_ 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::{InFlightHtlcs, Route, RouteHop, RouteParameters, Router};
  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::{InvoicePayer, Payer, Retry, ScoringRouter};
  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 //! #         payment_id: PaymentId
  64 //! #     ) -> Result<(), PaymentSendFailure> { unimplemented!() }
  65 //! #     fn send_spontaneous_payment(
  66 //! #         &self, route: &Route, payment_preimage: PaymentPreimage, payment_id: PaymentId,
  67 //! #     ) -> Result<(), PaymentSendFailure> { unimplemented!() }
  68 //! #     fn retry_payment(
  69 //! #         &self, route: &Route, payment_id: PaymentId
  70 //! #     ) -> Result<(), PaymentSendFailure> { unimplemented!() }
  71 //! #     fn abandon_payment(&self, payment_id: PaymentId) { unimplemented!() }
  72 //! # }
  73 //! #
  74 //! # struct FakeRouter {}
  75 //! # impl Router for FakeRouter {
  76 //! #     fn find_route(
  77 //! #         &self, payer: &PublicKey, params: &RouteParameters,
  78 //! #         first_hops: Option<&[&ChannelDetails]>, _inflight_htlcs: InFlightHtlcs
  79 //! #     ) -> Result<Route, LightningError> { unimplemented!() }
  80 //! # }
  81 //! # impl ScoringRouter for FakeRouter {
  82 //! #     fn notify_payment_path_failed(&self, path: &[&RouteHop], short_channel_id: u64) {  unimplemented!() }
  83 //! #     fn notify_payment_path_successful(&self, path: &[&RouteHop]) {  unimplemented!() }
  84 //! #     fn notify_payment_probe_successful(&self, path: &[&RouteHop]) {  unimplemented!() }
  85 //! #     fn notify_payment_probe_failed(&self, path: &[&RouteHop], short_channel_id: u64) { unimplemented!() }
  86 //! # }
  87 //! #
  88 //! # struct FakeScorer {}
  89 //! # impl Writeable for FakeScorer {
  90 //! #     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> { unimplemented!(); }
  91 //! # }
  92 //! # impl Score for FakeScorer {
  93 //! #     fn channel_penalty_msat(
  94 //! #         &self, _short_channel_id: u64, _source: &NodeId, _target: &NodeId, _usage: ChannelUsage
  95 //! #     ) -> u64 { 0 }
  96 //! #     fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
  97 //! #     fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
  98 //! #     fn probe_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
  99 //! #     fn probe_successful(&mut self, _path: &[&RouteHop]) {}
 100 //! # }
 101 //! #
 102 //! # struct FakeLogger {}
 103 //! # impl Logger for FakeLogger {
 104 //! #     fn log(&self, record: &Record) { unimplemented!() }
 105 //! # }
 106 //! #
 107 //! # fn main() {
 108 //! let event_handler = |event: &Event| {
 109 //!     match event {
 110 //!         Event::PaymentPathFailed { .. } => println!("payment failed after retries"),
 111 //!         Event::PaymentSent { .. } => println!("payment successful"),
 112 //!         _ => {},
 113 //!     }
 114 //! };
 115 //! # let payer = FakePayer {};
 116 //! # let router = FakeRouter {};
 117 //! # let scorer = RefCell::new(FakeScorer {});
 118 //! # let logger = FakeLogger {};
 119 //! let invoice_payer = InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
 120 //!
 121 //! let invoice = "...";
 122 //! if let Ok(invoice) = invoice.parse::<Invoice>() {
 123 //!     invoice_payer.pay_invoice(&invoice).unwrap();
 124 //!
 125 //! # let event_provider = FakeEventProvider {};
 126 //!     loop {
 127 //!         event_provider.process_pending_events(&invoice_payer);
 128 //!     }
 129 //! }
 130 //! # }
 131 //! ```
 132 //!
 133 //! # Note
 134 //!
 135 //! The [`Route`] is computed before each payment attempt. Any updates affecting path finding such
 136 //! as updates to the network graph or changes to channel scores should be applied prior to
 137 //! retries, typically by way of composing [`EventHandler`]s accordingly.
 138
 139 use crate::Invoice;
 140
 141 use bitcoin_hashes::Hash;
 142 use bitcoin_hashes::sha256::Hash as Sha256;
 143
 144 use crate::prelude::*;
 145 use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 146 use lightning::ln::channelmanager::{ChannelDetails, PaymentId, PaymentSendFailure};
 147 use lightning::ln::msgs::LightningError;
 148 use lightning::routing::gossip::NodeId;
 149 use lightning::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteHop, RouteParameters, Router};
 150 use lightning::util::errors::APIError;
 151 use lightning::util::events::{Event, EventHandler};
 152 use lightning::util::logger::Logger;
 153 use crate::time_utils::Time;
 154 use crate::sync::Mutex;
 155
 156 use secp256k1::PublicKey;
 157
 158 use core::fmt;
 159 use core::fmt::{Debug, Display, Formatter};
 160 use core::ops::Deref;
 161 use core::time::Duration;
 162 #[cfg(feature = "std")]
 163 use std::time::SystemTime;
 164
 165 /// A utility for paying [`Invoice`]s and sending spontaneous payments.
 166 ///
 167 /// See [module-level documentation] for details.
 168 ///
 169 /// [module-level documentation]: crate::payment
 170 pub type InvoicePayer<P, R, L, E> = InvoicePayerUsingTime::<P, R, L, E, ConfiguredTime>;
 171
 172 #[cfg(not(feature = "no-std"))]
 173 type ConfiguredTime = std::time::Instant;
 174 #[cfg(feature = "no-std")]
 175 use crate::time_utils;
 176 #[cfg(feature = "no-std")]
 177 type ConfiguredTime = time_utils::Eternity;
 178
 179 /// (C-not exported) generally all users should use the [`InvoicePayer`] type alias.
 180 pub struct InvoicePayerUsingTime<P: Deref, R: ScoringRouter, L: Deref, E: EventHandler, T: Time>
 181 where
 182         P::Target: Payer,
 183         L::Target: Logger,
 184 {
 185         payer: P,
 186         router: R,
 187         logger: L,
 188         event_handler: E,
 189         /// Caches the overall attempts at making a payment, which is updated prior to retrying.
 190         payment_cache: Mutex<HashMap<PaymentHash, PaymentInfo<T>>>,
 191         retry: Retry,
 192 }
 193
 194 /// Used by [`InvoicePayerUsingTime::payment_cache`] to track the payments that are either
 195 /// currently being made, or have outstanding paths that need retrying.
 196 struct PaymentInfo<T: Time> {
 197         attempts: PaymentAttempts<T>,
 198         paths: Vec<Vec<RouteHop>>,
 199 }
 200
 201 impl<T: Time> PaymentInfo<T> {
 202         fn new() -> Self {
 203                 PaymentInfo {
 204                         attempts: PaymentAttempts::new(),
 205                         paths: vec![],
 206                 }
 207         }
 208 }
 209
 210 /// Storing minimal payment attempts information required for determining if a outbound payment can
 211 /// be retried.
 212 #[derive(Clone, Copy)]
 213 struct PaymentAttempts<T: Time> {
 214         /// This count will be incremented only after the result of the attempt is known. When it's 0,
 215         /// it means the result of the first attempt is now known yet.
 216         count: usize,
 217         /// This field is only used when retry is [`Retry::Timeout`] which is only build with feature std
 218         first_attempted_at: T
 219 }
 220
 221 impl<T: Time> PaymentAttempts<T> {
 222         fn new() -> Self {
 223                 PaymentAttempts {
 224                         count: 0,
 225                         first_attempted_at: T::now()
 226                 }
 227         }
 228 }
 229
 230 impl<T: Time> Display for PaymentAttempts<T> {
 231         fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
 232                 #[cfg(feature = "no-std")]
 233                 return write!( f, "attempts: {}", self.count);
 234                 #[cfg(not(feature = "no-std"))]
 235                 return write!(
 236                         f,
 237                         "attempts: {}, duration: {}s",
 238                         self.count,
 239                         T::now().duration_since(self.first_attempted_at).as_secs()
 240                 );
 241         }
 242 }
 243
 244 /// A trait defining behavior of an [`Invoice`] payer.
 245 ///
 246 /// While the behavior of [`InvoicePayer`] provides idempotency of duplicate `send_*payment` calls
 247 /// with the same [`PaymentHash`], it is up to the `Payer` to provide idempotency across restarts.
 248 ///
 249 /// [`ChannelManager`] provides idempotency for duplicate payments with the same [`PaymentId`].
 250 ///
 251 /// In order to trivially ensure idempotency for payments, the default `Payer` implementation
 252 /// reuses the [`PaymentHash`] bytes as the [`PaymentId`]. Custom implementations wishing to
 253 /// provide payment idempotency with a different idempotency key (i.e. [`PaymentId`]) should map
 254 /// the [`Invoice`] or spontaneous payment target pubkey to their own idempotency key.
 255 ///
 256 /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
 257 pub trait Payer {
 258         /// Returns the payer's node id.
 259         fn node_id(&self) -> PublicKey;
 260
 261         /// Returns the payer's channels.
 262         fn first_hops(&self) -> Vec<ChannelDetails>;
 263
 264         /// Sends a payment over the Lightning Network using the given [`Route`].
 265         fn send_payment(
 266                 &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>,
 267                 payment_id: PaymentId
 268         ) -> Result<(), PaymentSendFailure>;
 269
 270         /// Sends a spontaneous payment over the Lightning Network using the given [`Route`].
 271         fn send_spontaneous_payment(
 272                 &self, route: &Route, payment_preimage: PaymentPreimage, payment_id: PaymentId
 273         ) -> Result<(), PaymentSendFailure>;
 274
 275         /// Retries a failed payment path for the [`PaymentId`] using the given [`Route`].
 276         fn retry_payment(&self, route: &Route, payment_id: PaymentId) -> Result<(), PaymentSendFailure>;
 277
 278         /// Signals that no further retries for the given payment will occur.
 279         fn abandon_payment(&self, payment_id: PaymentId);
 280 }
 281
 282 /// A trait defining behavior for a [`Router`] implementation that also supports scoring channels
 283 /// based on payment and probe success/failure.
 284 ///
 285 /// [`Router`]: lightning::routing::router::Router
 286 pub trait ScoringRouter: Router {
 287         /// Finds a [`Route`] between `payer` and `payee` for a payment with the given values. Includes
 288         /// `PaymentHash` and `PaymentId` to be able to correlate the request with a specific payment.
 289         fn find_route_with_id(
 290                 &self, payer: &PublicKey, route_params: &RouteParameters,
 291                 first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: InFlightHtlcs,
 292                 _payment_hash: PaymentHash, _payment_id: PaymentId
 293         ) -> Result<Route, LightningError> {
 294                 self.find_route(payer, route_params, first_hops, inflight_htlcs)
 295         }
 296         /// Lets the router know that payment through a specific path has failed.
 297         fn notify_payment_path_failed(&self, path: &[&RouteHop], short_channel_id: u64);
 298         /// Lets the router know that payment through a specific path was successful.
 299         fn notify_payment_path_successful(&self, path: &[&RouteHop]);
 300         /// Lets the router know that a payment probe was successful.
 301         fn notify_payment_probe_successful(&self, path: &[&RouteHop]);
 302         /// Lets the router know that a payment probe failed.
 303         fn notify_payment_probe_failed(&self, path: &[&RouteHop], short_channel_id: u64);
 304 }
 305
 306 /// Strategies available to retry payment path failures for an [`Invoice`].
 307 ///
 308 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 309 pub enum Retry {
 310         /// Max number of attempts to retry payment.
 311         ///
 312         /// Note that this is the number of *path* failures, not full payment retries. For multi-path
 313         /// payments, if this is less than the total number of paths, we will never even retry all of the
 314         /// payment's paths.
 315         Attempts(usize),
 316         #[cfg(feature = "std")]
 317         /// Time elapsed before abandoning retries for a payment.
 318         Timeout(Duration),
 319 }
 320
 321 impl Retry {
 322         fn is_retryable_now<T: Time>(&self, attempts: &PaymentAttempts<T>) -> bool {
 323                 match (self, attempts) {
 324                         (Retry::Attempts(max_retry_count), PaymentAttempts { count, .. }) => {
 325                                 max_retry_count >= &count
 326                         },
 327                         #[cfg(feature = "std")]
 328                         (Retry::Timeout(max_duration), PaymentAttempts { first_attempted_at, .. } ) =>
 329                                 *max_duration >= T::now().duration_since(*first_attempted_at),
 330                 }
 331         }
 332 }
 333
 334 /// An error that may occur when making a payment.
 335 #[derive(Clone, Debug)]
 336 pub enum PaymentError {
 337         /// An error resulting from the provided [`Invoice`] or payment hash.
 338         Invoice(&'static str),
 339         /// An error occurring when finding a route.
 340         Routing(LightningError),
 341         /// An error occurring when sending a payment.
 342         Sending(PaymentSendFailure),
 343 }
 344
 345 impl<P: Deref, R: ScoringRouter, L: Deref, E: EventHandler, T: Time> InvoicePayerUsingTime<P, R, L, E, T>
 346 where
 347         P::Target: Payer,
 348         L::Target: Logger,
 349 {
 350         /// Creates an invoice payer that retries failed payment paths.
 351         ///
 352         /// Will forward any [`Event::PaymentPathFailed`] events to the decorated `event_handler` once
 353         /// `retry` has been exceeded for a given [`Invoice`].
 354         pub fn new(
 355                 payer: P, router: R, logger: L, event_handler: E, retry: Retry
 356         ) -> Self {
 357                 Self {
 358                         payer,
 359                         router,
 360                         logger,
 361                         event_handler,
 362                         payment_cache: Mutex::new(HashMap::new()),
 363                         retry,
 364                 }
 365         }
 366
 367         /// Pays the given [`Invoice`], caching it for later use in case a retry is needed.
 368         ///
 369         /// [`Invoice::payment_hash`] is used as the [`PaymentId`], which ensures idempotency as long
 370         /// as the payment is still pending. Once the payment completes or fails, you must ensure that
 371         /// a second payment with the same [`PaymentHash`] is never sent.
 372         ///
 373         /// If you wish to use a different payment idempotency token, see
 374         /// [`Self::pay_invoice_with_id`].
 375         pub fn pay_invoice(&self, invoice: &Invoice) -> Result<PaymentId, PaymentError> {
 376                 let payment_id = PaymentId(invoice.payment_hash().into_inner());
 377                 self.pay_invoice_with_id(invoice, payment_id).map(|()| payment_id)
 378         }
 379
 380         /// Pays the given [`Invoice`] with a custom idempotency key, caching the invoice for later use
 381         /// in case a retry is needed.
 382         ///
 383         /// Note that idempotency is only guaranteed as long as the payment is still pending. Once the
 384         /// payment completes or fails, no idempotency guarantees are made.
 385         ///
 386         /// You should ensure that the [`Invoice::payment_hash`] is unique and the same [`PaymentHash`]
 387         /// has never been paid before.
 388         ///
 389         /// See [`Self::pay_invoice`] for a variant which uses the [`PaymentHash`] for the idempotency
 390         /// token.
 391         pub fn pay_invoice_with_id(&self, invoice: &Invoice, payment_id: PaymentId) -> Result<(), PaymentError> {
 392                 if invoice.amount_milli_satoshis().is_none() {
 393                         Err(PaymentError::Invoice("amount missing"))
 394                 } else {
 395                         self.pay_invoice_using_amount(invoice, None, payment_id)
 396                 }
 397         }
 398
 399         /// Pays the given zero-value [`Invoice`] using the given amount, caching it for later use in
 400         /// case a retry is needed.
 401         ///
 402         /// [`Invoice::payment_hash`] is used as the [`PaymentId`], which ensures idempotency as long
 403         /// as the payment is still pending. Once the payment completes or fails, you must ensure that
 404         /// a second payment with the same [`PaymentHash`] is never sent.
 405         ///
 406         /// If you wish to use a different payment idempotency token, see
 407         /// [`Self::pay_zero_value_invoice_with_id`].
 408         pub fn pay_zero_value_invoice(
 409                 &self, invoice: &Invoice, amount_msats: u64
 410         ) -> Result<PaymentId, PaymentError> {
 411                 let payment_id = PaymentId(invoice.payment_hash().into_inner());
 412                 self.pay_zero_value_invoice_with_id(invoice, amount_msats, payment_id).map(|()| payment_id)
 413         }
 414
 415         /// Pays the given zero-value [`Invoice`] using the given amount and custom idempotency key,
 416         /// caching the invoice for later use in case a retry is needed.
 417         ///
 418         /// Note that idempotency is only guaranteed as long as the payment is still pending. Once the
 419         /// payment completes or fails, no idempotency guarantees are made.
 420         ///
 421         /// You should ensure that the [`Invoice::payment_hash`] is unique and the same [`PaymentHash`]
 422         /// has never been paid before.
 423         ///
 424         /// See [`Self::pay_zero_value_invoice`] for a variant which uses the [`PaymentHash`] for the
 425         /// idempotency token.
 426         pub fn pay_zero_value_invoice_with_id(
 427                 &self, invoice: &Invoice, amount_msats: u64, payment_id: PaymentId
 428         ) -> Result<(), PaymentError> {
 429                 if invoice.amount_milli_satoshis().is_some() {
 430                         Err(PaymentError::Invoice("amount unexpected"))
 431                 } else {
 432                         self.pay_invoice_using_amount(invoice, Some(amount_msats), payment_id)
 433                 }
 434         }
 435
 436         fn pay_invoice_using_amount(
 437                 &self, invoice: &Invoice, amount_msats: Option<u64>, payment_id: PaymentId
 438         ) -> Result<(), PaymentError> {
 439                 debug_assert!(invoice.amount_milli_satoshis().is_some() ^ amount_msats.is_some());
 440
 441                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 442                 match self.payment_cache.lock().unwrap().entry(payment_hash) {
 443                         hash_map::Entry::Occupied(_) => return Err(PaymentError::Invoice("payment pending")),
 444                         hash_map::Entry::Vacant(entry) => entry.insert(PaymentInfo::new()),
 445                 };
 446
 447                 let payment_secret = Some(invoice.payment_secret().clone());
 448                 let mut payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key())
 449                         .with_expiry_time(expiry_time_from_unix_epoch(&invoice).as_secs())
 450                         .with_route_hints(invoice.route_hints());
 451                 if let Some(features) = invoice.features() {
 452                         payment_params = payment_params.with_features(features.clone());
 453                 }
 454                 let route_params = RouteParameters {
 455                         payment_params,
 456                         final_value_msat: invoice.amount_milli_satoshis().or(amount_msats).unwrap(),
 457                         final_cltv_expiry_delta: invoice.min_final_cltv_expiry() as u32,
 458                 };
 459
 460                 let send_payment = |route: &Route| {
 461                         self.payer.send_payment(route, payment_hash, &payment_secret, payment_id)
 462                 };
 463
 464                 self.pay_internal(&route_params, payment_hash, send_payment)
 465                         .map_err(|e| { self.payment_cache.lock().unwrap().remove(&payment_hash); e })
 466         }
 467
 468         /// Pays `pubkey` an amount using the hash of the given preimage, caching it for later use in
 469         /// case a retry is needed.
 470         ///
 471         /// The hash of the [`PaymentPreimage`] is used as the [`PaymentId`], which ensures idempotency
 472         /// as long as the payment is still pending. Once the payment completes or fails, you must
 473         /// ensure that a second payment with the same [`PaymentPreimage`] is never sent.
 474         pub fn pay_pubkey(
 475                 &self, pubkey: PublicKey, payment_preimage: PaymentPreimage, amount_msats: u64,
 476                 final_cltv_expiry_delta: u32
 477         ) -> Result<PaymentId, PaymentError> {
 478                 let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
 479                 let payment_id = PaymentId(payment_hash.0);
 480                 self.do_pay_pubkey(pubkey, payment_preimage, payment_hash, payment_id, amount_msats,
 481                                 final_cltv_expiry_delta)
 482                         .map(|()| payment_id)
 483         }
 484
 485         /// Pays `pubkey` an amount using the hash of the given preimage and a custom idempotency key,
 486         /// caching the invoice for later use in case a retry is needed.
 487         ///
 488         /// Note that idempotency is only guaranteed as long as the payment is still pending. Once the
 489         /// payment completes or fails, no idempotency guarantees are made.
 490         ///
 491         /// You should ensure that the [`PaymentPreimage`] is unique and the corresponding
 492         /// [`PaymentHash`] has never been paid before.
 493         pub fn pay_pubkey_with_id(
 494                 &self, pubkey: PublicKey, payment_preimage: PaymentPreimage, payment_id: PaymentId,
 495                 amount_msats: u64, final_cltv_expiry_delta: u32
 496         ) -> Result<(), PaymentError> {
 497                 let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
 498                 self.do_pay_pubkey(pubkey, payment_preimage, payment_hash, payment_id, amount_msats,
 499                                 final_cltv_expiry_delta)
 500         }
 501
 502         fn do_pay_pubkey(
 503                 &self, pubkey: PublicKey, payment_preimage: PaymentPreimage, payment_hash: PaymentHash,
 504                 payment_id: PaymentId, amount_msats: u64, final_cltv_expiry_delta: u32
 505         ) -> Result<(), PaymentError> {
 506                 match self.payment_cache.lock().unwrap().entry(payment_hash) {
 507                         hash_map::Entry::Occupied(_) => return Err(PaymentError::Invoice("payment pending")),
 508                         hash_map::Entry::Vacant(entry) => entry.insert(PaymentInfo::new()),
 509                 };
 510
 511                 let route_params = RouteParameters {
 512                         payment_params: PaymentParameters::for_keysend(pubkey),
 513                         final_value_msat: amount_msats,
 514                         final_cltv_expiry_delta,
 515                 };
 516
 517                 let send_payment = |route: &Route| {
 518                         self.payer.send_spontaneous_payment(route, payment_preimage, payment_id)
 519                 };
 520                 self.pay_internal(&route_params, payment_hash, send_payment)
 521                         .map_err(|e| { self.payment_cache.lock().unwrap().remove(&payment_hash); e })
 522         }
 523
 524         fn pay_internal<F: FnOnce(&Route) -> Result<(), PaymentSendFailure> + Copy>(
 525                 &self, params: &RouteParameters, payment_hash: PaymentHash, send_payment: F,
 526         ) -> Result<(), PaymentError> {
 527                 #[cfg(feature = "std")] {
 528                         if has_expired(params) {
 529                                 log_trace!(self.logger, "Invoice expired prior to send for payment {}", log_bytes!(payment_hash.0));
 530                                 return Err(PaymentError::Invoice("Invoice expired prior to send"));
 531                         }
 532                 }
 533
 534                 let payer = self.payer.node_id();
 535                 let first_hops = self.payer.first_hops();
 536                 let inflight_htlcs = self.create_inflight_map();
 537                 let route = self.router.find_route(
 538                         &payer, &params, Some(&first_hops.iter().collect::<Vec<_>>()), inflight_htlcs
 539                 ).map_err(|e| PaymentError::Routing(e))?;
 540
 541                 match send_payment(&route) {
 542                         Ok(()) => {
 543                                 for path in route.paths {
 544                                         self.process_path_inflight_htlcs(payment_hash, path);
 545                                 }
 546                                 Ok(())
 547                         },
 548                         Err(e) => match e {
 549                                 PaymentSendFailure::ParameterError(_) => Err(e),
 550                                 PaymentSendFailure::PathParameterError(_) => Err(e),
 551                                 PaymentSendFailure::AllFailedRetrySafe(_) => {
 552                                         let mut payment_cache = self.payment_cache.lock().unwrap();
 553                                         let payment_info = payment_cache.get_mut(&payment_hash).unwrap();
 554                                         payment_info.attempts.count += 1;
 555                                         if self.retry.is_retryable_now(&payment_info.attempts) {
 556                                                 core::mem::drop(payment_cache);
 557                                                 Ok(self.pay_internal(params, payment_hash, send_payment)?)
 558                                         } else {
 559                                                 Err(e)
 560                                         }
 561                                 },
 562                                 PaymentSendFailure::PartialFailure { failed_paths_retry, payment_id, results } => {
 563                                         // If a `PartialFailure` event returns a result that is an `Ok()`, it means that
 564                                         // part of our payment is retried. When we receive `MonitorUpdateInProgress`, it
 565                                         // means that we are still waiting for our channel monitor update to be completed.
 566                                         for (result, path) in results.iter().zip(route.paths.into_iter()) {
 567                                                 match result {
 568                                                         Ok(_) | Err(APIError::MonitorUpdateInProgress) => {
 569                                                                 self.process_path_inflight_htlcs(payment_hash, path);
 570                                                         },
 571                                                         _ => {},
 572                                                 }
 573                                         }
 574
 575                                         if let Some(retry_data) = failed_paths_retry {
 576                                                 // Some paths were sent, even if we failed to send the full MPP value our
 577                                                 // recipient may misbehave and claim the funds, at which point we have to
 578                                                 // consider the payment sent, so return `Ok()` here, ignoring any retry
 579                                                 // errors.
 580                                                 let _ = self.retry_payment(payment_id, payment_hash, &retry_data);
 581                                                 Ok(())
 582                                         } else {
 583                                                 // This may happen if we send a payment and some paths fail, but
 584                                                 // only due to a temporary monitor failure or the like, implying
 585                                                 // they're really in-flight, but we haven't sent the initial
 586                                                 // HTLC-Add messages yet.
 587                                                 Ok(())
 588                                         }
 589                                 },
 590                         },
 591                 }.map_err(|e| PaymentError::Sending(e))
 592         }
 593
 594         // Takes in a path to have its information stored in `payment_cache`. This is done for paths
 595         // that are pending retry.
 596         fn process_path_inflight_htlcs(&self, payment_hash: PaymentHash, path: Vec<RouteHop>) {
 597                 self.payment_cache.lock().unwrap().entry(payment_hash)
 598                         .or_insert_with(|| PaymentInfo::new())
 599                         .paths.push(path);
 600         }
 601
 602         // Find the path we want to remove in `payment_cache`. If it doesn't exist, do nothing.
 603         fn remove_path_inflight_htlcs(&self, payment_hash: PaymentHash, path: &Vec<RouteHop>) {
 604                 self.payment_cache.lock().unwrap().entry(payment_hash)
 605                         .and_modify(|payment_info| {
 606                                 if let Some(idx) = payment_info.paths.iter().position(|p| p == path) {
 607                                         payment_info.paths.swap_remove(idx);
 608                                 }
 609                         });
 610         }
 611
 612         fn retry_payment(
 613                 &self, payment_id: PaymentId, payment_hash: PaymentHash, params: &RouteParameters
 614         ) -> Result<(), ()> {
 615                 let attempts = self.payment_cache.lock().unwrap().entry(payment_hash)
 616                         .and_modify(|info| info.attempts.count += 1 )
 617                         .or_insert_with(|| PaymentInfo {
 618                                 attempts: PaymentAttempts {
 619                                         count: 1,
 620                                         first_attempted_at: T::now(),
 621                                 },
 622                                 paths: vec![],
 623                         }).attempts;
 624
 625                 if !self.retry.is_retryable_now(&attempts) {
 626                         log_trace!(self.logger, "Payment {} exceeded maximum attempts; not retrying ({})", log_bytes!(payment_hash.0), attempts);
 627                         return Err(());
 628                 }
 629
 630                 #[cfg(feature = "std")] {
 631                         if has_expired(params) {
 632                                 log_trace!(self.logger, "Invoice expired for payment {}; not retrying ({:})", log_bytes!(payment_hash.0), attempts);
 633                                 return Err(());
 634                         }
 635                 }
 636
 637                 let payer = self.payer.node_id();
 638                 let first_hops = self.payer.first_hops();
 639                 let inflight_htlcs = self.create_inflight_map();
 640
 641                 let route = self.router.find_route(
 642                         &payer, &params, Some(&first_hops.iter().collect::<Vec<_>>()), inflight_htlcs
 643                 );
 644
 645                 if route.is_err() {
 646                         log_trace!(self.logger, "Failed to find a route for payment {}; not retrying ({:})", log_bytes!(payment_hash.0), attempts);
 647                         return Err(());
 648                 }
 649
 650                 match self.payer.retry_payment(&route.as_ref().unwrap(), payment_id) {
 651                         Ok(()) => {
 652                                 for path in route.unwrap().paths.into_iter() {
 653                                         self.process_path_inflight_htlcs(payment_hash, path);
 654                                 }
 655                                 Ok(())
 656                         },
 657                         Err(PaymentSendFailure::ParameterError(_)) |
 658                         Err(PaymentSendFailure::PathParameterError(_)) => {
 659                                 log_trace!(self.logger, "Failed to retry for payment {} due to bogus route/payment data, not retrying.", log_bytes!(payment_hash.0));
 660                                 Err(())
 661                         },
 662                         Err(PaymentSendFailure::AllFailedRetrySafe(_)) => {
 663                                 self.retry_payment(payment_id, payment_hash, params)
 664                         },
 665                         Err(PaymentSendFailure::PartialFailure { failed_paths_retry, results, .. }) => {
 666                                 // If a `PartialFailure` error contains a result that is an `Ok()`, it means that
 667                                 // part of our payment is retried. When we receive `MonitorUpdateInProgress`, it
 668                                 // means that we are still waiting for our channel monitor update to complete.
 669                                 for (result, path) in results.iter().zip(route.unwrap().paths.into_iter()) {
 670                                         match result {
 671                                                 Ok(_) | Err(APIError::MonitorUpdateInProgress) => {
 672                                                         self.process_path_inflight_htlcs(payment_hash, path);
 673                                                 },
 674                                                 _ => {},
 675                                         }
 676                                 }
 677
 678                                 if let Some(retry) = failed_paths_retry {
 679                                         // Always return Ok for the same reason as noted in pay_internal.
 680                                         let _ = self.retry_payment(payment_id, payment_hash, &retry);
 681                                 }
 682                                 Ok(())
 683                         },
 684                 }
 685         }
 686
 687         /// Removes the payment cached by the given payment hash.
 688         ///
 689         /// Should be called once a payment has failed or succeeded if not using [`InvoicePayer`] as an
 690         /// [`EventHandler`]. Otherwise, calling this method is unnecessary.
 691         pub fn remove_cached_payment(&self, payment_hash: &PaymentHash) {
 692                 self.payment_cache.lock().unwrap().remove(payment_hash);
 693         }
 694
 695         /// Use path information in the payment_cache to construct a HashMap mapping a channel's short
 696         /// channel id and direction to the amount being sent through it.
 697         ///
 698         /// This function should be called whenever we need information about currently used up liquidity
 699         /// across payments.
 700         fn create_inflight_map(&self) -> InFlightHtlcs {
 701                 let mut total_inflight_map: HashMap<(u64, bool), u64> = HashMap::new();
 702                 // Make an attempt at finding existing payment information from `payment_cache`. If it
 703                 // does not exist, it probably is a fresh payment and we can just return an empty
 704                 // HashMap.
 705                 for payment_info in self.payment_cache.lock().unwrap().values() {
 706                         for path in &payment_info.paths {
 707                                 if path.is_empty() { break };
 708                                 // total_inflight_map needs to be direction-sensitive when keeping track of the HTLC value
 709                                 // that is held up. However, the `hops` array, which is a path returned by `find_route` in
 710                                 // the router excludes the payer node. In the following lines, the payer's information is
 711                                 // hardcoded with an inflight value of 0 so that we can correctly represent the first hop
 712                                 // in our sliding window of two.
 713                                 let our_node_id: PublicKey = self.payer.node_id();
 714                                 let reversed_hops_with_payer = path.iter().rev().skip(1)
 715                                         .map(|hop| hop.pubkey)
 716                                         .chain(core::iter::once(our_node_id));
 717                                 let mut cumulative_msat = 0;
 718
 719                                 // Taking the reversed vector from above, we zip it with just the reversed hops list to
 720                                 // work "backwards" of the given path, since the last hop's `fee_msat` actually represents
 721                                 // the total amount sent.
 722                                 for (next_hop, prev_hop) in path.iter().rev().zip(reversed_hops_with_payer) {
 723                                         cumulative_msat += next_hop.fee_msat;
 724                                         total_inflight_map
 725                                                 .entry((next_hop.short_channel_id, NodeId::from_pubkey(&prev_hop) < NodeId::from_pubkey(&next_hop.pubkey)))
 726                                                 .and_modify(|used_liquidity_msat| *used_liquidity_msat += cumulative_msat)
 727                                                 .or_insert(cumulative_msat);
 728                                 }
 729                         }
 730                 }
 731
 732                 InFlightHtlcs::new(total_inflight_map)
 733         }
 734 }
 735
 736 fn expiry_time_from_unix_epoch(invoice: &Invoice) -> Duration {
 737         invoice.signed_invoice.raw_invoice.data.timestamp.0 + invoice.expiry_time()
 738 }
 739
 740 #[cfg(feature = "std")]
 741 fn has_expired(route_params: &RouteParameters) -> bool {
 742         if let Some(expiry_time) = route_params.payment_params.expiry_time {
 743                 Invoice::is_expired_from_epoch(&SystemTime::UNIX_EPOCH, Duration::from_secs(expiry_time))
 744         } else { false }
 745 }
 746
 747 impl<P: Deref, R: ScoringRouter, L: Deref, E: EventHandler, T: Time> EventHandler for InvoicePayerUsingTime<P, R, L, E, T>
 748 where
 749         P::Target: Payer,
 750         L::Target: Logger,
 751 {
 752         fn handle_event(&self, event: &Event) {
 753                 match event {
 754                         Event::PaymentPathFailed { payment_hash, path, ..  }
 755                         | Event::PaymentPathSuccessful { path, payment_hash: Some(payment_hash), .. }
 756                         | Event::ProbeSuccessful { payment_hash, path, .. }
 757                         | Event::ProbeFailed { payment_hash, path, .. } => {
 758                                 self.remove_path_inflight_htlcs(*payment_hash, path);
 759                         },
 760                         _ => {},
 761                 }
 762
 763                 match event {
 764                         Event::PaymentPathFailed {
 765                                 payment_id, payment_hash, payment_failed_permanently, path, short_channel_id, retry, ..
 766                         } => {
 767                                 if let Some(short_channel_id) = short_channel_id {
 768                                         let path = path.iter().collect::<Vec<_>>();
 769                                         self.router.notify_payment_path_failed(&path, *short_channel_id)
 770                                 }
 771
 772                                 if payment_id.is_none() {
 773                                         log_trace!(self.logger, "Payment {} has no id; not retrying", log_bytes!(payment_hash.0));
 774                                 } else if *payment_failed_permanently {
 775                                         log_trace!(self.logger, "Payment {} rejected by destination; not retrying", log_bytes!(payment_hash.0));
 776                                         self.payer.abandon_payment(payment_id.unwrap());
 777                                 } else if retry.is_none() {
 778                                         log_trace!(self.logger, "Payment {} missing retry params; not retrying", log_bytes!(payment_hash.0));
 779                                         self.payer.abandon_payment(payment_id.unwrap());
 780                                 } else if self.retry_payment(payment_id.unwrap(), *payment_hash, retry.as_ref().unwrap()).is_ok() {
 781                                         // We retried at least somewhat, don't provide the PaymentPathFailed event to the user.
 782                                         return;
 783                                 } else {
 784                                         self.payer.abandon_payment(payment_id.unwrap());
 785                                 }
 786                         },
 787                         Event::PaymentFailed { payment_hash, .. } => {
 788                                 self.remove_cached_payment(&payment_hash);
 789                         },
 790                         Event::PaymentPathSuccessful { path, .. } => {
 791                                 let path = path.iter().collect::<Vec<_>>();
 792                                 self.router.notify_payment_path_successful(&path);
 793                         },
 794                         Event::PaymentSent { payment_hash, .. } => {
 795                                 let mut payment_cache = self.payment_cache.lock().unwrap();
 796                                 let attempts = payment_cache
 797                                         .remove(payment_hash)
 798                                         .map_or(1, |payment_info| payment_info.attempts.count + 1);
 799                                 log_trace!(self.logger, "Payment {} succeeded (attempts: {})", log_bytes!(payment_hash.0), attempts);
 800                         },
 801                         Event::ProbeSuccessful { payment_hash, path, .. } => {
 802                                 log_trace!(self.logger, "Probe payment {} of {}msat was successful", log_bytes!(payment_hash.0), path.last().unwrap().fee_msat);
 803                                 let path = path.iter().collect::<Vec<_>>();
 804                                 self.router.notify_payment_probe_successful(&path);
 805                         },
 806                         Event::ProbeFailed { payment_hash, path, short_channel_id, .. } => {
 807                                 if let Some(short_channel_id) = short_channel_id {
 808                                         log_trace!(self.logger, "Probe payment {} of {}msat failed at channel {}", log_bytes!(payment_hash.0), path.last().unwrap().fee_msat, *short_channel_id);
 809                                         let path = path.iter().collect::<Vec<_>>();
 810                                         self.router.notify_payment_probe_failed(&path, *short_channel_id);
 811                                 }
 812                         },
 813                         _ => {},
 814                 }
 815
 816                 // Delegate to the decorated event handler unless the payment is retried.
 817                 self.event_handler.handle_event(event)
 818         }
 819 }
 820
 821 #[cfg(test)]
 822 mod tests {
 823         use super::*;
 824         use crate::{InvoiceBuilder, Currency};
 825         use crate::utils::{ScorerAccountingForInFlightHtlcs, create_invoice_from_channelmanager_and_duration_since_epoch};
 826         use bitcoin_hashes::sha256::Hash as Sha256;
 827         use lightning::ln::PaymentPreimage;
 828         use lightning::ln::channelmanager;
 829         use lightning::ln::features::{ChannelFeatures, NodeFeatures};
 830         use lightning::ln::functional_test_utils::*;
 831         use lightning::ln::msgs::{ChannelMessageHandler, ErrorAction, LightningError};
 832         use lightning::routing::gossip::{EffectiveCapacity, NodeId};
 833         use lightning::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteHop, Router};
 834         use lightning::routing::scoring::{ChannelUsage, LockableScore, Score};
 835         use lightning::util::test_utils::TestLogger;
 836         use lightning::util::errors::APIError;
 837         use lightning::util::events::{Event, EventsProvider, MessageSendEvent, MessageSendEventsProvider};
 838         use secp256k1::{SecretKey, PublicKey, Secp256k1};
 839         use std::cell::RefCell;
 840         use std::collections::VecDeque;
 841         use std::ops::DerefMut;
 842         use std::time::{SystemTime, Duration};
 843         use crate::time_utils::tests::SinceEpoch;
 844         use crate::DEFAULT_EXPIRY_TIME;
 845         use lightning::util::errors::APIError::{ChannelUnavailable, MonitorUpdateInProgress};
 846
 847         fn invoice(payment_preimage: PaymentPreimage) -> Invoice {
 848                 let payment_hash = Sha256::hash(&payment_preimage.0);
 849                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 850
 851                 InvoiceBuilder::new(Currency::Bitcoin)
 852                         .description("test".into())
 853                         .payment_hash(payment_hash)
 854                         .payment_secret(PaymentSecret([0; 32]))
 855                         .duration_since_epoch(duration_since_epoch())
 856                         .min_final_cltv_expiry(144)
 857                         .amount_milli_satoshis(128)
 858                         .build_signed(|hash| {
 859                                 Secp256k1::new().sign_ecdsa_recoverable(hash, &private_key)
 860                         })
 861                         .unwrap()
 862         }
 863
 864         fn duration_since_epoch() -> Duration {
 865                 #[cfg(feature = "std")]
 866                         let duration_since_epoch =
 867                         SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap();
 868                 #[cfg(not(feature = "std"))]
 869                         let duration_since_epoch = Duration::from_secs(1234567);
 870                 duration_since_epoch
 871         }
 872
 873         fn zero_value_invoice(payment_preimage: PaymentPreimage) -> Invoice {
 874                 let payment_hash = Sha256::hash(&payment_preimage.0);
 875                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 876
 877                 InvoiceBuilder::new(Currency::Bitcoin)
 878                         .description("test".into())
 879                         .payment_hash(payment_hash)
 880                         .payment_secret(PaymentSecret([0; 32]))
 881                         .duration_since_epoch(duration_since_epoch())
 882                         .min_final_cltv_expiry(144)
 883                         .build_signed(|hash| {
 884                                 Secp256k1::new().sign_ecdsa_recoverable(hash, &private_key)
 885                         })
 886                         .unwrap()
 887         }
 888
 889         #[cfg(feature = "std")]
 890         fn expired_invoice(payment_preimage: PaymentPreimage) -> Invoice {
 891                 let payment_hash = Sha256::hash(&payment_preimage.0);
 892                 let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
 893                 let duration = duration_since_epoch()
 894                         .checked_sub(Duration::from_secs(DEFAULT_EXPIRY_TIME * 2))
 895                         .unwrap();
 896                 InvoiceBuilder::new(Currency::Bitcoin)
 897                         .description("test".into())
 898                         .payment_hash(payment_hash)
 899                         .payment_secret(PaymentSecret([0; 32]))
 900                         .duration_since_epoch(duration)
 901                         .min_final_cltv_expiry(144)
 902                         .amount_milli_satoshis(128)
 903                         .build_signed(|hash| {
 904                                 Secp256k1::new().sign_ecdsa_recoverable(hash, &private_key)
 905                         })
 906                         .unwrap()
 907         }
 908
 909         fn pubkey() -> PublicKey {
 910                 PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap()
 911         }
 912
 913         #[test]
 914         fn pays_invoice_on_first_attempt() {
 915                 let event_handled = core::cell::RefCell::new(false);
 916                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 917
 918                 let payment_preimage = PaymentPreimage([1; 32]);
 919                 let invoice = invoice(payment_preimage);
 920                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 921                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 922
 923                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
 924                 let router = TestRouter::new(TestScorer::new());
 925                 let logger = TestLogger::new();
 926                 let invoice_payer =
 927                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
 928
 929                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 930                 assert_eq!(*payer.attempts.borrow(), 1);
 931
 932                 invoice_payer.handle_event(&Event::PaymentSent {
 933                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
 934                 });
 935                 assert_eq!(*event_handled.borrow(), true);
 936                 assert_eq!(*payer.attempts.borrow(), 1);
 937         }
 938
 939         #[test]
 940         fn pays_invoice_on_retry() {
 941                 let event_handled = core::cell::RefCell::new(false);
 942                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
 943
 944                 let payment_preimage = PaymentPreimage([1; 32]);
 945                 let invoice = invoice(payment_preimage);
 946                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
 947                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 948
 949                 let payer = TestPayer::new()
 950                         .expect_send(Amount::ForInvoice(final_value_msat))
 951                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 952                 let router = TestRouter::new(TestScorer::new());
 953                 let logger = TestLogger::new();
 954                 let invoice_payer =
 955                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
 956
 957                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
 958                 assert_eq!(*payer.attempts.borrow(), 1);
 959
 960                 let event = Event::PaymentPathFailed {
 961                         payment_id,
 962                         payment_hash,
 963                         network_update: None,
 964                         payment_failed_permanently: false,
 965                         all_paths_failed: false,
 966                         path: TestRouter::path_for_value(final_value_msat),
 967                         short_channel_id: None,
 968                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
 969                 };
 970                 invoice_payer.handle_event(&event);
 971                 assert_eq!(*event_handled.borrow(), false);
 972                 assert_eq!(*payer.attempts.borrow(), 2);
 973
 974                 invoice_payer.handle_event(&Event::PaymentSent {
 975                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
 976                 });
 977                 assert_eq!(*event_handled.borrow(), true);
 978                 assert_eq!(*payer.attempts.borrow(), 2);
 979         }
 980
 981         #[test]
 982         fn pays_invoice_on_partial_failure() {
 983                 let event_handler = |_: &_| { panic!() };
 984
 985                 let payment_preimage = PaymentPreimage([1; 32]);
 986                 let invoice = invoice(payment_preimage);
 987                 let retry = TestRouter::retry_for_invoice(&invoice);
 988                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
 989
 990                 let payer = TestPayer::new()
 991                         .fails_with_partial_failure(retry.clone(), OnAttempt(1), None)
 992                         .fails_with_partial_failure(retry, OnAttempt(2), None)
 993                         .expect_send(Amount::ForInvoice(final_value_msat))
 994                         .expect_send(Amount::OnRetry(final_value_msat / 2))
 995                         .expect_send(Amount::OnRetry(final_value_msat / 2));
 996                 let router = TestRouter::new(TestScorer::new());
 997                 let logger = TestLogger::new();
 998                 let invoice_payer =
 999                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1000
1001                 assert!(invoice_payer.pay_invoice(&invoice).is_ok());
1002         }
1003
1004         #[test]
1005         fn retries_payment_path_for_unknown_payment() {
1006                 let event_handled = core::cell::RefCell::new(false);
1007                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1008
1009                 let payment_preimage = PaymentPreimage([1; 32]);
1010                 let invoice = invoice(payment_preimage);
1011                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1012                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1013
1014                 let payer = TestPayer::new()
1015                         .expect_send(Amount::OnRetry(final_value_msat / 2))
1016                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1017                 let router = TestRouter::new(TestScorer::new());
1018                 let logger = TestLogger::new();
1019                 let invoice_payer =
1020                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1021
1022                 let payment_id = Some(PaymentId([1; 32]));
1023                 let event = Event::PaymentPathFailed {
1024                         payment_id,
1025                         payment_hash,
1026                         network_update: None,
1027                         payment_failed_permanently: false,
1028                         all_paths_failed: false,
1029                         path: TestRouter::path_for_value(final_value_msat),
1030                         short_channel_id: None,
1031                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1032                 };
1033                 invoice_payer.handle_event(&event);
1034                 assert_eq!(*event_handled.borrow(), false);
1035                 assert_eq!(*payer.attempts.borrow(), 1);
1036
1037                 invoice_payer.handle_event(&event);
1038                 assert_eq!(*event_handled.borrow(), false);
1039                 assert_eq!(*payer.attempts.borrow(), 2);
1040
1041                 invoice_payer.handle_event(&Event::PaymentSent {
1042                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
1043                 });
1044                 assert_eq!(*event_handled.borrow(), true);
1045                 assert_eq!(*payer.attempts.borrow(), 2);
1046         }
1047
1048         #[test]
1049         fn fails_paying_invoice_after_max_retry_counts() {
1050                 let event_handled = core::cell::RefCell::new(false);
1051                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1052
1053                 let payment_preimage = PaymentPreimage([1; 32]);
1054                 let invoice = invoice(payment_preimage);
1055                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1056
1057                 let payer = TestPayer::new()
1058                         .expect_send(Amount::ForInvoice(final_value_msat))
1059                         .expect_send(Amount::OnRetry(final_value_msat / 2))
1060                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1061                 let router = TestRouter::new(TestScorer::new());
1062                 let logger = TestLogger::new();
1063                 let invoice_payer =
1064                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1065
1066                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1067                 assert_eq!(*payer.attempts.borrow(), 1);
1068
1069                 let event = Event::PaymentPathFailed {
1070                         payment_id,
1071                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1072                         network_update: None,
1073                         payment_failed_permanently: false,
1074                         all_paths_failed: true,
1075                         path: TestRouter::path_for_value(final_value_msat),
1076                         short_channel_id: None,
1077                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1078                 };
1079                 invoice_payer.handle_event(&event);
1080                 assert_eq!(*event_handled.borrow(), false);
1081                 assert_eq!(*payer.attempts.borrow(), 2);
1082
1083                 let event = Event::PaymentPathFailed {
1084                         payment_id,
1085                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1086                         network_update: None,
1087                         payment_failed_permanently: false,
1088                         all_paths_failed: false,
1089                         path: TestRouter::path_for_value(final_value_msat / 2),
1090                         short_channel_id: None,
1091                         retry: Some(RouteParameters {
1092                                 final_value_msat: final_value_msat / 2, ..TestRouter::retry_for_invoice(&invoice)
1093                         }),
1094                 };
1095                 invoice_payer.handle_event(&event);
1096                 assert_eq!(*event_handled.borrow(), false);
1097                 assert_eq!(*payer.attempts.borrow(), 3);
1098
1099                 invoice_payer.handle_event(&event);
1100                 assert_eq!(*event_handled.borrow(), true);
1101                 assert_eq!(*payer.attempts.borrow(), 3);
1102         }
1103
1104         #[cfg(feature = "std")]
1105         #[test]
1106         fn fails_paying_invoice_after_max_retry_timeout() {
1107                 let event_handled = core::cell::RefCell::new(false);
1108                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1109
1110                 let payment_preimage = PaymentPreimage([1; 32]);
1111                 let invoice = invoice(payment_preimage);
1112                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1113
1114                 let payer = TestPayer::new()
1115                         .expect_send(Amount::ForInvoice(final_value_msat))
1116                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1117
1118                 let router = TestRouter::new(TestScorer::new());
1119                 let logger = TestLogger::new();
1120                 type InvoicePayerUsingSinceEpoch <P, R, L, E> = InvoicePayerUsingTime::<P, R, L, E, SinceEpoch>;
1121
1122                 let invoice_payer =
1123                         InvoicePayerUsingSinceEpoch::new(&payer, router, &logger, event_handler, Retry::Timeout(Duration::from_secs(120)));
1124
1125                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1126                 assert_eq!(*payer.attempts.borrow(), 1);
1127
1128                 let event = Event::PaymentPathFailed {
1129                         payment_id,
1130                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1131                         network_update: None,
1132                         payment_failed_permanently: false,
1133                         all_paths_failed: true,
1134                         path: TestRouter::path_for_value(final_value_msat),
1135                         short_channel_id: None,
1136                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1137                 };
1138                 invoice_payer.handle_event(&event);
1139                 assert_eq!(*event_handled.borrow(), false);
1140                 assert_eq!(*payer.attempts.borrow(), 2);
1141
1142                 SinceEpoch::advance(Duration::from_secs(121));
1143
1144                 invoice_payer.handle_event(&event);
1145                 assert_eq!(*event_handled.borrow(), true);
1146                 assert_eq!(*payer.attempts.borrow(), 2);
1147         }
1148
1149         #[test]
1150         fn fails_paying_invoice_with_missing_retry_params() {
1151                 let event_handled = core::cell::RefCell::new(false);
1152                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1153
1154                 let payment_preimage = PaymentPreimage([1; 32]);
1155                 let invoice = invoice(payment_preimage);
1156                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1157
1158                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1159                 let router = TestRouter::new(TestScorer::new());
1160                 let logger = TestLogger::new();
1161                 let invoice_payer =
1162                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1163
1164                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1165                 assert_eq!(*payer.attempts.borrow(), 1);
1166
1167                 let event = Event::PaymentPathFailed {
1168                         payment_id,
1169                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1170                         network_update: None,
1171                         payment_failed_permanently: false,
1172                         all_paths_failed: false,
1173                         path: vec![],
1174                         short_channel_id: None,
1175                         retry: None,
1176                 };
1177                 invoice_payer.handle_event(&event);
1178                 assert_eq!(*event_handled.borrow(), true);
1179                 assert_eq!(*payer.attempts.borrow(), 1);
1180         }
1181
1182         // Expiration is checked only in an std environment
1183         #[cfg(feature = "std")]
1184         #[test]
1185         fn fails_paying_invoice_after_expiration() {
1186                 let event_handled = core::cell::RefCell::new(false);
1187                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1188
1189                 let payer = TestPayer::new();
1190                 let router = TestRouter::new(TestScorer::new());
1191                 let logger = TestLogger::new();
1192                 let invoice_payer =
1193                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1194
1195                 let payment_preimage = PaymentPreimage([1; 32]);
1196                 let invoice = expired_invoice(payment_preimage);
1197                 if let PaymentError::Invoice(msg) = invoice_payer.pay_invoice(&invoice).unwrap_err() {
1198                         assert_eq!(msg, "Invoice expired prior to send");
1199                 } else { panic!("Expected Invoice Error"); }
1200         }
1201
1202         // Expiration is checked only in an std environment
1203         #[cfg(feature = "std")]
1204         #[test]
1205         fn fails_retrying_invoice_after_expiration() {
1206                 let event_handled = core::cell::RefCell::new(false);
1207                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1208
1209                 let payment_preimage = PaymentPreimage([1; 32]);
1210                 let invoice = invoice(payment_preimage);
1211                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1212
1213                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1214                 let router = TestRouter::new(TestScorer::new());
1215                 let logger = TestLogger::new();
1216                 let invoice_payer =
1217                         InvoicePayer::new(&payer, router,  &logger, event_handler, Retry::Attempts(2));
1218
1219                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1220                 assert_eq!(*payer.attempts.borrow(), 1);
1221
1222                 let mut retry_data = TestRouter::retry_for_invoice(&invoice);
1223                 retry_data.payment_params.expiry_time = Some(SystemTime::now()
1224                         .checked_sub(Duration::from_secs(2)).unwrap()
1225                         .duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs());
1226                 let event = Event::PaymentPathFailed {
1227                         payment_id,
1228                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1229                         network_update: None,
1230                         payment_failed_permanently: false,
1231                         all_paths_failed: false,
1232                         path: vec![],
1233                         short_channel_id: None,
1234                         retry: Some(retry_data),
1235                 };
1236                 invoice_payer.handle_event(&event);
1237                 assert_eq!(*event_handled.borrow(), true);
1238                 assert_eq!(*payer.attempts.borrow(), 1);
1239         }
1240
1241         #[test]
1242         fn fails_paying_invoice_after_retry_error() {
1243                 let event_handled = core::cell::RefCell::new(false);
1244                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1245
1246                 let payment_preimage = PaymentPreimage([1; 32]);
1247                 let invoice = invoice(payment_preimage);
1248                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1249
1250                 let payer = TestPayer::new()
1251                         .fails_on_attempt(2)
1252                         .expect_send(Amount::ForInvoice(final_value_msat))
1253                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1254                 let router = TestRouter::new(TestScorer::new());
1255                 let logger = TestLogger::new();
1256                 let invoice_payer =
1257                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1258
1259                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1260                 assert_eq!(*payer.attempts.borrow(), 1);
1261
1262                 let event = Event::PaymentPathFailed {
1263                         payment_id,
1264                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1265                         network_update: None,
1266                         payment_failed_permanently: false,
1267                         all_paths_failed: false,
1268                         path: TestRouter::path_for_value(final_value_msat / 2),
1269                         short_channel_id: None,
1270                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1271                 };
1272                 invoice_payer.handle_event(&event);
1273                 assert_eq!(*event_handled.borrow(), true);
1274                 assert_eq!(*payer.attempts.borrow(), 2);
1275         }
1276
1277         #[test]
1278         fn fails_paying_invoice_after_rejected_by_payee() {
1279                 let event_handled = core::cell::RefCell::new(false);
1280                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1281
1282                 let payment_preimage = PaymentPreimage([1; 32]);
1283                 let invoice = invoice(payment_preimage);
1284                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1285
1286                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1287                 let router = TestRouter::new(TestScorer::new());
1288                 let logger = TestLogger::new();
1289                 let invoice_payer =
1290                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1291
1292                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1293                 assert_eq!(*payer.attempts.borrow(), 1);
1294
1295                 let event = Event::PaymentPathFailed {
1296                         payment_id,
1297                         payment_hash: PaymentHash(invoice.payment_hash().clone().into_inner()),
1298                         network_update: None,
1299                         payment_failed_permanently: true,
1300                         all_paths_failed: false,
1301                         path: vec![],
1302                         short_channel_id: None,
1303                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1304                 };
1305                 invoice_payer.handle_event(&event);
1306                 assert_eq!(*event_handled.borrow(), true);
1307                 assert_eq!(*payer.attempts.borrow(), 1);
1308         }
1309
1310         #[test]
1311         fn fails_repaying_invoice_with_pending_payment() {
1312                 let event_handled = core::cell::RefCell::new(false);
1313                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1314
1315                 let payment_preimage = PaymentPreimage([1; 32]);
1316                 let invoice = invoice(payment_preimage);
1317                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1318
1319                 let payer = TestPayer::new()
1320                         .expect_send(Amount::ForInvoice(final_value_msat))
1321                         .expect_send(Amount::ForInvoice(final_value_msat));
1322                 let router = TestRouter::new(TestScorer::new());
1323                 let logger = TestLogger::new();
1324                 let invoice_payer =
1325                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1326
1327                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1328
1329                 // Cannot repay an invoice pending payment.
1330                 match invoice_payer.pay_invoice(&invoice) {
1331                         Err(PaymentError::Invoice("payment pending")) => {},
1332                         Err(_) => panic!("unexpected error"),
1333                         Ok(_) => panic!("expected invoice error"),
1334                 }
1335
1336                 // Can repay an invoice once cleared from cache.
1337                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1338                 invoice_payer.remove_cached_payment(&payment_hash);
1339                 assert!(invoice_payer.pay_invoice(&invoice).is_ok());
1340
1341                 // Cannot retry paying an invoice if cleared from cache.
1342                 invoice_payer.remove_cached_payment(&payment_hash);
1343                 let event = Event::PaymentPathFailed {
1344                         payment_id,
1345                         payment_hash,
1346                         network_update: None,
1347                         payment_failed_permanently: false,
1348                         all_paths_failed: false,
1349                         path: vec![],
1350                         short_channel_id: None,
1351                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1352                 };
1353                 invoice_payer.handle_event(&event);
1354                 assert_eq!(*event_handled.borrow(), true);
1355         }
1356
1357         #[test]
1358         fn fails_paying_invoice_with_routing_errors() {
1359                 let payer = TestPayer::new();
1360                 let router = FailingRouter {};
1361                 let logger = TestLogger::new();
1362                 let invoice_payer =
1363                         InvoicePayer::new(&payer, router, &logger, |_: &_| {}, Retry::Attempts(0));
1364
1365                 let payment_preimage = PaymentPreimage([1; 32]);
1366                 let invoice = invoice(payment_preimage);
1367                 match invoice_payer.pay_invoice(&invoice) {
1368                         Err(PaymentError::Routing(_)) => {},
1369                         Err(_) => panic!("unexpected error"),
1370                         Ok(_) => panic!("expected routing error"),
1371                 }
1372         }
1373
1374         #[test]
1375         fn fails_paying_invoice_with_sending_errors() {
1376                 let payment_preimage = PaymentPreimage([1; 32]);
1377                 let invoice = invoice(payment_preimage);
1378                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1379
1380                 let payer = TestPayer::new()
1381                         .fails_on_attempt(1)
1382                         .expect_send(Amount::ForInvoice(final_value_msat));
1383                 let router = TestRouter::new(TestScorer::new());
1384                 let logger = TestLogger::new();
1385                 let invoice_payer =
1386                         InvoicePayer::new(&payer, router, &logger, |_: &_| {}, Retry::Attempts(0));
1387
1388                 match invoice_payer.pay_invoice(&invoice) {
1389                         Err(PaymentError::Sending(_)) => {},
1390                         Err(_) => panic!("unexpected error"),
1391                         Ok(_) => panic!("expected sending error"),
1392                 }
1393         }
1394
1395         #[test]
1396         fn pays_zero_value_invoice_using_amount() {
1397                 let event_handled = core::cell::RefCell::new(false);
1398                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1399
1400                 let payment_preimage = PaymentPreimage([1; 32]);
1401                 let invoice = zero_value_invoice(payment_preimage);
1402                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1403                 let final_value_msat = 100;
1404
1405                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1406                 let router = TestRouter::new(TestScorer::new());
1407                 let logger = TestLogger::new();
1408                 let invoice_payer =
1409                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1410
1411                 let payment_id =
1412                         Some(invoice_payer.pay_zero_value_invoice(&invoice, final_value_msat).unwrap());
1413                 assert_eq!(*payer.attempts.borrow(), 1);
1414
1415                 invoice_payer.handle_event(&Event::PaymentSent {
1416                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
1417                 });
1418                 assert_eq!(*event_handled.borrow(), true);
1419                 assert_eq!(*payer.attempts.borrow(), 1);
1420         }
1421
1422         #[test]
1423         fn fails_paying_zero_value_invoice_with_amount() {
1424                 let event_handled = core::cell::RefCell::new(false);
1425                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1426
1427                 let payer = TestPayer::new();
1428                 let router = TestRouter::new(TestScorer::new());
1429                 let logger = TestLogger::new();
1430                 let invoice_payer =
1431                         InvoicePayer::new(&payer, router,  &logger, event_handler, Retry::Attempts(0));
1432
1433                 let payment_preimage = PaymentPreimage([1; 32]);
1434                 let invoice = invoice(payment_preimage);
1435
1436                 // Cannot repay an invoice pending payment.
1437                 match invoice_payer.pay_zero_value_invoice(&invoice, 100) {
1438                         Err(PaymentError::Invoice("amount unexpected")) => {},
1439                         Err(_) => panic!("unexpected error"),
1440                         Ok(_) => panic!("expected invoice error"),
1441                 }
1442         }
1443
1444         #[test]
1445         fn pays_pubkey_with_amount() {
1446                 let event_handled = core::cell::RefCell::new(false);
1447                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1448
1449                 let pubkey = pubkey();
1450                 let payment_preimage = PaymentPreimage([1; 32]);
1451                 let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
1452                 let final_value_msat = 100;
1453                 let final_cltv_expiry_delta = 42;
1454
1455                 let payer = TestPayer::new()
1456                         .expect_send(Amount::Spontaneous(final_value_msat))
1457                         .expect_send(Amount::OnRetry(final_value_msat));
1458                 let router = TestRouter::new(TestScorer::new());
1459                 let logger = TestLogger::new();
1460                 let invoice_payer =
1461                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1462
1463                 let payment_id = Some(invoice_payer.pay_pubkey(
1464                                 pubkey, payment_preimage, final_value_msat, final_cltv_expiry_delta
1465                         ).unwrap());
1466                 assert_eq!(*payer.attempts.borrow(), 1);
1467
1468                 let retry = RouteParameters {
1469                         payment_params: PaymentParameters::for_keysend(pubkey),
1470                         final_value_msat,
1471                         final_cltv_expiry_delta,
1472                 };
1473                 let event = Event::PaymentPathFailed {
1474                         payment_id,
1475                         payment_hash,
1476                         network_update: None,
1477                         payment_failed_permanently: false,
1478                         all_paths_failed: false,
1479                         path: vec![],
1480                         short_channel_id: None,
1481                         retry: Some(retry),
1482                 };
1483                 invoice_payer.handle_event(&event);
1484                 assert_eq!(*event_handled.borrow(), false);
1485                 assert_eq!(*payer.attempts.borrow(), 2);
1486
1487                 invoice_payer.handle_event(&Event::PaymentSent {
1488                         payment_id, payment_preimage, payment_hash, fee_paid_msat: None
1489                 });
1490                 assert_eq!(*event_handled.borrow(), true);
1491                 assert_eq!(*payer.attempts.borrow(), 2);
1492         }
1493
1494         #[test]
1495         fn scores_failed_channel() {
1496                 let event_handled = core::cell::RefCell::new(false);
1497                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1498
1499                 let payment_preimage = PaymentPreimage([1; 32]);
1500                 let invoice = invoice(payment_preimage);
1501                 let payment_hash = PaymentHash(invoice.payment_hash().clone().into_inner());
1502                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1503                 let path = TestRouter::path_for_value(final_value_msat);
1504                 let short_channel_id = Some(path[0].short_channel_id);
1505
1506                 // Expect that scorer is given short_channel_id upon handling the event.
1507                 let payer = TestPayer::new()
1508                         .expect_send(Amount::ForInvoice(final_value_msat))
1509                         .expect_send(Amount::OnRetry(final_value_msat / 2));
1510                 let scorer = TestScorer::new().expect(TestResult::PaymentFailure {
1511                         path: path.clone(), short_channel_id: path[0].short_channel_id,
1512                 });
1513                 let router = TestRouter::new(scorer);
1514                 let logger = TestLogger::new();
1515                 let invoice_payer =
1516                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1517
1518                 let payment_id = Some(invoice_payer.pay_invoice(&invoice).unwrap());
1519                 let event = Event::PaymentPathFailed {
1520                         payment_id,
1521                         payment_hash,
1522                         network_update: None,
1523                         payment_failed_permanently: false,
1524                         all_paths_failed: false,
1525                         path,
1526                         short_channel_id,
1527                         retry: Some(TestRouter::retry_for_invoice(&invoice)),
1528                 };
1529                 invoice_payer.handle_event(&event);
1530         }
1531
1532         #[test]
1533         fn scores_successful_channels() {
1534                 let event_handled = core::cell::RefCell::new(false);
1535                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1536
1537                 let payment_preimage = PaymentPreimage([1; 32]);
1538                 let invoice = invoice(payment_preimage);
1539                 let payment_hash = Some(PaymentHash(invoice.payment_hash().clone().into_inner()));
1540                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1541                 let route = TestRouter::route_for_value(final_value_msat);
1542
1543                 // Expect that scorer is given short_channel_id upon handling the event.
1544                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1545                 let scorer = TestScorer::new()
1546                         .expect(TestResult::PaymentSuccess { path: route.paths[0].clone() })
1547                         .expect(TestResult::PaymentSuccess { path: route.paths[1].clone() });
1548                 let router = TestRouter::new(scorer);
1549                 let logger = TestLogger::new();
1550                 let invoice_payer =
1551                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1552
1553                 let payment_id = invoice_payer.pay_invoice(&invoice).unwrap();
1554                 let event = Event::PaymentPathSuccessful {
1555                         payment_id, payment_hash, path: route.paths[0].clone()
1556                 };
1557                 invoice_payer.handle_event(&event);
1558                 let event = Event::PaymentPathSuccessful {
1559                         payment_id, payment_hash, path: route.paths[1].clone()
1560                 };
1561                 invoice_payer.handle_event(&event);
1562         }
1563
1564         #[test]
1565         fn generates_correct_inflight_map_data() {
1566                 let event_handled = core::cell::RefCell::new(false);
1567                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1568
1569                 let payment_preimage = PaymentPreimage([1; 32]);
1570                 let invoice = invoice(payment_preimage);
1571                 let payment_hash = Some(PaymentHash(invoice.payment_hash().clone().into_inner()));
1572                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1573
1574                 let payer = TestPayer::new().expect_send(Amount::ForInvoice(final_value_msat));
1575                 let final_value_msat = invoice.amount_milli_satoshis().unwrap();
1576                 let route = TestRouter::route_for_value(final_value_msat);
1577                 let router = TestRouter::new(TestScorer::new());
1578                 let logger = TestLogger::new();
1579                 let invoice_payer =
1580                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1581
1582                 let payment_id = invoice_payer.pay_invoice(&invoice).unwrap();
1583
1584                 let inflight_map = invoice_payer.create_inflight_map();
1585                 // First path check
1586                 assert_eq!(inflight_map.0.get(&(0, false)).unwrap().clone(), 94);
1587                 assert_eq!(inflight_map.0.get(&(1, true)).unwrap().clone(), 84);
1588                 assert_eq!(inflight_map.0.get(&(2, false)).unwrap().clone(), 64);
1589
1590                 // Second path check
1591                 assert_eq!(inflight_map.0.get(&(3, false)).unwrap().clone(), 74);
1592                 assert_eq!(inflight_map.0.get(&(4, false)).unwrap().clone(), 64);
1593
1594                 invoice_payer.handle_event(&Event::PaymentPathSuccessful {
1595                         payment_id, payment_hash, path: route.paths[0].clone()
1596                 });
1597
1598                 let inflight_map = invoice_payer.create_inflight_map();
1599
1600                 assert_eq!(inflight_map.0.get(&(0, false)), None);
1601                 assert_eq!(inflight_map.0.get(&(1, true)), None);
1602                 assert_eq!(inflight_map.0.get(&(2, false)), None);
1603
1604                 // Second path should still be inflight
1605                 assert_eq!(inflight_map.0.get(&(3, false)).unwrap().clone(), 74);
1606                 assert_eq!(inflight_map.0.get(&(4, false)).unwrap().clone(), 64)
1607         }
1608
1609         #[test]
1610         fn considers_inflight_htlcs_between_invoice_payments_when_path_succeeds() {
1611                 // First, let's just send a payment through, but only make sure one of the path completes
1612                 let event_handled = core::cell::RefCell::new(false);
1613                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1614
1615                 let payment_preimage = PaymentPreimage([1; 32]);
1616                 let payment_invoice = invoice(payment_preimage);
1617                 let payment_hash = Some(PaymentHash(payment_invoice.payment_hash().clone().into_inner()));
1618                 let final_value_msat = payment_invoice.amount_milli_satoshis().unwrap();
1619
1620                 let payer = TestPayer::new()
1621                         .expect_send(Amount::ForInvoice(final_value_msat))
1622                         .expect_send(Amount::ForInvoice(final_value_msat));
1623                 let final_value_msat = payment_invoice.amount_milli_satoshis().unwrap();
1624                 let route = TestRouter::route_for_value(final_value_msat);
1625                 let scorer = TestScorer::new()
1626                         // 1st invoice, 1st path
1627                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1628                         .expect_usage(ChannelUsage { amount_msat: 84, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1629                         .expect_usage(ChannelUsage { amount_msat: 94, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1630                         // 1st invoice, 2nd path
1631                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1632                         .expect_usage(ChannelUsage { amount_msat: 74, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1633                         // 2nd invoice, 1st path
1634                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1635                         .expect_usage(ChannelUsage { amount_msat: 84, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1636                         .expect_usage(ChannelUsage { amount_msat: 94, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1637                         // 2nd invoice, 2nd path
1638                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 64, effective_capacity: EffectiveCapacity::Unknown } )
1639                         .expect_usage(ChannelUsage { amount_msat: 74, inflight_htlc_msat: 74, effective_capacity: EffectiveCapacity::Unknown } );
1640                 let router = TestRouter::new(scorer);
1641                 let logger = TestLogger::new();
1642                 let invoice_payer =
1643                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1644
1645                 // Succeed 1st path, leave 2nd path inflight
1646                 let payment_id = invoice_payer.pay_invoice(&payment_invoice).unwrap();
1647                 invoice_payer.handle_event(&Event::PaymentPathSuccessful {
1648                         payment_id, payment_hash, path: route.paths[0].clone()
1649                 });
1650
1651                 // Let's pay a second invoice that will be using the same path. This should trigger the
1652                 // assertions that expect the last 4 ChannelUsage values above where TestScorer is initialized.
1653                 // Particularly, the 2nd path of the 1st payment, since it is not yet complete, should still
1654                 // have 64 msats inflight for paths considering the channel with scid of 1.
1655                 let payment_preimage_2 = PaymentPreimage([2; 32]);
1656                 let payment_invoice_2 = invoice(payment_preimage_2);
1657                 invoice_payer.pay_invoice(&payment_invoice_2).unwrap();
1658         }
1659
1660         #[test]
1661         fn considers_inflight_htlcs_between_retries() {
1662                 // First, let's just send a payment through, but only make sure one of the path completes
1663                 let event_handled = core::cell::RefCell::new(false);
1664                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1665
1666                 let payment_preimage = PaymentPreimage([1; 32]);
1667                 let payment_invoice = invoice(payment_preimage);
1668                 let payment_hash = PaymentHash(payment_invoice.payment_hash().clone().into_inner());
1669                 let final_value_msat = payment_invoice.amount_milli_satoshis().unwrap();
1670
1671                 let payer = TestPayer::new()
1672                         .expect_send(Amount::ForInvoice(final_value_msat))
1673                         .expect_send(Amount::OnRetry(final_value_msat / 2))
1674                         .expect_send(Amount::OnRetry(final_value_msat / 4));
1675                 let final_value_msat = payment_invoice.amount_milli_satoshis().unwrap();
1676                 let scorer = TestScorer::new()
1677                         // 1st invoice, 1st path
1678                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1679                         .expect_usage(ChannelUsage { amount_msat: 84, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1680                         .expect_usage(ChannelUsage { amount_msat: 94, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1681                         // 1st invoice, 2nd path
1682                         .expect_usage(ChannelUsage { amount_msat: 64, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1683                         .expect_usage(ChannelUsage { amount_msat: 74, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1684                         // Retry 1, 1st path
1685                         .expect_usage(ChannelUsage { amount_msat: 32, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1686                         .expect_usage(ChannelUsage { amount_msat: 52, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1687                         .expect_usage(ChannelUsage { amount_msat: 62, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1688                         // Retry 1, 2nd path
1689                         .expect_usage(ChannelUsage { amount_msat: 32, inflight_htlc_msat: 64, effective_capacity: EffectiveCapacity::Unknown } )
1690                         .expect_usage(ChannelUsage { amount_msat: 42, inflight_htlc_msat: 64 + 10, effective_capacity: EffectiveCapacity::Unknown } )
1691                         // Retry 2, 1st path
1692                         .expect_usage(ChannelUsage { amount_msat: 16, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1693                         .expect_usage(ChannelUsage { amount_msat: 36, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1694                         .expect_usage(ChannelUsage { amount_msat: 46, inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Unknown } )
1695                         // Retry 2, 2nd path
1696                         .expect_usage(ChannelUsage { amount_msat: 16, inflight_htlc_msat: 64 + 32, effective_capacity: EffectiveCapacity::Unknown } )
1697                         .expect_usage(ChannelUsage { amount_msat: 26, inflight_htlc_msat: 74 + 32 + 10, effective_capacity: EffectiveCapacity::Unknown } );
1698                 let router = TestRouter::new(scorer);
1699                 let logger = TestLogger::new();
1700                 let invoice_payer =
1701                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(2));
1702
1703                 // Fail 1st path, leave 2nd path inflight
1704                 let payment_id = Some(invoice_payer.pay_invoice(&payment_invoice).unwrap());
1705                 invoice_payer.handle_event(&Event::PaymentPathFailed {
1706                         payment_id,
1707                         payment_hash,
1708                         network_update: None,
1709                         payment_failed_permanently: false,
1710                         all_paths_failed: false,
1711                         path: TestRouter::path_for_value(final_value_msat),
1712                         short_channel_id: None,
1713                         retry: Some(TestRouter::retry_for_invoice(&payment_invoice)),
1714                 });
1715
1716                 // Fails again the 1st path of our retry
1717                 invoice_payer.handle_event(&Event::PaymentPathFailed {
1718                         payment_id,
1719                         payment_hash,
1720                         network_update: None,
1721                         payment_failed_permanently: false,
1722                         all_paths_failed: false,
1723                         path: TestRouter::path_for_value(final_value_msat / 2),
1724                         short_channel_id: None,
1725                         retry: Some(RouteParameters {
1726                                 final_value_msat: final_value_msat / 4,
1727                                 ..TestRouter::retry_for_invoice(&payment_invoice)
1728                         }),
1729                 });
1730         }
1731
1732         #[test]
1733         fn accounts_for_some_inflight_htlcs_sent_during_partial_failure() {
1734                 let event_handled = core::cell::RefCell::new(false);
1735                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1736
1737                 let payment_preimage = PaymentPreimage([1; 32]);
1738                 let invoice_to_pay = invoice(payment_preimage);
1739                 let final_value_msat = invoice_to_pay.amount_milli_satoshis().unwrap();
1740
1741                 let retry = TestRouter::retry_for_invoice(&invoice_to_pay);
1742                 let payer = TestPayer::new()
1743                         .fails_with_partial_failure(
1744                                 retry.clone(), OnAttempt(1),
1745                                 Some(vec![
1746                                         Err(ChannelUnavailable { err: "abc".to_string() }), Err(MonitorUpdateInProgress)
1747                                 ]))
1748                         .expect_send(Amount::ForInvoice(final_value_msat));
1749
1750                 let router = TestRouter::new(TestScorer::new());
1751                 let logger = TestLogger::new();
1752                 let invoice_payer =
1753                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1754
1755                 invoice_payer.pay_invoice(&invoice_to_pay).unwrap();
1756                 let inflight_map = invoice_payer.create_inflight_map();
1757
1758                 // Only the second path, which failed with `MonitorUpdateInProgress` should be added to our
1759                 // inflight map because retries are disabled.
1760                 assert_eq!(inflight_map.0.len(), 2);
1761         }
1762
1763         #[test]
1764         fn accounts_for_all_inflight_htlcs_sent_during_partial_failure() {
1765                 let event_handled = core::cell::RefCell::new(false);
1766                 let event_handler = |_: &_| { *event_handled.borrow_mut() = true; };
1767
1768                 let payment_preimage = PaymentPreimage([1; 32]);
1769                 let invoice_to_pay = invoice(payment_preimage);
1770                 let final_value_msat = invoice_to_pay.amount_milli_satoshis().unwrap();
1771
1772                 let retry = TestRouter::retry_for_invoice(&invoice_to_pay);
1773                 let payer = TestPayer::new()
1774                         .fails_with_partial_failure(
1775                                 retry.clone(), OnAttempt(1),
1776                                 Some(vec![
1777                                         Ok(()), Err(MonitorUpdateInProgress)
1778                                 ]))
1779                         .expect_send(Amount::ForInvoice(final_value_msat));
1780
1781                 let router = TestRouter::new(TestScorer::new());
1782                 let logger = TestLogger::new();
1783                 let invoice_payer =
1784                         InvoicePayer::new(&payer, router, &logger, event_handler, Retry::Attempts(0));
1785
1786                 invoice_payer.pay_invoice(&invoice_to_pay).unwrap();
1787                 let inflight_map = invoice_payer.create_inflight_map();
1788
1789                 // All paths successful, hence we check of the existence of all 5 hops.
1790                 assert_eq!(inflight_map.0.len(), 5);
1791         }
1792
1793         struct TestRouter {
1794                 scorer: RefCell<TestScorer>,
1795         }
1796
1797         impl TestRouter {
1798                 fn new(scorer: TestScorer) -> Self {
1799                         TestRouter { scorer: RefCell::new(scorer) }
1800                 }
1801
1802                 fn route_for_value(final_value_msat: u64) -> Route {
1803                         Route {
1804                                 paths: vec![
1805                                         vec![
1806                                                 RouteHop {
1807                                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
1808                                                         channel_features: ChannelFeatures::empty(),
1809                                                         node_features: NodeFeatures::empty(),
1810                                                         short_channel_id: 0,
1811                                                         fee_msat: 10,
1812                                                         cltv_expiry_delta: 0
1813                                                 },
1814                                                 RouteHop {
1815                                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
1816                                                         channel_features: ChannelFeatures::empty(),
1817                                                         node_features: NodeFeatures::empty(),
1818                                                         short_channel_id: 1,
1819                                                         fee_msat: 20,
1820                                                         cltv_expiry_delta: 0
1821                                                 },
1822                                                 RouteHop {
1823                                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
1824                                                         channel_features: ChannelFeatures::empty(),
1825                                                         node_features: NodeFeatures::empty(),
1826                                                         short_channel_id: 2,
1827                                                         fee_msat: final_value_msat / 2,
1828                                                         cltv_expiry_delta: 0
1829                                                 },
1830                                         ],
1831                                         vec![
1832                                                 RouteHop {
1833                                                         pubkey: PublicKey::from_slice(&hex::decode("029e03a901b85534ff1e92c43c74431f7ce72046060fcf7a95c37e148f78c77255").unwrap()[..]).unwrap(),
1834                                                         channel_features: ChannelFeatures::empty(),
1835                                                         node_features: NodeFeatures::empty(),
1836                                                         short_channel_id: 3,
1837                                                         fee_msat: 10,
1838                                                         cltv_expiry_delta: 144
1839                                                 },
1840                                                 RouteHop {
1841                                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
1842                                                         channel_features: ChannelFeatures::empty(),
1843                                                         node_features: NodeFeatures::empty(),
1844                                                         short_channel_id: 4,
1845                                                         fee_msat: final_value_msat / 2,
1846                                                         cltv_expiry_delta: 144
1847                                                 }
1848                                         ],
1849                                 ],
1850                                 payment_params: None,
1851                         }
1852                 }
1853
1854                 fn path_for_value(final_value_msat: u64) -> Vec<RouteHop> {
1855                         TestRouter::route_for_value(final_value_msat).paths[0].clone()
1856                 }
1857
1858                 fn retry_for_invoice(invoice: &Invoice) -> RouteParameters {
1859                         let mut payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key())
1860                                 .with_expiry_time(expiry_time_from_unix_epoch(invoice).as_secs())
1861                                 .with_route_hints(invoice.route_hints());
1862                         if let Some(features) = invoice.features() {
1863                                 payment_params = payment_params.with_features(features.clone());
1864                         }
1865                         let final_value_msat = invoice.amount_milli_satoshis().unwrap() / 2;
1866                         RouteParameters {
1867                                 payment_params,
1868                                 final_value_msat,
1869                                 final_cltv_expiry_delta: invoice.min_final_cltv_expiry() as u32,
1870                         }
1871                 }
1872         }
1873
1874         impl Router for TestRouter {
1875                 fn find_route(
1876                         &self, payer: &PublicKey, route_params: &RouteParameters,
1877                         _first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: InFlightHtlcs
1878                 ) -> Result<Route, LightningError> {
1879                         // Simulate calling the Scorer just as you would in find_route
1880                         let route = Self::route_for_value(route_params.final_value_msat);
1881                         let mut locked_scorer = self.scorer.lock();
1882                         let scorer = ScorerAccountingForInFlightHtlcs::new(locked_scorer.deref_mut(), inflight_htlcs);
1883                         for path in route.paths {
1884                                 let mut aggregate_msat = 0u64;
1885                                 for (idx, hop) in path.iter().rev().enumerate() {
1886                                         aggregate_msat += hop.fee_msat;
1887                                         let usage = ChannelUsage {
1888                                                 amount_msat: aggregate_msat,
1889                                                 inflight_htlc_msat: 0,
1890                                                 effective_capacity: EffectiveCapacity::Unknown,
1891                                         };
1892
1893                                         // Since the path is reversed, the last element in our iteration is the first
1894                                         // hop.
1895                                         if idx == path.len() - 1 {
1896                                                 scorer.channel_penalty_msat(hop.short_channel_id, &NodeId::from_pubkey(payer), &NodeId::from_pubkey(&hop.pubkey), usage);
1897                                         } else {
1898                                                 scorer.channel_penalty_msat(hop.short_channel_id, &NodeId::from_pubkey(&path[idx + 1].pubkey), &NodeId::from_pubkey(&hop.pubkey), usage);
1899                                         }
1900                                 }
1901                         }
1902
1903                         Ok(Route {
1904                                 payment_params: Some(route_params.payment_params.clone()), ..Self::route_for_value(route_params.final_value_msat)
1905                         })
1906                 }
1907         }
1908
1909         impl ScoringRouter for TestRouter {
1910                 fn notify_payment_path_failed(&self, path: &[&RouteHop], short_channel_id: u64) {
1911                         self.scorer.lock().payment_path_failed(path, short_channel_id);
1912                 }
1913
1914                 fn notify_payment_path_successful(&self, path: &[&RouteHop]) {
1915                         self.scorer.lock().payment_path_successful(path);
1916                 }
1917
1918                 fn notify_payment_probe_successful(&self, path: &[&RouteHop]) {
1919                         self.scorer.lock().probe_successful(path);
1920                 }
1921
1922                 fn notify_payment_probe_failed(&self, path: &[&RouteHop], short_channel_id: u64) {
1923                         self.scorer.lock().probe_failed(path, short_channel_id);
1924                 }
1925         }
1926
1927         struct FailingRouter;
1928
1929         impl Router for FailingRouter {
1930                 fn find_route(
1931                         &self, _payer: &PublicKey, _params: &RouteParameters, _first_hops: Option<&[&ChannelDetails]>,
1932                         _inflight_htlcs: InFlightHtlcs,
1933                 ) -> Result<Route, LightningError> {
1934                         Err(LightningError { err: String::new(), action: ErrorAction::IgnoreError })
1935                 }
1936         }
1937
1938         impl ScoringRouter for FailingRouter {
1939                 fn notify_payment_path_failed(&self, _path: &[&RouteHop], _short_channel_id: u64) {}
1940
1941                 fn notify_payment_path_successful(&self, _path: &[&RouteHop]) {}
1942
1943                 fn notify_payment_probe_successful(&self, _path: &[&RouteHop]) {}
1944
1945                 fn notify_payment_probe_failed(&self, _path: &[&RouteHop], _short_channel_id: u64) {}
1946         }
1947
1948         struct TestScorer {
1949                 event_expectations: Option<VecDeque<TestResult>>,
1950                 scorer_expectations: RefCell<Option<VecDeque<ChannelUsage>>>,
1951         }
1952
1953         #[derive(Debug)]
1954         enum TestResult {
1955                 PaymentFailure { path: Vec<RouteHop>, short_channel_id: u64 },
1956                 PaymentSuccess { path: Vec<RouteHop> },
1957         }
1958
1959         impl TestScorer {
1960                 fn new() -> Self {
1961                         Self {
1962                                 event_expectations: None,
1963                                 scorer_expectations: RefCell::new(None),
1964                         }
1965                 }
1966
1967                 fn expect(mut self, expectation: TestResult) -> Self {
1968                         self.event_expectations.get_or_insert_with(|| VecDeque::new()).push_back(expectation);
1969                         self
1970                 }
1971
1972                 fn expect_usage(self, expectation: ChannelUsage) -> Self {
1973                         self.scorer_expectations.borrow_mut().get_or_insert_with(|| VecDeque::new()).push_back(expectation);
1974                         self
1975                 }
1976         }
1977
1978         #[cfg(c_bindings)]
1979         impl lightning::util::ser::Writeable for TestScorer {
1980                 fn write<W: lightning::util::ser::Writer>(&self, _: &mut W) -> Result<(), lightning::io::Error> { unreachable!(); }
1981         }
1982
1983         impl Score for TestScorer {
1984                 fn channel_penalty_msat(
1985                         &self, _short_channel_id: u64, _source: &NodeId, _target: &NodeId, usage: ChannelUsage
1986                 ) -> u64 {
1987                         if let Some(scorer_expectations) = self.scorer_expectations.borrow_mut().as_mut() {
1988                                 match scorer_expectations.pop_front() {
1989                                         Some(expectation) => {
1990                                                 assert_eq!(expectation.amount_msat, usage.amount_msat);
1991                                                 assert_eq!(expectation.inflight_htlc_msat, usage.inflight_htlc_msat);
1992                                         },
1993                                         None => {},
1994                                 }
1995                         }
1996                         0
1997                 }
1998
1999                 fn payment_path_failed(&mut self, actual_path: &[&RouteHop], actual_short_channel_id: u64) {
2000                         if let Some(expectations) = &mut self.event_expectations {
2001                                 match expectations.pop_front() {
2002                                         Some(TestResult::PaymentFailure { path, short_channel_id }) => {
2003                                                 assert_eq!(actual_path, &path.iter().collect::<Vec<_>>()[..]);
2004                                                 assert_eq!(actual_short_channel_id, short_channel_id);
2005                                         },
2006                                         Some(TestResult::PaymentSuccess { path }) => {
2007                                                 panic!("Unexpected successful payment path: {:?}", path)
2008                                         },
2009                                         None => panic!("Unexpected notify_payment_path_failed call: {:?}", actual_path),
2010                                 }
2011                         }
2012                 }
2013
2014                 fn payment_path_successful(&mut self, actual_path: &[&RouteHop]) {
2015                         if let Some(expectations) = &mut self.event_expectations {
2016                                 match expectations.pop_front() {
2017                                         Some(TestResult::PaymentFailure { path, .. }) => {
2018                                                 panic!("Unexpected payment path failure: {:?}", path)
2019                                         },
2020                                         Some(TestResult::PaymentSuccess { path }) => {
2021                                                 assert_eq!(actual_path, &path.iter().collect::<Vec<_>>()[..]);
2022                                         },
2023                                         None => panic!("Unexpected notify_payment_path_successful call: {:?}", actual_path),
2024                                 }
2025                         }
2026                 }
2027
2028                 fn probe_failed(&mut self, actual_path: &[&RouteHop], _: u64) {
2029                         if let Some(expectations) = &mut self.event_expectations {
2030                                 match expectations.pop_front() {
2031                                         Some(TestResult::PaymentFailure { path, .. }) => {
2032                                                 panic!("Unexpected failed payment path: {:?}", path)
2033                                         },
2034                                         Some(TestResult::PaymentSuccess { path }) => {
2035                                                 panic!("Unexpected successful payment path: {:?}", path)
2036                                         },
2037                                         None => panic!("Unexpected notify_payment_path_failed call: {:?}", actual_path),
2038                                 }
2039                         }
2040                 }
2041                 fn probe_successful(&mut self, actual_path: &[&RouteHop]) {
2042                         if let Some(expectations) = &mut self.event_expectations {
2043                                 match expectations.pop_front() {
2044                                         Some(TestResult::PaymentFailure { path, .. }) => {
2045                                                 panic!("Unexpected payment path failure: {:?}", path)
2046                                         },
2047                                         Some(TestResult::PaymentSuccess { path }) => {
2048                                                 panic!("Unexpected successful payment path: {:?}", path)
2049                                         },
2050                                         None => panic!("Unexpected notify_payment_path_successful call: {:?}", actual_path),
2051                                 }
2052                         }
2053                 }
2054         }
2055
2056         impl Drop for TestScorer {
2057                 fn drop(&mut self) {
2058                         if std::thread::panicking() {
2059                                 return;
2060                         }
2061
2062                         if let Some(event_expectations) = &self.event_expectations {
2063                                 if !event_expectations.is_empty() {
2064                                         panic!("Unsatisfied event expectations: {:?}", event_expectations);
2065                                 }
2066                         }
2067
2068                         if let Some(scorer_expectations) = self.scorer_expectations.borrow().as_ref() {
2069                                 if !scorer_expectations.is_empty() {
2070                                         panic!("Unsatisfied scorer expectations: {:?}", scorer_expectations)
2071                                 }
2072                         }
2073                 }
2074         }
2075
2076         struct TestPayer {
2077                 expectations: core::cell::RefCell<VecDeque<Amount>>,
2078                 attempts: core::cell::RefCell<usize>,
2079                 failing_on_attempt: core::cell::RefCell<HashMap<usize, PaymentSendFailure>>,
2080         }
2081
2082         #[derive(Clone, Debug, PartialEq, Eq)]
2083         enum Amount {
2084                 ForInvoice(u64),
2085                 Spontaneous(u64),
2086                 OnRetry(u64),
2087         }
2088
2089         struct OnAttempt(usize);
2090
2091         impl TestPayer {
2092                 fn new() -> Self {
2093                         Self {
2094                                 expectations: core::cell::RefCell::new(VecDeque::new()),
2095                                 attempts: core::cell::RefCell::new(0),
2096                                 failing_on_attempt: core::cell::RefCell::new(HashMap::new()),
2097                         }
2098                 }
2099
2100                 fn expect_send(self, value_msat: Amount) -> Self {
2101                         self.expectations.borrow_mut().push_back(value_msat);
2102                         self
2103                 }
2104
2105                 fn fails_on_attempt(self, attempt: usize) -> Self {
2106                         let failure = PaymentSendFailure::ParameterError(APIError::MonitorUpdateInProgress);
2107                         self.fails_with(failure, OnAttempt(attempt))
2108                 }
2109
2110                 fn fails_with_partial_failure(self, retry: RouteParameters, attempt: OnAttempt, results: Option<Vec<Result<(), APIError>>>) -> Self {
2111                         self.fails_with(PaymentSendFailure::PartialFailure {
2112                                 results: results.unwrap_or(vec![]),
2113                                 failed_paths_retry: Some(retry),
2114                                 payment_id: PaymentId([1; 32]),
2115                         }, attempt)
2116                 }
2117
2118                 fn fails_with(self, failure: PaymentSendFailure, attempt: OnAttempt) -> Self {
2119                         self.failing_on_attempt.borrow_mut().insert(attempt.0, failure);
2120                         self
2121                 }
2122
2123                 fn check_attempts(&self) -> Result<(), PaymentSendFailure> {
2124                         let mut attempts = self.attempts.borrow_mut();
2125                         *attempts += 1;
2126
2127                         match self.failing_on_attempt.borrow_mut().remove(&*attempts) {
2128                                 Some(failure) => Err(failure),
2129                                 None => Ok(())
2130                         }
2131                 }
2132
2133                 fn check_value_msats(&self, actual_value_msats: Amount) {
2134                         let expected_value_msats = self.expectations.borrow_mut().pop_front();
2135                         if let Some(expected_value_msats) = expected_value_msats {
2136                                 assert_eq!(actual_value_msats, expected_value_msats);
2137                         } else {
2138                                 panic!("Unexpected amount: {:?}", actual_value_msats);
2139                         }
2140                 }
2141         }
2142
2143         impl Drop for TestPayer {
2144                 fn drop(&mut self) {
2145                         if std::thread::panicking() {
2146                                 return;
2147                         }
2148
2149                         if !self.expectations.borrow().is_empty() {
2150                                 panic!("Unsatisfied payment expectations: {:?}", self.expectations.borrow());
2151                         }
2152                 }
2153         }
2154
2155         impl Payer for TestPayer {
2156                 fn node_id(&self) -> PublicKey {
2157                         let secp_ctx = Secp256k1::new();
2158                         PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap())
2159                 }
2160
2161                 fn first_hops(&self) -> Vec<ChannelDetails> {
2162                         Vec::new()
2163                 }
2164
2165                 fn send_payment(
2166                         &self, route: &Route, _payment_hash: PaymentHash,
2167                         _payment_secret: &Option<PaymentSecret>, _payment_id: PaymentId,
2168                 ) -> Result<(), PaymentSendFailure> {
2169                         self.check_value_msats(Amount::ForInvoice(route.get_total_amount()));
2170                         self.check_attempts()
2171                 }
2172
2173                 fn send_spontaneous_payment(
2174                         &self, route: &Route, _payment_preimage: PaymentPreimage, _payment_id: PaymentId,
2175                 ) -> Result<(), PaymentSendFailure> {
2176                         self.check_value_msats(Amount::Spontaneous(route.get_total_amount()));
2177                         self.check_attempts()
2178                 }
2179
2180                 fn retry_payment(
2181                         &self, route: &Route, _payment_id: PaymentId
2182                 ) -> Result<(), PaymentSendFailure> {
2183                         self.check_value_msats(Amount::OnRetry(route.get_total_amount()));
2184                         self.check_attempts()
2185                 }
2186
2187                 fn abandon_payment(&self, _payment_id: PaymentId) { }
2188         }
2189
2190         // *** Full Featured Functional Tests with a Real ChannelManager ***
2191         struct ManualRouter(RefCell<VecDeque<Result<Route, LightningError>>>);
2192
2193         impl Router for ManualRouter {
2194                 fn find_route(
2195                         &self, _payer: &PublicKey, _params: &RouteParameters, _first_hops: Option<&[&ChannelDetails]>,
2196                         _inflight_htlcs: InFlightHtlcs
2197                 ) -> Result<Route, LightningError> {
2198                         self.0.borrow_mut().pop_front().unwrap()
2199                 }
2200         }
2201         impl ScoringRouter for ManualRouter {
2202                 fn notify_payment_path_failed(&self, _path: &[&RouteHop], _short_channel_id: u64) {}
2203
2204                 fn notify_payment_path_successful(&self, _path: &[&RouteHop]) {}
2205
2206                 fn notify_payment_probe_successful(&self, _path: &[&RouteHop]) {}
2207
2208                 fn notify_payment_probe_failed(&self, _path: &[&RouteHop], _short_channel_id: u64) {}
2209         }
2210         impl ManualRouter {
2211                 fn expect_find_route(&self, result: Result<Route, LightningError>) {
2212                         self.0.borrow_mut().push_back(result);
2213                 }
2214         }
2215         impl Drop for ManualRouter {
2216                 fn drop(&mut self) {
2217                         if std::thread::panicking() {
2218                                 return;
2219                         }
2220                         assert!(self.0.borrow_mut().is_empty());
2221                 }
2222         }
2223
2224         #[test]
2225         fn retry_multi_path_single_failed_payment() {
2226                 // Tests that we can/will retry after a single path of an MPP payment failed immediately
2227                 let chanmon_cfgs = create_chanmon_cfgs(2);
2228                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
2229                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None, None]);
2230                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
2231
2232                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, channelmanager::provided_init_features(), channelmanager::provided_init_features());
2233                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, channelmanager::provided_init_features(), channelmanager::provided_init_features());
2234                 let chans = nodes[0].node.list_usable_channels();
2235                 let mut route = Route {
2236                         paths: vec![
2237                                 vec![RouteHop {
2238                                         pubkey: nodes[1].node.get_our_node_id(),
2239                                         node_features: channelmanager::provided_node_features(),
2240                                         short_channel_id: chans[0].short_channel_id.unwrap(),
2241                                         channel_features: channelmanager::provided_channel_features(),
2242                                         fee_msat: 10_000,
2243                                         cltv_expiry_delta: 100,
2244                                 }],
2245                                 vec![RouteHop {
2246                                         pubkey: nodes[1].node.get_our_node_id(),
2247                                         node_features: channelmanager::provided_node_features(),
2248                                         short_channel_id: chans[1].short_channel_id.unwrap(),
2249                                         channel_features: channelmanager::provided_channel_features(),
2250                                         fee_msat: 100_000_001, // Our default max-HTLC-value is 10% of the channel value, which this is one more than
2251                                         cltv_expiry_delta: 100,
2252                                 }],
2253                         ],
2254                         payment_params: Some(PaymentParameters::from_node_id(nodes[1].node.get_our_node_id())),
2255                 };
2256                 let router = ManualRouter(RefCell::new(VecDeque::new()));
2257                 router.expect_find_route(Ok(route.clone()));
2258                 // On retry, split the payment across both channels.
2259                 route.paths[0][0].fee_msat = 50_000_001;
2260                 route.paths[1][0].fee_msat = 50_000_000;
2261                 router.expect_find_route(Ok(route.clone()));
2262
2263                 let event_handler = |_: &_| { panic!(); };
2264                 let invoice_payer = InvoicePayer::new(nodes[0].node, router, nodes[0].logger, event_handler, Retry::Attempts(1));
2265
2266                 assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
2267                         &nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::Bitcoin,
2268                         Some(100_010_000), "Invoice".to_string(), duration_since_epoch(), 3600).unwrap())
2269                         .is_ok());
2270                 let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
2271                 assert_eq!(htlc_msgs.len(), 2);
2272                 check_added_monitors!(nodes[0], 2);
2273         }
2274
2275         #[test]
2276         fn immediate_retry_on_failure() {
2277                 // Tests that we can/will retry immediately after a failure
2278                 let chanmon_cfgs = create_chanmon_cfgs(2);
2279                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
2280                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None, None]);
2281                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
2282
2283                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, channelmanager::provided_init_features(), channelmanager::provided_init_features());
2284                 create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0, channelmanager::provided_init_features(), channelmanager::provided_init_features());
2285                 let chans = nodes[0].node.list_usable_channels();
2286                 let mut route = Route {
2287                         paths: vec![
2288                                 vec![RouteHop {
2289                                         pubkey: nodes[1].node.get_our_node_id(),
2290                                         node_features: channelmanager::provided_node_features(),
2291                                         short_channel_id: chans[0].short_channel_id.unwrap(),
2292                                         channel_features: channelmanager::provided_channel_features(),
2293                                         fee_msat: 100_000_001, // Our default max-HTLC-value is 10% of the channel value, which this is one more than
2294                                         cltv_expiry_delta: 100,
2295                                 }],
2296                         ],
2297                         payment_params: Some(PaymentParameters::from_node_id(nodes[1].node.get_our_node_id())),
2298                 };
2299                 let router = ManualRouter(RefCell::new(VecDeque::new()));
2300                 router.expect_find_route(Ok(route.clone()));
2301                 // On retry, split the payment across both channels.
2302                 route.paths.push(route.paths[0].clone());
2303                 route.paths[0][0].short_channel_id = chans[1].short_channel_id.unwrap();
2304                 route.paths[0][0].fee_msat = 50_000_000;
2305                 route.paths[1][0].fee_msat = 50_000_001;
2306                 router.expect_find_route(Ok(route.clone()));
2307
2308                 let event_handler = |_: &_| { panic!(); };
2309                 let invoice_payer = InvoicePayer::new(nodes[0].node, router, nodes[0].logger, event_handler, Retry::Attempts(1));
2310
2311                 assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
2312                         &nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::Bitcoin,
2313                         Some(100_010_000), "Invoice".to_string(), duration_since_epoch(), 3600).unwrap())
2314                         .is_ok());
2315                 let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
2316                 assert_eq!(htlc_msgs.len(), 2);
2317                 check_added_monitors!(nodes[0], 2);
2318         }
2319
2320         #[test]
2321         fn no_extra_retries_on_back_to_back_fail() {
2322                 // In a previous release, we had a race where we may exceed the payment retry count if we
2323                 // get two failures in a row with the second having `all_paths_failed` set.
2324                 // Generally, when we give up trying to retry a payment, we don't know for sure what the
2325                 // current state of the ChannelManager event queue is. Specifically, we cannot be sure that
2326                 // there are not multiple additional `PaymentPathFailed` or even `PaymentSent` events
2327                 // pending which we will see later. Thus, when we previously removed the retry tracking map
2328                 // entry after a `all_paths_failed` `PaymentPathFailed` event, we may have dropped the
2329                 // retry entry even though more events for the same payment were still pending. This led to
2330                 // us retrying a payment again even though we'd already given up on it.
2331                 //
2332                 // We now have a separate event - `PaymentFailed` which indicates no HTLCs remain and which
2333                 // is used to remove the payment retry counter entries instead. This tests for the specific
2334                 // excess-retry case while also testing `PaymentFailed` generation.
2335
2336                 let chanmon_cfgs = create_chanmon_cfgs(3);
2337                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
2338                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
2339                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
2340
2341                 let chan_1_scid = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 10_000_000, 0, channelmanager::provided_init_features(), channelmanager::provided_init_features()).0.contents.short_channel_id;
2342                 let chan_2_scid = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 10_000_000, 0, channelmanager::provided_init_features(), channelmanager::provided_init_features()).0.contents.short_channel_id;
2343
2344                 let mut route = Route {
2345                         paths: vec![
2346                                 vec![RouteHop {
2347                                         pubkey: nodes[1].node.get_our_node_id(),
2348                                         node_features: channelmanager::provided_node_features(),
2349                                         short_channel_id: chan_1_scid,
2350                                         channel_features: channelmanager::provided_channel_features(),
2351                                         fee_msat: 0,
2352                                         cltv_expiry_delta: 100,
2353                                 }, RouteHop {
2354                                         pubkey: nodes[2].node.get_our_node_id(),
2355                                         node_features: channelmanager::provided_node_features(),
2356                                         short_channel_id: chan_2_scid,
2357                                         channel_features: channelmanager::provided_channel_features(),
2358                                         fee_msat: 100_000_000,
2359                                         cltv_expiry_delta: 100,
2360                                 }],
2361                                 vec![RouteHop {
2362                                         pubkey: nodes[1].node.get_our_node_id(),
2363                                         node_features: channelmanager::provided_node_features(),
2364                                         short_channel_id: chan_1_scid,
2365                                         channel_features: channelmanager::provided_channel_features(),
2366                                         fee_msat: 0,
2367                                         cltv_expiry_delta: 100,
2368                                 }, RouteHop {
2369                                         pubkey: nodes[2].node.get_our_node_id(),
2370                                         node_features: channelmanager::provided_node_features(),
2371                                         short_channel_id: chan_2_scid,
2372                                         channel_features: channelmanager::provided_channel_features(),
2373                                         fee_msat: 100_000_000,
2374                                         cltv_expiry_delta: 100,
2375                                 }]
2376                         ],
2377                         payment_params: Some(PaymentParameters::from_node_id(nodes[2].node.get_our_node_id())),
2378                 };
2379                 let router = ManualRouter(RefCell::new(VecDeque::new()));
2380                 router.expect_find_route(Ok(route.clone()));
2381                 // On retry, we'll only be asked for one path
2382                 route.paths.remove(1);
2383                 router.expect_find_route(Ok(route.clone()));
2384
2385                 let expected_events: RefCell<VecDeque<&dyn Fn(&Event)>> = RefCell::new(VecDeque::new());
2386                 let event_handler = |event: &Event| {
2387                         let event_checker = expected_events.borrow_mut().pop_front().unwrap();
2388                         event_checker(event);
2389                 };
2390                 let invoice_payer = InvoicePayer::new(nodes[0].node, router, nodes[0].logger, event_handler, Retry::Attempts(1));
2391
2392                 assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
2393                         &nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::Bitcoin,
2394                         Some(100_010_000), "Invoice".to_string(), duration_since_epoch(), 3600).unwrap())
2395                         .is_ok());
2396                 let htlc_updates = SendEvent::from_node(&nodes[0]);
2397                 check_added_monitors!(nodes[0], 1);
2398                 assert_eq!(htlc_updates.msgs.len(), 1);
2399
2400                 nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &htlc_updates.msgs[0]);
2401                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &htlc_updates.commitment_msg);
2402                 check_added_monitors!(nodes[1], 1);
2403                 let (bs_first_raa, bs_first_cs) = get_revoke_commit_msgs!(nodes[1], nodes[0].node.get_our_node_id());
2404
2405                 nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_first_raa);
2406                 check_added_monitors!(nodes[0], 1);
2407                 let second_htlc_updates = SendEvent::from_node(&nodes[0]);
2408
2409                 nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_first_cs);
2410                 check_added_monitors!(nodes[0], 1);
2411                 let as_first_raa = get_event_msg!(nodes[0], MessageSendEvent::SendRevokeAndACK, nodes[1].node.get_our_node_id());
2412
2413                 nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &second_htlc_updates.msgs[0]);
2414                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &second_htlc_updates.commitment_msg);
2415                 check_added_monitors!(nodes[1], 1);
2416                 let bs_second_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
2417
2418                 nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_first_raa);
2419                 check_added_monitors!(nodes[1], 1);
2420                 let bs_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
2421
2422                 nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_second_raa);
2423                 check_added_monitors!(nodes[0], 1);
2424
2425                 nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_fail_update.update_fail_htlcs[0]);
2426                 nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_fail_update.commitment_signed);
2427                 check_added_monitors!(nodes[0], 1);
2428                 let (as_second_raa, as_third_cs) = get_revoke_commit_msgs!(nodes[0], nodes[1].node.get_our_node_id());
2429
2430                 nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_second_raa);
2431                 check_added_monitors!(nodes[1], 1);
2432                 let bs_second_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
2433
2434                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &as_third_cs);
2435                 check_added_monitors!(nodes[1], 1);
2436                 let bs_third_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
2437
2438                 nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_second_fail_update.update_fail_htlcs[0]);
2439                 nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_second_fail_update.commitment_signed);
2440                 check_added_monitors!(nodes[0], 1);
2441
2442                 nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_third_raa);
2443                 check_added_monitors!(nodes[0], 1);
2444                 let (as_third_raa, as_fourth_cs) = get_revoke_commit_msgs!(nodes[0], nodes[1].node.get_our_node_id());
2445
2446                 nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_third_raa);
2447                 check_added_monitors!(nodes[1], 1);
2448                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &as_fourth_cs);
2449                 check_added_monitors!(nodes[1], 1);
2450                 let bs_fourth_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
2451
2452                 nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_fourth_raa);
2453                 check_added_monitors!(nodes[0], 1);
2454
2455                 // At this point A has sent two HTLCs which both failed due to lack of fee. It now has two
2456                 // pending `PaymentPathFailed` events, one with `all_paths_failed` unset, and the second
2457                 // with it set. The first event will use up the only retry we are allowed, with the second
2458                 // `PaymentPathFailed` being passed up to the user (us, in this case). Previously, we'd
2459                 // treated this as "HTLC complete" and dropped the retry counter, causing us to retry again
2460                 // if the final HTLC failed.
2461                 expected_events.borrow_mut().push_back(&|ev: &Event| {
2462                         if let Event::PaymentPathFailed { payment_failed_permanently, all_paths_failed, .. } = ev {
2463                                 assert!(!payment_failed_permanently);
2464                                 assert!(all_paths_failed);
2465                         } else { panic!("Unexpected event"); }
2466                 });
2467                 nodes[0].node.process_pending_events(&invoice_payer);
2468                 assert!(expected_events.borrow().is_empty());
2469
2470                 let retry_htlc_updates = SendEvent::from_node(&nodes[0]);
2471                 check_added_monitors!(nodes[0], 1);
2472
2473                 nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &retry_htlc_updates.msgs[0]);
2474                 commitment_signed_dance!(nodes[1], nodes[0], &retry_htlc_updates.commitment_msg, false, true);
2475                 let bs_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
2476                 nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_fail_update.update_fail_htlcs[0]);
2477                 commitment_signed_dance!(nodes[0], nodes[1], &bs_fail_update.commitment_signed, false, true);
2478
2479                 expected_events.borrow_mut().push_back(&|ev: &Event| {
2480                         if let Event::PaymentPathFailed { payment_failed_permanently, all_paths_failed, .. } = ev {
2481                                 assert!(!payment_failed_permanently);
2482                                 assert!(all_paths_failed);
2483                         } else { panic!("Unexpected event"); }
2484                 });
2485                 expected_events.borrow_mut().push_back(&|ev: &Event| {
2486                         if let Event::PaymentFailed { .. } = ev {
2487                         } else { panic!("Unexpected event"); }
2488                 });
2489                 nodes[0].node.process_pending_events(&invoice_payer);
2490                 assert!(expected_events.borrow().is_empty());
2491         }
2492 }