_ Git - rust-lightning/blob - lightning-invoice/src/utils.rs

   1 //! Convenient utilities to create an invoice.
   2
   3 use crate::{CreationError, Currency, Invoice, InvoiceBuilder, SignOrCreationError};
   4
   5 use crate::{prelude::*, Description, InvoiceDescription, Sha256};
   6 use bech32::ToBase32;
   7 use bitcoin_hashes::Hash;
   8 use lightning::chain;
   9 use lightning::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
  10 use lightning::sign::{Recipient, NodeSigner, SignerProvider, EntropySource};
  11 use lightning::ln::{PaymentHash, PaymentSecret};
  12 use lightning::ln::channelmanager::{ChannelDetails, ChannelManager, MIN_FINAL_CLTV_EXPIRY_DELTA};
  13 use lightning::ln::channelmanager::{PhantomRouteHints, MIN_CLTV_EXPIRY_DELTA};
  14 use lightning::ln::inbound_payment::{create, create_from_hash, ExpandedKey};
  15 use lightning::routing::gossip::RoutingFees;
  16 use lightning::routing::router::{RouteHint, RouteHintHop, Router};
  17 use lightning::util::logger::Logger;
  18 use secp256k1::PublicKey;
  19 use core::ops::Deref;
  20 use core::time::Duration;
  21 use core::iter::Iterator;
  22
  23 /// Utility to create an invoice that can be paid to one of multiple nodes, or a "phantom invoice."
  24 /// See [`PhantomKeysManager`] for more information on phantom node payments.
  25 ///
  26 /// `phantom_route_hints` parameter:
  27 /// * Contains channel info for all nodes participating in the phantom invoice
  28 /// * Entries are retrieved from a call to [`ChannelManager::get_phantom_route_hints`] on each
  29 ///   participating node
  30 /// * It is fine to cache `phantom_route_hints` and reuse it across invoices, as long as the data is
  31 ///   updated when a channel becomes disabled or closes
  32 /// * Note that if too many channels are included in [`PhantomRouteHints::channels`], the invoice
  33 ///   may be too long for QR code scanning. To fix this, `PhantomRouteHints::channels` may be pared
  34 ///   down
  35 ///
  36 /// `payment_hash` can be specified if you have a specific need for a custom payment hash (see the difference
  37 /// between [`ChannelManager::create_inbound_payment`] and [`ChannelManager::create_inbound_payment_for_hash`]).
  38 /// If `None` is provided for `payment_hash`, then one will be created.
  39 ///
  40 /// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
  41 /// in excess of the current time.
  42 ///
  43 /// `duration_since_epoch` is the current time since epoch in seconds.
  44 ///
  45 /// You can specify a custom `min_final_cltv_expiry_delta`, or let LDK default it to
  46 /// [`MIN_FINAL_CLTV_EXPIRY_DELTA`]. The provided expiry must be at least [`MIN_FINAL_CLTV_EXPIRY_DELTA`] - 3.
  47 /// Note that LDK will add a buffer of 3 blocks to the delta to allow for up to a few new block
  48 /// confirmations during routing.
  49 ///
  50 /// Note that the provided `keys_manager`'s `NodeSigner` implementation must support phantom
  51 /// invoices in its `sign_invoice` implementation ([`PhantomKeysManager`] satisfies this
  52 /// requirement).
  53 ///
  54 /// [`PhantomKeysManager`]: lightning::sign::PhantomKeysManager
  55 /// [`ChannelManager::get_phantom_route_hints`]: lightning::ln::channelmanager::ChannelManager::get_phantom_route_hints
  56 /// [`ChannelManager::create_inbound_payment`]: lightning::ln::channelmanager::ChannelManager::create_inbound_payment
  57 /// [`ChannelManager::create_inbound_payment_for_hash`]: lightning::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash
  58 /// [`PhantomRouteHints::channels`]: lightning::ln::channelmanager::PhantomRouteHints::channels
  59 /// [`MIN_FINAL_CLTV_EXPIRY_DETLA`]: lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA
  60 ///
  61 /// This can be used in a `no_std` environment, where [`std::time::SystemTime`] is not
  62 /// available and the current time is supplied by the caller.
  63 pub fn create_phantom_invoice<ES: Deref, NS: Deref, L: Deref>(
  64         amt_msat: Option<u64>, payment_hash: Option<PaymentHash>, description: String,
  65         invoice_expiry_delta_secs: u32, phantom_route_hints: Vec<PhantomRouteHints>, entropy_source: ES,
  66         node_signer: NS, logger: L, network: Currency, min_final_cltv_expiry_delta: Option<u16>, duration_since_epoch: Duration,
  67 ) -> Result<Invoice, SignOrCreationError<()>>
  68 where
  69         ES::Target: EntropySource,
  70         NS::Target: NodeSigner,
  71         L::Target: Logger,
  72 {
  73         let description = Description::new(description).map_err(SignOrCreationError::CreationError)?;
  74         let description = InvoiceDescription::Direct(&description,);
  75         _create_phantom_invoice::<ES, NS, L>(
  76                 amt_msat, payment_hash, description, invoice_expiry_delta_secs, phantom_route_hints,
  77                 entropy_source, node_signer, logger, network, min_final_cltv_expiry_delta, duration_since_epoch,
  78         )
  79 }
  80
  81 /// Utility to create an invoice that can be paid to one of multiple nodes, or a "phantom invoice."
  82 /// See [`PhantomKeysManager`] for more information on phantom node payments.
  83 ///
  84 /// `phantom_route_hints` parameter:
  85 /// * Contains channel info for all nodes participating in the phantom invoice
  86 /// * Entries are retrieved from a call to [`ChannelManager::get_phantom_route_hints`] on each
  87 ///   participating node
  88 /// * It is fine to cache `phantom_route_hints` and reuse it across invoices, as long as the data is
  89 ///   updated when a channel becomes disabled or closes
  90 /// * Note that the route hints generated from `phantom_route_hints` will be limited to a maximum
  91 ///   of 3 hints to ensure that the invoice can be scanned in a QR code. These hints are selected
  92 ///   in the order that the nodes in `PhantomRouteHints` are specified, selecting one hint per node
  93 ///   until the maximum is hit. Callers may provide as many `PhantomRouteHints::channels` as
  94 ///   desired, but note that some nodes will be trimmed if more than 3 nodes are provided.
  95 ///
  96 /// `description_hash` is a SHA-256 hash of the description text
  97 ///
  98 /// `payment_hash` can be specified if you have a specific need for a custom payment hash (see the difference
  99 /// between [`ChannelManager::create_inbound_payment`] and [`ChannelManager::create_inbound_payment_for_hash`]).
 100 /// If `None` is provided for `payment_hash`, then one will be created.
 101 ///
 102 /// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
 103 /// in excess of the current time.
 104 ///
 105 /// `duration_since_epoch` is the current time since epoch in seconds.
 106 ///
 107 /// Note that the provided `keys_manager`'s `NodeSigner` implementation must support phantom
 108 /// invoices in its `sign_invoice` implementation ([`PhantomKeysManager`] satisfies this
 109 /// requirement).
 110 ///
 111 /// [`PhantomKeysManager`]: lightning::sign::PhantomKeysManager
 112 /// [`ChannelManager::get_phantom_route_hints`]: lightning::ln::channelmanager::ChannelManager::get_phantom_route_hints
 113 /// [`ChannelManager::create_inbound_payment`]: lightning::ln::channelmanager::ChannelManager::create_inbound_payment
 114 /// [`ChannelManager::create_inbound_payment_for_hash`]: lightning::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash
 115 /// [`PhantomRouteHints::channels`]: lightning::ln::channelmanager::PhantomRouteHints::channels
 116 ///
 117 /// This can be used in a `no_std` environment, where [`std::time::SystemTime`] is not
 118 /// available and the current time is supplied by the caller.
 119 pub fn create_phantom_invoice_with_description_hash<ES: Deref, NS: Deref, L: Deref>(
 120         amt_msat: Option<u64>, payment_hash: Option<PaymentHash>, invoice_expiry_delta_secs: u32,
 121         description_hash: Sha256, phantom_route_hints: Vec<PhantomRouteHints>, entropy_source: ES,
 122         node_signer: NS, logger: L, network: Currency, min_final_cltv_expiry_delta: Option<u16>, duration_since_epoch: Duration,
 123 ) -> Result<Invoice, SignOrCreationError<()>>
 124 where
 125         ES::Target: EntropySource,
 126         NS::Target: NodeSigner,
 127         L::Target: Logger,
 128 {
 129         _create_phantom_invoice::<ES, NS, L>(
 130                 amt_msat, payment_hash, InvoiceDescription::Hash(&description_hash),
 131                 invoice_expiry_delta_secs, phantom_route_hints, entropy_source, node_signer, logger, network,
 132                 min_final_cltv_expiry_delta, duration_since_epoch,
 133         )
 134 }
 135
 136 const MAX_CHANNEL_HINTS: usize = 3;
 137
 138 fn _create_phantom_invoice<ES: Deref, NS: Deref, L: Deref>(
 139         amt_msat: Option<u64>, payment_hash: Option<PaymentHash>, description: InvoiceDescription,
 140         invoice_expiry_delta_secs: u32, phantom_route_hints: Vec<PhantomRouteHints>, entropy_source: ES,
 141         node_signer: NS, logger: L, network: Currency, min_final_cltv_expiry_delta: Option<u16>, duration_since_epoch: Duration,
 142 ) -> Result<Invoice, SignOrCreationError<()>>
 143 where
 144         ES::Target: EntropySource,
 145         NS::Target: NodeSigner,
 146         L::Target: Logger,
 147 {
 148
 149         if phantom_route_hints.is_empty() {
 150                 return Err(SignOrCreationError::CreationError(
 151                         CreationError::MissingRouteHints,
 152                 ));
 153         }
 154
 155         if min_final_cltv_expiry_delta.is_some() && min_final_cltv_expiry_delta.unwrap().saturating_add(3) < MIN_FINAL_CLTV_EXPIRY_DELTA {
 156                 return Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort));
 157         }
 158
 159         let invoice = match description {
 160                 InvoiceDescription::Direct(description) => {
 161                         InvoiceBuilder::new(network).description(description.0.clone())
 162                 }
 163                 InvoiceDescription::Hash(hash) => InvoiceBuilder::new(network).description_hash(hash.0),
 164         };
 165
 166         // If we ever see performance here being too slow then we should probably take this ExpandedKey as a parameter instead.
 167         let keys = ExpandedKey::new(&node_signer.get_inbound_payment_key_material());
 168         let (payment_hash, payment_secret) = if let Some(payment_hash) = payment_hash {
 169                 let payment_secret = create_from_hash(
 170                         &keys,
 171                         amt_msat,
 172                         payment_hash,
 173                         invoice_expiry_delta_secs,
 174                         duration_since_epoch
 175                                 .as_secs(),
 176                         min_final_cltv_expiry_delta,
 177                 )
 178                 .map_err(|_| SignOrCreationError::CreationError(CreationError::InvalidAmount))?;
 179                 (payment_hash, payment_secret)
 180         } else {
 181                 create(
 182                         &keys,
 183                         amt_msat,
 184                         invoice_expiry_delta_secs,
 185                         &entropy_source,
 186                         duration_since_epoch
 187                                 .as_secs(),
 188                         min_final_cltv_expiry_delta,
 189                 )
 190                 .map_err(|_| SignOrCreationError::CreationError(CreationError::InvalidAmount))?
 191         };
 192
 193         log_trace!(logger, "Creating phantom invoice from {} participating nodes with payment hash {}",
 194                 phantom_route_hints.len(), log_bytes!(payment_hash.0));
 195
 196         let mut invoice = invoice
 197                 .duration_since_epoch(duration_since_epoch)
 198                 .payment_hash(Hash::from_slice(&payment_hash.0).unwrap())
 199                 .payment_secret(payment_secret)
 200                 .min_final_cltv_expiry_delta(
 201                         // Add a buffer of 3 to the delta if present, otherwise use LDK's minimum.
 202                         min_final_cltv_expiry_delta.map(|x| x.saturating_add(3)).unwrap_or(MIN_FINAL_CLTV_EXPIRY_DELTA).into())
 203                 .expiry_time(Duration::from_secs(invoice_expiry_delta_secs.into()));
 204         if let Some(amt) = amt_msat {
 205                 invoice = invoice.amount_milli_satoshis(amt);
 206         }
 207
 208
 209         for route_hint in select_phantom_hints(amt_msat, phantom_route_hints, logger).take(MAX_CHANNEL_HINTS) {
 210                 invoice = invoice.private_route(route_hint);
 211         }
 212
 213         let raw_invoice = match invoice.build_raw() {
 214                 Ok(inv) => inv,
 215                 Err(e) => return Err(SignOrCreationError::CreationError(e))
 216         };
 217         let hrp_str = raw_invoice.hrp.to_string();
 218         let hrp_bytes = hrp_str.as_bytes();
 219         let data_without_signature = raw_invoice.data.to_base32();
 220         let signed_raw_invoice = raw_invoice.sign(|_| node_signer.sign_invoice(hrp_bytes, &data_without_signature, Recipient::PhantomNode));
 221         match signed_raw_invoice {
 222                 Ok(inv) => Ok(Invoice::from_signed(inv).unwrap()),
 223                 Err(e) => Err(SignOrCreationError::SignError(e))
 224         }
 225 }
 226
 227 /// Utility to select route hints for phantom invoices.
 228 /// See [`PhantomKeysManager`] for more information on phantom node payments.
 229 ///
 230 /// To ensure that the phantom invoice is still readable by QR code, we limit to 3 hints per invoice:
 231 /// * Select up to three channels per node.
 232 /// * Select one hint from each node, up to three hints or until we run out of hints.
 233 ///
 234 /// [`PhantomKeysManager`]: lightning::sign::PhantomKeysManager
 235 fn select_phantom_hints<L: Deref>(amt_msat: Option<u64>, phantom_route_hints: Vec<PhantomRouteHints>,
 236         logger: L) -> impl Iterator<Item = RouteHint>
 237 where
 238         L::Target: Logger,
 239 {
 240         let mut phantom_hints: Vec<_> = Vec::new();
 241
 242         for PhantomRouteHints { channels, phantom_scid, real_node_pubkey } in phantom_route_hints {
 243                 log_trace!(logger, "Generating phantom route hints for node {}",
 244                         log_pubkey!(real_node_pubkey));
 245                 let route_hints = sort_and_filter_channels(channels, amt_msat, &logger);
 246
 247                 // If we have any public channel, the route hints from `sort_and_filter_channels` will be
 248                 // empty. In that case we create a RouteHint on which we will push a single hop with the
 249                 // phantom route into the invoice, and let the sender find the path to the `real_node_pubkey`
 250                 // node by looking at our public channels.
 251                 let empty_route_hints = route_hints.len() == 0;
 252                 let mut have_pushed_empty = false;
 253                 let route_hints = route_hints
 254                         .chain(core::iter::from_fn(move || {
 255                                 if empty_route_hints && !have_pushed_empty {
 256                                         // set flag of having handled the empty route_hints and ensure empty vector
 257                                         // returned only once
 258                                         have_pushed_empty = true;
 259                                         Some(RouteHint(Vec::new()))
 260                                 } else {
 261                                         None
 262                                 }
 263                         }))
 264                         .map(move |mut hint| {
 265                                 hint.0.push(RouteHintHop {
 266                                         src_node_id: real_node_pubkey,
 267                                         short_channel_id: phantom_scid,
 268                                         fees: RoutingFees {
 269                                                 base_msat: 0,
 270                                                 proportional_millionths: 0,
 271                                         },
 272                                         cltv_expiry_delta: MIN_CLTV_EXPIRY_DELTA,
 273                                         htlc_minimum_msat: None,
 274                                         htlc_maximum_msat: None,
 275                                 });
 276                                 hint
 277                         });
 278
 279                 phantom_hints.push(route_hints);
 280         }
 281
 282         // We have one vector per real node involved in creating the phantom invoice. To distribute
 283         // the hints across our real nodes we add one hint from each in turn until no node has any hints
 284         // left (if one node has more hints than any other, these will accumulate at the end of the
 285         // vector).
 286         rotate_through_iterators(phantom_hints)
 287 }
 288
 289 /// Draw items iteratively from multiple iterators.  The items are retrieved by index and
 290 /// rotates through the iterators - first the zero index then the first index then second index, etc.
 291 fn rotate_through_iterators<T, I: Iterator<Item = T>>(mut vecs: Vec<I>) -> impl Iterator<Item = T> {
 292         let mut iterations = 0;
 293
 294         core::iter::from_fn(move || {
 295                 let mut exhausted_iterators = 0;
 296                 loop {
 297                         if vecs.is_empty() {
 298                                 return None;
 299                         }
 300                         let next_idx = iterations % vecs.len();
 301                         iterations += 1;
 302                         if let Some(item) = vecs[next_idx].next() {
 303                                 return Some(item);
 304                         }
 305                         // exhausted_vectors increase when the "next_idx" vector is exhausted
 306                         exhausted_iterators += 1;
 307                         // The check for exhausted iterators gets reset to 0 after each yield of `Some()`
 308                         // The loop will return None when all of the nested iterators are exhausted
 309                         if exhausted_iterators == vecs.len() {
 310                                 return None;
 311                         }
 312                 }
 313         })
 314 }
 315
 316 #[cfg(feature = "std")]
 317 /// Utility to construct an invoice. Generally, unless you want to do something like a custom
 318 /// cltv_expiry, this is what you should be using to create an invoice. The reason being, this
 319 /// method stores the invoice's payment secret and preimage in `ChannelManager`, so (a) the user
 320 /// doesn't have to store preimage/payment secret information and (b) `ChannelManager` can verify
 321 /// that the payment secret is valid when the invoice is paid.
 322 ///
 323 /// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
 324 /// in excess of the current time.
 325 ///
 326 /// You can specify a custom `min_final_cltv_expiry_delta`, or let LDK default it to
 327 /// [`MIN_FINAL_CLTV_EXPIRY_DELTA`]. The provided expiry must be at least [`MIN_FINAL_CLTV_EXPIRY_DELTA`].
 328 /// Note that LDK will add a buffer of 3 blocks to the delta to allow for up to a few new block
 329 /// confirmations during routing.
 330 ///
 331 /// [`MIN_FINAL_CLTV_EXPIRY_DETLA`]: lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA
 332 pub fn create_invoice_from_channelmanager<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
 333         channelmanager: &ChannelManager<M, T, ES, NS, SP, F, R, L>, node_signer: NS, logger: L,
 334         network: Currency, amt_msat: Option<u64>, description: String, invoice_expiry_delta_secs: u32,
 335         min_final_cltv_expiry_delta: Option<u16>,
 336 ) -> Result<Invoice, SignOrCreationError<()>>
 337 where
 338         M::Target: chain::Watch<<SP::Target as SignerProvider>::Signer>,
 339         T::Target: BroadcasterInterface,
 340         ES::Target: EntropySource,
 341         NS::Target: NodeSigner,
 342         SP::Target: SignerProvider,
 343         F::Target: FeeEstimator,
 344         R::Target: Router,
 345         L::Target: Logger,
 346 {
 347         use std::time::SystemTime;
 348         let duration = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)
 349                 .expect("for the foreseeable future this shouldn't happen");
 350         create_invoice_from_channelmanager_and_duration_since_epoch(
 351                 channelmanager, node_signer, logger, network, amt_msat,
 352                 description, duration, invoice_expiry_delta_secs, min_final_cltv_expiry_delta,
 353         )
 354 }
 355
 356 #[cfg(feature = "std")]
 357 /// Utility to construct an invoice. Generally, unless you want to do something like a custom
 358 /// cltv_expiry, this is what you should be using to create an invoice. The reason being, this
 359 /// method stores the invoice's payment secret and preimage in `ChannelManager`, so (a) the user
 360 /// doesn't have to store preimage/payment secret information and (b) `ChannelManager` can verify
 361 /// that the payment secret is valid when the invoice is paid.
 362 /// Use this variant if you want to pass the `description_hash` to the invoice.
 363 ///
 364 /// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
 365 /// in excess of the current time.
 366 ///
 367 /// You can specify a custom `min_final_cltv_expiry_delta`, or let LDK default it to
 368 /// [`MIN_FINAL_CLTV_EXPIRY_DELTA`]. The provided expiry must be at least [`MIN_FINAL_CLTV_EXPIRY_DELTA`].
 369 /// Note that LDK will add a buffer of 3 blocks to the delta to allow for up to a few new block
 370 /// confirmations during routing.
 371 ///
 372 /// [`MIN_FINAL_CLTV_EXPIRY_DETLA`]: lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA
 373 pub fn create_invoice_from_channelmanager_with_description_hash<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
 374         channelmanager: &ChannelManager<M, T, ES, NS, SP, F, R, L>, node_signer: NS, logger: L,
 375         network: Currency, amt_msat: Option<u64>, description_hash: Sha256,
 376         invoice_expiry_delta_secs: u32, min_final_cltv_expiry_delta: Option<u16>,
 377 ) -> Result<Invoice, SignOrCreationError<()>>
 378 where
 379         M::Target: chain::Watch<<SP::Target as SignerProvider>::Signer>,
 380         T::Target: BroadcasterInterface,
 381         ES::Target: EntropySource,
 382         NS::Target: NodeSigner,
 383         SP::Target: SignerProvider,
 384         F::Target: FeeEstimator,
 385         R::Target: Router,
 386         L::Target: Logger,
 387 {
 388         use std::time::SystemTime;
 389
 390         let duration = SystemTime::now()
 391                 .duration_since(SystemTime::UNIX_EPOCH)
 392                 .expect("for the foreseeable future this shouldn't happen");
 393
 394         create_invoice_from_channelmanager_with_description_hash_and_duration_since_epoch(
 395                 channelmanager, node_signer, logger, network, amt_msat,
 396                 description_hash, duration, invoice_expiry_delta_secs, min_final_cltv_expiry_delta,
 397         )
 398 }
 399
 400 /// See [`create_invoice_from_channelmanager_with_description_hash`]
 401 /// This version can be used in a `no_std` environment, where [`std::time::SystemTime`] is not
 402 /// available and the current time is supplied by the caller.
 403 pub fn create_invoice_from_channelmanager_with_description_hash_and_duration_since_epoch<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
 404         channelmanager: &ChannelManager<M, T, ES, NS, SP, F, R, L>, node_signer: NS, logger: L,
 405         network: Currency, amt_msat: Option<u64>, description_hash: Sha256,
 406         duration_since_epoch: Duration, invoice_expiry_delta_secs: u32, min_final_cltv_expiry_delta: Option<u16>,
 407 ) -> Result<Invoice, SignOrCreationError<()>>
 408                 where
 409                         M::Target: chain::Watch<<SP::Target as SignerProvider>::Signer>,
 410                         T::Target: BroadcasterInterface,
 411                         ES::Target: EntropySource,
 412                         NS::Target: NodeSigner,
 413                         SP::Target: SignerProvider,
 414                         F::Target: FeeEstimator,
 415                         R::Target: Router,
 416                         L::Target: Logger,
 417 {
 418         _create_invoice_from_channelmanager_and_duration_since_epoch(
 419                 channelmanager, node_signer, logger, network, amt_msat,
 420                 InvoiceDescription::Hash(&description_hash),
 421                 duration_since_epoch, invoice_expiry_delta_secs, min_final_cltv_expiry_delta,
 422         )
 423 }
 424
 425 /// See [`create_invoice_from_channelmanager`]
 426 /// This version can be used in a `no_std` environment, where [`std::time::SystemTime`] is not
 427 /// available and the current time is supplied by the caller.
 428 pub fn create_invoice_from_channelmanager_and_duration_since_epoch<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
 429         channelmanager: &ChannelManager<M, T, ES, NS, SP, F, R, L>, node_signer: NS, logger: L,
 430         network: Currency, amt_msat: Option<u64>, description: String, duration_since_epoch: Duration,
 431         invoice_expiry_delta_secs: u32, min_final_cltv_expiry_delta: Option<u16>,
 432 ) -> Result<Invoice, SignOrCreationError<()>>
 433                 where
 434                         M::Target: chain::Watch<<SP::Target as SignerProvider>::Signer>,
 435                         T::Target: BroadcasterInterface,
 436                         ES::Target: EntropySource,
 437                         NS::Target: NodeSigner,
 438                         SP::Target: SignerProvider,
 439                         F::Target: FeeEstimator,
 440                         R::Target: Router,
 441                         L::Target: Logger,
 442 {
 443         _create_invoice_from_channelmanager_and_duration_since_epoch(
 444                 channelmanager, node_signer, logger, network, amt_msat,
 445                 InvoiceDescription::Direct(
 446                         &Description::new(description).map_err(SignOrCreationError::CreationError)?,
 447                 ),
 448                 duration_since_epoch, invoice_expiry_delta_secs, min_final_cltv_expiry_delta,
 449         )
 450 }
 451
 452 fn _create_invoice_from_channelmanager_and_duration_since_epoch<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
 453         channelmanager: &ChannelManager<M, T, ES, NS, SP, F, R, L>, node_signer: NS, logger: L,
 454         network: Currency, amt_msat: Option<u64>, description: InvoiceDescription,
 455         duration_since_epoch: Duration, invoice_expiry_delta_secs: u32, min_final_cltv_expiry_delta: Option<u16>,
 456 ) -> Result<Invoice, SignOrCreationError<()>>
 457                 where
 458                         M::Target: chain::Watch<<SP::Target as SignerProvider>::Signer>,
 459                         T::Target: BroadcasterInterface,
 460                         ES::Target: EntropySource,
 461                         NS::Target: NodeSigner,
 462                         SP::Target: SignerProvider,
 463                         F::Target: FeeEstimator,
 464                         R::Target: Router,
 465                         L::Target: Logger,
 466 {
 467         if min_final_cltv_expiry_delta.is_some() && min_final_cltv_expiry_delta.unwrap().saturating_add(3) < MIN_FINAL_CLTV_EXPIRY_DELTA {
 468                 return Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort));
 469         }
 470
 471         // `create_inbound_payment` only returns an error if the amount is greater than the total bitcoin
 472         // supply.
 473         let (payment_hash, payment_secret) = channelmanager
 474                 .create_inbound_payment(amt_msat, invoice_expiry_delta_secs, min_final_cltv_expiry_delta)
 475                 .map_err(|()| SignOrCreationError::CreationError(CreationError::InvalidAmount))?;
 476         _create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_hash(
 477                 channelmanager, node_signer, logger, network, amt_msat, description, duration_since_epoch,
 478                 invoice_expiry_delta_secs, payment_hash, payment_secret, min_final_cltv_expiry_delta)
 479 }
 480
 481 /// See [`create_invoice_from_channelmanager_and_duration_since_epoch`]
 482 /// This version allows for providing a custom [`PaymentHash`] for the invoice.
 483 /// This may be useful if you're building an on-chain swap or involving another protocol where
 484 /// the payment hash is also involved outside the scope of lightning.
 485 pub fn create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_hash<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
 486         channelmanager: &ChannelManager<M, T, ES, NS, SP, F, R, L>, node_signer: NS, logger: L,
 487         network: Currency, amt_msat: Option<u64>, description: String, duration_since_epoch: Duration,
 488         invoice_expiry_delta_secs: u32, payment_hash: PaymentHash, min_final_cltv_expiry_delta: Option<u16>,
 489 ) -> Result<Invoice, SignOrCreationError<()>>
 490         where
 491                 M::Target: chain::Watch<<SP::Target as SignerProvider>::Signer>,
 492                 T::Target: BroadcasterInterface,
 493                 ES::Target: EntropySource,
 494                 NS::Target: NodeSigner,
 495                 SP::Target: SignerProvider,
 496                 F::Target: FeeEstimator,
 497                 R::Target: Router,
 498                 L::Target: Logger,
 499 {
 500         let payment_secret = channelmanager
 501                 .create_inbound_payment_for_hash(payment_hash, amt_msat, invoice_expiry_delta_secs,
 502                         min_final_cltv_expiry_delta)
 503                 .map_err(|()| SignOrCreationError::CreationError(CreationError::InvalidAmount))?;
 504         _create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_hash(
 505                 channelmanager, node_signer, logger, network, amt_msat,
 506                 InvoiceDescription::Direct(
 507                         &Description::new(description).map_err(SignOrCreationError::CreationError)?,
 508                 ),
 509                 duration_since_epoch, invoice_expiry_delta_secs, payment_hash, payment_secret,
 510                 min_final_cltv_expiry_delta,
 511         )
 512 }
 513
 514 fn _create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_hash<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
 515         channelmanager: &ChannelManager<M, T, ES, NS, SP, F, R, L>, node_signer: NS, logger: L,
 516         network: Currency, amt_msat: Option<u64>, description: InvoiceDescription, duration_since_epoch: Duration,
 517         invoice_expiry_delta_secs: u32, payment_hash: PaymentHash, payment_secret: PaymentSecret,
 518         min_final_cltv_expiry_delta: Option<u16>,
 519 ) -> Result<Invoice, SignOrCreationError<()>>
 520         where
 521                 M::Target: chain::Watch<<SP::Target as SignerProvider>::Signer>,
 522                 T::Target: BroadcasterInterface,
 523                 ES::Target: EntropySource,
 524                 NS::Target: NodeSigner,
 525                 SP::Target: SignerProvider,
 526                 F::Target: FeeEstimator,
 527                 R::Target: Router,
 528                 L::Target: Logger,
 529 {
 530         let our_node_pubkey = channelmanager.get_our_node_id();
 531         let channels = channelmanager.list_channels();
 532
 533         if min_final_cltv_expiry_delta.is_some() && min_final_cltv_expiry_delta.unwrap().saturating_add(3) < MIN_FINAL_CLTV_EXPIRY_DELTA {
 534                 return Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort));
 535         }
 536
 537         log_trace!(logger, "Creating invoice with payment hash {}", log_bytes!(payment_hash.0));
 538
 539         let invoice = match description {
 540                 InvoiceDescription::Direct(description) => {
 541                         InvoiceBuilder::new(network).description(description.0.clone())
 542                 }
 543                 InvoiceDescription::Hash(hash) => InvoiceBuilder::new(network).description_hash(hash.0),
 544         };
 545
 546         let mut invoice = invoice
 547                 .duration_since_epoch(duration_since_epoch)
 548                 .payee_pub_key(our_node_pubkey)
 549                 .payment_hash(Hash::from_slice(&payment_hash.0).unwrap())
 550                 .payment_secret(payment_secret)
 551                 .basic_mpp()
 552                 .min_final_cltv_expiry_delta(
 553                         // Add a buffer of 3 to the delta if present, otherwise use LDK's minimum.
 554                         min_final_cltv_expiry_delta.map(|x| x.saturating_add(3)).unwrap_or(MIN_FINAL_CLTV_EXPIRY_DELTA).into())
 555                 .expiry_time(Duration::from_secs(invoice_expiry_delta_secs.into()));
 556         if let Some(amt) = amt_msat {
 557                 invoice = invoice.amount_milli_satoshis(amt);
 558         }
 559
 560         let route_hints = sort_and_filter_channels(channels, amt_msat, &logger);
 561         for hint in route_hints {
 562                 invoice = invoice.private_route(hint);
 563         }
 564
 565         let raw_invoice = match invoice.build_raw() {
 566                 Ok(inv) => inv,
 567                 Err(e) => return Err(SignOrCreationError::CreationError(e))
 568         };
 569         let hrp_str = raw_invoice.hrp.to_string();
 570         let hrp_bytes = hrp_str.as_bytes();
 571         let data_without_signature = raw_invoice.data.to_base32();
 572         let signed_raw_invoice = raw_invoice.sign(|_| node_signer.sign_invoice(hrp_bytes, &data_without_signature, Recipient::Node));
 573         match signed_raw_invoice {
 574                 Ok(inv) => Ok(Invoice::from_signed(inv).unwrap()),
 575                 Err(e) => Err(SignOrCreationError::SignError(e))
 576         }
 577 }
 578
 579 /// Sorts and filters the `channels` for an invoice, and returns the corresponding `RouteHint`s to include
 580 /// in the invoice.
 581 ///
 582 /// The filtering is based on the following criteria:
 583 /// * Only one channel per counterparty node
 584 /// * If the counterparty has a channel that is above the `min_inbound_capacity_msat` + 10% scaling
 585 ///   factor (to allow some margin for change in inbound), select the channel with the lowest
 586 ///   inbound capacity that is above this threshold.
 587 /// * If no `min_inbound_capacity_msat` is specified, or the counterparty has no channels above the
 588 ///   minimum + 10% scaling factor, select the channel with the highest inbound capacity per counterparty.
 589 /// * Prefer channels with capacity at least `min_inbound_capacity_msat` and where the channel
 590 ///   `is_usable` (i.e. the peer is connected).
 591 /// * If any public channel exists, only public [`RouteHint`]s will be returned.
 592 /// * If any public, announced, channel exists (i.e. a channel with 7+ confs, to ensure the
 593 ///   announcement has had a chance to propagate), no [`RouteHint`]s will be returned, as the
 594 ///   sender is expected to find the path by looking at the public channels instead.
 595 /// * Limited to a total of 3 channels.
 596 /// * Sorted by lowest inbound capacity if an online channel with the minimum amount requested exists,
 597 ///   otherwise sort by highest inbound capacity to give the payment the best chance of succeeding.
 598 fn sort_and_filter_channels<L: Deref>(
 599         channels: Vec<ChannelDetails>,
 600         min_inbound_capacity_msat: Option<u64>,
 601         logger: &L,
 602 ) -> impl ExactSizeIterator<Item = RouteHint>
 603 where
 604         L::Target: Logger,
 605 {
 606         let mut filtered_channels: HashMap<PublicKey, ChannelDetails> = HashMap::new();
 607         let min_inbound_capacity = min_inbound_capacity_msat.unwrap_or(0);
 608         let mut min_capacity_channel_exists = false;
 609         let mut online_channel_exists = false;
 610         let mut online_min_capacity_channel_exists = false;
 611         let mut has_pub_unconf_chan = false;
 612
 613         let route_hint_from_channel = |channel: ChannelDetails| {
 614                 let forwarding_info = channel.counterparty.forwarding_info.as_ref().unwrap();
 615                 RouteHint(vec![RouteHintHop {
 616                         src_node_id: channel.counterparty.node_id,
 617                         short_channel_id: channel.get_inbound_payment_scid().unwrap(),
 618                         fees: RoutingFees {
 619                                 base_msat: forwarding_info.fee_base_msat,
 620                                 proportional_millionths: forwarding_info.fee_proportional_millionths,
 621                         },
 622                         cltv_expiry_delta: forwarding_info.cltv_expiry_delta,
 623                         htlc_minimum_msat: channel.inbound_htlc_minimum_msat,
 624                         htlc_maximum_msat: channel.inbound_htlc_maximum_msat,}])
 625         };
 626
 627         log_trace!(logger, "Considering {} channels for invoice route hints", channels.len());
 628         for channel in channels.into_iter().filter(|chan| chan.is_channel_ready) {
 629                 if channel.get_inbound_payment_scid().is_none() || channel.counterparty.forwarding_info.is_none() {
 630                         log_trace!(logger, "Ignoring channel {} for invoice route hints", log_bytes!(channel.channel_id));
 631                         continue;
 632                 }
 633
 634                 if channel.is_public {
 635                         if channel.confirmations.is_some() && channel.confirmations < Some(7) {
 636                                 // If we have a public channel, but it doesn't have enough confirmations to (yet)
 637                                 // be in the public network graph (and have gotten a chance to propagate), include
 638                                 // route hints but only for public channels to protect private channel privacy.
 639                                 has_pub_unconf_chan = true;
 640                         } else {
 641                                 // If any public channel exists, return no hints and let the sender
 642                                 // look at the public channels instead.
 643                                 log_trace!(logger, "Not including channels in invoice route hints on account of public channel {}",
 644                                         log_bytes!(channel.channel_id));
 645                                 return vec![].into_iter().take(MAX_CHANNEL_HINTS).map(route_hint_from_channel);
 646                         }
 647                 }
 648
 649                 if channel.inbound_capacity_msat >= min_inbound_capacity {
 650                         if !min_capacity_channel_exists {
 651                                 log_trace!(logger, "Channel with enough inbound capacity exists for invoice route hints");
 652                                 min_capacity_channel_exists = true;
 653                         }
 654
 655                         if channel.is_usable {
 656                                 online_min_capacity_channel_exists = true;
 657                         }
 658                 }
 659
 660                 if channel.is_usable && !online_channel_exists {
 661                         log_trace!(logger, "Channel with connected peer exists for invoice route hints");
 662                         online_channel_exists = true;
 663                 }
 664
 665                 match filtered_channels.entry(channel.counterparty.node_id) {
 666                         hash_map::Entry::Occupied(mut entry) => {
 667                                 let current_max_capacity = entry.get().inbound_capacity_msat;
 668                                 // If this channel is public and the previous channel is not, ensure we replace the
 669                                 // previous channel to avoid announcing non-public channels.
 670                                 let new_now_public = channel.is_public && !entry.get().is_public;
 671                                 // Decide whether we prefer the currently selected channel with the node to the new one,
 672                                 // based on their inbound capacity.
 673                                 let prefer_current = prefer_current_channel(min_inbound_capacity_msat, current_max_capacity,
 674                                         channel.inbound_capacity_msat);
 675                                 // If the public-ness of the channel has not changed (in which case simply defer to
 676                                 // `new_now_public), and this channel has more desirable inbound than the incumbent,
 677                                 // prefer to include this channel.
 678                                 let new_channel_preferable = channel.is_public == entry.get().is_public && !prefer_current;
 679
 680                                 if new_now_public || new_channel_preferable {
 681                                         log_trace!(logger,
 682                                                 "Preferring counterparty {} channel {} (SCID {:?}, {} msats) over {} (SCID {:?}, {} msats) for invoice route hints",
 683                                                 log_pubkey!(channel.counterparty.node_id),
 684                                                 log_bytes!(channel.channel_id), channel.short_channel_id,
 685                                                 channel.inbound_capacity_msat,
 686                                                 log_bytes!(entry.get().channel_id), entry.get().short_channel_id,
 687                                                 current_max_capacity);
 688                                         entry.insert(channel);
 689                                 } else {
 690                                         log_trace!(logger,
 691                                                 "Preferring counterparty {} channel {} (SCID {:?}, {} msats) over {} (SCID {:?}, {} msats) for invoice route hints",
 692                                                 log_pubkey!(channel.counterparty.node_id),
 693                                                 log_bytes!(entry.get().channel_id), entry.get().short_channel_id,
 694                                                 current_max_capacity,
 695                                                 log_bytes!(channel.channel_id), channel.short_channel_id,
 696                                                 channel.inbound_capacity_msat);
 697                                 }
 698                         }
 699                         hash_map::Entry::Vacant(entry) => {
 700                                 entry.insert(channel);
 701                         }
 702                 }
 703         }
 704
 705         // If all channels are private, prefer to return route hints which have a higher capacity than
 706         // the payment value and where we're currently connected to the channel counterparty.
 707         // Even if we cannot satisfy both goals, always ensure we include *some* hints, preferring
 708         // those which meet at least one criteria.
 709         let mut eligible_channels = filtered_channels
 710                 .into_iter()
 711                 .map(|(_, channel)| channel)
 712                 .filter(|channel| {
 713                         let has_enough_capacity = channel.inbound_capacity_msat >= min_inbound_capacity;
 714                         let include_channel = if has_pub_unconf_chan {
 715                                 // If we have a public channel, but it doesn't have enough confirmations to (yet)
 716                                 // be in the public network graph (and have gotten a chance to propagate), include
 717                                 // route hints but only for public channels to protect private channel privacy.
 718                                 channel.is_public
 719                         } else if online_min_capacity_channel_exists {
 720                                 has_enough_capacity && channel.is_usable
 721                         } else if min_capacity_channel_exists && online_channel_exists {
 722                                 // If there are some online channels and some min_capacity channels, but no
 723                                 // online-and-min_capacity channels, just include the min capacity ones and ignore
 724                                 // online-ness.
 725                                 has_enough_capacity
 726                         } else if min_capacity_channel_exists {
 727                                 has_enough_capacity
 728                         } else if online_channel_exists {
 729                                 channel.is_usable
 730                         } else { true };
 731
 732                         if include_channel {
 733                                 log_trace!(logger, "Including channel {} in invoice route hints",
 734                                         log_bytes!(channel.channel_id));
 735                         } else if !has_enough_capacity {
 736                                 log_trace!(logger, "Ignoring channel {} without enough capacity for invoice route hints",
 737                                         log_bytes!(channel.channel_id));
 738                         } else {
 739                                 debug_assert!(!channel.is_usable || (has_pub_unconf_chan && !channel.is_public));
 740                                 log_trace!(logger, "Ignoring channel {} with disconnected peer",
 741                                         log_bytes!(channel.channel_id));
 742                         }
 743
 744                         include_channel
 745                 })
 746                 .collect::<Vec<ChannelDetails>>();
 747
 748                 eligible_channels.sort_unstable_by(|a, b| {
 749                         if online_min_capacity_channel_exists {
 750                                 a.inbound_capacity_msat.cmp(&b.inbound_capacity_msat)
 751                         } else {
 752                                 b.inbound_capacity_msat.cmp(&a.inbound_capacity_msat)
 753                         }});
 754
 755                 eligible_channels.into_iter().take(MAX_CHANNEL_HINTS).map(route_hint_from_channel)
 756 }
 757
 758 /// prefer_current_channel chooses a channel to use for route hints between a currently selected and candidate
 759 /// channel based on the inbound capacity of each channel and the minimum inbound capacity requested for the hints,
 760 /// returning true if the current channel should be preferred over the candidate channel.
 761 /// * If no minimum amount is requested, the channel with the most inbound is chosen to maximize the chances that a
 762 ///   payment of any size will succeed.
 763 /// * If we have channels with inbound above our minimum requested inbound (plus a 10% scaling factor, expressed as a
 764 ///   percentage) then we choose the lowest inbound channel with above this amount. If we have sufficient inbound
 765 ///   channels, we don't want to deplete our larger channels with small payments (the off-chain version of "grinding
 766 ///   our change").
 767 /// * If no channel above our minimum amount exists, then we just prefer the channel with the most inbound to give
 768 ///   payments the best chance of succeeding in multiple parts.
 769 fn prefer_current_channel(min_inbound_capacity_msat: Option<u64>, current_channel: u64,
 770         candidate_channel: u64) -> bool {
 771
 772         // If no min amount is given for the hints, err of the side of caution and choose the largest channel inbound to
 773         // maximize chances of any payment succeeding.
 774         if min_inbound_capacity_msat.is_none() {
 775                 return current_channel > candidate_channel
 776         }
 777
 778         let scaled_min_inbound = min_inbound_capacity_msat.unwrap() * 110;
 779         let current_sufficient = current_channel * 100 >= scaled_min_inbound;
 780         let candidate_sufficient = candidate_channel * 100 >= scaled_min_inbound;
 781
 782         if current_sufficient && candidate_sufficient {
 783                 return current_channel < candidate_channel
 784         } else if current_sufficient {
 785                 return true
 786         } else if candidate_sufficient {
 787                 return false
 788         }
 789
 790         current_channel > candidate_channel
 791 }
 792
 793 #[cfg(test)]
 794 mod test {
 795         use core::time::Duration;
 796         use crate::{Currency, Description, InvoiceDescription, SignOrCreationError, CreationError};
 797         use bitcoin_hashes::{Hash, sha256};
 798         use bitcoin_hashes::sha256::Hash as Sha256;
 799         use lightning::sign::PhantomKeysManager;
 800         use lightning::events::{MessageSendEvent, MessageSendEventsProvider, Event};
 801         use lightning::ln::{PaymentPreimage, PaymentHash};
 802         use lightning::ln::channelmanager::{PhantomRouteHints, MIN_FINAL_CLTV_EXPIRY_DELTA, PaymentId, RecipientOnionFields, Retry};
 803         use lightning::ln::functional_test_utils::*;
 804         use lightning::ln::msgs::ChannelMessageHandler;
 805         use lightning::routing::router::{PaymentParameters, RouteParameters};
 806         use lightning::util::test_utils;
 807         use lightning::util::config::UserConfig;
 808         use crate::utils::{create_invoice_from_channelmanager_and_duration_since_epoch, rotate_through_iterators};
 809         use std::collections::HashSet;
 810
 811         #[test]
 812         fn test_prefer_current_channel() {
 813                 // No minimum, prefer larger candidate channel.
 814                 assert_eq!(crate::utils::prefer_current_channel(None, 100, 200), false);
 815
 816                 // No minimum, prefer larger current channel.
 817                 assert_eq!(crate::utils::prefer_current_channel(None, 200, 100), true);
 818
 819                 // Minimum set, prefer current channel over minimum + buffer.
 820                 assert_eq!(crate::utils::prefer_current_channel(Some(100), 115, 100), true);
 821
 822                 // Minimum set, prefer candidate channel over minimum + buffer.
 823                 assert_eq!(crate::utils::prefer_current_channel(Some(100), 105, 125), false);
 824
 825                 // Minimum set, both channels sufficient, prefer smaller current channel.
 826                 assert_eq!(crate::utils::prefer_current_channel(Some(100), 115, 125), true);
 827
 828                 // Minimum set, both channels sufficient, prefer smaller candidate channel.
 829                 assert_eq!(crate::utils::prefer_current_channel(Some(100), 200, 160), false);
 830
 831                 // Minimum set, neither sufficient, prefer larger current channel.
 832                 assert_eq!(crate::utils::prefer_current_channel(Some(200), 100, 50), true);
 833
 834                 // Minimum set, neither sufficient, prefer larger candidate channel.
 835                 assert_eq!(crate::utils::prefer_current_channel(Some(200), 100, 150), false);
 836         }
 837
 838
 839         #[test]
 840         fn test_from_channelmanager() {
 841                 let chanmon_cfgs = create_chanmon_cfgs(2);
 842                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
 843                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
 844                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 845                 create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
 846                 let non_default_invoice_expiry_secs = 4200;
 847                 let invoice = create_invoice_from_channelmanager_and_duration_since_epoch(
 848                         nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
 849                         Some(10_000), "test".to_string(), Duration::from_secs(1234567),
 850                         non_default_invoice_expiry_secs, None).unwrap();
 851                 assert_eq!(invoice.amount_pico_btc(), Some(100_000));
 852                 // If no `min_final_cltv_expiry_delta` is specified, then it should be `MIN_FINAL_CLTV_EXPIRY_DELTA`.
 853                 assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
 854                 assert_eq!(invoice.description(), InvoiceDescription::Direct(&Description("test".to_string())));
 855                 assert_eq!(invoice.expiry_time(), Duration::from_secs(non_default_invoice_expiry_secs.into()));
 856
 857                 // Invoice SCIDs should always use inbound SCID aliases over the real channel ID, if one is
 858                 // available.
 859                 let chan = &nodes[1].node.list_usable_channels()[0];
 860                 assert_eq!(invoice.route_hints().len(), 1);
 861                 assert_eq!(invoice.route_hints()[0].0.len(), 1);
 862                 assert_eq!(invoice.route_hints()[0].0[0].short_channel_id, chan.inbound_scid_alias.unwrap());
 863
 864                 assert_eq!(invoice.route_hints()[0].0[0].htlc_minimum_msat, chan.inbound_htlc_minimum_msat);
 865                 assert_eq!(invoice.route_hints()[0].0[0].htlc_maximum_msat, chan.inbound_htlc_maximum_msat);
 866
 867                 let payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key(),
 868                                 invoice.min_final_cltv_expiry_delta() as u32)
 869                         .with_bolt11_features(invoice.features().unwrap().clone()).unwrap()
 870                         .with_route_hints(invoice.route_hints()).unwrap();
 871                 let route_params = RouteParameters {
 872                         payment_params,
 873                         final_value_msat: invoice.amount_milli_satoshis().unwrap(),
 874                 };
 875                 let payment_event = {
 876                         let mut payment_hash = PaymentHash([0; 32]);
 877                         payment_hash.0.copy_from_slice(&invoice.payment_hash().as_ref()[0..32]);
 878                         nodes[0].node.send_payment(payment_hash,
 879                                 RecipientOnionFields::secret_only(*invoice.payment_secret()),
 880                                 PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
 881                         let mut added_monitors = nodes[0].chain_monitor.added_monitors.lock().unwrap();
 882                         assert_eq!(added_monitors.len(), 1);
 883                         added_monitors.clear();
 884
 885                         let mut events = nodes[0].node.get_and_clear_pending_msg_events();
 886                         assert_eq!(events.len(), 1);
 887                         SendEvent::from_event(events.remove(0))
 888
 889                 };
 890                 nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
 891                 nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &payment_event.commitment_msg);
 892                 let mut added_monitors = nodes[1].chain_monitor.added_monitors.lock().unwrap();
 893                 assert_eq!(added_monitors.len(), 1);
 894                 added_monitors.clear();
 895                 let events = nodes[1].node.get_and_clear_pending_msg_events();
 896                 assert_eq!(events.len(), 2);
 897         }
 898
 899         fn do_create_invoice_min_final_cltv_delta(with_custom_delta: bool) {
 900                 let chanmon_cfgs = create_chanmon_cfgs(2);
 901                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
 902                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
 903                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 904                 let custom_min_final_cltv_expiry_delta = Some(50);
 905
 906                 let invoice = crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch(
 907                         nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
 908                         Some(10_000), "".into(), Duration::from_secs(1234567), 3600,
 909                         if with_custom_delta { custom_min_final_cltv_expiry_delta } else { None },
 910                 ).unwrap();
 911                 assert_eq!(invoice.min_final_cltv_expiry_delta(), if with_custom_delta {
 912                         custom_min_final_cltv_expiry_delta.unwrap() + 3 /* Buffer */} else { MIN_FINAL_CLTV_EXPIRY_DELTA } as u64);
 913         }
 914
 915         #[test]
 916         fn test_create_invoice_custom_min_final_cltv_delta() {
 917                 do_create_invoice_min_final_cltv_delta(true);
 918                 do_create_invoice_min_final_cltv_delta(false);
 919         }
 920
 921         #[test]
 922         fn create_invoice_min_final_cltv_delta_equals_htlc_fail_buffer() {
 923                 let chanmon_cfgs = create_chanmon_cfgs(2);
 924                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
 925                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
 926                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 927                 let custom_min_final_cltv_expiry_delta = Some(21);
 928
 929                 let invoice = crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch(
 930                         nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
 931                         Some(10_000), "".into(), Duration::from_secs(1234567), 3600,
 932                         custom_min_final_cltv_expiry_delta,
 933                 ).unwrap();
 934                 assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
 935         }
 936
 937         #[test]
 938         fn test_create_invoice_with_description_hash() {
 939                 let chanmon_cfgs = create_chanmon_cfgs(2);
 940                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
 941                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
 942                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 943                 let description_hash = crate::Sha256(Hash::hash("Testing description_hash".as_bytes()));
 944                 let invoice = crate::utils::create_invoice_from_channelmanager_with_description_hash_and_duration_since_epoch(
 945                         nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
 946                         Some(10_000), description_hash, Duration::from_secs(1234567), 3600, None,
 947                 ).unwrap();
 948                 assert_eq!(invoice.amount_pico_btc(), Some(100_000));
 949                 assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
 950                 assert_eq!(invoice.description(), InvoiceDescription::Hash(&crate::Sha256(Sha256::hash("Testing description_hash".as_bytes()))));
 951         }
 952
 953         #[test]
 954         fn test_create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_hash() {
 955                 let chanmon_cfgs = create_chanmon_cfgs(2);
 956                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
 957                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
 958                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 959                 let payment_hash = PaymentHash([0; 32]);
 960                 let invoice = crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_hash(
 961                         nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
 962                         Some(10_000), "test".to_string(), Duration::from_secs(1234567), 3600,
 963                         payment_hash, None,
 964                 ).unwrap();
 965                 assert_eq!(invoice.amount_pico_btc(), Some(100_000));
 966                 assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
 967                 assert_eq!(invoice.description(), InvoiceDescription::Direct(&Description("test".to_string())));
 968                 assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&payment_hash.0[..]).unwrap());
 969         }
 970
 971         #[test]
 972         fn test_hints_has_only_public_confd_channels() {
 973                 let chanmon_cfgs = create_chanmon_cfgs(2);
 974                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
 975                 let mut config = test_default_channel_config();
 976                 config.channel_handshake_config.minimum_depth = 1;
 977                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[Some(config), Some(config)]);
 978                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 979
 980                 // Create a private channel with lots of capacity and a lower value public channel (without
 981                 // confirming the funding tx yet).
 982                 let unannounced_scid = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 10_000_000, 0);
 983                 let conf_tx = create_chan_between_nodes_with_value_init(&nodes[0], &nodes[1], 10_000, 0);
 984
 985                 // Before the channel is available, we should include the unannounced_scid.
 986                 let mut scid_aliases = HashSet::new();
 987                 scid_aliases.insert(unannounced_scid.0.short_channel_id_alias.unwrap());
 988                 match_invoice_routes(Some(5000), &nodes[1], scid_aliases.clone());
 989
 990                 // However after we mine the funding tx and exchange channel_ready messages for the public
 991                 // channel we'll immediately switch to including it as a route hint, even though it isn't
 992                 // yet announced.
 993                 let pub_channel_scid = mine_transaction(&nodes[0], &conf_tx);
 994                 let node_a_pub_channel_ready = get_event_msg!(nodes[0], MessageSendEvent::SendChannelReady, nodes[1].node.get_our_node_id());
 995                 nodes[1].node.handle_channel_ready(&nodes[0].node.get_our_node_id(), &node_a_pub_channel_ready);
 996
 997                 assert_eq!(mine_transaction(&nodes[1], &conf_tx), pub_channel_scid);
 998                 let events = nodes[1].node.get_and_clear_pending_msg_events();
 999                 assert_eq!(events.len(), 2);
1000                 if let MessageSendEvent::SendChannelReady { msg, .. } = &events[0] {
1001                         nodes[0].node.handle_channel_ready(&nodes[1].node.get_our_node_id(), msg);
1002                 } else { panic!(); }
1003                 if let MessageSendEvent::SendChannelUpdate { msg, .. } = &events[1] {
1004                         nodes[0].node.handle_channel_update(&nodes[1].node.get_our_node_id(), msg);
1005                 } else { panic!(); }
1006
1007                 nodes[1].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &get_event_msg!(nodes[0], MessageSendEvent::SendChannelUpdate, nodes[1].node.get_our_node_id()));
1008
1009                 expect_channel_ready_event(&nodes[0], &nodes[1].node.get_our_node_id());
1010                 expect_channel_ready_event(&nodes[1], &nodes[0].node.get_our_node_id());
1011
1012                 scid_aliases.clear();
1013                 scid_aliases.insert(node_a_pub_channel_ready.short_channel_id_alias.unwrap());
1014                 match_invoice_routes(Some(5000), &nodes[1], scid_aliases.clone());
1015                 // This also applies even if the amount is more than the payment amount, to ensure users
1016                 // dont screw up their privacy.
1017                 match_invoice_routes(Some(50_000_000), &nodes[1], scid_aliases.clone());
1018
1019                 // The same remains true until the channel has 7 confirmations, at which point we include
1020                 // no hints.
1021                 connect_blocks(&nodes[1], 5);
1022                 match_invoice_routes(Some(5000), &nodes[1], scid_aliases.clone());
1023                 connect_blocks(&nodes[1], 1);
1024                 get_event_msg!(nodes[1], MessageSendEvent::SendAnnouncementSignatures, nodes[0].node.get_our_node_id());
1025                 match_invoice_routes(Some(5000), &nodes[1], HashSet::new());
1026         }
1027
1028         #[test]
1029         fn test_hints_includes_single_channels_to_nodes() {
1030                 let chanmon_cfgs = create_chanmon_cfgs(3);
1031                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1032                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1033                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1034
1035                 let chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100000, 10001);
1036                 let chan_2_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);
1037
1038                 let mut scid_aliases = HashSet::new();
1039                 scid_aliases.insert(chan_1_0.0.short_channel_id_alias.unwrap());
1040                 scid_aliases.insert(chan_2_0.0.short_channel_id_alias.unwrap());
1041
1042                 match_invoice_routes(Some(5000), &nodes[0], scid_aliases);
1043         }
1044
1045         #[test]
1046         fn test_hints_has_only_lowest_inbound_capacity_channel_above_minimum() {
1047                 let chanmon_cfgs = create_chanmon_cfgs(2);
1048                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
1049                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
1050                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
1051
1052                 let _chan_1_0_inbound_below_amt = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 10_000, 0);
1053                 let _chan_1_0_large_inbound_above_amt = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 500_000, 0);
1054                 let chan_1_0_low_inbound_above_amt = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 200_000, 0);
1055
1056                 let mut scid_aliases = HashSet::new();
1057                 scid_aliases.insert(chan_1_0_low_inbound_above_amt.0.short_channel_id_alias.unwrap());
1058                 match_invoice_routes(Some(100_000_000), &nodes[0], scid_aliases);
1059         }
1060
1061         #[test]
1062         fn test_hints_has_only_online_channels() {
1063                 let chanmon_cfgs = create_chanmon_cfgs(4);
1064                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1065                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1066                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1067                 let chan_a = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 10_000_000, 0);
1068                 let chan_b = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 10_000_000, 0);
1069                 let _chan_c = create_unannounced_chan_between_nodes_with_value(&nodes, 3, 0, 1_000_000, 0);
1070
1071                 // With all peers connected we should get all hints that have sufficient value
1072                 let mut scid_aliases = HashSet::new();
1073                 scid_aliases.insert(chan_a.0.short_channel_id_alias.unwrap());
1074                 scid_aliases.insert(chan_b.0.short_channel_id_alias.unwrap());
1075
1076                 match_invoice_routes(Some(1_000_000_000), &nodes[0], scid_aliases.clone());
1077
1078                 // With only one sufficient-value peer connected we should only get its hint
1079                 scid_aliases.remove(&chan_b.0.short_channel_id_alias.unwrap());
1080                 nodes[0].node.peer_disconnected(&nodes[2].node.get_our_node_id());
1081                 match_invoice_routes(Some(1_000_000_000), &nodes[0], scid_aliases.clone());
1082
1083                 // If we don't have any sufficient-value peers connected we should get all hints with
1084                 // sufficient value, even though there is a connected insufficient-value peer.
1085                 scid_aliases.insert(chan_b.0.short_channel_id_alias.unwrap());
1086                 nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id());
1087                 match_invoice_routes(Some(1_000_000_000), &nodes[0], scid_aliases);
1088         }
1089
1090         #[test]
1091         fn test_insufficient_inbound_sort_by_highest_capacity() {
1092                 let chanmon_cfgs = create_chanmon_cfgs(5);
1093                 let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
1094                 let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
1095                 let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
1096                 let _chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100_000, 0);
1097                 let chan_2_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 200_000, 0);
1098                 let chan_3_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 3, 0, 300_000, 0);
1099                 let chan_4_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 4, 0, 400_000, 0);
1100
1101                 // When no single channel has enough inbound capacity for the payment, we expect the three
1102                 // highest inbound channels to be chosen.
1103                 let mut scid_aliases = HashSet::new();
1104                 scid_aliases.insert(chan_2_0.0.short_channel_id_alias.unwrap());
1105                 scid_aliases.insert(chan_3_0.0.short_channel_id_alias.unwrap());
1106                 scid_aliases.insert(chan_4_0.0.short_channel_id_alias.unwrap());
1107
1108                 match_invoice_routes(Some(1_000_000_000), &nodes[0], scid_aliases.clone());
1109         }
1110
1111         #[test]
1112         fn test_sufficient_inbound_sort_by_lowest_capacity() {
1113                 let chanmon_cfgs = create_chanmon_cfgs(5);
1114                 let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
1115                 let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
1116                 let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
1117                 let chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100_000, 0);
1118                 let chan_2_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 200_000, 0);
1119                 let chan_3_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 3, 0, 300_000, 0);
1120                 let _chan_4_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 4, 0, 400_000, 0);
1121
1122                 // When we have channels that have sufficient inbound for the payment, test that we sort
1123                 // by lowest inbound capacity.
1124                 let mut scid_aliases = HashSet::new();
1125                 scid_aliases.insert(chan_1_0.0.short_channel_id_alias.unwrap());
1126                 scid_aliases.insert(chan_2_0.0.short_channel_id_alias.unwrap());
1127                 scid_aliases.insert(chan_3_0.0.short_channel_id_alias.unwrap());
1128
1129                 match_invoice_routes(Some(50_000_000), &nodes[0], scid_aliases.clone());
1130         }
1131
1132         #[test]
1133         fn test_forwarding_info_not_assigned_channel_excluded_from_hints() {
1134                 let chanmon_cfgs = create_chanmon_cfgs(3);
1135                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1136                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1137                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1138                 let chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100000, 10001);
1139
1140                 // Create an unannonced channel between `nodes[2]` and `nodes[0]`, for which the
1141                 // `msgs::ChannelUpdate` is never handled for the node(s). As the `msgs::ChannelUpdate`
1142                 // is never handled, the `channel.counterparty.forwarding_info` is never assigned.
1143                 let mut private_chan_cfg = UserConfig::default();
1144                 private_chan_cfg.channel_handshake_config.announced_channel = false;
1145                 let temporary_channel_id = nodes[2].node.create_channel(nodes[0].node.get_our_node_id(), 1_000_000, 500_000_000, 42, Some(private_chan_cfg)).unwrap();
1146                 let open_channel = get_event_msg!(nodes[2], MessageSendEvent::SendOpenChannel, nodes[0].node.get_our_node_id());
1147                 nodes[0].node.handle_open_channel(&nodes[2].node.get_our_node_id(), &open_channel);
1148                 let accept_channel = get_event_msg!(nodes[0], MessageSendEvent::SendAcceptChannel, nodes[2].node.get_our_node_id());
1149                 nodes[2].node.handle_accept_channel(&nodes[0].node.get_our_node_id(), &accept_channel);
1150
1151                 let tx = sign_funding_transaction(&nodes[2], &nodes[0], 1_000_000, temporary_channel_id);
1152
1153                 let conf_height = core::cmp::max(nodes[2].best_block_info().1 + 1, nodes[0].best_block_info().1 + 1);
1154                 confirm_transaction_at(&nodes[2], &tx, conf_height);
1155                 connect_blocks(&nodes[2], CHAN_CONFIRM_DEPTH - 1);
1156                 confirm_transaction_at(&nodes[0], &tx, conf_height);
1157                 connect_blocks(&nodes[0], CHAN_CONFIRM_DEPTH - 1);
1158                 let as_channel_ready = get_event_msg!(nodes[2], MessageSendEvent::SendChannelReady, nodes[0].node.get_our_node_id());
1159                 nodes[2].node.handle_channel_ready(&nodes[0].node.get_our_node_id(), &get_event_msg!(nodes[0], MessageSendEvent::SendChannelReady, nodes[2].node.get_our_node_id()));
1160                 get_event_msg!(nodes[2], MessageSendEvent::SendChannelUpdate, nodes[0].node.get_our_node_id());
1161                 nodes[0].node.handle_channel_ready(&nodes[2].node.get_our_node_id(), &as_channel_ready);
1162                 get_event_msg!(nodes[0], MessageSendEvent::SendChannelUpdate, nodes[2].node.get_our_node_id());
1163                 expect_channel_ready_event(&nodes[0], &nodes[2].node.get_our_node_id());
1164                 expect_channel_ready_event(&nodes[2], &nodes[0].node.get_our_node_id());
1165
1166                 // As `msgs::ChannelUpdate` was never handled for the participating node(s) of the second
1167                 // channel, the channel will never be assigned any `counterparty.forwarding_info`.
1168                 // Therefore only `chan_1_0` should be included in the hints.
1169                 let mut scid_aliases = HashSet::new();
1170                 scid_aliases.insert(chan_1_0.0.short_channel_id_alias.unwrap());
1171                 match_invoice_routes(Some(5000), &nodes[0], scid_aliases);
1172         }
1173
1174         #[test]
1175         fn test_no_hints_if_a_mix_between_public_and_private_channel_exists() {
1176                 let chanmon_cfgs = create_chanmon_cfgs(3);
1177                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1178                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1179                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1180                 let _chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100000, 10001);
1181
1182                 let chan_2_0 = create_announced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);
1183                 nodes[2].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_2_0.1);
1184                 nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan_2_0.0);
1185
1186                 // Ensure that the invoice doesn't include any route hints for any of `nodes[0]` channels,
1187                 // even though all channels between `nodes[1]` and `nodes[0]` are private, as there is a
1188                 // public channel between `nodes[2]` and `nodes[0]`
1189                 match_invoice_routes(Some(5000), &nodes[0], HashSet::new());
1190         }
1191
1192         #[test]
1193         fn test_only_public_channels_includes_no_channels_in_hints() {
1194                 let chanmon_cfgs = create_chanmon_cfgs(3);
1195                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1196                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1197                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1198                 let chan_1_0 = create_announced_chan_between_nodes_with_value(&nodes, 1, 0, 100000, 10001);
1199                 nodes[0].node.handle_channel_update(&nodes[1].node.get_our_node_id(), &chan_1_0.0);
1200                 nodes[1].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_1_0.1);
1201
1202                 let chan_2_0 = create_announced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);
1203                 nodes[2].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_2_0.1);
1204                 nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan_2_0.0);
1205
1206                 // As all of `nodes[0]` channels are public, no channels should be included in the hints
1207                 match_invoice_routes(Some(5000), &nodes[0], HashSet::new());
1208         }
1209
1210         #[test]
1211         fn test_channels_with_lower_inbound_capacity_than_invoice_amt_hints_filtering() {
1212                 let chanmon_cfgs = create_chanmon_cfgs(3);
1213                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1214                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1215                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1216                 let chan_1_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 0, 100_000, 0);
1217                 let chan_2_0 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 0, 1_000_000, 0);
1218
1219                 // As the invoice amt is 1 msat above chan_1_0's inbound capacity, it shouldn't be included
1220                 let mut scid_aliases_99_000_001_msat = HashSet::new();
1221                 scid_aliases_99_000_001_msat.insert(chan_2_0.0.short_channel_id_alias.unwrap());
1222
1223                 match_invoice_routes(Some(99_000_001), &nodes[0], scid_aliases_99_000_001_msat);
1224
1225                 // As the invoice amt is exactly at chan_1_0's inbound capacity, it should be included
1226                 let mut scid_aliases_99_000_000_msat = HashSet::new();
1227                 scid_aliases_99_000_000_msat.insert(chan_1_0.0.short_channel_id_alias.unwrap());
1228                 scid_aliases_99_000_000_msat.insert(chan_2_0.0.short_channel_id_alias.unwrap());
1229
1230                 match_invoice_routes(Some(99_000_000), &nodes[0], scid_aliases_99_000_000_msat);
1231
1232                 // As the invoice amt is above all channels' inbound capacity, they will still be included
1233                 let mut scid_aliases_2_000_000_000_msat = HashSet::new();
1234                 scid_aliases_2_000_000_000_msat.insert(chan_1_0.0.short_channel_id_alias.unwrap());
1235                 scid_aliases_2_000_000_000_msat.insert(chan_2_0.0.short_channel_id_alias.unwrap());
1236
1237                 match_invoice_routes(Some(2_000_000_000), &nodes[0], scid_aliases_2_000_000_000_msat);
1238
1239                 // An invoice with no specified amount should include all channels in the route hints.
1240                 let mut scid_aliases_no_specified_amount = HashSet::new();
1241                 scid_aliases_no_specified_amount.insert(chan_1_0.0.short_channel_id_alias.unwrap());
1242                 scid_aliases_no_specified_amount.insert(chan_2_0.0.short_channel_id_alias.unwrap());
1243
1244                 match_invoice_routes(None, &nodes[0], scid_aliases_no_specified_amount);
1245         }
1246
1247         fn match_invoice_routes<'a, 'b: 'a, 'c: 'b>(
1248                 invoice_amt: Option<u64>,
1249                 invoice_node: &Node<'a, 'b, 'c>,
1250                 mut chan_ids_to_match: HashSet<u64>
1251         ) {
1252                 let invoice = create_invoice_from_channelmanager_and_duration_since_epoch(
1253                         invoice_node.node, invoice_node.keys_manager, invoice_node.logger,
1254                         Currency::BitcoinTestnet, invoice_amt, "test".to_string(), Duration::from_secs(1234567),
1255                         3600, None).unwrap();
1256                 let hints = invoice.private_routes();
1257
1258                 for hint in hints {
1259                         let hint_short_chan_id = (hint.0).0[0].short_channel_id;
1260                         assert!(chan_ids_to_match.remove(&hint_short_chan_id));
1261                 }
1262                 assert!(chan_ids_to_match.is_empty(), "Unmatched short channel ids: {:?}", chan_ids_to_match);
1263         }
1264
1265         #[test]
1266         #[cfg(feature = "std")]
1267         fn test_multi_node_receive() {
1268                 do_test_multi_node_receive(true);
1269                 do_test_multi_node_receive(false);
1270         }
1271
1272         #[cfg(feature = "std")]
1273         fn do_test_multi_node_receive(user_generated_pmt_hash: bool) {
1274                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1275                 let seed_1 = [42u8; 32];
1276                 let seed_2 = [43u8; 32];
1277                 let cross_node_seed = [44u8; 32];
1278                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1279                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1280                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1281                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1282                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1283                 let chan_0_1 = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
1284                 nodes[0].node.handle_channel_update(&nodes[1].node.get_our_node_id(), &chan_0_1.1);
1285                 nodes[1].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_0_1.0);
1286                 let chan_0_2 = create_announced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1287                 nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan_0_2.1);
1288                 nodes[2].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_0_2.0);
1289
1290                 let payment_amt = 10_000;
1291                 let route_hints = vec![
1292                         nodes[1].node.get_phantom_route_hints(),
1293                         nodes[2].node.get_phantom_route_hints(),
1294                 ];
1295
1296                 let user_payment_preimage = PaymentPreimage([1; 32]);
1297                 let payment_hash = if user_generated_pmt_hash {
1298                         Some(PaymentHash(Sha256::hash(&user_payment_preimage.0[..]).into_inner()))
1299                 } else {
1300                         None
1301                 };
1302                 let genesis_timestamp = bitcoin::blockdata::constants::genesis_block(bitcoin::Network::Testnet).header.time as u64;
1303                 let non_default_invoice_expiry_secs = 4200;
1304
1305                 let invoice =
1306                         crate::utils::create_phantom_invoice::<&test_utils::TestKeysInterface, &test_utils::TestKeysInterface, &test_utils::TestLogger>(
1307                                 Some(payment_amt), payment_hash, "test".to_string(), non_default_invoice_expiry_secs,
1308                                 route_hints, nodes[1].keys_manager, nodes[1].keys_manager, nodes[1].logger,
1309                                 Currency::BitcoinTestnet, None, Duration::from_secs(genesis_timestamp)
1310                         ).unwrap();
1311                 let (payment_hash, payment_secret) = (PaymentHash(invoice.payment_hash().into_inner()), *invoice.payment_secret());
1312                 let payment_preimage = if user_generated_pmt_hash {
1313                         user_payment_preimage
1314                 } else {
1315                         nodes[1].node.get_payment_preimage(payment_hash, payment_secret).unwrap()
1316                 };
1317
1318                 assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
1319                 assert_eq!(invoice.description(), InvoiceDescription::Direct(&Description("test".to_string())));
1320                 assert_eq!(invoice.route_hints().len(), 2);
1321                 assert_eq!(invoice.expiry_time(), Duration::from_secs(non_default_invoice_expiry_secs.into()));
1322                 assert!(!invoice.features().unwrap().supports_basic_mpp());
1323
1324                 let payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key(),
1325                                 invoice.min_final_cltv_expiry_delta() as u32)
1326                         .with_bolt11_features(invoice.features().unwrap().clone()).unwrap()
1327                         .with_route_hints(invoice.route_hints()).unwrap();
1328                 let params = RouteParameters {
1329                         payment_params,
1330                         final_value_msat: invoice.amount_milli_satoshis().unwrap(),
1331                 };
1332                 let (payment_event, fwd_idx) = {
1333                         let mut payment_hash = PaymentHash([0; 32]);
1334                         payment_hash.0.copy_from_slice(&invoice.payment_hash().as_ref()[0..32]);
1335                         nodes[0].node.send_payment(payment_hash,
1336                                 RecipientOnionFields::secret_only(*invoice.payment_secret()),
1337                                 PaymentId(payment_hash.0), params, Retry::Attempts(0)).unwrap();
1338                         let mut added_monitors = nodes[0].chain_monitor.added_monitors.lock().unwrap();
1339                         assert_eq!(added_monitors.len(), 1);
1340                         added_monitors.clear();
1341
1342                         let mut events = nodes[0].node.get_and_clear_pending_msg_events();
1343                         assert_eq!(events.len(), 1);
1344                         let fwd_idx = match events[0] {
1345                                 MessageSendEvent::UpdateHTLCs { node_id, .. } => {
1346                                         if node_id == nodes[1].node.get_our_node_id() {
1347                                                 1
1348                                         } else { 2 }
1349                                 },
1350                                 _ => panic!("Unexpected event")
1351                         };
1352                         (SendEvent::from_event(events.remove(0)), fwd_idx)
1353                 };
1354                 nodes[fwd_idx].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
1355                 commitment_signed_dance!(nodes[fwd_idx], nodes[0], &payment_event.commitment_msg, false, true);
1356
1357                 // Note that we have to "forward pending HTLCs" twice before we see the PaymentClaimable as
1358                 // this "emulates" the payment taking two hops, providing some privacy to make phantom node
1359                 // payments "look real" by taking more time.
1360                 expect_pending_htlcs_forwardable_ignore!(nodes[fwd_idx]);
1361                 nodes[fwd_idx].node.process_pending_htlc_forwards();
1362                 expect_pending_htlcs_forwardable_ignore!(nodes[fwd_idx]);
1363                 nodes[fwd_idx].node.process_pending_htlc_forwards();
1364
1365                 let payment_preimage_opt = if user_generated_pmt_hash { None } else { Some(payment_preimage) };
1366                 expect_payment_claimable!(&nodes[fwd_idx], payment_hash, payment_secret, payment_amt, payment_preimage_opt, invoice.recover_payee_pub_key());
1367                 do_claim_payment_along_route(&nodes[0], &[&vec!(&nodes[fwd_idx])[..]], false, payment_preimage);
1368                 let events = nodes[0].node.get_and_clear_pending_events();
1369                 assert_eq!(events.len(), 2);
1370                 match events[0] {
1371                         Event::PaymentSent { payment_preimage: ref ev_preimage, payment_hash: ref ev_hash, ref fee_paid_msat, .. } => {
1372                                 assert_eq!(payment_preimage, *ev_preimage);
1373                                 assert_eq!(payment_hash, *ev_hash);
1374                                 assert_eq!(fee_paid_msat, &Some(0));
1375                         },
1376                         _ => panic!("Unexpected event")
1377                 }
1378                 match events[1] {
1379                         Event::PaymentPathSuccessful { payment_hash: hash, .. } => {
1380                                 assert_eq!(hash, Some(payment_hash));
1381                         },
1382                         _ => panic!("Unexpected event")
1383                 }
1384         }
1385
1386         #[test]
1387         #[cfg(feature = "std")]
1388         fn test_multi_node_hints_has_htlc_min_max_values() {
1389                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1390                 let seed_1 = [42u8; 32];
1391                 let seed_2 = [43u8; 32];
1392                 let cross_node_seed = [44u8; 32];
1393                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1394                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1395                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1396                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1397                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1398
1399                 create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
1400                 create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1401
1402                 let payment_amt = 20_000;
1403                 let (payment_hash, _payment_secret) = nodes[1].node.create_inbound_payment(Some(payment_amt), 3600, None).unwrap();
1404                 let route_hints = vec![
1405                         nodes[1].node.get_phantom_route_hints(),
1406                         nodes[2].node.get_phantom_route_hints(),
1407                 ];
1408
1409                 let invoice = crate::utils::create_phantom_invoice::<&test_utils::TestKeysInterface,
1410                         &test_utils::TestKeysInterface, &test_utils::TestLogger>(Some(payment_amt), Some(payment_hash),
1411                                 "test".to_string(), 3600, route_hints, nodes[1].keys_manager, nodes[1].keys_manager,
1412                                 nodes[1].logger, Currency::BitcoinTestnet, None, Duration::from_secs(1234567)).unwrap();
1413
1414                 let chan_0_1 = &nodes[1].node.list_usable_channels()[0];
1415                 assert_eq!(invoice.route_hints()[0].0[0].htlc_minimum_msat, chan_0_1.inbound_htlc_minimum_msat);
1416                 assert_eq!(invoice.route_hints()[0].0[0].htlc_maximum_msat, chan_0_1.inbound_htlc_maximum_msat);
1417
1418                 let chan_0_2 = &nodes[2].node.list_usable_channels()[0];
1419                 assert_eq!(invoice.route_hints()[1].0[0].htlc_minimum_msat, chan_0_2.inbound_htlc_minimum_msat);
1420                 assert_eq!(invoice.route_hints()[1].0[0].htlc_maximum_msat, chan_0_2.inbound_htlc_maximum_msat);
1421         }
1422
1423         #[test]
1424         #[cfg(feature = "std")]
1425         fn create_phantom_invoice_with_description_hash() {
1426                 let chanmon_cfgs = create_chanmon_cfgs(3);
1427                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1428                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1429                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1430
1431                 let payment_amt = 20_000;
1432                 let route_hints = vec![
1433                         nodes[1].node.get_phantom_route_hints(),
1434                         nodes[2].node.get_phantom_route_hints(),
1435                 ];
1436
1437                 let description_hash = crate::Sha256(Hash::hash("Description hash phantom invoice".as_bytes()));
1438                 let non_default_invoice_expiry_secs = 4200;
1439                 let invoice = crate::utils::create_phantom_invoice_with_description_hash::<
1440                         &test_utils::TestKeysInterface, &test_utils::TestKeysInterface, &test_utils::TestLogger,
1441                 >(
1442                         Some(payment_amt), None, non_default_invoice_expiry_secs, description_hash,
1443                         route_hints, nodes[1].keys_manager, nodes[1].keys_manager, nodes[1].logger,
1444                         Currency::BitcoinTestnet, None, Duration::from_secs(1234567),
1445                 )
1446                 .unwrap();
1447                 assert_eq!(invoice.amount_pico_btc(), Some(200_000));
1448                 assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
1449                 assert_eq!(invoice.expiry_time(), Duration::from_secs(non_default_invoice_expiry_secs.into()));
1450                 assert_eq!(invoice.description(), InvoiceDescription::Hash(&crate::Sha256(Sha256::hash("Description hash phantom invoice".as_bytes()))));
1451         }
1452
1453         #[test]
1454         #[cfg(feature = "std")]
1455         fn create_phantom_invoice_with_custom_payment_hash_and_custom_min_final_cltv_delta() {
1456                 let chanmon_cfgs = create_chanmon_cfgs(3);
1457                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1458                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1459                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1460
1461                 let payment_amt = 20_000;
1462                 let route_hints = vec![
1463                         nodes[1].node.get_phantom_route_hints(),
1464                         nodes[2].node.get_phantom_route_hints(),
1465                 ];
1466                 let user_payment_preimage = PaymentPreimage([1; 32]);
1467                 let payment_hash = Some(PaymentHash(Sha256::hash(&user_payment_preimage.0[..]).into_inner()));
1468                 let non_default_invoice_expiry_secs = 4200;
1469                 let min_final_cltv_expiry_delta = Some(100);
1470                 let duration_since_epoch = Duration::from_secs(1234567);
1471                 let invoice = crate::utils::create_phantom_invoice::<&test_utils::TestKeysInterface,
1472                         &test_utils::TestKeysInterface, &test_utils::TestLogger>(Some(payment_amt), payment_hash,
1473                                 "".to_string(), non_default_invoice_expiry_secs, route_hints, nodes[1].keys_manager, nodes[1].keys_manager,
1474                                 nodes[1].logger, Currency::BitcoinTestnet, min_final_cltv_expiry_delta, duration_since_epoch).unwrap();
1475                 assert_eq!(invoice.amount_pico_btc(), Some(200_000));
1476                 assert_eq!(invoice.min_final_cltv_expiry_delta(), (min_final_cltv_expiry_delta.unwrap() + 3) as u64);
1477                 assert_eq!(invoice.expiry_time(), Duration::from_secs(non_default_invoice_expiry_secs.into()));
1478         }
1479
1480         #[test]
1481         #[cfg(feature = "std")]
1482         fn test_multi_node_hints_includes_single_channels_to_participating_nodes() {
1483                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1484                 let seed_1 = [42u8; 32];
1485                 let seed_2 = [43u8; 32];
1486                 let cross_node_seed = [44u8; 32];
1487                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1488                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1489                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1490                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1491                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1492
1493                 let chan_0_1 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
1494                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1495
1496                 let mut scid_aliases = HashSet::new();
1497                 scid_aliases.insert(chan_0_1.0.short_channel_id_alias.unwrap());
1498                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1499
1500                 match_multi_node_invoice_routes(
1501                         Some(10_000),
1502                         &nodes[1],
1503                         vec![&nodes[1], &nodes[2],],
1504                         scid_aliases,
1505                         false
1506                 );
1507         }
1508
1509         #[test]
1510         #[cfg(feature = "std")]
1511         fn test_multi_node_hints_includes_one_channel_of_each_counterparty_nodes_per_participating_node() {
1512                 let mut chanmon_cfgs = create_chanmon_cfgs(4);
1513                 let seed_1 = [42u8; 32];
1514                 let seed_2 = [43u8; 32];
1515                 let cross_node_seed = [44u8; 32];
1516                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1517                 chanmon_cfgs[3].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1518                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1519                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1520                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1521
1522                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1523                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 1000000, 10001);
1524                 let chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 3_000_000, 10005);
1525
1526                 let mut scid_aliases = HashSet::new();
1527                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1528                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1529                 scid_aliases.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1530
1531                 match_multi_node_invoice_routes(
1532                         Some(10_000),
1533                         &nodes[2],
1534                         vec![&nodes[2], &nodes[3],],
1535                         scid_aliases,
1536                         false
1537                 );
1538         }
1539
1540         #[test]
1541         #[cfg(feature = "std")]
1542         fn test_multi_node_forwarding_info_not_assigned_channel_excluded_from_hints() {
1543                 let mut chanmon_cfgs = create_chanmon_cfgs(4);
1544                 let seed_1 = [42u8; 32];
1545                 let seed_2 = [43u8; 32];
1546                 let cross_node_seed = [44u8; 32];
1547                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1548                 chanmon_cfgs[3].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1549                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1550                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1551                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1552
1553                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1554                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 1000000, 10001);
1555
1556                 // Create an unannonced channel between `nodes[1]` and `nodes[3]`, for which the
1557                 // `msgs::ChannelUpdate` is never handled for the node(s). As the `msgs::ChannelUpdate`
1558                 // is never handled, the `channel.counterparty.forwarding_info` is never assigned.
1559                 let mut private_chan_cfg = UserConfig::default();
1560                 private_chan_cfg.channel_handshake_config.announced_channel = false;
1561                 let temporary_channel_id = nodes[1].node.create_channel(nodes[3].node.get_our_node_id(), 1_000_000, 500_000_000, 42, Some(private_chan_cfg)).unwrap();
1562                 let open_channel = get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, nodes[3].node.get_our_node_id());
1563                 nodes[3].node.handle_open_channel(&nodes[1].node.get_our_node_id(), &open_channel);
1564                 let accept_channel = get_event_msg!(nodes[3], MessageSendEvent::SendAcceptChannel, nodes[1].node.get_our_node_id());
1565                 nodes[1].node.handle_accept_channel(&nodes[3].node.get_our_node_id(), &accept_channel);
1566
1567                 let tx = sign_funding_transaction(&nodes[1], &nodes[3], 1_000_000, temporary_channel_id);
1568
1569                 let conf_height = core::cmp::max(nodes[1].best_block_info().1 + 1, nodes[3].best_block_info().1 + 1);
1570                 confirm_transaction_at(&nodes[1], &tx, conf_height);
1571                 connect_blocks(&nodes[1], CHAN_CONFIRM_DEPTH - 1);
1572                 confirm_transaction_at(&nodes[3], &tx, conf_height);
1573                 connect_blocks(&nodes[3], CHAN_CONFIRM_DEPTH - 1);
1574                 let as_channel_ready = get_event_msg!(nodes[1], MessageSendEvent::SendChannelReady, nodes[3].node.get_our_node_id());
1575                 nodes[1].node.handle_channel_ready(&nodes[3].node.get_our_node_id(), &get_event_msg!(nodes[3], MessageSendEvent::SendChannelReady, nodes[1].node.get_our_node_id()));
1576                 get_event_msg!(nodes[1], MessageSendEvent::SendChannelUpdate, nodes[3].node.get_our_node_id());
1577                 nodes[3].node.handle_channel_ready(&nodes[1].node.get_our_node_id(), &as_channel_ready);
1578                 get_event_msg!(nodes[3], MessageSendEvent::SendChannelUpdate, nodes[1].node.get_our_node_id());
1579                 expect_channel_ready_event(&nodes[1], &nodes[3].node.get_our_node_id());
1580                 expect_channel_ready_event(&nodes[3], &nodes[1].node.get_our_node_id());
1581
1582                 // As `msgs::ChannelUpdate` was never handled for the participating node(s) of the third
1583                 // channel, the channel will never be assigned any `counterparty.forwarding_info`.
1584                 // Therefore only `chan_0_3` should be included in the hints for `nodes[3]`.
1585                 let mut scid_aliases = HashSet::new();
1586                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1587                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1588
1589                 match_multi_node_invoice_routes(
1590                         Some(10_000),
1591                         &nodes[2],
1592                         vec![&nodes[2], &nodes[3],],
1593                         scid_aliases,
1594                         false
1595                 );
1596         }
1597
1598         #[test]
1599         #[cfg(feature = "std")]
1600         fn test_multi_node_with_only_public_channels_hints_includes_only_phantom_route() {
1601                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1602                 let seed_1 = [42u8; 32];
1603                 let seed_2 = [43u8; 32];
1604                 let cross_node_seed = [44u8; 32];
1605                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1606                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1607                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1608                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1609                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1610
1611                 let chan_0_1 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
1612
1613                 let chan_2_0 = create_announced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);
1614                 nodes[2].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_2_0.1);
1615                 nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan_2_0.0);
1616
1617                 // Hints should include `chan_0_1` from as `nodes[1]` only have private channels, but not
1618                 // `chan_0_2` as `nodes[2]` only has public channels.
1619                 let mut scid_aliases = HashSet::new();
1620                 scid_aliases.insert(chan_0_1.0.short_channel_id_alias.unwrap());
1621
1622                 match_multi_node_invoice_routes(
1623                         Some(10_000),
1624                         &nodes[1],
1625                         vec![&nodes[1], &nodes[2],],
1626                         scid_aliases,
1627                         true
1628                 );
1629         }
1630
1631         #[test]
1632         #[cfg(feature = "std")]
1633         fn test_multi_node_with_mixed_public_and_private_channel_hints_includes_only_phantom_route() {
1634                 let mut chanmon_cfgs = create_chanmon_cfgs(4);
1635                 let seed_1 = [42u8; 32];
1636                 let seed_2 = [43u8; 32];
1637                 let cross_node_seed = [44u8; 32];
1638                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1639                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1640                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1641                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1642                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1643
1644                 let chan_0_2 = create_announced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1645                 nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan_0_2.1);
1646                 nodes[2].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_0_2.0);
1647                 let _chan_1_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 100000, 10001);
1648
1649                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 100000, 10001);
1650
1651                 // Hints should include `chan_0_3` from as `nodes[3]` only have private channels, and no
1652                 // channels for `nodes[2]` as it contains a mix of public and private channels.
1653                 let mut scid_aliases = HashSet::new();
1654                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1655
1656                 match_multi_node_invoice_routes(
1657                         Some(10_000),
1658                         &nodes[2],
1659                         vec![&nodes[2], &nodes[3],],
1660                         scid_aliases,
1661                         true
1662                 );
1663         }
1664
1665         #[test]
1666         #[cfg(feature = "std")]
1667         fn test_multi_node_hints_has_only_lowest_inbound_channel_above_minimum() {
1668                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1669                 let seed_1 = [42u8; 32];
1670                 let seed_2 = [43u8; 32];
1671                 let cross_node_seed = [44u8; 32];
1672                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1673                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1674                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1675                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1676                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1677
1678                 let _chan_0_1_below_amt = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100_000, 0);
1679                 let _chan_0_1_above_amt_high_inbound = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 500_000, 0);
1680                 let chan_0_1_above_amt_low_inbound = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 180_000, 0);
1681                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1682
1683                 let mut scid_aliases = HashSet::new();
1684                 scid_aliases.insert(chan_0_1_above_amt_low_inbound.0.short_channel_id_alias.unwrap());
1685                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1686
1687                 match_multi_node_invoice_routes(
1688                         Some(100_000_000),
1689                         &nodes[1],
1690                         vec![&nodes[1], &nodes[2],],
1691                         scid_aliases,
1692                         false
1693                 );
1694         }
1695
1696         #[test]
1697         #[cfg(feature = "std")]
1698         fn test_multi_node_channels_inbound_capacity_lower_than_invoice_amt_filtering() {
1699                 let mut chanmon_cfgs = create_chanmon_cfgs(4);
1700                 let seed_1 = [42u8; 32];
1701                 let seed_2 = [43u8; 32];
1702                 let cross_node_seed = [44u8; 32];
1703                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1704                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1705                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1706                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1707                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1708
1709                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 1_000_000, 0);
1710                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 100_000, 0);
1711                 let chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 200_000, 0);
1712
1713                 // Since the invoice 1 msat above chan_0_3's inbound capacity, it should be filtered out.
1714                 let mut scid_aliases_99_000_001_msat = HashSet::new();
1715                 scid_aliases_99_000_001_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1716                 scid_aliases_99_000_001_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1717
1718                 match_multi_node_invoice_routes(
1719                         Some(99_000_001),
1720                         &nodes[2],
1721                         vec![&nodes[2], &nodes[3],],
1722                         scid_aliases_99_000_001_msat,
1723                         false
1724                 );
1725
1726                 // Since the invoice is exactly at chan_0_3's inbound capacity, it should be included.
1727                 let mut scid_aliases_99_000_000_msat = HashSet::new();
1728                 scid_aliases_99_000_000_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1729                 scid_aliases_99_000_000_msat.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1730                 scid_aliases_99_000_000_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1731
1732                 match_multi_node_invoice_routes(
1733                         Some(99_000_000),
1734                         &nodes[2],
1735                         vec![&nodes[2], &nodes[3],],
1736                         scid_aliases_99_000_000_msat,
1737                         false
1738                 );
1739
1740                 // Since the invoice is above all of `nodes[2]` channels' inbound capacity, all of
1741                 // `nodes[2]` them should be included.
1742                 let mut scid_aliases_300_000_000_msat = HashSet::new();
1743                 scid_aliases_300_000_000_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1744                 scid_aliases_300_000_000_msat.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1745                 scid_aliases_300_000_000_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1746
1747                 match_multi_node_invoice_routes(
1748                         Some(300_000_000),
1749                         &nodes[2],
1750                         vec![&nodes[2], &nodes[3],],
1751                         scid_aliases_300_000_000_msat,
1752                         false
1753                 );
1754
1755                 // Since the no specified amount, all channels should included.
1756                 let mut scid_aliases_no_specified_amount = HashSet::new();
1757                 scid_aliases_no_specified_amount.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1758                 scid_aliases_no_specified_amount.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1759                 scid_aliases_no_specified_amount.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1760
1761                 match_multi_node_invoice_routes(
1762                         None,
1763                         &nodes[2],
1764                         vec![&nodes[2], &nodes[3],],
1765                         scid_aliases_no_specified_amount,
1766                         false
1767                 );
1768         }
1769
1770         #[test]
1771         fn test_multi_node_hints_limited_to_3() {
1772                 let mut chanmon_cfgs = create_chanmon_cfgs(6);
1773                 let seed_1 = [42 as u8; 32];
1774                 let seed_2 = [43 as u8; 32];
1775                 let seed_3 = [44 as u8; 32];
1776                 let seed_4 = [45 as u8; 32];
1777                 let cross_node_seed = [44 as u8; 32];
1778                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1779                 chanmon_cfgs[3].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1780                 chanmon_cfgs[4].keys_manager.backing = PhantomKeysManager::new(&seed_3, 43, 44, &cross_node_seed);
1781                 chanmon_cfgs[5].keys_manager.backing = PhantomKeysManager::new(&seed_4, 43, 44, &cross_node_seed);
1782                 let node_cfgs = create_node_cfgs(6, &chanmon_cfgs);
1783                 let node_chanmgrs = create_node_chanmgrs(6, &node_cfgs, &[None, None, None, None, None, None]);
1784                 let nodes = create_network(6, &node_cfgs, &node_chanmgrs);
1785
1786                 // Setup each phantom node with two channels from distinct peers.
1787                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 10_000, 0);
1788                 let chan_1_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 20_000, 0);
1789                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 20_000, 0);
1790                 let _chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 10_000, 0);
1791                 let chan_0_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 4, 20_000, 0);
1792                 let _chan_1_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 4, 10_000, 0);
1793                 let _chan_0_5 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 5, 20_000, 0);
1794                 let _chan_1_5 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 5, 10_000, 0);
1795
1796                 // Set invoice amount > all channels inbound so that every one is eligible for inclusion
1797                 // and hints will be sorted by largest inbound capacity.
1798                 let invoice_amt = Some(100_000_000);
1799
1800                 // With 4 phantom nodes, assert that we include 1 hint per node, up to 3 nodes.
1801                 let mut scid_aliases = HashSet::new();
1802                 scid_aliases.insert(chan_1_2.0.short_channel_id_alias.unwrap());
1803                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1804                 scid_aliases.insert(chan_0_4.0.short_channel_id_alias.unwrap());
1805
1806                 match_multi_node_invoice_routes(
1807                         invoice_amt,
1808                         &nodes[3],
1809                         vec![&nodes[2], &nodes[3], &nodes[4], &nodes[5]],
1810                         scid_aliases,
1811                         false,
1812                 );
1813
1814                 // With 2 phantom nodes, assert that we include no more than 3 hints.
1815                 let mut scid_aliases = HashSet::new();
1816                 scid_aliases.insert(chan_1_2.0.short_channel_id_alias.unwrap());
1817                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1818                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1819
1820                 match_multi_node_invoice_routes(
1821                         invoice_amt,
1822                         &nodes[3],
1823                         vec![&nodes[2], &nodes[3]],
1824                         scid_aliases,
1825                         false,
1826                 );
1827         }
1828
1829         #[test]
1830         fn test_multi_node_hints_at_least_3() {
1831                 let mut chanmon_cfgs = create_chanmon_cfgs(5);
1832                 let seed_1 = [42 as u8; 32];
1833                 let seed_2 = [43 as u8; 32];
1834                 let cross_node_seed = [44 as u8; 32];
1835                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1836                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1837                 let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
1838                 let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
1839                 let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
1840
1841                 let _chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 10_000, 0);
1842                 let chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 20_000, 0);
1843                 let chan_2_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 3, 30_000, 0);
1844                 let chan_0_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 4, 10_000, 0);
1845
1846                 // Since the invoice amount is above all channels inbound, all four are eligible. Test that
1847                 // we still include 3 hints from 2 distinct nodes sorted by inbound.
1848                 let mut scid_aliases = HashSet::new();
1849                 scid_aliases.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1850                 scid_aliases.insert(chan_2_3.0.short_channel_id_alias.unwrap());
1851                 scid_aliases.insert(chan_0_4.0.short_channel_id_alias.unwrap());
1852
1853                 match_multi_node_invoice_routes(
1854                         Some(100_000_000),
1855                         &nodes[3],
1856                         vec![&nodes[3], &nodes[4],],
1857                         scid_aliases,
1858                         false,
1859                 );
1860         }
1861
1862         fn match_multi_node_invoice_routes<'a, 'b: 'a, 'c: 'b>(
1863                 invoice_amt: Option<u64>,
1864                 invoice_node: &Node<'a, 'b, 'c>,
1865                 network_multi_nodes: Vec<&Node<'a, 'b, 'c>>,
1866                 mut chan_ids_to_match: HashSet<u64>,
1867                 nodes_contains_public_channels: bool
1868         ){
1869                 let phantom_route_hints = network_multi_nodes.iter()
1870                         .map(|node| node.node.get_phantom_route_hints())
1871                         .collect::<Vec<PhantomRouteHints>>();
1872                 let phantom_scids = phantom_route_hints.iter()
1873                         .map(|route_hint| route_hint.phantom_scid)
1874                         .collect::<HashSet<u64>>();
1875
1876                 let invoice = crate::utils::create_phantom_invoice::<&test_utils::TestKeysInterface,
1877                         &test_utils::TestKeysInterface, &test_utils::TestLogger>(invoice_amt, None, "test".to_string(),
1878                                 3600, phantom_route_hints, invoice_node.keys_manager, invoice_node.keys_manager,
1879                                 invoice_node.logger, Currency::BitcoinTestnet, None, Duration::from_secs(1234567)).unwrap();
1880
1881                 let invoice_hints = invoice.private_routes();
1882
1883                 for hint in invoice_hints {
1884                         let hints = &(hint.0).0;
1885                         match hints.len() {
1886                                 1 => {
1887                                         assert!(nodes_contains_public_channels);
1888                                         let phantom_scid = hints[0].short_channel_id;
1889                                         assert!(phantom_scids.contains(&phantom_scid));
1890                                 },
1891                                 2 => {
1892                                         let hint_short_chan_id = hints[0].short_channel_id;
1893                                         assert!(chan_ids_to_match.remove(&hint_short_chan_id));
1894                                         let phantom_scid = hints[1].short_channel_id;
1895                                         assert!(phantom_scids.contains(&phantom_scid));
1896                                 },
1897                                 _ => panic!("Incorrect hint length generated")
1898                         }
1899                 }
1900                 assert!(chan_ids_to_match.is_empty(), "Unmatched short channel ids: {:?}", chan_ids_to_match);
1901         }
1902
1903         #[test]
1904         fn test_create_invoice_fails_with_invalid_custom_min_final_cltv_expiry_delta() {
1905                 let chanmon_cfgs = create_chanmon_cfgs(2);
1906                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
1907                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
1908                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
1909                 let result = crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch(
1910                         nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
1911                         Some(10_000), "Some description".into(), Duration::from_secs(1234567), 3600, Some(MIN_FINAL_CLTV_EXPIRY_DELTA - 4),
1912                 );
1913                 match result {
1914                         Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort)) => {},
1915                         _ => panic!(),
1916                 }
1917         }
1918
1919         #[test]
1920         fn test_rotate_through_iterators() {
1921                 // two nested vectors
1922                 let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec!["a1", "b1"].into_iter()];
1923                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1924
1925                 let expected = vec!["a0", "a1", "b0", "b1", "c0"];
1926                 assert_eq!(expected, result);
1927
1928                 // test single nested vector
1929                 let a = vec![vec!["a0", "b0", "c0"].into_iter()];
1930                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1931
1932                 let expected = vec!["a0", "b0", "c0"];
1933                 assert_eq!(expected, result);
1934
1935                 // test second vector with only one element
1936                 let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec!["a1"].into_iter()];
1937                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1938
1939                 let expected = vec!["a0", "a1", "b0", "c0"];
1940                 assert_eq!(expected, result);
1941
1942                 // test three nestend vectors
1943                 let a = vec![vec!["a0"].into_iter(), vec!["a1", "b1", "c1"].into_iter(), vec!["a2"].into_iter()];
1944                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1945
1946                 let expected = vec!["a0", "a1", "a2", "b1", "c1"];
1947                 assert_eq!(expected, result);
1948
1949                 // test single nested vector with a single value
1950                 let a = vec![vec!["a0"].into_iter()];
1951                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1952
1953                 let expected = vec!["a0"];
1954                 assert_eq!(expected, result);
1955
1956                 // test single empty nested vector
1957                 let a:Vec<std::vec::IntoIter<&str>> = vec![vec![].into_iter()];
1958                 let result = rotate_through_iterators(a).collect::<Vec<&str>>();
1959                 let expected:Vec<&str> = vec![];
1960
1961                 assert_eq!(expected, result);
1962
1963                 // test first nested vector is empty
1964                 let a:Vec<std::vec::IntoIter<&str>>= vec![vec![].into_iter(), vec!["a1", "b1", "c1"].into_iter()];
1965                 let result = rotate_through_iterators(a).collect::<Vec<&str>>();
1966
1967                 let expected = vec!["a1", "b1", "c1"];
1968                 assert_eq!(expected, result);
1969
1970                 // test two empty vectors
1971                 let a:Vec<std::vec::IntoIter<&str>> = vec![vec![].into_iter(), vec![].into_iter()];
1972                 let result = rotate_through_iterators(a).collect::<Vec<&str>>();
1973
1974                 let expected:Vec<&str> = vec![];
1975                 assert_eq!(expected, result);
1976
1977                 // test an empty vector amongst other filled vectors
1978                 let a = vec![
1979                         vec!["a0", "b0", "c0"].into_iter(),
1980                         vec![].into_iter(),
1981                         vec!["a1", "b1", "c1"].into_iter(),
1982                         vec!["a2", "b2", "c2"].into_iter(),
1983                 ];
1984                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1985
1986                 let expected = vec!["a0", "a1", "a2", "b0", "b1", "b2", "c0", "c1", "c2"];
1987                 assert_eq!(expected, result);
1988
1989                 // test a filled vector between two empty vectors
1990                 let a = vec![vec![].into_iter(), vec!["a1", "b1", "c1"].into_iter(), vec![].into_iter()];
1991                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1992
1993                 let expected = vec!["a1", "b1", "c1"];
1994                 assert_eq!(expected, result);
1995
1996                 // test an empty vector at the end of the vectors
1997                 let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec![].into_iter()];
1998                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1999
2000                 let expected = vec!["a0", "b0", "c0"];
2001                 assert_eq!(expected, result);
2002
2003                 // test multiple empty vectors amongst multiple filled vectors
2004                 let a = vec![
2005                         vec![].into_iter(),
2006                         vec!["a1", "b1", "c1"].into_iter(),
2007                         vec![].into_iter(),
2008                         vec!["a3", "b3"].into_iter(),
2009                         vec![].into_iter(),
2010                 ];
2011
2012                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
2013
2014                 let expected = vec!["a1", "a3", "b1", "b3", "c1"];
2015                 assert_eq!(expected, result);
2016
2017                 // test one element in the first nested vectore and two elements in the second nested
2018                 // vector
2019                 let a = vec![vec!["a0"].into_iter(), vec!["a1", "b1"].into_iter()];
2020                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
2021
2022                 let expected = vec!["a0", "a1", "b1"];
2023                 assert_eq!(expected, result);
2024         }
2025 }