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

   1 //! Convenient utilities to create an invoice.
   2
   3 use crate::{Bolt11Invoice, CreationError, Currency, InvoiceBuilder, SignOrCreationError};
   4
   5 use crate::{prelude::*, Description, Bolt11InvoiceDescription, 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<Bolt11Invoice, 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 = Bolt11InvoiceDescription::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<Bolt11Invoice, 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, Bolt11InvoiceDescription::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: Bolt11InvoiceDescription,
 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<Bolt11Invoice, 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                 Bolt11InvoiceDescription::Direct(description) => {
 161                         InvoiceBuilder::new(network).description(description.0.0.clone())
 162                 }
 163                 Bolt11InvoiceDescription::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(), &payment_hash);
 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(Bolt11Invoice::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<Bolt11Invoice, 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<Bolt11Invoice, 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<Bolt11Invoice, 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                 Bolt11InvoiceDescription::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<Bolt11Invoice, 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                 Bolt11InvoiceDescription::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: Bolt11InvoiceDescription,
 455         duration_since_epoch: Duration, invoice_expiry_delta_secs: u32, min_final_cltv_expiry_delta: Option<u16>,
 456 ) -> Result<Bolt11Invoice, 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<Bolt11Invoice, 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                 Bolt11InvoiceDescription::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: Bolt11InvoiceDescription,
 517         duration_since_epoch: Duration, invoice_expiry_delta_secs: u32, payment_hash: PaymentHash,
 518         payment_secret: PaymentSecret, min_final_cltv_expiry_delta: Option<u16>,
 519 ) -> Result<Bolt11Invoice, 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 {}", &payment_hash);
 538
 539         let invoice = match description {
 540                 Bolt11InvoiceDescription::Direct(description) => {
 541                         InvoiceBuilder::new(network).description(description.0.0.clone())
 542                 }
 543                 Bolt11InvoiceDescription::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(Bolt11Invoice::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", &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                                         &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                                                 &channel.channel_id, channel.short_channel_id,
 685                                                 channel.inbound_capacity_msat,
 686                                                 &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                                                 &entry.get().channel_id, entry.get().short_channel_id,
 694                                                 current_max_capacity,
 695                                                 &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                                         &channel.channel_id);
 735                         } else if !has_enough_capacity {
 736                                 log_trace!(logger, "Ignoring channel {} without enough capacity for invoice route hints",
 737                                         &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                                         &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::cell::RefCell;
 796         use core::time::Duration;
 797         use crate::{Currency, Description, Bolt11InvoiceDescription, SignOrCreationError, CreationError};
 798         use bitcoin_hashes::{Hash, sha256};
 799         use bitcoin_hashes::sha256::Hash as Sha256;
 800         use lightning::sign::PhantomKeysManager;
 801         use lightning::events::{MessageSendEvent, MessageSendEventsProvider, Event, EventsProvider};
 802         use lightning::ln::{PaymentPreimage, PaymentHash};
 803         use lightning::ln::channelmanager::{PhantomRouteHints, MIN_FINAL_CLTV_EXPIRY_DELTA, PaymentId, RecipientOnionFields, Retry};
 804         use lightning::ln::functional_test_utils::*;
 805         use lightning::ln::msgs::ChannelMessageHandler;
 806         use lightning::routing::router::{PaymentParameters, RouteParameters};
 807         use lightning::util::test_utils;
 808         use lightning::util::config::UserConfig;
 809         use crate::utils::{create_invoice_from_channelmanager_and_duration_since_epoch, rotate_through_iterators};
 810         use std::collections::HashSet;
 811         use lightning::util::string::UntrustedString;
 812
 813         #[test]
 814         fn test_prefer_current_channel() {
 815                 // No minimum, prefer larger candidate channel.
 816                 assert_eq!(crate::utils::prefer_current_channel(None, 100, 200), false);
 817
 818                 // No minimum, prefer larger current channel.
 819                 assert_eq!(crate::utils::prefer_current_channel(None, 200, 100), true);
 820
 821                 // Minimum set, prefer current channel over minimum + buffer.
 822                 assert_eq!(crate::utils::prefer_current_channel(Some(100), 115, 100), true);
 823
 824                 // Minimum set, prefer candidate channel over minimum + buffer.
 825                 assert_eq!(crate::utils::prefer_current_channel(Some(100), 105, 125), false);
 826
 827                 // Minimum set, both channels sufficient, prefer smaller current channel.
 828                 assert_eq!(crate::utils::prefer_current_channel(Some(100), 115, 125), true);
 829
 830                 // Minimum set, both channels sufficient, prefer smaller candidate channel.
 831                 assert_eq!(crate::utils::prefer_current_channel(Some(100), 200, 160), false);
 832
 833                 // Minimum set, neither sufficient, prefer larger current channel.
 834                 assert_eq!(crate::utils::prefer_current_channel(Some(200), 100, 50), true);
 835
 836                 // Minimum set, neither sufficient, prefer larger candidate channel.
 837                 assert_eq!(crate::utils::prefer_current_channel(Some(200), 100, 150), false);
 838         }
 839
 840
 841         #[test]
 842         fn test_from_channelmanager() {
 843                 let chanmon_cfgs = create_chanmon_cfgs(2);
 844                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
 845                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
 846                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 847                 create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
 848                 let non_default_invoice_expiry_secs = 4200;
 849                 let invoice = create_invoice_from_channelmanager_and_duration_since_epoch(
 850                         nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
 851                         Some(10_000), "test".to_string(), Duration::from_secs(1234567),
 852                         non_default_invoice_expiry_secs, None).unwrap();
 853                 assert_eq!(invoice.amount_pico_btc(), Some(100_000));
 854                 // If no `min_final_cltv_expiry_delta` is specified, then it should be `MIN_FINAL_CLTV_EXPIRY_DELTA`.
 855                 assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
 856                 assert_eq!(invoice.description(), Bolt11InvoiceDescription::Direct(&Description(UntrustedString("test".to_string()))));
 857                 assert_eq!(invoice.expiry_time(), Duration::from_secs(non_default_invoice_expiry_secs.into()));
 858
 859                 // Invoice SCIDs should always use inbound SCID aliases over the real channel ID, if one is
 860                 // available.
 861                 let chan = &nodes[1].node.list_usable_channels()[0];
 862                 assert_eq!(invoice.route_hints().len(), 1);
 863                 assert_eq!(invoice.route_hints()[0].0.len(), 1);
 864                 assert_eq!(invoice.route_hints()[0].0[0].short_channel_id, chan.inbound_scid_alias.unwrap());
 865
 866                 assert_eq!(invoice.route_hints()[0].0[0].htlc_minimum_msat, chan.inbound_htlc_minimum_msat);
 867                 assert_eq!(invoice.route_hints()[0].0[0].htlc_maximum_msat, chan.inbound_htlc_maximum_msat);
 868
 869                 let payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key(),
 870                                 invoice.min_final_cltv_expiry_delta() as u32)
 871                         .with_bolt11_features(invoice.features().unwrap().clone()).unwrap()
 872                         .with_route_hints(invoice.route_hints()).unwrap();
 873                 let route_params = RouteParameters::from_payment_params_and_value(
 874                         payment_params, invoice.amount_milli_satoshis().unwrap());
 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(), Bolt11InvoiceDescription::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(), Bolt11InvoiceDescription::Direct(&Description(UntrustedString("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, None, 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(), Bolt11InvoiceDescription::Direct(&Description(UntrustedString("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::from_payment_params_and_value(
1329                         payment_params, invoice.amount_milli_satoshis().unwrap());
1330                 let (payment_event, fwd_idx) = {
1331                         let mut payment_hash = PaymentHash([0; 32]);
1332                         payment_hash.0.copy_from_slice(&invoice.payment_hash().as_ref()[0..32]);
1333                         nodes[0].node.send_payment(payment_hash,
1334                                 RecipientOnionFields::secret_only(*invoice.payment_secret()),
1335                                 PaymentId(payment_hash.0), params, Retry::Attempts(0)).unwrap();
1336                         let mut added_monitors = nodes[0].chain_monitor.added_monitors.lock().unwrap();
1337                         assert_eq!(added_monitors.len(), 1);
1338                         added_monitors.clear();
1339
1340                         let mut events = nodes[0].node.get_and_clear_pending_msg_events();
1341                         assert_eq!(events.len(), 1);
1342                         let fwd_idx = match events[0] {
1343                                 MessageSendEvent::UpdateHTLCs { node_id, .. } => {
1344                                         if node_id == nodes[1].node.get_our_node_id() {
1345                                                 1
1346                                         } else { 2 }
1347                                 },
1348                                 _ => panic!("Unexpected event")
1349                         };
1350                         (SendEvent::from_event(events.remove(0)), fwd_idx)
1351                 };
1352                 nodes[fwd_idx].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
1353                 commitment_signed_dance!(nodes[fwd_idx], nodes[0], &payment_event.commitment_msg, false, true);
1354
1355                 // Note that we have to "forward pending HTLCs" twice before we see the PaymentClaimable as
1356                 // this "emulates" the payment taking two hops, providing some privacy to make phantom node
1357                 // payments "look real" by taking more time.
1358                 let other_events = RefCell::new(Vec::new());
1359                 let forward_event_handler = |event: Event| {
1360                         if let Event::PendingHTLCsForwardable { .. } = event {
1361                                 nodes[fwd_idx].node.process_pending_htlc_forwards();
1362                         } else {
1363                                 other_events.borrow_mut().push(event);
1364                         }
1365                 };
1366                 nodes[fwd_idx].node.process_pending_events(&forward_event_handler);
1367                 nodes[fwd_idx].node.process_pending_events(&forward_event_handler);
1368
1369                 let payment_preimage_opt = if user_generated_pmt_hash { None } else { Some(payment_preimage) };
1370                 assert_eq!(other_events.borrow().len(), 1);
1371                 check_payment_claimable(&other_events.borrow()[0], payment_hash, payment_secret, payment_amt, payment_preimage_opt, invoice.recover_payee_pub_key());
1372                 do_claim_payment_along_route(&nodes[0], &[&vec!(&nodes[fwd_idx])[..]], false, payment_preimage);
1373                 expect_payment_sent(&nodes[0], payment_preimage, None, true, true);
1374         }
1375
1376         #[test]
1377         #[cfg(feature = "std")]
1378         fn test_multi_node_hints_has_htlc_min_max_values() {
1379                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1380                 let seed_1 = [42u8; 32];
1381                 let seed_2 = [43u8; 32];
1382                 let cross_node_seed = [44u8; 32];
1383                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1384                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1385                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1386                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1387                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1388
1389                 create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
1390                 create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1391
1392                 let payment_amt = 20_000;
1393                 let (payment_hash, _payment_secret) = nodes[1].node.create_inbound_payment(Some(payment_amt), 3600, None).unwrap();
1394                 let route_hints = vec![
1395                         nodes[1].node.get_phantom_route_hints(),
1396                         nodes[2].node.get_phantom_route_hints(),
1397                 ];
1398
1399                 let invoice = crate::utils::create_phantom_invoice::<&test_utils::TestKeysInterface,
1400                         &test_utils::TestKeysInterface, &test_utils::TestLogger>(Some(payment_amt), Some(payment_hash),
1401                                 "test".to_string(), 3600, route_hints, nodes[1].keys_manager, nodes[1].keys_manager,
1402                                 nodes[1].logger, Currency::BitcoinTestnet, None, Duration::from_secs(1234567)).unwrap();
1403
1404                 let chan_0_1 = &nodes[1].node.list_usable_channels()[0];
1405                 assert_eq!(invoice.route_hints()[0].0[0].htlc_minimum_msat, chan_0_1.inbound_htlc_minimum_msat);
1406                 assert_eq!(invoice.route_hints()[0].0[0].htlc_maximum_msat, chan_0_1.inbound_htlc_maximum_msat);
1407
1408                 let chan_0_2 = &nodes[2].node.list_usable_channels()[0];
1409                 assert_eq!(invoice.route_hints()[1].0[0].htlc_minimum_msat, chan_0_2.inbound_htlc_minimum_msat);
1410                 assert_eq!(invoice.route_hints()[1].0[0].htlc_maximum_msat, chan_0_2.inbound_htlc_maximum_msat);
1411         }
1412
1413         #[test]
1414         #[cfg(feature = "std")]
1415         fn create_phantom_invoice_with_description_hash() {
1416                 let chanmon_cfgs = create_chanmon_cfgs(3);
1417                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1418                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1419                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1420
1421                 let payment_amt = 20_000;
1422                 let route_hints = vec![
1423                         nodes[1].node.get_phantom_route_hints(),
1424                         nodes[2].node.get_phantom_route_hints(),
1425                 ];
1426
1427                 let description_hash = crate::Sha256(Hash::hash("Description hash phantom invoice".as_bytes()));
1428                 let non_default_invoice_expiry_secs = 4200;
1429                 let invoice = crate::utils::create_phantom_invoice_with_description_hash::<
1430                         &test_utils::TestKeysInterface, &test_utils::TestKeysInterface, &test_utils::TestLogger,
1431                 >(
1432                         Some(payment_amt), None, non_default_invoice_expiry_secs, description_hash,
1433                         route_hints, nodes[1].keys_manager, nodes[1].keys_manager, nodes[1].logger,
1434                         Currency::BitcoinTestnet, None, Duration::from_secs(1234567),
1435                 )
1436                 .unwrap();
1437                 assert_eq!(invoice.amount_pico_btc(), Some(200_000));
1438                 assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
1439                 assert_eq!(invoice.expiry_time(), Duration::from_secs(non_default_invoice_expiry_secs.into()));
1440                 assert_eq!(invoice.description(), Bolt11InvoiceDescription::Hash(&crate::Sha256(Sha256::hash("Description hash phantom invoice".as_bytes()))));
1441         }
1442
1443         #[test]
1444         #[cfg(feature = "std")]
1445         fn create_phantom_invoice_with_custom_payment_hash_and_custom_min_final_cltv_delta() {
1446                 let chanmon_cfgs = create_chanmon_cfgs(3);
1447                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1448                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1449                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1450
1451                 let payment_amt = 20_000;
1452                 let route_hints = vec![
1453                         nodes[1].node.get_phantom_route_hints(),
1454                         nodes[2].node.get_phantom_route_hints(),
1455                 ];
1456                 let user_payment_preimage = PaymentPreimage([1; 32]);
1457                 let payment_hash = Some(PaymentHash(Sha256::hash(&user_payment_preimage.0[..]).into_inner()));
1458                 let non_default_invoice_expiry_secs = 4200;
1459                 let min_final_cltv_expiry_delta = Some(100);
1460                 let duration_since_epoch = Duration::from_secs(1234567);
1461                 let invoice = crate::utils::create_phantom_invoice::<&test_utils::TestKeysInterface,
1462                         &test_utils::TestKeysInterface, &test_utils::TestLogger>(Some(payment_amt), payment_hash,
1463                                 "".to_string(), non_default_invoice_expiry_secs, route_hints, nodes[1].keys_manager, nodes[1].keys_manager,
1464                                 nodes[1].logger, Currency::BitcoinTestnet, min_final_cltv_expiry_delta, duration_since_epoch).unwrap();
1465                 assert_eq!(invoice.amount_pico_btc(), Some(200_000));
1466                 assert_eq!(invoice.min_final_cltv_expiry_delta(), (min_final_cltv_expiry_delta.unwrap() + 3) as u64);
1467                 assert_eq!(invoice.expiry_time(), Duration::from_secs(non_default_invoice_expiry_secs.into()));
1468         }
1469
1470         #[test]
1471         #[cfg(feature = "std")]
1472         fn test_multi_node_hints_includes_single_channels_to_participating_nodes() {
1473                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1474                 let seed_1 = [42u8; 32];
1475                 let seed_2 = [43u8; 32];
1476                 let cross_node_seed = [44u8; 32];
1477                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1478                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1479                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1480                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1481                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1482
1483                 let chan_0_1 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
1484                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1485
1486                 let mut scid_aliases = HashSet::new();
1487                 scid_aliases.insert(chan_0_1.0.short_channel_id_alias.unwrap());
1488                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1489
1490                 match_multi_node_invoice_routes(
1491                         Some(10_000),
1492                         &nodes[1],
1493                         vec![&nodes[1], &nodes[2],],
1494                         scid_aliases,
1495                         false
1496                 );
1497         }
1498
1499         #[test]
1500         #[cfg(feature = "std")]
1501         fn test_multi_node_hints_includes_one_channel_of_each_counterparty_nodes_per_participating_node() {
1502                 let mut chanmon_cfgs = create_chanmon_cfgs(4);
1503                 let seed_1 = [42u8; 32];
1504                 let seed_2 = [43u8; 32];
1505                 let cross_node_seed = [44u8; 32];
1506                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1507                 chanmon_cfgs[3].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1508                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1509                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1510                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1511
1512                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1513                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 1000000, 10001);
1514                 let chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 3_000_000, 10005);
1515
1516                 let mut scid_aliases = HashSet::new();
1517                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1518                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1519                 scid_aliases.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1520
1521                 match_multi_node_invoice_routes(
1522                         Some(10_000),
1523                         &nodes[2],
1524                         vec![&nodes[2], &nodes[3],],
1525                         scid_aliases,
1526                         false
1527                 );
1528         }
1529
1530         #[test]
1531         #[cfg(feature = "std")]
1532         fn test_multi_node_forwarding_info_not_assigned_channel_excluded_from_hints() {
1533                 let mut chanmon_cfgs = create_chanmon_cfgs(4);
1534                 let seed_1 = [42u8; 32];
1535                 let seed_2 = [43u8; 32];
1536                 let cross_node_seed = [44u8; 32];
1537                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1538                 chanmon_cfgs[3].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1539                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1540                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1541                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1542
1543                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1544                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 1000000, 10001);
1545
1546                 // Create an unannonced channel between `nodes[1]` and `nodes[3]`, for which the
1547                 // `msgs::ChannelUpdate` is never handled for the node(s). As the `msgs::ChannelUpdate`
1548                 // is never handled, the `channel.counterparty.forwarding_info` is never assigned.
1549                 let mut private_chan_cfg = UserConfig::default();
1550                 private_chan_cfg.channel_handshake_config.announced_channel = false;
1551                 let temporary_channel_id = nodes[1].node.create_channel(nodes[3].node.get_our_node_id(), 1_000_000, 500_000_000, 42, None, Some(private_chan_cfg)).unwrap();
1552                 let open_channel = get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, nodes[3].node.get_our_node_id());
1553                 nodes[3].node.handle_open_channel(&nodes[1].node.get_our_node_id(), &open_channel);
1554                 let accept_channel = get_event_msg!(nodes[3], MessageSendEvent::SendAcceptChannel, nodes[1].node.get_our_node_id());
1555                 nodes[1].node.handle_accept_channel(&nodes[3].node.get_our_node_id(), &accept_channel);
1556
1557                 let tx = sign_funding_transaction(&nodes[1], &nodes[3], 1_000_000, temporary_channel_id);
1558
1559                 let conf_height = core::cmp::max(nodes[1].best_block_info().1 + 1, nodes[3].best_block_info().1 + 1);
1560                 confirm_transaction_at(&nodes[1], &tx, conf_height);
1561                 connect_blocks(&nodes[1], CHAN_CONFIRM_DEPTH - 1);
1562                 confirm_transaction_at(&nodes[3], &tx, conf_height);
1563                 connect_blocks(&nodes[3], CHAN_CONFIRM_DEPTH - 1);
1564                 let as_channel_ready = get_event_msg!(nodes[1], MessageSendEvent::SendChannelReady, nodes[3].node.get_our_node_id());
1565                 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()));
1566                 get_event_msg!(nodes[1], MessageSendEvent::SendChannelUpdate, nodes[3].node.get_our_node_id());
1567                 nodes[3].node.handle_channel_ready(&nodes[1].node.get_our_node_id(), &as_channel_ready);
1568                 get_event_msg!(nodes[3], MessageSendEvent::SendChannelUpdate, nodes[1].node.get_our_node_id());
1569                 expect_channel_ready_event(&nodes[1], &nodes[3].node.get_our_node_id());
1570                 expect_channel_ready_event(&nodes[3], &nodes[1].node.get_our_node_id());
1571
1572                 // As `msgs::ChannelUpdate` was never handled for the participating node(s) of the third
1573                 // channel, the channel will never be assigned any `counterparty.forwarding_info`.
1574                 // Therefore only `chan_0_3` should be included in the hints for `nodes[3]`.
1575                 let mut scid_aliases = HashSet::new();
1576                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1577                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1578
1579                 match_multi_node_invoice_routes(
1580                         Some(10_000),
1581                         &nodes[2],
1582                         vec![&nodes[2], &nodes[3],],
1583                         scid_aliases,
1584                         false
1585                 );
1586         }
1587
1588         #[test]
1589         #[cfg(feature = "std")]
1590         fn test_multi_node_with_only_public_channels_hints_includes_only_phantom_route() {
1591                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1592                 let seed_1 = [42u8; 32];
1593                 let seed_2 = [43u8; 32];
1594                 let cross_node_seed = [44u8; 32];
1595                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1596                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1597                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1598                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1599                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1600
1601                 let chan_0_1 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100000, 10001);
1602
1603                 let chan_2_0 = create_announced_chan_between_nodes_with_value(&nodes, 2, 0, 100000, 10001);
1604                 nodes[2].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_2_0.1);
1605                 nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan_2_0.0);
1606
1607                 // Hints should include `chan_0_1` from as `nodes[1]` only have private channels, but not
1608                 // `chan_0_2` as `nodes[2]` only has public channels.
1609                 let mut scid_aliases = HashSet::new();
1610                 scid_aliases.insert(chan_0_1.0.short_channel_id_alias.unwrap());
1611
1612                 match_multi_node_invoice_routes(
1613                         Some(10_000),
1614                         &nodes[1],
1615                         vec![&nodes[1], &nodes[2],],
1616                         scid_aliases,
1617                         true
1618                 );
1619         }
1620
1621         #[test]
1622         #[cfg(feature = "std")]
1623         fn test_multi_node_with_mixed_public_and_private_channel_hints_includes_only_phantom_route() {
1624                 let mut chanmon_cfgs = create_chanmon_cfgs(4);
1625                 let seed_1 = [42u8; 32];
1626                 let seed_2 = [43u8; 32];
1627                 let cross_node_seed = [44u8; 32];
1628                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1629                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1630                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1631                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1632                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1633
1634                 let chan_0_2 = create_announced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1635                 nodes[0].node.handle_channel_update(&nodes[2].node.get_our_node_id(), &chan_0_2.1);
1636                 nodes[2].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &chan_0_2.0);
1637                 let _chan_1_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 100000, 10001);
1638
1639                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 100000, 10001);
1640
1641                 // Hints should include `chan_0_3` from as `nodes[3]` only have private channels, and no
1642                 // channels for `nodes[2]` as it contains a mix of public and private channels.
1643                 let mut scid_aliases = HashSet::new();
1644                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1645
1646                 match_multi_node_invoice_routes(
1647                         Some(10_000),
1648                         &nodes[2],
1649                         vec![&nodes[2], &nodes[3],],
1650                         scid_aliases,
1651                         true
1652                 );
1653         }
1654
1655         #[test]
1656         #[cfg(feature = "std")]
1657         fn test_multi_node_hints_has_only_lowest_inbound_channel_above_minimum() {
1658                 let mut chanmon_cfgs = create_chanmon_cfgs(3);
1659                 let seed_1 = [42u8; 32];
1660                 let seed_2 = [43u8; 32];
1661                 let cross_node_seed = [44u8; 32];
1662                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1663                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1664                 let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
1665                 let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
1666                 let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
1667
1668                 let _chan_0_1_below_amt = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 100_000, 0);
1669                 let _chan_0_1_above_amt_high_inbound = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 500_000, 0);
1670                 let chan_0_1_above_amt_low_inbound = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 1, 180_000, 0);
1671                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 100000, 10001);
1672
1673                 let mut scid_aliases = HashSet::new();
1674                 scid_aliases.insert(chan_0_1_above_amt_low_inbound.0.short_channel_id_alias.unwrap());
1675                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1676
1677                 match_multi_node_invoice_routes(
1678                         Some(100_000_000),
1679                         &nodes[1],
1680                         vec![&nodes[1], &nodes[2],],
1681                         scid_aliases,
1682                         false
1683                 );
1684         }
1685
1686         #[test]
1687         #[cfg(feature = "std")]
1688         fn test_multi_node_channels_inbound_capacity_lower_than_invoice_amt_filtering() {
1689                 let mut chanmon_cfgs = create_chanmon_cfgs(4);
1690                 let seed_1 = [42u8; 32];
1691                 let seed_2 = [43u8; 32];
1692                 let cross_node_seed = [44u8; 32];
1693                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1694                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1695                 let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
1696                 let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
1697                 let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
1698
1699                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 1_000_000, 0);
1700                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 100_000, 0);
1701                 let chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 200_000, 0);
1702
1703                 // Since the invoice 1 msat above chan_0_3's inbound capacity, it should be filtered out.
1704                 let mut scid_aliases_99_000_001_msat = HashSet::new();
1705                 scid_aliases_99_000_001_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1706                 scid_aliases_99_000_001_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1707
1708                 match_multi_node_invoice_routes(
1709                         Some(99_000_001),
1710                         &nodes[2],
1711                         vec![&nodes[2], &nodes[3],],
1712                         scid_aliases_99_000_001_msat,
1713                         false
1714                 );
1715
1716                 // Since the invoice is exactly at chan_0_3's inbound capacity, it should be included.
1717                 let mut scid_aliases_99_000_000_msat = HashSet::new();
1718                 scid_aliases_99_000_000_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1719                 scid_aliases_99_000_000_msat.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1720                 scid_aliases_99_000_000_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1721
1722                 match_multi_node_invoice_routes(
1723                         Some(99_000_000),
1724                         &nodes[2],
1725                         vec![&nodes[2], &nodes[3],],
1726                         scid_aliases_99_000_000_msat,
1727                         false
1728                 );
1729
1730                 // Since the invoice is above all of `nodes[2]` channels' inbound capacity, all of
1731                 // `nodes[2]` them should be included.
1732                 let mut scid_aliases_300_000_000_msat = HashSet::new();
1733                 scid_aliases_300_000_000_msat.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1734                 scid_aliases_300_000_000_msat.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1735                 scid_aliases_300_000_000_msat.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1736
1737                 match_multi_node_invoice_routes(
1738                         Some(300_000_000),
1739                         &nodes[2],
1740                         vec![&nodes[2], &nodes[3],],
1741                         scid_aliases_300_000_000_msat,
1742                         false
1743                 );
1744
1745                 // Since the no specified amount, all channels should included.
1746                 let mut scid_aliases_no_specified_amount = HashSet::new();
1747                 scid_aliases_no_specified_amount.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1748                 scid_aliases_no_specified_amount.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1749                 scid_aliases_no_specified_amount.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1750
1751                 match_multi_node_invoice_routes(
1752                         None,
1753                         &nodes[2],
1754                         vec![&nodes[2], &nodes[3],],
1755                         scid_aliases_no_specified_amount,
1756                         false
1757                 );
1758         }
1759
1760         #[test]
1761         fn test_multi_node_hints_limited_to_3() {
1762                 let mut chanmon_cfgs = create_chanmon_cfgs(6);
1763                 let seed_1 = [42 as u8; 32];
1764                 let seed_2 = [43 as u8; 32];
1765                 let seed_3 = [44 as u8; 32];
1766                 let seed_4 = [45 as u8; 32];
1767                 let cross_node_seed = [44 as u8; 32];
1768                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1769                 chanmon_cfgs[3].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1770                 chanmon_cfgs[4].keys_manager.backing = PhantomKeysManager::new(&seed_3, 43, 44, &cross_node_seed);
1771                 chanmon_cfgs[5].keys_manager.backing = PhantomKeysManager::new(&seed_4, 43, 44, &cross_node_seed);
1772                 let node_cfgs = create_node_cfgs(6, &chanmon_cfgs);
1773                 let node_chanmgrs = create_node_chanmgrs(6, &node_cfgs, &[None, None, None, None, None, None]);
1774                 let nodes = create_network(6, &node_cfgs, &node_chanmgrs);
1775
1776                 // Setup each phantom node with two channels from distinct peers.
1777                 let chan_0_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 2, 10_000, 0);
1778                 let chan_1_2 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 2, 20_000, 0);
1779                 let chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 20_000, 0);
1780                 let _chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 10_000, 0);
1781                 let chan_0_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 4, 20_000, 0);
1782                 let _chan_1_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 4, 10_000, 0);
1783                 let _chan_0_5 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 5, 20_000, 0);
1784                 let _chan_1_5 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 5, 10_000, 0);
1785
1786                 // Set invoice amount > all channels inbound so that every one is eligible for inclusion
1787                 // and hints will be sorted by largest inbound capacity.
1788                 let invoice_amt = Some(100_000_000);
1789
1790                 // With 4 phantom nodes, assert that we include 1 hint per node, up to 3 nodes.
1791                 let mut scid_aliases = HashSet::new();
1792                 scid_aliases.insert(chan_1_2.0.short_channel_id_alias.unwrap());
1793                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1794                 scid_aliases.insert(chan_0_4.0.short_channel_id_alias.unwrap());
1795
1796                 match_multi_node_invoice_routes(
1797                         invoice_amt,
1798                         &nodes[3],
1799                         vec![&nodes[2], &nodes[3], &nodes[4], &nodes[5]],
1800                         scid_aliases,
1801                         false,
1802                 );
1803
1804                 // With 2 phantom nodes, assert that we include no more than 3 hints.
1805                 let mut scid_aliases = HashSet::new();
1806                 scid_aliases.insert(chan_1_2.0.short_channel_id_alias.unwrap());
1807                 scid_aliases.insert(chan_0_3.0.short_channel_id_alias.unwrap());
1808                 scid_aliases.insert(chan_0_2.0.short_channel_id_alias.unwrap());
1809
1810                 match_multi_node_invoice_routes(
1811                         invoice_amt,
1812                         &nodes[3],
1813                         vec![&nodes[2], &nodes[3]],
1814                         scid_aliases,
1815                         false,
1816                 );
1817         }
1818
1819         #[test]
1820         fn test_multi_node_hints_at_least_3() {
1821                 let mut chanmon_cfgs = create_chanmon_cfgs(5);
1822                 let seed_1 = [42 as u8; 32];
1823                 let seed_2 = [43 as u8; 32];
1824                 let cross_node_seed = [44 as u8; 32];
1825                 chanmon_cfgs[1].keys_manager.backing = PhantomKeysManager::new(&seed_1, 43, 44, &cross_node_seed);
1826                 chanmon_cfgs[2].keys_manager.backing = PhantomKeysManager::new(&seed_2, 43, 44, &cross_node_seed);
1827                 let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
1828                 let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
1829                 let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
1830
1831                 let _chan_0_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 3, 10_000, 0);
1832                 let chan_1_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 1, 3, 20_000, 0);
1833                 let chan_2_3 = create_unannounced_chan_between_nodes_with_value(&nodes, 2, 3, 30_000, 0);
1834                 let chan_0_4 = create_unannounced_chan_between_nodes_with_value(&nodes, 0, 4, 10_000, 0);
1835
1836                 // Since the invoice amount is above all channels inbound, all four are eligible. Test that
1837                 // we still include 3 hints from 2 distinct nodes sorted by inbound.
1838                 let mut scid_aliases = HashSet::new();
1839                 scid_aliases.insert(chan_1_3.0.short_channel_id_alias.unwrap());
1840                 scid_aliases.insert(chan_2_3.0.short_channel_id_alias.unwrap());
1841                 scid_aliases.insert(chan_0_4.0.short_channel_id_alias.unwrap());
1842
1843                 match_multi_node_invoice_routes(
1844                         Some(100_000_000),
1845                         &nodes[3],
1846                         vec![&nodes[3], &nodes[4],],
1847                         scid_aliases,
1848                         false,
1849                 );
1850         }
1851
1852         fn match_multi_node_invoice_routes<'a, 'b: 'a, 'c: 'b>(
1853                 invoice_amt: Option<u64>,
1854                 invoice_node: &Node<'a, 'b, 'c>,
1855                 network_multi_nodes: Vec<&Node<'a, 'b, 'c>>,
1856                 mut chan_ids_to_match: HashSet<u64>,
1857                 nodes_contains_public_channels: bool
1858         ){
1859                 let phantom_route_hints = network_multi_nodes.iter()
1860                         .map(|node| node.node.get_phantom_route_hints())
1861                         .collect::<Vec<PhantomRouteHints>>();
1862                 let phantom_scids = phantom_route_hints.iter()
1863                         .map(|route_hint| route_hint.phantom_scid)
1864                         .collect::<HashSet<u64>>();
1865
1866                 let invoice = crate::utils::create_phantom_invoice::<&test_utils::TestKeysInterface,
1867                         &test_utils::TestKeysInterface, &test_utils::TestLogger>(invoice_amt, None, "test".to_string(),
1868                                 3600, phantom_route_hints, invoice_node.keys_manager, invoice_node.keys_manager,
1869                                 invoice_node.logger, Currency::BitcoinTestnet, None, Duration::from_secs(1234567)).unwrap();
1870
1871                 let invoice_hints = invoice.private_routes();
1872
1873                 for hint in invoice_hints {
1874                         let hints = &(hint.0).0;
1875                         match hints.len() {
1876                                 1 => {
1877                                         assert!(nodes_contains_public_channels);
1878                                         let phantom_scid = hints[0].short_channel_id;
1879                                         assert!(phantom_scids.contains(&phantom_scid));
1880                                 },
1881                                 2 => {
1882                                         let hint_short_chan_id = hints[0].short_channel_id;
1883                                         assert!(chan_ids_to_match.remove(&hint_short_chan_id));
1884                                         let phantom_scid = hints[1].short_channel_id;
1885                                         assert!(phantom_scids.contains(&phantom_scid));
1886                                 },
1887                                 _ => panic!("Incorrect hint length generated")
1888                         }
1889                 }
1890                 assert!(chan_ids_to_match.is_empty(), "Unmatched short channel ids: {:?}", chan_ids_to_match);
1891         }
1892
1893         #[test]
1894         fn test_create_invoice_fails_with_invalid_custom_min_final_cltv_expiry_delta() {
1895                 let chanmon_cfgs = create_chanmon_cfgs(2);
1896                 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
1897                 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
1898                 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
1899                 let result = crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch(
1900                         nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
1901                         Some(10_000), "Some description".into(), Duration::from_secs(1234567), 3600, Some(MIN_FINAL_CLTV_EXPIRY_DELTA - 4),
1902                 );
1903                 match result {
1904                         Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort)) => {},
1905                         _ => panic!(),
1906                 }
1907         }
1908
1909         #[test]
1910         fn test_rotate_through_iterators() {
1911                 // two nested vectors
1912                 let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec!["a1", "b1"].into_iter()];
1913                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1914
1915                 let expected = vec!["a0", "a1", "b0", "b1", "c0"];
1916                 assert_eq!(expected, result);
1917
1918                 // test single nested vector
1919                 let a = vec![vec!["a0", "b0", "c0"].into_iter()];
1920                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1921
1922                 let expected = vec!["a0", "b0", "c0"];
1923                 assert_eq!(expected, result);
1924
1925                 // test second vector with only one element
1926                 let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec!["a1"].into_iter()];
1927                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1928
1929                 let expected = vec!["a0", "a1", "b0", "c0"];
1930                 assert_eq!(expected, result);
1931
1932                 // test three nestend vectors
1933                 let a = vec![vec!["a0"].into_iter(), vec!["a1", "b1", "c1"].into_iter(), vec!["a2"].into_iter()];
1934                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1935
1936                 let expected = vec!["a0", "a1", "a2", "b1", "c1"];
1937                 assert_eq!(expected, result);
1938
1939                 // test single nested vector with a single value
1940                 let a = vec![vec!["a0"].into_iter()];
1941                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1942
1943                 let expected = vec!["a0"];
1944                 assert_eq!(expected, result);
1945
1946                 // test single empty nested vector
1947                 let a:Vec<std::vec::IntoIter<&str>> = vec![vec![].into_iter()];
1948                 let result = rotate_through_iterators(a).collect::<Vec<&str>>();
1949                 let expected:Vec<&str> = vec![];
1950
1951                 assert_eq!(expected, result);
1952
1953                 // test first nested vector is empty
1954                 let a:Vec<std::vec::IntoIter<&str>>= vec![vec![].into_iter(), vec!["a1", "b1", "c1"].into_iter()];
1955                 let result = rotate_through_iterators(a).collect::<Vec<&str>>();
1956
1957                 let expected = vec!["a1", "b1", "c1"];
1958                 assert_eq!(expected, result);
1959
1960                 // test two empty vectors
1961                 let a:Vec<std::vec::IntoIter<&str>> = vec![vec![].into_iter(), vec![].into_iter()];
1962                 let result = rotate_through_iterators(a).collect::<Vec<&str>>();
1963
1964                 let expected:Vec<&str> = vec![];
1965                 assert_eq!(expected, result);
1966
1967                 // test an empty vector amongst other filled vectors
1968                 let a = vec![
1969                         vec!["a0", "b0", "c0"].into_iter(),
1970                         vec![].into_iter(),
1971                         vec!["a1", "b1", "c1"].into_iter(),
1972                         vec!["a2", "b2", "c2"].into_iter(),
1973                 ];
1974                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1975
1976                 let expected = vec!["a0", "a1", "a2", "b0", "b1", "b2", "c0", "c1", "c2"];
1977                 assert_eq!(expected, result);
1978
1979                 // test a filled vector between two empty vectors
1980                 let a = vec![vec![].into_iter(), vec!["a1", "b1", "c1"].into_iter(), vec![].into_iter()];
1981                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1982
1983                 let expected = vec!["a1", "b1", "c1"];
1984                 assert_eq!(expected, result);
1985
1986                 // test an empty vector at the end of the vectors
1987                 let a = vec![vec!["a0", "b0", "c0"].into_iter(), vec![].into_iter()];
1988                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
1989
1990                 let expected = vec!["a0", "b0", "c0"];
1991                 assert_eq!(expected, result);
1992
1993                 // test multiple empty vectors amongst multiple filled vectors
1994                 let a = vec![
1995                         vec![].into_iter(),
1996                         vec!["a1", "b1", "c1"].into_iter(),
1997                         vec![].into_iter(),
1998                         vec!["a3", "b3"].into_iter(),
1999                         vec![].into_iter(),
2000                 ];
2001
2002                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
2003
2004                 let expected = vec!["a1", "a3", "b1", "b3", "c1"];
2005                 assert_eq!(expected, result);
2006
2007                 // test one element in the first nested vectore and two elements in the second nested
2008                 // vector
2009                 let a = vec![vec!["a0"].into_iter(), vec!["a1", "b1"].into_iter()];
2010                 let result = rotate_through_iterators(a).collect::<Vec<_>>();
2011
2012                 let expected = vec!["a0", "a1", "b1"];
2013                 assert_eq!(expected, result);
2014         }
2015 }