /// A trait defining behavior for routing an [`Invoice`] payment.
 269 pub trait Router {
 270         /// Finds a [`Route`] between `payer` and `payee` for a payment with the given values.
 271         fn find_route(
 272                 &self, payer: &PublicKey, route_params: &RouteParameters, payment_hash: &PaymentHash,
 273                 first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: InFlightHtlcs
 274         ) -> Result<Route, LightningError>;
 275         /// Lets the router know that payment through a specific path has failed.
 276         fn notify_payment_path_failed(&self, path: Vec<&RouteHop>, short_channel_id: u64);
 277         /// Lets the router know that payment through a specific path was successful.
 278         fn notify_payment_path_successful(&self, path: Vec<&RouteHop>);
 279         /// Lets the router know that a payment probe was successful.
 280         fn notify_payment_probe_successful(&self, path: Vec<&RouteHop>);
 281         /// Lets the router know that a payment probe failed.
 282         fn notify_payment_probe_failed(&self, path: Vec<&RouteHop>, short_channel_id: u64);
 283 }
 284
 285 /// Strategies available to retry payment path failures for an [`Invoice`].
 286 ///
 287 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 288 pub enum Retry {
 289         /// Max number of attempts to retry payment.
 290         ///
 291         /// Note that this is the number of *path* failures, not full payment retries. For multi-path
 292         /// payments, if this is less than the total number of paths, we will never even retry all of the
 293         /// payment's paths.
 294         Attempts(usize),
 295         #[cfg(feature = "std")]
 296         /// Time elapsed before abandoning retries for a payment.
 297         Timeout(Duration),
 298 }
 299
 300 impl Retry {
 301         fn is_retryable_now<T: Time>(&self, attempts: &PaymentAttempts<T>) -> bool {
 302                 match (self, attempts) {
 303                         (Retry::Attempts(max_retry_count), PaymentAttempts { count, .. }) => {
 304                                 max_retry_count >= &count
 305                         },
 306                         #[cfg(feature = "std")]
 307                         (Retry::Timeout(max_duration), PaymentAttempts { first_attempted_at, .. } ) =>
 308                                 *max_duration >= T::now().duration_since(*first_attempted_at),
 309                 }
 310         }
 311 }
 312
 313 /// An error that may occur when making a payment.
 314 #[derive(Clone, Debug)]
 315 pub enum PaymentError {
 316         /// An error resulting from the provided [`Invoice`] or payment hash.
 317         Invoice(&'static str),
 318         /// An error occurring when finding a route.
 319         Routing(LightningError),
 320         /// An error occurring when sending a payment.
 321         Sending(PaymentSendFailure),
 322 }
 323
 324 impl<P: Deref, R: Router, L: Deref, E: EventHandler, T: Time> InvoicePayerUsingTime<P, R, L, E, T>
 325 where
 326         P::Target: Payer,
 327         L::Target: Logger,
 328 {
 329         /// Creates an invoice payer that retries failed payment paths.
 330         ///
 331         /// Will forward any [`Event::PaymentPathFailed`] events to the decorated `event_handler` once
 332         /// `retry` has been exceeded for a given [`Invoice`].
 333         pub fn new(
 334                 payer: P, router: R, logger: L, event_handler: E, retry: Retry
 335         ) -> Self {
 336                 Self {
 337                         payer,
 338                         router,
 339                         logger,
 340                         event_handler,
 341                         payment_cache: Mutex::new(HashMap::new()),
 342                         retry,
 343                 }
 344         }
 345
 346         /// Pays the given [`Invoice`], caching it for later use in case a retry is needed.
 347         ///
 348         /// You should ensure that the `invoice.payment_hash()` is unique and the same payment_hash has
 349         /// never been paid before. Because [`InvoicePayer`] is stateless no effort is made to do so
 350         /// for you.
 351         pub fn pay_invoice(&self, invoice: &Invoice) -> Result<PaymentId, PaymentError> {
 352                 if invoice.amount_milli_satoshis().is_none() {
 353                         Err(PaymentError::Invoice("amount missing"))
 354                 } else {
 355                         self.pay_invoice_using_amount(invoice, None)
 356                 }
 357         }
 358
 359         /// Pays the given zero-value [`Invoice`] using the given amount, caching it for later use in
 360         /// case a retry is needed.
 361         ///
 362         /// You should ensure that the `invoice.payment_hash()` is unique and the same payment_hash has
 363         /// never been paid before. Because [`InvoicePayer`] is stateless no effort is made to do so
 364         /// for you.
 365         pub fn pay_zero_value_invoice(
 366                 &self, invoice: &Invoice, amount_msats: u64
 367         ) -> Result<PaymentId, PaymentError> {
 368                 if invoice.amount_milli_satoshis().is_some() {
 369                         Err(PaymentError::Invoice("amount unexpected"))
 370                 } else {
 371                         self.pay_invoice_using_amount(invoice, Some(amount_msats))
 372                 }
 373         }
 374
 375         fn pay_invoice_using_amount(
 376                 &self, invoice: &Invoice, amount_msats: Option<u64>
 377         ) -> Result<PaymentId, PaymentError> {
 378                 debug_assert!(invoice.amount_milli_satoshis().is_some() ^ amount_msats.is_some());
 379
 380                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 381                 match self.payment_cache.lock().unwrap().entry(payment_hash) {
 382                         hash_map::Entry::Occupied(_) => return Err(PaymentError::Invoice("payment pending")),
 383                         hash_map::Entry::Vacant(entry) => entry.insert(PaymentInfo::new()),
 384                 };
 385
 386                 let payment_secret = Some(invoice.payment_secret().clone());
 387                 let mut payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key())
 388                         .with_expiry_time(expiry_time_from_unix_epoch(&invoice).as_secs())
 389                         .with_route_hints(invoice.route_hints());
 390                 if let Some(features) = invoice.features() {
 391                         payment_params = payment_params.with_features(features.clone());
 392                 }
 393                 let route_params = RouteParameters {
 394                         payment_params,
 395                         final_value_msat: invoice.amount_milli_satoshis().or(amount_msats).unwrap(),
 396                         final_cltv_expiry_delta: invoice.min_final_cltv_expiry() as u32,
 397                 };
 398
 399                 let send_payment = |route: &Route| {
 400                         self.payer.send_payment(route, payment_hash, &payment_secret)
 401                 };
 402
 403                 self.pay_internal(&route_params, payment_hash, send_payment)
 404                         .map_err(|e| { self.payment_cache.lock().unwrap().remove(&payment_hash); e })
 405         }
 406
 407         /// Pays `pubkey` an amount using the hash of the given preimage, caching it for later use in
 408         /// case a retry is needed.
 409         ///
 410         /// You should ensure that `payment_preimage` is unique and that its `payment_hash` has never
 411         /// been paid before. Because [`InvoicePayer`] is stateless no effort is made to do so for you.
 412         pub fn pay_pubkey(
 413                 &self, pubkey: PublicKey, payment_preimage: PaymentPreimage, amount_msats: u64,
 414                 final_cltv_expiry_delta: u32
 415         ) -> Result<PaymentId, PaymentError> {
 416                 let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
 417                 match self.payment_cache.lock().unwrap().entry(payment_hash) {
 418                         hash_map::Entry::Occupied(_) => return Err(PaymentError::Invoice("payment pending")),
 419                         hash_map::Entry::Vacant(entry) => entry.insert(PaymentInfo::new()),
 420                 };
 421
 422                 let route_params = RouteParameters {
 423                         payment_params: PaymentParameters::for_keysend(pubkey),
 424                         final_value_msat: amount_msats,
 425                         final_cltv_expiry_delta,
 426                 };
 427
 428                 let send_payment = |route: &Route| {
 429                         self.payer.send_spontaneous_payment(route, payment_preimage)
 430                 };
 431                 self.pay_internal(&route_params, payment_hash, send_payment)
 432                         .map_err(|e| { self.payment_cache.lock().unwrap().remove(&payment_hash); e })
 433         }
 434
 435         fn pay_internal<F: FnOnce(&Route) -> Result<PaymentId, PaymentSendFailure> + Copy>(
 436                 &self, params: &RouteParameters, payment_hash: PaymentHash, send_payment: F,
 437         ) -> Result<PaymentId, PaymentError> {
 438                 #[cfg(feature = "std")] {
 439                         if has_expired(params) {
 440                                 log_trace!(self.logger, "Invoice expired prior to send for payment {}", log_bytes!(payment_hash.0));
 441                                 return Err(PaymentError::Invoice("Invoice expired prior to send"));
 442                         }
 443                 }
 444
 445                 let payer = self.payer.node_id();
 446                 let first_hops = self.payer.first_hops();
 447                 let inflight_htlcs = self.create_inflight_map();
 448                 let route = self.router.find_route(
 449                         &payer, &params, &payment_hash, Some(&first_hops.iter().collect::<Vec<_>>()),
 450                         inflight_htlcs
 451                 ).map_err(|e| PaymentError::Routing(e))?;
 452
 453                 match send_payment(&route) {
 454                         Ok(payment_id) => {
 455                                 for path in route.paths {
 456                                         self.process_path_inflight_htlcs(payment_hash, path);
 457                                 }
 458                                 Ok(payment_id)
 459                         },
 460                         Err(e) => match e {
 461                                 PaymentSendFailure::ParameterError(_) => Err(e),
 462                                 PaymentSendFailure::PathParameterError(_) => Err(e),
 463                                 PaymentSendFailure::AllFailedRetrySafe(_) => {
 464                                         let mut payment_cache = self.payment_cache.lock().unwrap();
 465                                         let payment_info = payment_cache.get_mut(&payment_hash).unwrap();
 466                                         payment_info.attempts.count += 1;
 467                                         if self.retry.is_retryable_now(&payment_info.attempts) {
 468                                                 core::mem::drop(payment_cache);
 469                                                 Ok(self.pay_internal(params, payment_hash, send_payment)?)
 470                                         } else {
 471                                                 Err(e)
 472                                         }
 473                                 },
 474                                 PaymentSendFailure::PartialFailure { failed_paths_retry, payment_id, results } => {
 475                                         // If a `PartialFailure` event returns a result that is an `Ok()`, it means that
 476                                         // part of our payment is retried. When we receive `MonitorUpdateFailed`, it
 477                                         // means that we are still waiting for our channel monitor update to be completed.
 478                                         for (result, path) in results.iter().zip(route.paths.into_iter()) {
 479                                                 match result {
 480                                                         Ok(_) | Err(APIError::MonitorUpdateFailed) => {
 481                                                                 self.process_path_inflight_htlcs(payment_hash, path);
 482                                                         },
 483                                                         _ => {},
 484                                                 }
 485                                         }
 486
 487                                         if let Some(retry_data) = failed_paths_retry {
 488                                                 // Some paths were sent, even if we failed to send the full MPP value our
 489                                                 // recipient may misbehave and claim the funds, at which point we have to
 490                                                 // consider the payment sent, so return `Ok()` here, ignoring any retry
 491                                                 // errors.
 492                                                 let _ = self.retry_payment(payment_id, payment_hash, &retry_data);
 493                                                 Ok(payment_id)
 494                                         } else {
 495                                                 // This may happen if we send a payment and some paths fail, but
 496                                                 // only due to a temporary monitor failure or the like, implying
 497                                                 // they're really in-flight, but we haven't sent the initial
 498                                                 // HTLC-Add messages yet.
 499                                                 Ok(payment_id)
 500                                         }
 501                                 },
 502                         },
 503                 }.map_err(|e| PaymentError::Sending(e))
 504         }
 505
 506         // Takes in a path to have its information stored in `payment_cache`. This is done for paths
 507         // that are pending retry.
 508         fn process_path_inflight_htlcs(&self, payment_hash: PaymentHash, path: Vec<RouteHop>) {
 509                 self.payment_cache.lock().unwrap().entry(payment_hash)
 510                         .or_insert_with(|| PaymentInfo::new())
 511                         .paths.push(path);
 512         }
 513
 514         // Find the path we want to remove in `payment_cache`. If it doesn't exist, do nothing.
 515         fn remove_path_inflight_htlcs(&self, payment_hash: PaymentHash, path: &Vec<RouteHop>) {
 516                 self.payment_cache.lock().unwrap().entry(payment_hash)
 517                         .and_modify(|payment_info| {
 518                                 if let Some(idx) = payment_info.paths.iter().position(|p| p == path) {
 519                                         payment_info.paths.swap_remove(idx);
 520                                 }
 521                         });
 522         }
 523
 524         fn retry_payment(
 525                 &self, payment_id: PaymentId, payment_hash: PaymentHash, params: &RouteParameters
 526         ) -> Result<(), ()> {
 527                 let attempts = self.payment_cache.lock().unwrap().entry(payment_hash)
 528                         .and_modify(|info| info.attempts.count += 1 )
 529                         .or_insert_with(|| PaymentInfo {
 530                                 attempts: PaymentAttempts {
 531                                         count: 1,
 532                                         first_attempted_at: T::now(),
 533                                 },
 534                                 paths: vec![],
 535                         }).attempts;
 536
 537                 if !self.retry.is_retryable_now(&attempts) {
 538                         log_trace!(self.logger, "Payment {} exceeded maximum attempts; not retrying ({})", log_bytes!(payment_hash.0), attempts);
 539                         return Err(());
 540                 }
 541
 542                 #[cfg(feature = "std")] {
 543                         if has_expired(params) {
 544                                 log_trace!(self.logger, "Invoice expired for payment {}; not retrying ({:})", log_bytes!(payment_hash.0), attempts);
 545                                 return Err(());
 546                         }
 547                 }
 548
 549                 let payer = self.payer.node_id();
 550                 let first_hops = self.payer.first_hops();
 551                 let inflight_htlcs = self.create_inflight_map();
 552
 553                 let route = self.router.find_route(
 554                         &payer, &params, &payment_hash, Some(&first_hops.iter().collect::<Vec<_>>()),
 555                         inflight_htlcs
 556                 );
 557
 558                 if route.is_err() {
 559                         log_trace!(self.logger, "Failed to find a route for payment {}; not retrying ({:})", log_bytes!(payment_hash.0), attempts);
 560                         return Err(());
 561                 }
 562
 563                 match self.payer.retry_payment(&route.as_ref().unwrap(), payment_id) {
 564                         Ok(()) => {
 565                                 for path in route.unwrap().paths.into_iter() {
 566                                         self.process_path_inflight_htlcs(payment_hash, path);
 567                                 }
 568                                 Ok(())
 569                         },
 570                         Err(PaymentSendFailure::ParameterError(_)) |
 571                         Err(PaymentSendFailure::PathParameterError(_)) => {
 572                                 log_trace!(self.logger, "Failed to retry for payment {} due to bogus route/payment data, not retrying.", log_bytes!(payment_hash.0));
 573                                 Err(())
 574                         },
 575                         Err(PaymentSendFailure::AllFailedRetrySafe(_)) => {
 576                                 self.retry_payment(payment_id, payment_hash, params)
 577                         },
 578                         Err(PaymentSendFailure::PartialFailure { failed_paths_retry, results, .. }) => {
 579                                 // If a `PartialFailure` error contains a result that is an `Ok()`, it means that
 580                                 // part of our payment is retried. When we receive `MonitorUpdateFailed`, it
 581                                 // means that we are still waiting for our channel monitor update to complete.
 582                                 for (result, path) in results.iter().zip(route.unwrap().paths.into_iter()) {
 583                                         match result {
 584                                                 Ok(_) | Err(APIError::MonitorUpdateFailed) => {
 585                                                         self.process_path_inflight_htlcs(payment_hash, path);
 586                                                 },
 587                                                 _ => {},
 588                                         }
 589                                 }
 590
 591                                 if let Some(retry) = failed_paths_retry {
 592                                         // Always return Ok for the same reason as noted in pay_internal.
 593                                         let _ = self.retry_payment(payment_id, payment_hash, &retry);
 594                                 }
 595                                 Ok(())
 596                         },
 597                 }
 598         }
 599
 600         /// Removes the payment cached by the given payment hash.
 601         ///
 602         /// Should be called once a payment has failed or succeeded if not using [`InvoicePayer`] as an
 603         /// [`EventHandler`]. Otherwise, calling this method is unnecessary.
 604         pub fn remove_cached_payment(&self, payment_hash: &PaymentHash) {
 605                 self.payment_cache.lock().unwrap().remove(payment_hash);
 606         }
 607
 608         /// Given a [`PaymentHash`], this function looks up inflight path attempts in the payment_cache.
 609         /// Then, it uses the path information inside the cache to construct a HashMap mapping a channel's
 610         /// short channel id and direction to the amount being sent through it.
 611         ///
 612         /// This function should be called whenever we need information about currently used up liquidity
 613         /// across payments.
 614         fn create_inflight_map(&self) -> InFlightHtlcs {
 615                 let mut total_inflight_map: HashMap<(u64, bool), u64> = HashMap::new();
 616                 // Make an attempt at finding existing payment information from `payment_cache`. If it
 617                 // does not exist, it probably is a fresh payment and we can just return an empty
 618                 // HashMap.
 619                 for payment_info in self.payment_cache.lock().unwrap().values() {
 620                         for path in &payment_info.paths {
 621                                 if path.is_empty() { break };
 622                                 // total_inflight_map needs to be direction-sensitive when keeping track of the HTLC value
 623                                 // that is held up. However, the `hops` array, which is a path returned by `find_route` in
 624                                 // the router excludes the payer node. In the following lines, the payer's information is
 625                                 // hardcoded with an inflight value of 0 so that we can correctly represent the first hop
 626                                 // in our sliding window of two.
 627                                 let our_node_id: PublicKey = self.payer.node_id();
 628                                 let reversed_hops_with_payer = path.iter().rev().skip(1)
 629                                         .map(|hop| hop.pubkey)
 630                                         .chain(core::iter::once(our_node_id));
 631                                 let mut cumulative_msat = 0;
 632
 633                                 // Taking the reversed vector from above, we zip it with just the reversed hops list to
 634                                 // work "backwards" of the given path, since the last hop's `fee_msat` actually represents
 635                                 // the total amount sent.
 636                                 for (next_hop, prev_hop) in path.iter().rev().zip(reversed_hops_with_payer) {
 637                                         cumulative_msat += next_hop.fee_msat;
 638                                         total_inflight_map
 639                                                 .entry((next_hop.short_channel_id, NodeId::from_pubkey(&prev_hop) < NodeId::from_pubkey(&next_hop.pubkey)))
 640                                                 .and_modify(|used_liquidity_msat| *used_liquidity_msat += cumulative_msat)
 641                                                 .or_insert(cumulative_msat);
 642                                 }
 643                         }
 644                 }
 645
 646                 InFlightHtlcs(total_inflight_map)
 647         }
 648 }
 649
 650 fn expiry_time_from_unix_epoch(invoice: &Invoice) -> Duration {
 651         invoice.signed_invoice.raw_invoice.data.timestamp.0 + invoice.expiry_time()
 652 }
 653
 654 #[cfg(feature = "std")]
 655 fn has_expired(route_params: &RouteParameters) -> bool {
 656         if let Some(expiry_time) = route_params.payment_params.expiry_time {
 657                 Invoice::is_expired_from_epoch(&SystemTime::UNIX_EPOCH, Duration::from_secs(expiry_time))
 658         } else { false }
 659 }
 660
 661 impl<P: Deref, R: Router, L: Deref, E: EventHandler, T: Time> EventHandler for InvoicePayerUsingTime<P, R, L, E, T>
 662 where
 663         P::Target: Payer,
 664         L::Target: Logger,
 665 {
 666         fn handle_event(&self, event: &Event) {
 667                 match event {
 668                         Event::PaymentPathFailed { payment_hash, path, ..  }
 669                         | Event::PaymentPathSuccessful { path, payment_hash: Some(payment_hash), .. }
 670                         | Event::ProbeSuccessful { payment_hash, path, .. }
 671                         | Event::ProbeFailed { payment_hash, path, .. } => {
 672                                 self.remove_path_inflight_htlcs(*payment_hash, path);
 673                         },
 674                         _ => {},
 675                 }
 676
 677                 match event {
 678                         Event::PaymentPathFailed {
 679                                 payment_id, payment_hash, payment_failed_permanently, path, short_channel_id, retry, ..
 680                         } => {
 681                                 if let Some(short_channel_id) = short_channel_id {
 682                                         let path = path.iter().collect::<Vec<_>>();
 683                                         self.router.notify_payment_path_failed(path, *short_channel_id)
 684                                 }
 685
 686                                 if payment_id.is_none() {
 687                                         log_trace!(self.logger, "Payment {} has no id; not retrying", log_bytes!(payment_hash.0));
 688                                 } else if *payment_failed_permanently {
 689                                         log_trace!(self.logger, "Payment {} rejected by destination; not retrying", log_bytes!(payment_hash.0));
 690                                         self.payer.abandon_payment(payment_id.unwrap());
 691                                 } else if retry.is_none() {
 692                                         log_trace!(self.logger, "Payment {} missing retry params; not retrying", log_bytes!(payment_hash.0));
 693                                         self.payer.abandon_payment(payment_id.unwrap());
 694                                 } else if self.retry_payment(payment_id.unwrap(), *payment_hash, retry.as_ref().unwrap()).is_ok() {
 695                                         // We retried at least somewhat, don't provide the PaymentPathFailed event to the user.
 696                                         return;
 697                                 } else {
 698                                         self.payer.abandon_payment(payment_id.unwrap());
 699                                 }
 700                         },
 701                         Event::PaymentFailed { payment_hash, .. } => {
 702                                 self.remove_cached_payment(&payment_hash);
 703                         },
 704                         Event::PaymentPathSuccessful { path, .. } => {
 705                                 let path = path.iter().collect::<Vec<_>>();
 706                                 self.router.notify_payment_path_successful(path);
 707                         },
 708                         Event::PaymentSent { payment_hash, .. } => {
 709                                 let mut payment_cache = self.payment_cache.lock().unwrap();
 710                                 let attempts = payment_cache
 711                                         .remove(payment_hash)
 712                                         .map_or(1, |payment_info| payment_info.attempts.count + 1);
 713                                 log_trace!(self.logger, "Payment {} succeeded (attempts: {})", log_bytes!(payment_hash.0), attempts);
 714                         },
 715                         Event::ProbeSuccessful { payment_hash, path, .. } => {
 716                                 log_trace!(self.logger, "Probe payment {} of {}msat was successful", log_bytes!(payment_hash.0), path.last().unwrap().fee_msat);
 717                                 let path = path.iter().collect::<Vec<_>>();
 718                                 self.router.notify_payment_probe_successful(path);
 719                         },
 720                         Event::ProbeFailed { payment_hash, path, short_channel_id, .. } => {
 721                                 if let Some(short_channel_id) = short_channel_id {
 722                                         log_trace!(self.logger, "Probe payment {} of {}msat failed at channel {}", log_bytes!(payment_hash.0), path.last().unwrap().fee_msat, *short_channel_id);
 723                                         let path = path.iter().collect::<Vec<_>>();
 724                                         self.router.notify_payment_probe_failed(path, *short_channel_id);
 725                                 }
 726                         },
 727                         _ => {},
 728                 }
 729
 730                 // Delegate to the decorated event handler unless the payment is retried.
 731                 self.event_handler.handle_event(event)
 732         }
 733 }
 734
 735 /// A map with liquidity value (in msat) keyed by a short channel id and the direction the HTLC
 736 /// is traveling in. The direction boolean is determined by checking if the HTLC source's public
 737 /// key is less than its destination. See [`InFlightHtlcs::used_liquidity_msat`] for more
 738 /// details.
 739 pub struct InFlightHtlcs(HashMap<(u64, bool), u64>);
 740
 741 impl InFlightHtlcs {
 742         /// Returns liquidity in msat given the public key of the HTLC source, target, and short channel
 743         /// id.
 744         pub fn used_liquidity_msat(&self, source: &NodeId, target: &NodeId, channel_scid: u64) -> Option<&u64> {
 745                 self.0.get(&(channel_scid, source < target))
 746         }
 747 }
 748
 749 impl lightning::util::ser::Writeable for InFlightHtlcs {
 750         fn write<W: lightning::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> { self.0.write(writer) }
 751 }
 752
 753 impl lightning::util::ser::Readable for InFlightHtlcs {
 754         fn read<R: io::Read>(reader: &mut R) -> Result<Self, lightning::ln::msgs::DecodeError> {
 755                 let infight_map: HashMap<(u64, bool), u64> = lightning::util::ser::Readable::read(reader)?;
 756                 Ok(Self(infight_map))
 757         }
 758 }
 759
 760 #[cfg(test)]
 761 mod tests {
 762         use super::*;
 763         use crate::{InvoiceBuilder, Currency};
 764         use utils::{ScorerAccountingForInFlightHtlcs, create_invoice_from_channelmanager_and_duration_since_epoch};
 765         use bitcoin_hashes::sha256::Hash as Sha256;
 766         use lightning::ln::PaymentPreimage;
 767         use lightning::ln::features::{ChannelFeatures, NodeFeatures, InitFeatures};
 768         use lightning::ln::functional_test_utils::*;
 769         use lightning::ln::msgs::{ChannelMessageHandler, ErrorAction, LightningError};
 770         use lightning::routing::gossip::{EffectiveCapacity, NodeId};
 771         use lightning::routing::router::{PaymentParameters, Route, RouteHop};
 772         use lightning::routing::scoring::{ChannelUsage, LockableScore, Score};
 773         use lightning::util::test_utils::TestLogger;
 774         use lightning::util::errors::APIError;
 775         use lightning::util::events::{Event, EventsProvider, MessageSendEvent, MessageSendEventsProvider};
 776         use secp256k1::{SecretKey, PublicKey, Secp256k1};
 777         use std::cell::RefCell;
 778         use std::collections::VecDeque;
 779         use std::ops::DerefMut;
 780         use std::time::{SystemTime, Duration};
 781         use time_utils::tests::SinceEpoch;
 782         use DEFAULT_EXPIRY_TIME;
 783         use lightning::util::errors::APIError::{ChannelUnavailable, MonitorUpdateFailed};
 784
 785         fn invoice(payment_preimage: PaymentPreimage) -> Invoice {
 786                 let payment_hash = Sha256::hash(&payment_preimage.0);
 787                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 788
 789                 InvoiceBuilder::new(Currency::Bitcoin)
 790                         .description("test".into())
 791                         .payment_hash(payment_hash)
 792                         .payment_secret(PaymentSecret([0; 32]))
 793                         .duration_since_epoch(duration_since_epoch())
 794                         .min_final_cltv_expiry(144)
 795                         .amount_milli_satoshis(128)
 796                         .build_signed(|hash| {
 797                                 Secp256k1::new().sign_ecdsa_recoverable(hash, &private_key)
 798                         })
 799                         .unwrap()
 800         }
 801
 802         fn duration_since_epoch() -> Duration {
 803                 #[cfg(feature = "std")]
 804                         let duration_since_epoch =
 805                         SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap();
 806                 #[cfg(not(feature = "std"))]
 807                         let duration_since_epoch = Duration::from_secs(1234567);
 808                 duration_since_epoch
 809         }
 810
 811         fn zero_value_invoice(payment_preimage: PaymentPreimage) -> Invoice {
 812                 let payment_hash = Sha256::hash(&payment_preimage.0);
 813                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 814
 815                 InvoiceBuilder::new(Currency::Bitcoin)
 816                         .description("test".into())
 817                         .payment_hash(payment_hash)
 818                         .payment_secret(PaymentSecret([0; 32]))
 819                         .duration_since_epoch(duration_since_epoch())
 820                         .min_final_cltv_expiry(144)
 821                         .build_signed(|hash| {
 822                                 Secp256k1::new().sign_ecdsa_recoverable(hash, &private_key)
 823                         })
 824                         .unwrap()
 825         }
 826
 827         #[cfg(feature = "std")]
 828         fn expired_invoice(payment_preimage: PaymentPreimage) -> Invoice {
 829                 let payment_hash = Sha256::hash(&payment_preimage.0);
 830                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 831                 let duration = duration_since_epoch()
 832                         .checked_sub(Duration::from_secs(DEFAULT_EXPIRY_TIME * 2))
 833                         .unwrap();
 834                 InvoiceBuilder::new(Currency::Bitcoin)
 835                         .description("test".into())
 836                         .payment_hash(payment_hash)
 837                         .payment_secret(PaymentSecret([0; 32]))
 838                         .duration_since_epoch(duration)
 839                         .min_final_cltv_expiry(144)
 840                         .amount_milli_satoshis(128)
 841                         .build_signed(|hash| {
 842                                 Secp256k1::new().sign_ecdsa_recoverable(hash, &private_key)
 843                         })
 844                         .unwrap()
 845         }
 846
 847         fn pubkey() -> PublicKey {
 848                 PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap()
 849         }
 850
 851         #[test]
 852         fn pays_invoice_on_first_attempt() {
 853                 let event_handled = core::cell::RefCell::new(false);
 854                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 855
 856                 let payment_preimage = PaymentPreimage([1; 32]);
 857                 let invoice = invoice(payment_preimage);
 858                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 859                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 860
 861                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
 862                 let router = TestRouter::new(TestScorer::new());
 863                 let logger = TestLogger::new();
 864                 let invoice_payer =
 865                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
 866
 867                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 868                 assert_eq!(*payer.attempts.borrow(), 1);
 869
 870                 invoice_payer.handle_event(&Event::PaymentSent {
 871                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
 872                 });
 873                 assert_eq!(*event_handled.borrow(), true);
 874                 assert_eq!(*payer.attempts.borrow(), 1);
 875         }
 876
 877         #[test]
 878         fn pays_invoice_on_retry() {
 879                 let event_handled = core::cell::RefCell::new(false);
 880                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 881
 882                 let payment_preimage = PaymentPreimage([1; 32]);
 883                 let invoice = invoice(payment_preimage);
 884                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 885                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 886
 887                 let payer = TestPayer::new()
 888                         .expect_send(Amount::ForInvoice(final_value_msat))
 889                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 890                 let router = TestRouter::new(TestScorer::new());
 891                 let logger = TestLogger::new();
 892                 let invoice_payer =
 893                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
 894
 895                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 896                 assert_eq!(*payer.attempts.borrow(), 1);
 897
 898                 let event = Event::PaymentPathFailed {
 899                         payment_id,
 900                         payment_hash,
 901                         network_update: None,
 902                         payment_failed_permanently: false,
 903                         all_paths_failed: false,
 904                         path: TestRouter::path_for_value(final_value_msat),
 905                         short_channel_id: None,
 906                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 907                 };
 908                 invoice_payer.handle_event(&event);
 909                 assert_eq!(*event_handled.borrow(), false);
 910                 assert_eq!(*payer.attempts.borrow(), 2);
 911
 912                 invoice_payer.handle_event(&Event::PaymentSent {
 913                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
 914                 });
 915                 assert_eq!(*event_handled.borrow(), true);
 916                 assert_eq!(*payer.attempts.borrow(), 2);
 917         }
 918
 919         #[test]
 920         fn pays_invoice_on_partial_failure() {
 921                 let event_handler = |_: &_| { panic!() };
 922
 923                 let payment_preimage = PaymentPreimage([1; 32]);
 924                 let invoice = invoice(payment_preimage);
 925                 let retry = TestRouter::retry_for_invoice(&invoice);
 926                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 927
 928                 let payer = TestPayer::new()
 929                         .fails_with_partial_failure(retry.clone(), OnAttempt(1), None)
 930                         .fails_with_partial_failure(retry, OnAttempt(2), None)
 931                         .expect_send(Amount::ForInvoice(final_value_msat))
 932                         .expect_send(Amount::OnRetry(final_value_msat / 2))
 933                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 934                 let router = TestRouter::new(TestScorer::new());
 935                 let logger = TestLogger::new();
 936                 let invoice_payer =
 937                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
 938
 939                 assert!(invoice_payer.pay_invoice(&invoice).is_ok());
 940         }
 941
 942         #[test]
 943         fn retries_payment_path_for_unknown_payment() {
 944                 let event_handled = core::cell::RefCell::new(false);
 945                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 946
 947                 let payment_preimage = PaymentPreimage([1; 32]);
 948                 let invoice = invoice(payment_preimage);
 949                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 950                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 951
 952                 let payer = TestPayer::new()
 953                         .expect_send(Amount::OnRetry(final_value_msat / 2))
 954                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 955                 let router = TestRouter::new(TestScorer::new());
 956                 let logger = TestLogger::new();
 957                 let invoice_payer =
 958                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
 959
 960                 let payment_id = Some(PaymentId([1; 32]));
 961                 let event = Event::PaymentPathFailed {
 962                         payment_id,
 963                         payment_hash,
 964                         network_update: None,
 965                         payment_failed_permanently: false,
 966                         all_paths_failed: false,
 967                         path: TestRouter::path_for_value(final_value_msat),
 968                         short_channel_id: None,
 969                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 970                 };
 971                 invoice_payer.handle_event(&event);
 972                 assert_eq!(*event_handled.borrow(), false);
 973                 assert_eq!(*payer.attempts.borrow(), 1);
 974
 975                 invoice_payer.handle_event(&event);
 976                 assert_eq!(*event_handled.borrow(), false);
 977                 assert_eq!(*payer.attempts.borrow(), 2);
 978
 979                 invoice_payer.handle_event(&Event::PaymentSent {
 980                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
 981                 });
 982                 assert_eq!(*event_handled.borrow(), true);
 983                 assert_eq!(*payer.attempts.borrow(), 2);
 984         }
 985
 986         #[test]
 987         fn fails_paying_invoice_after_max_retry_counts() {
 988                 let event_handled = core::cell::RefCell::new(false);
 989                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 990
 991                 let payment_preimage = PaymentPreimage([1; 32]);
 992                 let invoice = invoice(payment_preimage);
 993                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 994
 995                 let payer = TestPayer::new()
 996                         .expect_send(Amount::ForInvoice(final_value_msat))
 997                         .expect_send(Amount::OnRetry(final_value_msat / 2))
 998                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 999                 let router = TestRouter::new(TestScorer::new());
1000                 let logger = TestLogger::new();
1001                 let invoice_payer =
1002                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1003
1004                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1005                 assert_eq!(*payer.attempts.borrow(), 1);
1006
1007                 let event = Event::PaymentPathFailed {
1008                         payment_id,
1009                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1010                         network_update: None,
1011                         payment_failed_permanently: false,
1012                         all_paths_failed: true,
1013                         path: TestRouter::path_for_value(final_value_msat),
1014                         short_channel_id: None,
1015                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1016                 };
1017                 invoice_payer.handle_event(&event);
1018                 assert_eq!(*event_handled.borrow(), false);
1019                 assert_eq!(*payer.attempts.borrow(), 2);
1020
1021                 let event = Event::PaymentPathFailed {
1022                         payment_id,
1023                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1024                         network_update: None,
1025                         payment_failed_permanently: false,
1026                         all_paths_failed: false,
1027                         path: TestRouter::path_for_value(final_value_msat / 2),
1028                         short_channel_id: None,
1029                         retry: Some(RouteParameters {
1030                                 final_value_msat: final_value_msat / 2, ..TestRouter::retry_for_invoice(&invoice)
1031                         }),
1032                 };
1033                 invoice_payer.handle_event(&event);
1034                 assert_eq!(*event_handled.borrow(), false);
1035                 assert_eq!(*payer.attempts.borrow(), 3);
1036
1037                 invoice_payer.handle_event(&event);
1038                 assert_eq!(*event_handled.borrow(), true);
1039                 assert_eq!(*payer.attempts.borrow(), 3);
1040         }
1041
1042         #[cfg(feature = "std")]
1043         #[test]
1044         fn fails_paying_invoice_after_max_retry_timeout() {
1045                 let event_handled = core::cell::RefCell::new(false);
1046                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1047
1048                 let payment_preimage = PaymentPreimage([1; 32]);
1049                 let invoice = invoice(payment_preimage);
1050                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1051
1052                 let payer = TestPayer::new()
1053                         .expect_send(Amount::ForInvoice(final_value_msat))
1054                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1055
1056                 let router = TestRouter::new(TestScorer::new());
1057                 let logger = TestLogger::new();
1058                 type InvoicePayerUsingSinceEpoch <P, R, L, E> = InvoicePayerUsingTime::<P, R, L, E, SinceEpoch>;
1059
1060                 let invoice_payer =
1061                         InvoicePayerUsingSinceEpoch::new(&payer, router, &logger, event_handler, Retry::Timeout(Duration::from_secs(120)));
1062
1063                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1064                 assert_eq!(*payer.attempts.borrow(), 1);
1065
1066                 let event = Event::PaymentPathFailed {
1067                         payment_id,
1068                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1069                         network_update: None,
1070                         payment_failed_permanently: false,
1071                         all_paths_failed: true,
1072                         path: TestRouter::path_for_value(final_value_msat),
1073                         short_channel_id: None,
1074                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1075                 };
1076                 invoice_payer.handle_event(&event);
1077                 assert_eq!(*event_handled.borrow(), false);
1078                 assert_eq!(*payer.attempts.borrow(), 2);
1079
1080                 SinceEpoch::advance(Duration::from_secs(121));
1081
1082                 invoice_payer.handle_event(&event);
1083                 assert_eq!(*event_handled.borrow(), true);
1084                 assert_eq!(*payer.attempts.borrow(), 2);
1085         }
1086
1087         #[test]
1088         fn fails_paying_invoice_with_missing_retry_params() {
1089                 let event_handled = core::cell::RefCell::new(false);
1090                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1091
1092                 let payment_preimage = PaymentPreimage([1; 32]);
1093                 let invoice = invoice(payment_preimage);
1094                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1095
1096                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1097                 let router = TestRouter::new(TestScorer::new());
1098                 let logger = TestLogger::new();
1099                 let invoice_payer =
1100                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1101
1102                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1103                 assert_eq!(*payer.attempts.borrow(), 1);
1104
1105                 let event = Event::PaymentPathFailed {
1106                         payment_id,
1107                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1108                         network_update: None,
1109                         payment_failed_permanently: false,
1110                         all_paths_failed: false,
1111                         path: vec![],
1112                         short_channel_id: None,
1113                         retry: None,
1114                 };
1115                 invoice_payer.handle_event(&event);
1116                 assert_eq!(*event_handled.borrow(), true);
1117                 assert_eq!(*payer.attempts.borrow(), 1);
1118         }
1119
1120         // Expiration is checked only in an std environment
1121         #[cfg(feature = "std")]
1122         #[test]
1123         fn fails_paying_invoice_after_expiration() {
1124                 let event_handled = core::cell::RefCell::new(false);
1125                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1126
1127                 let payer = TestPayer::new();
1128                 let router = TestRouter::new(TestScorer::new());
1129                 let logger = TestLogger::new();
1130                 let invoice_payer =
1131                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1132
1133                 let payment_preimage = PaymentPreimage([1; 32]);
1134                 let invoice = expired_invoice(payment_preimage);
1135                 if let PaymentError::Invoice(msg) = invoice_payer.pay_invoice(&invoice).unwrap_err() {
1136                         assert_eq!(msg, "Invoice expired prior to send");
1137                 } else { panic!("Expected Invoice Error"); }
1138         }
1139
1140         // Expiration is checked only in an std environment
1141         #[cfg(feature = "std")]
1142         #[test]
1143         fn fails_retrying_invoice_after_expiration() {
1144                 let event_handled = core::cell::RefCell::new(false);
1145                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1146
1147                 let payment_preimage = PaymentPreimage([1; 32]);
1148                 let invoice = invoice(payment_preimage);
1149                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1150
1151                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1152                 let router = TestRouter::new(TestScorer::new());
1153                 let logger = TestLogger::new();
1154                 let invoice_payer =
1155                         InvoicePayer::new(&payer, router,  &logger, event_handler, Retry::Attempts(2));
1156
1157                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1158                 assert_eq!(*payer.attempts.borrow(), 1);
1159
1160                 let mut retry_data = TestRouter::retry_for_invoice(&invoice);
1161                 retry_data.payment_params.expiry_time = Some(SystemTime::now()
1162                         .checked_sub(Duration::from_secs(2)).unwrap()
1163                         .duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs());
1164                 let event = Event::PaymentPathFailed {
1165                         payment_id,
1166                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1167                         network_update: None,
1168                         payment_failed_permanently: false,
1169                         all_paths_failed: false,
1170                         path: vec![],
1171                         short_channel_id: None,
1172                         retry: Some(retry_data),
1173                 };
1174                 invoice_payer.handle_event(&event);
1175                 assert_eq!(*event_handled.borrow(), true);
1176                 assert_eq!(*payer.attempts.borrow(), 1);
1177         }
1178
1179         #[test]
1180         fn fails_paying_invoice_after_retry_error() {
1181                 let event_handled = core::cell::RefCell::new(false);
1182                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1183
1184                 let payment_preimage = PaymentPreimage([1; 32]);
1185                 let invoice = invoice(payment_preimage);
1186                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1187
1188                 let payer = TestPayer::new()
1189                         .fails_on_attempt(2)
1190                         .expect_send(Amount::ForInvoice(final_value_msat))
1191                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1192                 let router = TestRouter::new(TestScorer::new());
1193                 let logger = TestLogger::new();
1194                 let invoice_payer =
1195                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1196
1197                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1198                 assert_eq!(*payer.attempts.borrow(), 1);
1199
1200                 let event = Event::PaymentPathFailed {
1201                         payment_id,
1202                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1203                         network_update: None,
1204                         payment_failed_permanently: false,
1205                         all_paths_failed: false,
1206                         path: TestRouter::path_for_value(final_value_msat / 2),
1207                         short_channel_id: None,
1208                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1209                 };
1210                 invoice_payer.handle_event(&event);
1211                 assert_eq!(*event_handled.borrow(), true);
1212                 assert_eq!(*payer.attempts.borrow(), 2);
1213         }
1214
1215         #[test]
1216         fn fails_paying_invoice_after_rejected_by_payee() {
1217                 let event_handled = core::cell::RefCell::new(false);
1218                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1219
1220                 let payment_preimage = PaymentPreimage([1; 32]);
1221                 let invoice = invoice(payment_preimage);
1222                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1223
1224                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1225                 let router = TestRouter::new(TestScorer::new());
1226                 let logger = TestLogger::new();
1227                 let invoice_payer =
1228                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1229
1230                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1231                 assert_eq!(*payer.attempts.borrow(), 1);
1232
1233                 let event = Event::PaymentPathFailed {
1234                         payment_id,
1235                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1236                         network_update: None,
1237                         payment_failed_permanently: true,
1238                         all_paths_failed: false,
1239                         path: vec![],
1240                         short_channel_id: None,
1241                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1242                 };
1243                 invoice_payer.handle_event(&event);
1244                 assert_eq!(*event_handled.borrow(), true);
1245                 assert_eq!(*payer.attempts.borrow(), 1);
1246         }
1247
1248         #[test]
1249         fn fails_repaying_invoice_with_pending_payment() {
1250                 let event_handled = core::cell::RefCell::new(false);
1251                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1252
1253                 let payment_preimage = PaymentPreimage([1; 32]);
1254                 let invoice = invoice(payment_preimage);
1255                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1256
1257                 let payer = TestPayer::new()
1258                         .expect_send(Amount::ForInvoice(final_value_msat))
1259                         .expect_send(Amount::ForInvoice(final_value_msat));
1260                 let router = TestRouter::new(TestScorer::new());
1261                 let logger = TestLogger::new();
1262                 let invoice_payer =
1263                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1264
1265                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1266
1267                 // Cannot repay an invoice pending payment.
1268                 match invoice_payer.pay_invoice(&invoice) {
1269                         Err(PaymentError::Invoice("payment pending")) => {},
1270                         Err(_) => panic!("unexpected error"),
1271                         Ok(_) => panic!("expected invoice error"),
1272                 }
1273
1274                 // Can repay an invoice once cleared from cache.
1275                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1276                 invoice_payer.remove_cached_payment(&payment_hash);
1277                 assert!(invoice_payer.pay_invoice(&invoice).is_ok());
1278
1279                 // Cannot retry paying an invoice if cleared from cache.
1280                 invoice_payer.remove_cached_payment(&payment_hash);
1281                 let event = Event::PaymentPathFailed {
1282                         payment_id,
1283                         payment_hash,
1284                         network_update: None,
1285                         payment_failed_permanently: false,
1286                         all_paths_failed: false,
1287                         path: vec![],
1288                         short_channel_id: None,
1289                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1290                 };
1291                 invoice_payer.handle_event(&event);
1292                 assert_eq!(*event_handled.borrow(), true);
1293         }
1294
1295         #[test]
1296         fn fails_paying_invoice_with_routing_errors() {
1297                 let payer = TestPayer::new();
1298                 let router = FailingRouter {};
1299                 let logger = TestLogger::new();
1300                 let invoice_payer =
1301                         InvoicePayer::new(&payer, router, &logger, |_: &_| {}, Retry::Attempts(0));
1302
1303                 let payment_preimage = PaymentPreimage([1; 32]);
1304                 let invoice = invoice(payment_preimage);
1305                 match invoice_payer.pay_invoice(&invoice) {
1306                         Err(PaymentError::Routing(_)) => {},
1307                         Err(_) => panic!("unexpected error"),
1308                         Ok(_) => panic!("expected routing error"),
1309                 }
1310         }
1311
1312         #[test]
1313         fn fails_paying_invoice_with_sending_errors() {
1314                 let payment_preimage = PaymentPreimage([1; 32]);
1315                 let invoice = invoice(payment_preimage);
1316                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1317
1318                 let payer = TestPayer::new()
1319                         .fails_on_attempt(1)
1320                         .expect_send(Amount::ForInvoice(final_value_msat));
1321                 let router = TestRouter::new(TestScorer::new());
1322                 let logger = TestLogger::new();
1323                 let invoice_payer =
1324                         InvoicePayer::new(&payer, router, &logger, |_: &_| {}, Retry::Attempts(0));
1325
1326                 match invoice_payer.pay_invoice(&invoice) {
1327                         Err(PaymentError::Sending(_)) => {},
1328                         Err(_) => panic!("unexpected error"),
1329                         Ok(_) => panic!("expected sending error"),
1330                 }
1331         }
1332
1333         #[test]
1334         fn pays_zero_value_invoice_using_amount() {
1335                 let event_handled = core::cell::RefCell::new(false);
1336                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1337
1338                 let payment_preimage = PaymentPreimage([1; 32]);
1339                 let invoice = zero_value_invoice(payment_preimage);
1340                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1341                 let final_value_msat = 100;
1342
1343                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1344                 let router = TestRouter::new(TestScorer::new());
1345                 let logger = TestLogger::new();
1346                 let invoice_payer =
1347                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1348
1349                 let payment_id =
1350                         Some(invoice_payer.pay_zero_value_invoice(&invoice, final_value_msat).unwrap());
1351                 assert_eq!(*payer.attempts.borrow(), 1);
1352
1353                 invoice_payer.handle_event(&Event::PaymentSent {
1354                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
1355                 });
1356                 assert_eq!(*event_handled.borrow(), true);
1357                 assert_eq!(*payer.attempts.borrow(), 1);
1358         }
1359
1360         #[test]
1361         fn fails_paying_zero_value_invoice_with_amount() {
1362                 let event_handled = core::cell::RefCell::new(false);
1363                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1364
1365                 let payer = TestPayer::new();
1366                 let router = TestRouter::new(TestScorer::new());
1367                 let logger = TestLogger::new();
1368                 let invoice_payer =
1369                         InvoicePayer::new(&payer, router,  &logger, event_handler, Retry::Attempts(0));
1370
1371                 let payment_preimage = PaymentPreimage([1; 32]);
1372                 let invoice = invoice(payment_preimage);
1373
1374                 // Cannot repay an invoice pending payment.
1375                 match invoice_payer.pay_zero_value_invoice(&invoice, 100) {
1376                         Err(PaymentError::Invoice("amount unexpected")) => {},
1377                         Err(_) => panic!("unexpected error"),
1378                         Ok(_) => panic!("expected invoice error"),
1379                 }
1380         }
1381
1382         #[test]
1383         fn pays_pubkey_with_amount() {
1384                 let event_handled = core::cell::RefCell::new(false);
1385                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1386
1387                 let pubkey = pubkey();
1388                 let payment_preimage = PaymentPreimage([1; 32]);
1389                 let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
1390                 let final_value_msat = 100;
1391                 let final_cltv_expiry_delta = 42;
1392
1393                 let payer = TestPayer::new()
1394                         .expect_send(Amount::Spontaneous(final_value_msat))
1395                         .expect_send(Amount::OnRetry(final_value_msat));
1396                 let router = TestRouter::new(TestScorer::new());
1397                 let logger = TestLogger::new();
1398                 let invoice_payer =
1399                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1400
1401                 let payment_id = Some(invoice_payer.pay_pubkey(
1402                                 pubkey, payment_preimage, final_value_msat, final_cltv_expiry_delta
1403                         ).unwrap());
1404                 assert_eq!(*payer.attempts.borrow(), 1);
1405
1406                 let retry = RouteParameters {
1407                         payment_params: PaymentParameters::for_keysend(pubkey),
1408                         final_value_msat,
1409                         final_cltv_expiry_delta,
1410                 };
1411                 let event = Event::PaymentPathFailed {
1412                         payment_id,
1413                         payment_hash,
1414                         network_update: None,
1415                         payment_failed_permanently: false,
1416                         all_paths_failed: false,
1417                         path: vec![],
1418                         short_channel_id: None,
1419                         retry: Some(retry),
1420                 };
1421                 invoice_payer.handle_event(&event);
1422                 assert_eq!(*event_handled.borrow(), false);
1423                 assert_eq!(*payer.attempts.borrow(), 2);
1424
1425                 invoice_payer.handle_event(&Event::PaymentSent {
1426                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
1427                 });
1428                 assert_eq!(*event_handled.borrow(), true);
1429                 assert_eq!(*payer.attempts.borrow(), 2);
1430         }
1431
1432         #[test]
1433         fn scores_failed_channel() {
1434                 let event_handled = core::cell::RefCell::new(false);
1435                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1436
1437                 let payment_preimage = PaymentPreimage([1; 32]);
1438                 let invoice = invoice(payment_preimage);
1439                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1440                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1441                 let path = TestRouter::path_for_value(final_value_msat);
1442                 let short_channel_id = Some(path[0].short_channel_id);
1443
1444                 // Expect that scorer is given short_channel_id upon handling the event.
1445                 let payer = TestPayer::new()
1446                         .expect_send(Amount::ForInvoice(final_value_msat))
1447                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1448                 let scorer = TestScorer::new().expect(TestResult::PaymentFailure {
1449                         path: path.clone(), short_channel_id: path[0].short_channel_id,
1450                 });
1451                 let router = TestRouter::new(scorer);
1452                 let logger = TestLogger::new();
1453                 let invoice_payer =
1454                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1455
1456                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1457                 let event = Event::PaymentPathFailed {
1458                         payment_id,
1459                         payment_hash,
1460                         network_update: None,
1461                         payment_failed_permanently: false,
1462                         all_paths_failed: false,
1463                         path,
1464                         short_channel_id,
1465                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1466                 };
1467                 invoice_payer.handle_event(&event);
1468         }
1469
1470         #[test]
1471         fn scores_successful_channels() {
1472                 let event_handled = core::cell::RefCell::new(false);
1473                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1474
1475                 let payment_preimage = PaymentPreimage([1; 32]);
1476                 let invoice = invoice(payment_preimage);
1477                 let payment_hash = Some(PaymentHash(invoice.payment_hash().clone().into_inner()));
1478                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1479                 let route = TestRouter::route_for_value(final_value_msat);
1480
1481                 // Expect that scorer is given short_channel_id upon handling the event.
1482                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1483                 let scorer = TestScorer::new()
1484                         .expect(TestResult::PaymentSuccess { path: route.paths[0].clone() })
1485                         .expect(TestResult::PaymentSuccess { path: route.paths[1].clone() });
1486                 let router = TestRouter::new(scorer);
1487                 let logger = TestLogger::new();
1488                 let invoice_payer =
1489                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1490
1491                 let payment_id = invoice_payer.pay_invoice(&invoice).unwrap();
1492                 let event = Event::PaymentPathSuccessful {
1493                         payment_id, payment_hash, path: route.paths[0].clone()
1494                 };
1495                 invoice_payer.handle_event(&event);
1496                 let event = Event::PaymentPathSuccessful {
1497                         payment_id, payment_hash, path: route.paths[1].clone()
1498                 };
1499                 invoice_payer.handle_event(&event);
1500         }
1501
1502         #[test]
1503         fn generates_correct_inflight_map_data() {
1504                 let event_handled = core::cell::RefCell::new(false);
1505                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1506
1507                 let payment_preimage = PaymentPreimage([1; 32]);
1508                 let invoice = invoice(payment_preimage);
1509                 let payment_hash = Some(PaymentHash(invoice.payment_hash().clone().into_inner()));
1510                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1511
1512                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1513                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1514                 let route = TestRouter::route_for_value(final_value_msat);
1515                 let router = TestRouter::new(TestScorer::new());
1516                 let logger = TestLogger::new();
1517                 let invoice_payer =
1518                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1519
1520                 let payment_id = invoice_payer.pay_invoice(&invoice).unwrap();
1521
1522                 let inflight_map = invoice_payer.create_inflight_map();
1523                 // First path check
1524                 assert_eq!(inflight_map.0.get(&(0, false)).unwrap().clone(), 94);
1525                 assert_eq!(inflight_map.0.get(&(1, true)).unwrap().clone(), 84);
1526                 assert_eq!(inflight_map.0.get(&(2, false)).unwrap().clone(), 64);
1527
1528                 // Second path check
1529                 assert_eq!(inflight_map.0.get(&(3, false)).unwrap().clone(), 74);
1530                 assert_eq!(inflight_map.0.get(&(4, false)).unwrap().clone(), 64);
1531
1532                 invoice_payer.handle_event(&Event::PaymentPathSuccessful {
1533                         payment_id, payment_hash, path: route.paths[0].clone()
1534                 });
1535
1536                 let inflight_map = invoice_payer.create_inflight_map();
1537
1538                 assert_eq!(inflight_map.0.get(&(0, false)), None);
1539                 assert_eq!(inflight_map.0.get(&(1, true)), None);
1540                 assert_eq!(inflight_map.0.get(&(2, false)), None);
1541
1542                 // Second path should still be inflight
1543                 assert_eq!(inflight_map.0.get(&(3, false)).unwrap().clone(), 74);
1544                 assert_eq!(inflight_map.0.get(&(4, false)).unwrap().clone(), 64)
1545         }
1546
1547         #[test]
1548         fn considers_inflight_htlcs_between_invoice_payments_when_path_succeeds() {
1549                 // First, let's just send a payment through, but only make sure one of the path completes
1550                 let event_handled = core::cell::RefCell::new(false);
1551                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1552
1553                 let payment_preimage = PaymentPreimage([1; 32]);
1554                 let payment_invoice = invoice(payment_preimage);
1555                 let payment_hash = Some(PaymentHash(payment_invoice.payment_hash().clone().into_inner()));
1556                 let final_value_msat = payment_invoice.amount_milli_satoshis().unwrap();
1557
1558                 let payer = TestPayer::new()
1559                         .expect_send(Amount::ForInvoice(final_value_msat))
1560                         .expect_send(Amount::ForInvoice(final_value_msat));
1561                 let final_value_msat = payment_invoice.amount_milli_satoshis().unwrap();
1562                 let route = TestRouter::route_for_value(final_value_msat);
1563                 let scorer = TestScorer::new()
1564                         // 1st invoice, 1st path
1565                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1566                         .expect_usage(ChannelUsage { amount_msat: 84, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1567                         .expect_usage(ChannelUsage { amount_msat: 94, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1568                         // 1st invoice, 2nd path
1569                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1570                         .expect_usage(ChannelUsage { amount_msat: 74, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1571                         // 2nd invoice, 1st path
1572                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1573                         .expect_usage(ChannelUsage { amount_msat: 84, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1574                         .expect_usage(ChannelUsage { amount_msat: 94, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1575                         // 2nd invoice, 2nd path
1576                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 64, effective_capacity: EffectiveCapacity::Unknown } )
1577                         .expect_usage(ChannelUsage { amount_msat: 74, inflight_htlc_msat: 74, effective_capacity: EffectiveCapacity::Unknown } );
1578                 let router = TestRouter::new(scorer);
1579                 let logger = TestLogger::new();
1580                 let invoice_payer =
1581                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1582
1583                 // Succeed 1st path, leave 2nd path inflight
1584                 let payment_id = invoice_payer.pay_invoice(&payment_invoice).unwrap();
1585                 invoice_payer.handle_event(&Event::PaymentPathSuccessful {
1586                         payment_id, payment_hash, path: route.paths[0].clone()
1587                 });
1588
1589                 // Let's pay a second invoice that will be using the same path. This should trigger the
1590                 // assertions that expect the last 4 ChannelUsage values above where TestScorer is initialized.
1591                 // Particularly, the 2nd path of the 1st payment, since it is not yet complete, should still
1592                 // have 64 msats inflight for paths considering the channel with scid of 1.
1593                 let payment_preimage_2 = PaymentPreimage([2; 32]);
1594                 let payment_invoice_2 = invoice(payment_preimage_2);
1595                 invoice_payer.pay_invoice(&payment_invoice_2).unwrap();
1596         }
1597
1598         #[test]
1599         fn considers_inflight_htlcs_between_retries() {
1600                 // First, let's just send a payment through, but only make sure one of the path completes
1601                 let event_handled = core::cell::RefCell::new(false);
1602                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1603
1604                 let payment_preimage = PaymentPreimage([1; 32]);
1605                 let payment_invoice = invoice(payment_preimage);
1606                 let payment_hash = PaymentHash(payment_invoice.payment_hash().clone().into_inner());
1607                 let final_value_msat = payment_invoice.amount_milli_satoshis().unwrap();
1608
1609                 let payer = TestPayer::new()
1610                         .expect_send(Amount::ForInvoice(final_value_msat))
1611                         .expect_send(Amount::OnRetry(final_value_msat / 2))
1612                         .expect_send(Amount::OnRetry(final_value_msat / 4));
1613                 let final_value_msat = payment_invoice.amount_milli_satoshis().unwrap();
1614                 let scorer = TestScorer::new()
1615                         // 1st invoice, 1st path
1616                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1617                         .expect_usage(ChannelUsage { amount_msat: 84, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1618                         .expect_usage(ChannelUsage { amount_msat: 94, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1619                         // 1st invoice, 2nd path
1620                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1621                         .expect_usage(ChannelUsage { amount_msat: 74, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1622                         // Retry 1, 1st path
1623                         .expect_usage(ChannelUsage { amount_msat: 32, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1624                         .expect_usage(ChannelUsage { amount_msat: 52, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1625                         .expect_usage(ChannelUsage { amount_msat: 62, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1626                         // Retry 1, 2nd path
1627                         .expect_usage(ChannelUsage { amount_msat: 32, inflight_htlc_msat: 64, effective_capacity: EffectiveCapacity::Unknown } )
1628                         .expect_usage(ChannelUsage { amount_msat: 42, inflight_htlc_msat: 64 + 10, effective_capacity: EffectiveCapacity::Unknown } )
1629                         // Retry 2, 1st path
1630                         .expect_usage(ChannelUsage { amount_msat: 16, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1631                         .expect_usage(ChannelUsage { amount_msat: 36, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1632                         .expect_usage(ChannelUsage { amount_msat: 46, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1633                         // Retry 2, 2nd path
1634                         .expect_usage(ChannelUsage { amount_msat: 16, inflight_htlc_msat: 64 + 32, effective_capacity: EffectiveCapacity::Unknown } )
1635                         .expect_usage(ChannelUsage { amount_msat: 26, inflight_htlc_msat: 74 + 32 + 10, effective_capacity: EffectiveCapacity::Unknown } );
1636                 let router = TestRouter::new(scorer);
1637                 let logger = TestLogger::new();
1638                 let invoice_payer =
1639                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1640
1641                 // Fail 1st path, leave 2nd path inflight
1642                 let payment_id = Some(invoice_payer.pay_invoice(&payment_invoice).unwrap());
1643                 invoice_payer.handle_event(&Event::PaymentPathFailed {
1644                         payment_id,
1645                         payment_hash,
1646                         network_update: None,
1647                         payment_failed_permanently: false,
1648                         all_paths_failed: false,
1649                         path: TestRouter::path_for_value(final_value_msat),
1650                         short_channel_id: None,
1651                         retry: Some(TestRouter::retry_for_invoice(&payment_invoice)),
1652                 });
1653
1654                 // Fails again the 1st path of our retry
1655                 invoice_payer.handle_event(&Event::PaymentPathFailed {
1656                         payment_id,
1657                         payment_hash,
1658                         network_update: None,
1659                         payment_failed_permanently: false,
1660                         all_paths_failed: false,
1661                         path: TestRouter::path_for_value(final_value_msat / 2),
1662                         short_channel_id: None,
1663                         retry: Some(RouteParameters {
1664                                 final_value_msat: final_value_msat / 4,
1665                                 ..TestRouter::retry_for_invoice(&payment_invoice)
1666                         }),
1667                 });
1668         }
1669
1670         #[test]
1671         fn accounts_for_some_inflight_htlcs_sent_during_partial_failure() {
1672                 let event_handled = core::cell::RefCell::new(false);
1673                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1674
1675                 let payment_preimage = PaymentPreimage([1; 32]);
1676                 let invoice_to_pay = invoice(payment_preimage);
1677                 let final_value_msat = invoice_to_pay.amount_milli_satoshis().unwrap();
1678
1679                 let retry = TestRouter::retry_for_invoice(&invoice_to_pay);
1680                 let payer = TestPayer::new()
1681                         .fails_with_partial_failure(
1682                                 retry.clone(), OnAttempt(1),
1683                                 Some(vec![
1684                                         Err(ChannelUnavailable { err: "abc".to_string() }), Err(MonitorUpdateFailed)
1685                                 ]))
1686                         .expect_send(Amount::ForInvoice(final_value_msat));
1687
1688                 let router = TestRouter::new(TestScorer::new());
1689                 let logger = TestLogger::new();
1690                 let invoice_payer =
1691                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1692
1693                 invoice_payer.pay_invoice(&invoice_to_pay).unwrap();
1694                 let inflight_map = invoice_payer.create_inflight_map();
1695
1696                 // Only the second path, which failed with `MonitorUpdateFailed` should be added to our
1697                 // inflight map because retries are disabled.
1698                 assert_eq!(inflight_map.0.len(), 2);
1699         }
1700
1701         #[test]
1702         fn accounts_for_all_inflight_htlcs_sent_during_partial_failure() {
1703                 let event_handled = core::cell::RefCell::new(false);
1704                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1705
1706                 let payment_preimage = PaymentPreimage([1; 32]);
1707                 let invoice_to_pay = invoice(payment_preimage);
1708                 let final_value_msat = invoice_to_pay.amount_milli_satoshis().unwrap();
1709
1710                 let retry = TestRouter::retry_for_invoice(&invoice_to_pay);
1711                 let payer = TestPayer::new()
1712                         .fails_with_partial_failure(
1713                                 retry.clone(), OnAttempt(1),
1714                                 Some(vec![
1715                                         Ok(()), Err(MonitorUpdateFailed)
1716                                 ]))
1717                         .expect_send(Amount::ForInvoice(final_value_msat));
1718
1719                 let router = TestRouter::new(TestScorer::new());
1720                 let logger = TestLogger::new();
1721                 let invoice_payer =
1722                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1723
1724                 invoice_payer.pay_invoice(&invoice_to_pay).unwrap();
1725                 let inflight_map = invoice_payer.create_inflight_map();
1726
1727                 // All paths successful, hence we check of the existence of all 5 hops.
1728                 assert_eq!(inflight_map.0.len(), 5);
1729         }
1730
1731         struct TestRouter {
1732                 scorer: RefCell<TestScorer>,
1733         }
1734
1735         impl TestRouter {
1736                 fn new(scorer: TestScorer) -> Self {
1737                         TestRouter { scorer: RefCell::new(scorer) }
1738                 }
1739
1740                 fn route_for_value(final_value_msat: u64) -> Route {
1741                         Route {
1742                                 paths: vec![
1743                                         vec![
1744                                                 RouteHop {
1745                                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
1746                                                         channel_features: ChannelFeatures::empty(),
1747                                                         node_features: NodeFeatures::empty(),
1748                                                         short_channel_id: 0,
1749                                                         fee_msat: 10,
1750                                                         cltv_expiry_delta: 0
1751                                                 },
1752                                                 RouteHop {
1753                                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
1754                                                         channel_features: ChannelFeatures::empty(),
1755                                                         node_features: NodeFeatures::empty(),
1756                                                         short_channel_id: 1,
1757                                                         fee_msat: 20,
1758                                                         cltv_expiry_delta: 0
1759                                                 },
1760                                                 RouteHop {
1761                                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
1762                                                         channel_features: ChannelFeatures::empty(),
1763                                                         node_features: NodeFeatures::empty(),
1764                                                         short_channel_id: 2,
1765                                                         fee_msat: final_value_msat / 2,
1766                                                         cltv_expiry_delta: 0
1767                                                 },
1768                                         ],
1769                                         vec![
1770                                                 RouteHop {
1771                                                         pubkey: PublicKey::from_slice(&hex::decode("029e03a901b85534ff1e92c43c74431f7ce72046060fcf7a95c37e148f78c77255").unwrap()[..]).unwrap(),
1772                                                         channel_features: ChannelFeatures::empty(),
1773                                                         node_features: NodeFeatures::empty(),
1774                                                         short_channel_id: 3,
1775                                                         fee_msat: 10,
1776                                                         cltv_expiry_delta: 144
1777                                                 },
1778                                                 RouteHop {
1779                                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
1780                                                         channel_features: ChannelFeatures::empty(),
1781                                                         node_features: NodeFeatures::empty(),
1782                                                         short_channel_id: 4,
1783                                                         fee_msat: final_value_msat / 2,
1784                                                         cltv_expiry_delta: 144
1785                                                 }
1786                                         ],
1787                                 ],
1788                                 payment_params: None,
1789                         }
1790                 }
1791
1792                 fn path_for_value(final_value_msat: u64) -> Vec<RouteHop> {
1793                         TestRouter::route_for_value(final_value_msat).paths[0].clone()
1794                 }
1795
1796                 fn retry_for_invoice(invoice: &Invoice) -> RouteParameters {
1797                         let mut payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key())
1798                                 .with_expiry_time(expiry_time_from_unix_epoch(invoice).as_secs())
1799                                 .with_route_hints(invoice.route_hints());
1800                         if let Some(features) = invoice.features() {
1801                                 payment_params = payment_params.with_features(features.clone());
1802                         }
1803                         let final_value_msat = invoice.amount_milli_satoshis().unwrap() / 2;
1804                         RouteParameters {
1805                                 payment_params,
1806                                 final_value_msat,
1807                                 final_cltv_expiry_delta: invoice.min_final_cltv_expiry() as u32,
1808                         }
1809                 }
1810         }
1811
1812         impl Router for TestRouter {
1813                 fn find_route(
1814                         &self, payer: &PublicKey, route_params: &RouteParameters, _payment_hash: &PaymentHash,
1815                         _first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: InFlightHtlcs
1816                 ) -> Result<Route, LightningError> {
1817                         // Simulate calling the Scorer just as you would in find_route
1818                         let route = Self::route_for_value(route_params.final_value_msat);
1819                         let mut locked_scorer = self.scorer.lock();
1820                         let scorer = ScorerAccountingForInFlightHtlcs::new(locked_scorer.deref_mut(), inflight_htlcs);
1821                         for path in route.paths {
1822                                 let mut aggregate_msat = 0u64;
1823                                 for (idx, hop) in path.iter().rev().enumerate() {
1824                                         aggregate_msat += hop.fee_msat;
1825                                         let usage = ChannelUsage {
1826                                                 amount_msat: aggregate_msat,
1827                                                 inflight_htlc_msat: 0,
1828                                                 effective_capacity: EffectiveCapacity::Unknown,
1829                                         };
1830
1831                                         // Since the path is reversed, the last element in our iteration is the first
1832                                         // hop.
1833                                         if idx == path.len() - 1 {
1834                                                 scorer.channel_penalty_msat(hop.short_channel_id, &NodeId::from_pubkey(payer), &NodeId::from_pubkey(&hop.pubkey), usage);
1835                                         } else {
1836                                                 scorer.channel_penalty_msat(hop.short_channel_id, &NodeId::from_pubkey(&path[idx + 1].pubkey), &NodeId::from_pubkey(&hop.pubkey), usage);
1837                                         }
1838                                 }
1839                         }
1840
1841                         Ok(Route {
1842                                 payment_params: Some(route_params.payment_params.clone()), ..Self::route_for_value(route_params.final_value_msat)
1843                         })
1844                 }
1845
1846                 fn notify_payment_path_failed(&self, path: Vec<&RouteHop>, short_channel_id: u64) {
1847                         self.scorer.lock().payment_path_failed(&path, short_channel_id);
1848                 }
1849
1850                 fn notify_payment_path_successful(&self, path: Vec<&RouteHop>) {
1851                         self.scorer.lock().payment_path_successful(&path);
1852                 }
1853
1854                 fn notify_payment_probe_successful(&self, path: Vec<&RouteHop>) {
1855                         self.scorer.lock().probe_successful(&path);
1856                 }
1857
1858                 fn notify_payment_probe_failed(&self, path: Vec<&RouteHop>, short_channel_id: u64) {
1859                         self.scorer.lock().probe_failed(&path, short_channel_id);
1860                 }
1861         }
1862
1863         struct FailingRouter;
1864
1865         impl Router for FailingRouter {
1866                 fn find_route(
1867                         &self, _payer: &PublicKey, _params: &RouteParameters, _payment_hash: &PaymentHash,
1868                         _first_hops: Option<&[&ChannelDetails]>, _inflight_htlcs: InFlightHtlcs
1869                 ) -> Result<Route, LightningError> {
1870                         Err(LightningError { err: String::new(), action: ErrorAction::IgnoreError })
1871                 }
1872
1873                 fn notify_payment_path_failed(&self, _path: Vec<&RouteHop>, _short_channel_id: u64) {}
1874
1875                 fn notify_payment_path_successful(&self, _path: Vec<&RouteHop>) {}
1876
1877                 fn notify_payment_probe_successful(&self, _path: Vec<&RouteHop>) {}
1878
1879                 fn notify_payment_probe_failed(&self, _path: Vec<&RouteHop>, _short_channel_id: u64) {}
1880         }
1881
1882         struct TestScorer {
1883                 event_expectations: Option<VecDeque<TestResult>>,
1884                 scorer_expectations: RefCell<Option<VecDeque<ChannelUsage>>>,
1885         }
1886
1887         #[derive(Debug)]
1888         enum TestResult {
1889                 PaymentFailure { path: Vec<RouteHop>, short_channel_id: u64 },
1890                 PaymentSuccess { path: Vec<RouteHop> },
1891         }
1892
1893         impl TestScorer {
1894                 fn new() -> Self {
1895                         Self {
1896                                 event_expectations: None,
1897                                 scorer_expectations: RefCell::new(None),
1898                         }
1899                 }
1900
1901                 fn expect(mut self, expectation: TestResult) -> Self {
1902                         self.event_expectations.get_or_insert_with(|| VecDeque::new()).push_back(expectation);
1903                         self
1904                 }
1905
1906                 fn expect_usage(self, expectation: ChannelUsage) -> Self {
1907                         self.scorer_expectations.borrow_mut().get_or_insert_with(|| VecDeque::new()).push_back(expectation);
1908                         self
1909                 }
1910         }
1911
1912         #[cfg(c_bindings)]
1913         impl lightning::util::ser::Writeable for TestScorer {
1914                 fn write<W: lightning::util::ser::Writer>(&self, _: &mut W) -> Result<(), std::io::Error> { unreachable!(); }
1915         }
1916
1917         impl Score for TestScorer {
1918                 fn channel_penalty_msat(
1919                         &self, _short_channel_id: u64, _source: &NodeId, _target: &NodeId, usage: ChannelUsage
1920                 ) -> u64 {
1921                         if let Some(scorer_expectations) = self.scorer_expectations.borrow_mut().as_mut() {
1922                                 match scorer_expectations.pop_front() {
1923                                         Some(expectation) => {
1924                                                 assert_eq!(expectation.amount_msat, usage.amount_msat);
1925                                                 assert_eq!(expectation.inflight_htlc_msat, usage.inflight_htlc_msat);
1926                                         },
1927                                         None => {},
1928                                 }
1929                         }
1930                         0
1931                 }
1932
1933                 fn payment_path_failed(&mut self, actual_path: &[&RouteHop], actual_short_channel_id: u64) {
1934                         if let Some(expectations) = &mut self.event_expectations {
1935                                 match expectations.pop_front() {
1936                                         Some(TestResult::PaymentFailure { path, short_channel_id }) => {
1937                                                 assert_eq!(actual_path, &path.iter().collect::<Vec<_>>()[..]);
1938                                                 assert_eq!(actual_short_channel_id, short_channel_id);
1939                                         },
1940                                         Some(TestResult::PaymentSuccess { path }) => {
1941                                                 panic!("Unexpected successful payment path: {:?}", path)
1942                                         },
1943                                         None => panic!("Unexpected notify_payment_path_failed call: {:?}", actual_path),
1944                                 }
1945                         }
1946                 }
1947
1948                 fn payment_path_successful(&mut self, actual_path: &[&RouteHop]) {
1949                         if let Some(expectations) = &mut self.event_expectations {
1950                                 match expectations.pop_front() {
1951                                         Some(TestResult::PaymentFailure { path, .. }) => {
1952                                                 panic!("Unexpected payment path failure: {:?}", path)
1953                                         },
1954                                         Some(TestResult::PaymentSuccess { path }) => {
1955                                                 assert_eq!(actual_path, &path.iter().collect::<Vec<_>>()[..]);
1956                                         },
1957                                         None => panic!("Unexpected notify_payment_path_successful call: {:?}", actual_path),
1958                                 }
1959                         }
1960                 }
1961
1962                 fn probe_failed(&mut self, actual_path: &[&RouteHop], _: u64) {
1963                         if let Some(expectations) = &mut self.event_expectations {
1964                                 match expectations.pop_front() {
1965                                         Some(TestResult::PaymentFailure { path, .. }) => {
1966                                                 panic!("Unexpected failed payment path: {:?}", path)
1967                                         },
1968                                         Some(TestResult::PaymentSuccess { path }) => {
1969                                                 panic!("Unexpected successful payment path: {:?}", path)
1970                                         },
1971                                         None => panic!("Unexpected notify_payment_path_failed call: {:?}", actual_path),
1972                                 }
1973                         }
1974                 }
1975                 fn probe_successful(&mut self, actual_path: &[&RouteHop]) {
1976                         if let Some(expectations) = &mut self.event_expectations {
1977                                 match expectations.pop_front() {
1978                                         Some(TestResult::PaymentFailure { path, .. }) => {
1979                                                 panic!("Unexpected payment path failure: {:?}", path)
1980                                         },
1981                                         Some(TestResult::PaymentSuccess { path }) => {
1982                                                 panic!("Unexpected successful payment path: {:?}", path)
1983                                         },
1984                                         None => panic!("Unexpected notify_payment_path_successful call: {:?}", actual_path),
1985                                 }
1986                         }
1987                 }
1988         }
1989
1990         impl Drop for TestScorer {
1991                 fn drop(&mut self) {
1992                         if std::thread::panicking() {
1993                                 return;
1994                         }
1995
1996                         if let Some(event_expectations) = &self.event_expectations {
1997                                 if !event_expectations.is_empty() {
1998                                         panic!("Unsatisfied event expectations: {:?}", event_expectations);
1999                                 }
2000                         }
2001
2002                         if let Some(scorer_expectations) = self.scorer_expectations.borrow().as_ref() {
2003                                 if !scorer_expectations.is_empty() {
2004                                         panic!("Unsatisfied scorer expectations: {:?}", scorer_expectations)
2005                                 }
2006                         }
2007                 }
2008         }
2009
2010         struct TestPayer {
2011                 expectations: core::cell::RefCell<VecDeque<Amount>>,
2012                 attempts: core::cell::RefCell<usize>,
2013                 failing_on_attempt: core::cell::RefCell<HashMap<usize, PaymentSendFailure>>,
2014         }
2015
2016         #[derive(Clone, Debug, PartialEq, Eq)]
2017         enum Amount {
2018                 ForInvoice(u64),
2019                 Spontaneous(u64),
2020                 OnRetry(u64),
2021         }
2022
2023         struct OnAttempt(usize);
2024
2025         impl TestPayer {
2026                 fn new() -> Self {
2027                         Self {
2028                                 expectations: core::cell::RefCell::new(VecDeque::new()),
2029                                 attempts: core::cell::RefCell::new(0),
2030                                 failing_on_attempt: core::cell::RefCell::new(HashMap::new()),
2031                         }
2032                 }
2033
2034                 fn expect_send(self, value_msat: Amount) -> Self {
2035                         self.expectations.borrow_mut().push_back(value_msat);
2036                         self
2037                 }
2038
2039                 fn fails_on_attempt(self, attempt: usize) -> Self {
2040                         let failure = PaymentSendFailure::ParameterError(APIError::MonitorUpdateFailed);
2041                         self.fails_with(failure, OnAttempt(attempt))
2042                 }
2043
2044                 fn fails_with_partial_failure(self, retry: RouteParameters, attempt: OnAttempt, results: Option<Vec<Result<(), APIError>>>) -> Self {
2045                         self.fails_with(PaymentSendFailure::PartialFailure {
2046                                 results: results.unwrap_or(vec![]),
2047                                 failed_paths_retry: Some(retry),
2048                                 payment_id: PaymentId([1; 32]),
2049                         }, attempt)
2050                 }
2051
2052                 fn fails_with(self, failure: PaymentSendFailure, attempt: OnAttempt) -> Self {
2053                         self.failing_on_attempt.borrow_mut().insert(attempt.0, failure);
2054                         self
2055                 }
2056
2057                 fn check_attempts(&self) -> Result<PaymentId, PaymentSendFailure> {
2058                         let mut attempts = self.attempts.borrow_mut();
2059                         *attempts += 1;
2060
2061                         match self.failing_on_attempt.borrow_mut().remove(&*attempts) {
2062                                 Some(failure) => Err(failure),
2063                                 None => Ok(PaymentId([1; 32])),
2064                         }
2065                 }
2066
2067                 fn check_value_msats(&self, actual_value_msats: Amount) {
2068                         let expected_value_msats = self.expectations.borrow_mut().pop_front();
2069                         if let Some(expected_value_msats) = expected_value_msats {
2070                                 assert_eq!(actual_value_msats, expected_value_msats);
2071                         } else {
2072                                 panic!("Unexpected amount: {:?}", actual_value_msats);
2073                         }
2074                 }
2075         }
2076
2077         impl Drop for TestPayer {
2078                 fn drop(&mut self) {
2079                         if std::thread::panicking() {
2080                                 return;
2081                         }
2082
2083                         if !self.expectations.borrow().is_empty() {
2084                                 panic!("Unsatisfied payment expectations: {:?}", self.expectations.borrow());
2085                         }
2086                 }
2087         }
2088
2089         impl Payer for TestPayer {
2090                 fn node_id(&self) -> PublicKey {
2091                         let secp_ctx = Secp256k1::new();
2092                         PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap())
2093                 }
2094
2095                 fn first_hops(&self) -> Vec<ChannelDetails> {
2096                         Vec::new()
2097                 }
2098
2099                 fn send_payment(
2100                         &self, route: &Route, _payment_hash: PaymentHash,
2101                         _payment_secret: &Option<PaymentSecret>
2102                 ) -> Result<PaymentId, PaymentSendFailure> {
2103                         self.check_value_msats(Amount::ForInvoice(route.get_total_amount()));
2104                         self.check_attempts()
2105                 }
2106
2107                 fn send_spontaneous_payment(
2108                         &self, route: &Route, _payment_preimage: PaymentPreimage,
2109                 ) -> Result<PaymentId, PaymentSendFailure> {
2110                         self.check_value_msats(Amount::Spontaneous(route.get_total_amount()));
2111                         self.check_attempts()
2112                 }
2113
2114                 fn retry_payment(
2115                         &self, route: &Route, _payment_id: PaymentId
2116                 ) -> Result<(), PaymentSendFailure> {
2117                         self.check_value_msats(Amount::OnRetry(route.get_total_amount()));
2118                         self.check_attempts().map(|_| ())
2119                 }
2120
2121                 fn abandon_payment(&self, _payment_id: PaymentId) { }
2122         }
2123
2124         // *** Full Featured Functional Tests with a Real ChannelManager ***
2125         struct ManualRouter(RefCell<VecDeque<Result<Route, LightningError>>>);
2126
2127         impl Router for ManualRouter {
2128                 fn find_route(
2129                         &self, _payer: &PublicKey, _params: &RouteParameters, _payment_hash: &PaymentHash,
2130                         _first_hops: Option<&[&ChannelDetails]>, _inflight_htlcs: InFlightHtlcs
2131                 ) -> Result<Route, LightningError> {
2132                         self.0.borrow_mut().pop_front().unwrap()
2133                 }
2134
2135                 fn notify_payment_path_failed(&self, _path: Vec<&RouteHop>, _short_channel_id: u64) {}
2136
2137                 fn notify_payment_path_successful(&self, _path: Vec<&RouteHop>) {}
2138
2139                 fn notify_payment_probe_successful(&self, _path: Vec<&RouteHop>) {}
2140
2141                 fn notify_payment_probe_failed(&self, _path: Vec<&RouteHop>, _short_channel_id: u64) {}
2142         }
2143         impl ManualRouter {
2144                 fn expect_find_route(&self, result: Result<Route, LightningError>) {
2145                         self.0.borrow_mut().push_back(result);
2146                 }
2147         }
2148         impl Drop for ManualRouter {
2149                 fn drop(&mut self) {
2150                         if std::thread::panicking() {
2151                                 return;
2152                         }
2153                         assert!(self.0.borrow_mut().is_empty());
2154                 }
2155         }
2156
2157         #[test]
2158         fn retry_multi_path_single_failed_payment() {
2159                 // Tests that we can/will retry after a single path of an MPP payment failed immediately
2160                 let chanmon_cfgs = create_chanmon_cfgs(2);
2161                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
2162                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None, None]);
2163                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
2164
2165                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
2166                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
2167                 let chans = nodes[0].node.list_usable_channels();
2168                 let mut route = Route {
2169                         paths: vec![
2170                                 vec![RouteHop {
2171                                         pubkey: nodes[1].node.get_our_node_id(),
2172                                         node_features: NodeFeatures::known(),
2173                                         short_channel_id: chans[0].short_channel_id.unwrap(),
2174                                         channel_features: ChannelFeatures::known(),
2175                                         fee_msat: 10_000,
2176                                         cltv_expiry_delta: 100,
2177                                 }],
2178                                 vec![RouteHop {
2179                                         pubkey: nodes[1].node.get_our_node_id(),
2180                                         node_features: NodeFeatures::known(),
2181                                         short_channel_id: chans[1].short_channel_id.unwrap(),
2182                                         channel_features: ChannelFeatures::known(),
2183                                         fee_msat: 100_000_001, // Our default max-HTLC-value is 10% of the channel value, which this is one more than
2184                                         cltv_expiry_delta: 100,
2185                                 }],
2186                         ],
2187                         payment_params: Some(PaymentParameters::from_node_id(nodes[1].node.get_our_node_id())),
2188                 };
2189                 let router = ManualRouter(RefCell::new(VecDeque::new()));
2190                 router.expect_find_route(Ok(route.clone()));
2191                 // On retry, split the payment across both channels.
2192                 route.paths[0][0].fee_msat = 50_000_001;
2193                 route.paths[1][0].fee_msat = 50_000_000;
2194                 router.expect_find_route(Ok(route.clone()));
2195
2196                 let event_handler = |_: &_| { panic!(); };
2197                 let invoice_payer = InvoicePayer::new(nodes[0].node, router, nodes[0].logger, event_handler, Retry::Attempts(1));
2198
2199                 assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
2200                         &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string(),
2201                         duration_since_epoch(), 3600).unwrap())
2202                         .is_ok());
2203                 let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
2204                 assert_eq!(htlc_msgs.len(), 2);
2205                 check_added_monitors!(nodes[0], 2);
2206         }
2207
2208         #[test]
2209         fn immediate_retry_on_failure() {
2210                 // Tests that we can/will retry immediately after a failure
2211                 let chanmon_cfgs = create_chanmon_cfgs(2);
2212                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
2213                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None, None]);
2214                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
2215
2216                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
2217                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, InitFeatures::known(), InitFeatures::known());
2218                 let chans = nodes[0].node.list_usable_channels();
2219                 let mut route = Route {
2220                         paths: vec![
2221                                 vec![RouteHop {
2222                                         pubkey: nodes[1].node.get_our_node_id(),
2223                                         node_features: NodeFeatures::known(),
2224                                         short_channel_id: chans[0].short_channel_id.unwrap(),
2225                                         channel_features: ChannelFeatures::known(),
2226                                         fee_msat: 100_000_001, // Our default max-HTLC-value is 10% of the channel value, which this is one more than
2227                                         cltv_expiry_delta: 100,
2228                                 }],
2229                         ],
2230                         payment_params: Some(PaymentParameters::from_node_id(nodes[1].node.get_our_node_id())),
2231                 };
2232                 let router = ManualRouter(RefCell::new(VecDeque::new()));
2233                 router.expect_find_route(Ok(route.clone()));
2234                 // On retry, split the payment across both channels.
2235                 route.paths.push(route.paths[0].clone());
2236                 route.paths[0][0].short_channel_id = chans[1].short_channel_id.unwrap();
2237                 route.paths[0][0].fee_msat = 50_000_000;
2238                 route.paths[1][0].fee_msat = 50_000_001;
2239                 router.expect_find_route(Ok(route.clone()));
2240
2241                 let event_handler = |_: &_| { panic!(); };
2242                 let invoice_payer = InvoicePayer::new(nodes[0].node, router, nodes[0].logger, event_handler, Retry::Attempts(1));
2243
2244                 assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
2245                         &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string(),
2246                         duration_since_epoch(), 3600).unwrap())
2247                         .is_ok());
2248                 let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
2249                 assert_eq!(htlc_msgs.len(), 2);
2250                 check_added_monitors!(nodes[0], 2);
2251         }
2252
2253         #[test]
2254         fn no_extra_retries_on_back_to_back_fail() {
2255                 // In a previous release, we had a race where we may exceed the payment retry count if we
2256                 // get two failures in a row with the second having `all_paths_failed` set.
2257                 // Generally, when we give up trying to retry a payment, we don't know for sure what the
2258                 // current state of the ChannelManager event queue is. Specifically, we cannot be sure that
2259                 // there are not multiple additional `PaymentPathFailed` or even `PaymentSent` events
2260                 // pending which we will see later. Thus, when we previously removed the retry tracking map
2261                 // entry after a `all_paths_failed` `PaymentPathFailed` event, we may have dropped the
2262                 // retry entry even though more events for the same payment were still pending. This led to
2263                 // us retrying a payment again even though we'd already given up on it.
2264                 //
2265                 // We now have a separate event - `PaymentFailed` which indicates no HTLCs remain and which
2266                 // is used to remove the payment retry counter entries instead. This tests for the specific
2267                 // excess-retry case while also testing `PaymentFailed` generation.
2268
2269                 let chanmon_cfgs = create_chanmon_cfgs(3);
2270                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
2271                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
2272                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
2273
2274                 let chan_1_scid = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 10_000_000, 0, InitFeatures::known(), InitFeatures::known()).0.contents.short_channel_id;
2275                 let chan_2_scid = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 10_000_000, 0, InitFeatures::known(), InitFeatures::known()).0.contents.short_channel_id;
2276
2277                 let mut route = Route {
2278                         paths: vec![
2279                                 vec![RouteHop {
2280                                         pubkey: nodes[1].node.get_our_node_id(),
2281                                         node_features: NodeFeatures::known(),
2282                                         short_channel_id: chan_1_scid,
2283                                         channel_features: ChannelFeatures::known(),
2284                                         fee_msat: 0,
2285                                         cltv_expiry_delta: 100,
2286                                 }, RouteHop {
2287                                         pubkey: nodes[2].node.get_our_node_id(),
2288                                         node_features: NodeFeatures::known(),
2289                                         short_channel_id: chan_2_scid,
2290                                         channel_features: ChannelFeatures::known(),
2291                                         fee_msat: 100_000_000,
2292                                         cltv_expiry_delta: 100,
2293                                 }],
2294                                 vec![RouteHop {
2295                                         pubkey: nodes[1].node.get_our_node_id(),
2296                                         node_features: NodeFeatures::known(),
2297                                         short_channel_id: chan_1_scid,
2298                                         channel_features: ChannelFeatures::known(),
2299                                         fee_msat: 0,
2300                                         cltv_expiry_delta: 100,
2301                                 }, RouteHop {
2302                                         pubkey: nodes[2].node.get_our_node_id(),
2303                                         node_features: NodeFeatures::known(),
2304                                         short_channel_id: chan_2_scid,
2305                                         channel_features: ChannelFeatures::known(),
2306                                         fee_msat: 100_000_000,
2307                                         cltv_expiry_delta: 100,
2308                                 }]
2309                         ],
2310                         payment_params: Some(PaymentParameters::from_node_id(nodes[2].node.get_our_node_id())),
2311                 };
2312                 let router = ManualRouter(RefCell::new(VecDeque::new()));
2313                 router.expect_find_route(Ok(route.clone()));
2314                 // On retry, we'll only be asked for one path
2315                 route.paths.remove(1);
2316                 router.expect_find_route(Ok(route.clone()));
2317
2318                 let expected_events: RefCell<VecDeque<&dyn Fn(&Event)>> = RefCell::new(VecDeque::new());
2319                 let event_handler = |event: &Event| {
2320                         let event_checker = expected_events.borrow_mut().pop_front().unwrap();
2321                         event_checker(event);
2322                 };
2323                 let invoice_payer = InvoicePayer::new(nodes[0].node, router, nodes[0].logger, event_handler, Retry::Attempts(1));
2324
2325                 assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
2326                         &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string(),
2327                         duration_since_epoch(), 3600).unwrap())
2328                         .is_ok());
2329                 let htlc_updates = SendEvent::from_node(&nodes[0]);
2330                 check_added_monitors!(nodes[0], 1);
2331                 assert_eq!(htlc_updates.msgs.len(), 1);
2332
2333                 nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &htlc_updates.msgs[0]);
2334                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &htlc_updates.commitment_msg);
2335                 check_added_monitors!(nodes[1], 1);
2336                 let (bs_first_raa, bs_first_cs) = get_revoke_commit_msgs!(nodes[1], nodes[0].node.get_our_node_id());
2337
2338                 nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_first_raa);
2339                 check_added_monitors!(nodes[0], 1);
2340                 let second_htlc_updates = SendEvent::from_node(&nodes[0]);
2341
2342                 nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_first_cs);
2343                 check_added_monitors!(nodes[0], 1);
2344                 let as_first_raa = get_event_msg!(nodes[0], MessageSendEvent::SendRevokeAndACK, nodes[1].node.get_our_node_id());
2345
2346                 nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &second_htlc_updates.msgs[0]);
2347                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &second_htlc_updates.commitment_msg);
2348                 check_added_monitors!(nodes[1], 1);
2349                 let bs_second_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
2350
2351                 nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_first_raa);
2352                 check_added_monitors!(nodes[1], 1);
2353                 let bs_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
2354
2355                 nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_second_raa);
2356                 check_added_monitors!(nodes[0], 1);
2357
2358                 nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_fail_update.update_fail_htlcs[0]);
2359                 nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_fail_update.commitment_signed);
2360                 check_added_monitors!(nodes[0], 1);
2361                 let (as_second_raa, as_third_cs) = get_revoke_commit_msgs!(nodes[0], nodes[1].node.get_our_node_id());
2362
2363                 nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_second_raa);
2364                 check_added_monitors!(nodes[1], 1);
2365                 let bs_second_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
2366
2367                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &as_third_cs);
2368                 check_added_monitors!(nodes[1], 1);
2369                 let bs_third_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
2370
2371                 nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_second_fail_update.update_fail_htlcs[0]);
2372                 nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_second_fail_update.commitment_signed);
2373                 check_added_monitors!(nodes[0], 1);
2374
2375                 nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_third_raa);
2376                 check_added_monitors!(nodes[0], 1);
2377                 let (as_third_raa, as_fourth_cs) = get_revoke_commit_msgs!(nodes[0], nodes[1].node.get_our_node_id());
2378
2379                 nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_third_raa);
2380                 check_added_monitors!(nodes[1], 1);
2381                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &as_fourth_cs);
2382                 check_added_monitors!(nodes[1], 1);
2383                 let bs_fourth_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
2384
2385                 nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_fourth_raa);
2386                 check_added_monitors!(nodes[0], 1);
2387
2388                 // At this point A has sent two HTLCs which both failed due to lack of fee. It now has two
2389                 // pending `PaymentPathFailed` events, one with `all_paths_failed` unset, and the second
2390                 // with it set. The first event will use up the only retry we are allowed, with the second
2391                 // `PaymentPathFailed` being passed up to the user (us, in this case). Previously, we'd
2392                 // treated this as "HTLC complete" and dropped the retry counter, causing us to retry again
2393                 // if the final HTLC failed.
2394                 expected_events.borrow_mut().push_back(&|ev: &Event| {
2395                         if let Event::PaymentPathFailed { payment_failed_permanently, all_paths_failed, .. } = ev {
2396                                 assert!(!payment_failed_permanently);
2397                                 assert!(all_paths_failed);
2398                         } else { panic!("Unexpected event"); }
2399                 });
2400                 nodes[0].node.process_pending_events(&invoice_payer);
2401                 assert!(expected_events.borrow().is_empty());
2402
2403                 let retry_htlc_updates = SendEvent::from_node(&nodes[0]);
2404                 check_added_monitors!(nodes[0], 1);
2405
2406                 nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &retry_htlc_updates.msgs[0]);
2407                 commitment_signed_dance!(nodes[1], nodes[0], &retry_htlc_updates.commitment_msg, false, true);
2408                 let bs_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
2409                 nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_fail_update.update_fail_htlcs[0]);
2410                 commitment_signed_dance!(nodes[0], nodes[1], &bs_fail_update.commitment_signed, false, true);
2411
2412                 expected_events.borrow_mut().push_back(&|ev: &Event| {
2413                         if let Event::PaymentPathFailed { payment_failed_permanently, all_paths_failed, .. } = ev {
2414                                 assert!(!payment_failed_permanently);
2415                                 assert!(all_paths_failed);
2416                         } else { panic!("Unexpected event"); }
2417                 });
2418                 expected_events.borrow_mut().push_back(&|ev: &Event| {
2419                         if let Event::PaymentFailed { .. } = ev {
2420                         } else { panic!("Unexpected event"); }
2421                 });
2422                 nodes[0].node.process_pending_events(&invoice_payer);
2423                 assert!(expected_events.borrow().is_empty());
2424         }
2425 }