_ Git - rust-lightning/blob - lightning/src/blinded_path/payment.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! Data structures and methods for constructing [`BlindedPath`]s to send a payment over.
  11 //!
  12 //! [`BlindedPath`]: crate::blinded_path::BlindedPath
  13
  14 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
  15
  16 use crate::blinded_path::{BlindedHop, BlindedPath, IntroductionNode, NodeIdLookUp};
  17 use crate::blinded_path::utils;
  18 use crate::crypto::streams::ChaChaPolyReadAdapter;
  19 use crate::io;
  20 use crate::io::Cursor;
  21 use crate::ln::types::PaymentSecret;
  22 use crate::ln::channel_state::CounterpartyForwardingInfo;
  23 use crate::ln::features::BlindedHopFeatures;
  24 use crate::ln::msgs::DecodeError;
  25 use crate::ln::onion_utils;
  26 use crate::offers::invoice::BlindedPayInfo;
  27 use crate::offers::invoice_request::InvoiceRequestFields;
  28 use crate::offers::offer::OfferId;
  29 use crate::sign::{NodeSigner, Recipient};
  30 use crate::util::ser::{FixedLengthReader, LengthReadableArgs, HighZeroBytesDroppedBigSize, Readable, Writeable, Writer};
  31
  32 use core::mem;
  33 use core::ops::Deref;
  34
  35 #[allow(unused_imports)]
  36 use crate::prelude::*;
  37
  38 /// An intermediate node, its outbound channel, and relay parameters.
  39 #[derive(Clone, Debug)]
  40 pub struct ForwardNode {
  41         /// The TLVs for this node's [`BlindedHop`], where the fee parameters contained within are also
  42         /// used for [`BlindedPayInfo`] construction.
  43         pub tlvs: ForwardTlvs,
  44         /// This node's pubkey.
  45         pub node_id: PublicKey,
  46         /// The maximum value, in msat, that may be accepted by this node.
  47         pub htlc_maximum_msat: u64,
  48 }
  49
  50 /// Data to construct a [`BlindedHop`] for forwarding a payment.
  51 #[derive(Clone, Debug)]
  52 pub struct ForwardTlvs {
  53         /// The short channel id this payment should be forwarded out over.
  54         pub short_channel_id: u64,
  55         /// Payment parameters for relaying over [`Self::short_channel_id`].
  56         pub payment_relay: PaymentRelay,
  57         /// Payment constraints for relaying over [`Self::short_channel_id`].
  58         pub payment_constraints: PaymentConstraints,
  59         /// Supported and required features when relaying a payment onion containing this object's
  60         /// corresponding [`BlindedHop::encrypted_payload`].
  61         ///
  62         /// [`BlindedHop::encrypted_payload`]: crate::blinded_path::BlindedHop::encrypted_payload
  63         pub features: BlindedHopFeatures,
  64 }
  65
  66 /// Data to construct a [`BlindedHop`] for receiving a payment. This payload is custom to LDK and
  67 /// may not be valid if received by another lightning implementation.
  68 #[derive(Clone, Debug)]
  69 pub struct ReceiveTlvs {
  70         /// Used to authenticate the sender of a payment to the receiver and tie MPP HTLCs together.
  71         pub payment_secret: PaymentSecret,
  72         /// Constraints for the receiver of this payment.
  73         pub payment_constraints: PaymentConstraints,
  74         /// Context for the receiver of this payment.
  75         pub payment_context: PaymentContext,
  76 }
  77
  78 /// Data to construct a [`BlindedHop`] for sending a payment over.
  79 ///
  80 /// [`BlindedHop`]: crate::blinded_path::BlindedHop
  81 pub(crate) enum BlindedPaymentTlvs {
  82         /// This blinded payment data is for a forwarding node.
  83         Forward(ForwardTlvs),
  84         /// This blinded payment data is for the receiving node.
  85         Receive(ReceiveTlvs),
  86 }
  87
  88 // Used to include forward and receive TLVs in the same iterator for encoding.
  89 enum BlindedPaymentTlvsRef<'a> {
  90         Forward(&'a ForwardTlvs),
  91         Receive(&'a ReceiveTlvs),
  92 }
  93
  94 /// Parameters for relaying over a given [`BlindedHop`].
  95 ///
  96 /// [`BlindedHop`]: crate::blinded_path::BlindedHop
  97 #[derive(Clone, Debug)]
  98 pub struct PaymentRelay {
  99         /// Number of blocks subtracted from an incoming HTLC's `cltv_expiry` for this [`BlindedHop`].
 100         pub cltv_expiry_delta: u16,
 101         /// Liquidity fee charged (in millionths of the amount transferred) for relaying a payment over
 102         /// this [`BlindedHop`], (i.e., 10,000 is 1%).
 103         pub fee_proportional_millionths: u32,
 104         /// Base fee charged (in millisatoshi) for relaying a payment over this [`BlindedHop`].
 105         pub fee_base_msat: u32,
 106 }
 107
 108 /// Constraints for relaying over a given [`BlindedHop`].
 109 ///
 110 /// [`BlindedHop`]: crate::blinded_path::BlindedHop
 111 #[derive(Clone, Debug)]
 112 pub struct PaymentConstraints {
 113         /// The maximum total CLTV that is acceptable when relaying a payment over this [`BlindedHop`].
 114         pub max_cltv_expiry: u32,
 115         /// The minimum value, in msat, that may be accepted by the node corresponding to this
 116         /// [`BlindedHop`].
 117         pub htlc_minimum_msat: u64,
 118 }
 119
 120 /// The context of an inbound payment, which is included in a [`BlindedPath`] via [`ReceiveTlvs`]
 121 /// and surfaced in [`PaymentPurpose`].
 122 ///
 123 /// [`BlindedPath`]: crate::blinded_path::BlindedPath
 124 /// [`PaymentPurpose`]: crate::events::PaymentPurpose
 125 #[derive(Clone, Debug, Eq, PartialEq)]
 126 pub enum PaymentContext {
 127         /// The payment context was unknown.
 128         Unknown(UnknownPaymentContext),
 129
 130         /// The payment was made for an invoice requested from a BOLT 12 [`Offer`].
 131         ///
 132         /// [`Offer`]: crate::offers::offer::Offer
 133         Bolt12Offer(Bolt12OfferContext),
 134
 135         /// The payment was made for an invoice sent for a BOLT 12 [`Refund`].
 136         ///
 137         /// [`Refund`]: crate::offers::refund::Refund
 138         Bolt12Refund(Bolt12RefundContext),
 139 }
 140
 141 // Used when writing PaymentContext in Event::PaymentClaimable to avoid cloning.
 142 pub(crate) enum PaymentContextRef<'a> {
 143         Bolt12Offer(&'a Bolt12OfferContext),
 144         Bolt12Refund(&'a Bolt12RefundContext),
 145 }
 146
 147 /// An unknown payment context.
 148 #[derive(Clone, Debug, Eq, PartialEq)]
 149 pub struct UnknownPaymentContext(());
 150
 151 /// The context of a payment made for an invoice requested from a BOLT 12 [`Offer`].
 152 ///
 153 /// [`Offer`]: crate::offers::offer::Offer
 154 #[derive(Clone, Debug, Eq, PartialEq)]
 155 pub struct Bolt12OfferContext {
 156         /// The identifier of the [`Offer`].
 157         ///
 158         /// [`Offer`]: crate::offers::offer::Offer
 159         pub offer_id: OfferId,
 160
 161         /// Fields from an [`InvoiceRequest`] sent for a [`Bolt12Invoice`].
 162         ///
 163         /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 164         /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 165         pub invoice_request: InvoiceRequestFields,
 166 }
 167
 168 /// The context of a payment made for an invoice sent for a BOLT 12 [`Refund`].
 169 ///
 170 /// [`Refund`]: crate::offers::refund::Refund
 171 #[derive(Clone, Debug, Eq, PartialEq)]
 172 pub struct Bolt12RefundContext {}
 173
 174 impl PaymentContext {
 175         pub(crate) fn unknown() -> Self {
 176                 PaymentContext::Unknown(UnknownPaymentContext(()))
 177         }
 178 }
 179
 180 impl TryFrom<CounterpartyForwardingInfo> for PaymentRelay {
 181         type Error = ();
 182
 183         fn try_from(info: CounterpartyForwardingInfo) -> Result<Self, ()> {
 184                 let CounterpartyForwardingInfo {
 185                         fee_base_msat, fee_proportional_millionths, cltv_expiry_delta
 186                 } = info;
 187
 188                 // Avoid exposing esoteric CLTV expiry deltas
 189                 let cltv_expiry_delta = match cltv_expiry_delta {
 190                         0..=40 => 40,
 191                         41..=80 => 80,
 192                         81..=144 => 144,
 193                         145..=216 => 216,
 194                         _ => return Err(()),
 195                 };
 196
 197                 Ok(Self { cltv_expiry_delta, fee_proportional_millionths, fee_base_msat })
 198         }
 199 }
 200
 201 impl Writeable for ForwardTlvs {
 202         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 203                 let features_opt =
 204                         if self.features == BlindedHopFeatures::empty() { None }
 205                         else { Some(&self.features) };
 206                 encode_tlv_stream!(w, {
 207                         (2, self.short_channel_id, required),
 208                         (10, self.payment_relay, required),
 209                         (12, self.payment_constraints, required),
 210                         (14, features_opt, option)
 211                 });
 212                 Ok(())
 213         }
 214 }
 215
 216 impl Writeable for ReceiveTlvs {
 217         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 218                 encode_tlv_stream!(w, {
 219                         (12, self.payment_constraints, required),
 220                         (65536, self.payment_secret, required),
 221                         (65537, self.payment_context, required)
 222                 });
 223                 Ok(())
 224         }
 225 }
 226
 227 impl<'a> Writeable for BlindedPaymentTlvsRef<'a> {
 228         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 229                 // TODO: write padding
 230                 match self {
 231                         Self::Forward(tlvs) => tlvs.write(w)?,
 232                         Self::Receive(tlvs) => tlvs.write(w)?,
 233                 }
 234                 Ok(())
 235         }
 236 }
 237
 238 impl Readable for BlindedPaymentTlvs {
 239         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 240                 _init_and_read_tlv_stream!(r, {
 241                         (1, _padding, option),
 242                         (2, scid, option),
 243                         (10, payment_relay, option),
 244                         (12, payment_constraints, required),
 245                         (14, features, option),
 246                         (65536, payment_secret, option),
 247                         (65537, payment_context, (default_value, PaymentContext::unknown())),
 248                 });
 249                 let _padding: Option<utils::Padding> = _padding;
 250
 251                 if let Some(short_channel_id) = scid {
 252                         if payment_secret.is_some() {
 253                                 return Err(DecodeError::InvalidValue)
 254                         }
 255                         Ok(BlindedPaymentTlvs::Forward(ForwardTlvs {
 256                                 short_channel_id,
 257                                 payment_relay: payment_relay.ok_or(DecodeError::InvalidValue)?,
 258                                 payment_constraints: payment_constraints.0.unwrap(),
 259                                 features: features.unwrap_or_else(BlindedHopFeatures::empty),
 260                         }))
 261                 } else {
 262                         if payment_relay.is_some() || features.is_some() { return Err(DecodeError::InvalidValue) }
 263                         Ok(BlindedPaymentTlvs::Receive(ReceiveTlvs {
 264                                 payment_secret: payment_secret.ok_or(DecodeError::InvalidValue)?,
 265                                 payment_constraints: payment_constraints.0.unwrap(),
 266                                 payment_context: payment_context.0.unwrap(),
 267                         }))
 268                 }
 269         }
 270 }
 271
 272 /// Construct blinded payment hops for the given `intermediate_nodes` and payee info.
 273 pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 274         secp_ctx: &Secp256k1<T>, intermediate_nodes: &[ForwardNode],
 275         payee_node_id: PublicKey, payee_tlvs: ReceiveTlvs, session_priv: &SecretKey
 276 ) -> Result<Vec<BlindedHop>, secp256k1::Error> {
 277         let pks = intermediate_nodes.iter().map(|node| &node.node_id)
 278                 .chain(core::iter::once(&payee_node_id));
 279         let tlvs = intermediate_nodes.iter().map(|node| BlindedPaymentTlvsRef::Forward(&node.tlvs))
 280                 .chain(core::iter::once(BlindedPaymentTlvsRef::Receive(&payee_tlvs)));
 281         utils::construct_blinded_hops(secp_ctx, pks, tlvs, session_priv)
 282 }
 283
 284 // Advance the blinded onion payment path by one hop, so make the second hop into the new
 285 // introduction node.
 286 //
 287 // Will only modify `path` when returning `Ok`.
 288 pub(crate) fn advance_path_by_one<NS: Deref, NL: Deref, T>(
 289         path: &mut BlindedPath, node_signer: &NS, node_id_lookup: &NL, secp_ctx: &Secp256k1<T>
 290 ) -> Result<(), ()>
 291 where
 292         NS::Target: NodeSigner,
 293         NL::Target: NodeIdLookUp,
 294         T: secp256k1::Signing + secp256k1::Verification,
 295 {
 296         let control_tlvs_ss = node_signer.ecdh(Recipient::Node, &path.blinding_point, None)?;
 297         let rho = onion_utils::gen_rho_from_shared_secret(&control_tlvs_ss.secret_bytes());
 298         let encrypted_control_tlvs = &path.blinded_hops.get(0).ok_or(())?.encrypted_payload;
 299         let mut s = Cursor::new(encrypted_control_tlvs);
 300         let mut reader = FixedLengthReader::new(&mut s, encrypted_control_tlvs.len() as u64);
 301         match ChaChaPolyReadAdapter::read(&mut reader, rho) {
 302                 Ok(ChaChaPolyReadAdapter {
 303                         readable: BlindedPaymentTlvs::Forward(ForwardTlvs { short_channel_id, .. })
 304                 }) => {
 305                         let next_node_id = match node_id_lookup.next_node_id(short_channel_id) {
 306                                 Some(node_id) => node_id,
 307                                 None => return Err(()),
 308                         };
 309                         let mut new_blinding_point = onion_utils::next_hop_pubkey(
 310                                 secp_ctx, path.blinding_point, control_tlvs_ss.as_ref()
 311                         ).map_err(|_| ())?;
 312                         mem::swap(&mut path.blinding_point, &mut new_blinding_point);
 313                         path.introduction_node = IntroductionNode::NodeId(next_node_id);
 314                         path.blinded_hops.remove(0);
 315                         Ok(())
 316                 },
 317                 _ => Err(())
 318         }
 319 }
 320
 321 /// `None` if underflow occurs.
 322 pub(crate) fn amt_to_forward_msat(inbound_amt_msat: u64, payment_relay: &PaymentRelay) -> Option<u64> {
 323         let inbound_amt = inbound_amt_msat as u128;
 324         let base = payment_relay.fee_base_msat as u128;
 325         let prop = payment_relay.fee_proportional_millionths as u128;
 326
 327         let post_base_fee_inbound_amt =
 328                 if let Some(amt) = inbound_amt.checked_sub(base) { amt } else { return None };
 329         let mut amt_to_forward =
 330                 (post_base_fee_inbound_amt * 1_000_000 + 1_000_000 + prop - 1) / (prop + 1_000_000);
 331
 332         let fee = ((amt_to_forward * prop) / 1_000_000) + base;
 333         if inbound_amt - fee < amt_to_forward {
 334                 // Rounding up the forwarded amount resulted in underpaying this node, so take an extra 1 msat
 335                 // in fee to compensate.
 336                 amt_to_forward -= 1;
 337         }
 338         debug_assert_eq!(amt_to_forward + fee, inbound_amt);
 339         u64::try_from(amt_to_forward).ok()
 340 }
 341
 342 pub(super) fn compute_payinfo(
 343         intermediate_nodes: &[ForwardNode], payee_tlvs: &ReceiveTlvs, payee_htlc_maximum_msat: u64,
 344         min_final_cltv_expiry_delta: u16
 345 ) -> Result<BlindedPayInfo, ()> {
 346         let mut curr_base_fee: u64 = 0;
 347         let mut curr_prop_mil: u64 = 0;
 348         let mut cltv_expiry_delta: u16 = min_final_cltv_expiry_delta;
 349         for tlvs in intermediate_nodes.iter().rev().map(|n| &n.tlvs) {
 350                 // In the future, we'll want to take the intersection of all supported features for the
 351                 // `BlindedPayInfo`, but there are no features in that context right now.
 352                 if tlvs.features.requires_unknown_bits_from(&BlindedHopFeatures::empty()) { return Err(()) }
 353
 354                 let next_base_fee = tlvs.payment_relay.fee_base_msat as u64;
 355                 let next_prop_mil = tlvs.payment_relay.fee_proportional_millionths as u64;
 356                 // Use integer arithmetic to compute `ceil(a/b)` as `(a+b-1)/b`
 357                 // ((curr_base_fee * (1_000_000 + next_prop_mil)) / 1_000_000) + next_base_fee
 358                 curr_base_fee = curr_base_fee.checked_mul(1_000_000 + next_prop_mil)
 359                         .and_then(|f| f.checked_add(1_000_000 - 1))
 360                         .map(|f| f / 1_000_000)
 361                         .and_then(|f| f.checked_add(next_base_fee))
 362                         .ok_or(())?;
 363                 // ceil(((curr_prop_mil + 1_000_000) * (next_prop_mil + 1_000_000)) / 1_000_000) - 1_000_000
 364                 curr_prop_mil = curr_prop_mil.checked_add(1_000_000)
 365                         .and_then(|f1| next_prop_mil.checked_add(1_000_000).and_then(|f2| f2.checked_mul(f1)))
 366                         .and_then(|f| f.checked_add(1_000_000 - 1))
 367                         .map(|f| f / 1_000_000)
 368                         .and_then(|f| f.checked_sub(1_000_000))
 369                         .ok_or(())?;
 370
 371                 cltv_expiry_delta = cltv_expiry_delta.checked_add(tlvs.payment_relay.cltv_expiry_delta).ok_or(())?;
 372         }
 373
 374         let mut htlc_minimum_msat: u64 = 1;
 375         let mut htlc_maximum_msat: u64 = 21_000_000 * 100_000_000 * 1_000; // Total bitcoin supply
 376         for node in intermediate_nodes.iter() {
 377                 // The min htlc for an intermediate node is that node's min minus the fees charged by all of the
 378                 // following hops for forwarding that min, since that fee amount will automatically be included
 379                 // in the amount that this node receives and contribute towards reaching its min.
 380                 htlc_minimum_msat = amt_to_forward_msat(
 381                         core::cmp::max(node.tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat),
 382                         &node.tlvs.payment_relay
 383                 ).unwrap_or(1); // If underflow occurs, we definitely reached this node's min
 384                 htlc_maximum_msat = amt_to_forward_msat(
 385                         core::cmp::min(node.htlc_maximum_msat, htlc_maximum_msat), &node.tlvs.payment_relay
 386                 ).ok_or(())?; // If underflow occurs, we cannot send to this hop without exceeding their max
 387         }
 388         htlc_minimum_msat = core::cmp::max(
 389                 payee_tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat
 390         );
 391         htlc_maximum_msat = core::cmp::min(payee_htlc_maximum_msat, htlc_maximum_msat);
 392
 393         if htlc_maximum_msat < htlc_minimum_msat { return Err(()) }
 394         Ok(BlindedPayInfo {
 395                 fee_base_msat: u32::try_from(curr_base_fee).map_err(|_| ())?,
 396                 fee_proportional_millionths: u32::try_from(curr_prop_mil).map_err(|_| ())?,
 397                 cltv_expiry_delta,
 398                 htlc_minimum_msat,
 399                 htlc_maximum_msat,
 400                 features: BlindedHopFeatures::empty(),
 401         })
 402 }
 403
 404 impl Writeable for PaymentRelay {
 405         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 406                 self.cltv_expiry_delta.write(w)?;
 407                 self.fee_proportional_millionths.write(w)?;
 408                 HighZeroBytesDroppedBigSize(self.fee_base_msat).write(w)
 409         }
 410 }
 411 impl Readable for PaymentRelay {
 412         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 413                 let cltv_expiry_delta: u16 = Readable::read(r)?;
 414                 let fee_proportional_millionths: u32 = Readable::read(r)?;
 415                 let fee_base_msat: HighZeroBytesDroppedBigSize<u32> = Readable::read(r)?;
 416                 Ok(Self { cltv_expiry_delta, fee_proportional_millionths, fee_base_msat: fee_base_msat.0 })
 417         }
 418 }
 419
 420 impl Writeable for PaymentConstraints {
 421         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 422                 self.max_cltv_expiry.write(w)?;
 423                 HighZeroBytesDroppedBigSize(self.htlc_minimum_msat).write(w)
 424         }
 425 }
 426 impl Readable for PaymentConstraints {
 427         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 428                 let max_cltv_expiry: u32 = Readable::read(r)?;
 429                 let htlc_minimum_msat: HighZeroBytesDroppedBigSize<u64> = Readable::read(r)?;
 430                 Ok(Self { max_cltv_expiry, htlc_minimum_msat: htlc_minimum_msat.0 })
 431         }
 432 }
 433
 434 impl_writeable_tlv_based_enum!(PaymentContext,
 435         ;
 436         (0, Unknown),
 437         (1, Bolt12Offer),
 438         (2, Bolt12Refund),
 439 );
 440
 441 impl<'a> Writeable for PaymentContextRef<'a> {
 442         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 443                 match self {
 444                         PaymentContextRef::Bolt12Offer(context) => {
 445                                 1u8.write(w)?;
 446                                 context.write(w)?;
 447                         },
 448                         PaymentContextRef::Bolt12Refund(context) => {
 449                                 2u8.write(w)?;
 450                                 context.write(w)?;
 451                         },
 452                 }
 453
 454                 Ok(())
 455         }
 456 }
 457
 458 impl Writeable for UnknownPaymentContext {
 459         fn write<W: Writer>(&self, _w: &mut W) -> Result<(), io::Error> {
 460                 Ok(())
 461         }
 462 }
 463
 464 impl Readable for UnknownPaymentContext {
 465         fn read<R: io::Read>(_r: &mut R) -> Result<Self, DecodeError> {
 466                 Ok(UnknownPaymentContext(()))
 467         }
 468 }
 469
 470 impl_writeable_tlv_based!(Bolt12OfferContext, {
 471         (0, offer_id, required),
 472         (2, invoice_request, required),
 473 });
 474
 475 impl_writeable_tlv_based!(Bolt12RefundContext, {});
 476
 477 #[cfg(test)]
 478 mod tests {
 479         use bitcoin::secp256k1::PublicKey;
 480         use crate::blinded_path::payment::{ForwardNode, ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentContext, PaymentRelay};
 481         use crate::ln::types::PaymentSecret;
 482         use crate::ln::features::BlindedHopFeatures;
 483         use crate::ln::functional_test_utils::TEST_FINAL_CLTV;
 484
 485         #[test]
 486         fn compute_payinfo() {
 487                 // Taken from the spec example for aggregating blinded payment info. See
 488                 // https://github.com/lightning/bolts/blob/master/proposals/route-blinding.md#blinded-payments
 489                 let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap();
 490                 let intermediate_nodes = vec![ForwardNode {
 491                         node_id: dummy_pk,
 492                         tlvs: ForwardTlvs {
 493                                 short_channel_id: 0,
 494                                 payment_relay: PaymentRelay {
 495                                         cltv_expiry_delta: 144,
 496                                         fee_proportional_millionths: 500,
 497                                         fee_base_msat: 100,
 498                                 },
 499                                 payment_constraints: PaymentConstraints {
 500                                         max_cltv_expiry: 0,
 501                                         htlc_minimum_msat: 100,
 502                                 },
 503                                 features: BlindedHopFeatures::empty(),
 504                         },
 505                         htlc_maximum_msat: u64::max_value(),
 506                 }, ForwardNode {
 507                         node_id: dummy_pk,
 508                         tlvs: ForwardTlvs {
 509                                 short_channel_id: 0,
 510                                 payment_relay: PaymentRelay {
 511                                         cltv_expiry_delta: 144,
 512                                         fee_proportional_millionths: 500,
 513                                         fee_base_msat: 100,
 514                                 },
 515                                 payment_constraints: PaymentConstraints {
 516                                         max_cltv_expiry: 0,
 517                                         htlc_minimum_msat: 1_000,
 518                                 },
 519                                 features: BlindedHopFeatures::empty(),
 520                         },
 521                         htlc_maximum_msat: u64::max_value(),
 522                 }];
 523                 let recv_tlvs = ReceiveTlvs {
 524                         payment_secret: PaymentSecret([0; 32]),
 525                         payment_constraints: PaymentConstraints {
 526                                 max_cltv_expiry: 0,
 527                                 htlc_minimum_msat: 1,
 528                         },
 529                         payment_context: PaymentContext::unknown(),
 530                 };
 531                 let htlc_maximum_msat = 100_000;
 532                 let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, 12).unwrap();
 533                 assert_eq!(blinded_payinfo.fee_base_msat, 201);
 534                 assert_eq!(blinded_payinfo.fee_proportional_millionths, 1001);
 535                 assert_eq!(blinded_payinfo.cltv_expiry_delta, 300);
 536                 assert_eq!(blinded_payinfo.htlc_minimum_msat, 900);
 537                 assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat);
 538         }
 539
 540         #[test]
 541         fn compute_payinfo_1_hop() {
 542                 let recv_tlvs = ReceiveTlvs {
 543                         payment_secret: PaymentSecret([0; 32]),
 544                         payment_constraints: PaymentConstraints {
 545                                 max_cltv_expiry: 0,
 546                                 htlc_minimum_msat: 1,
 547                         },
 548                         payment_context: PaymentContext::unknown(),
 549                 };
 550                 let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs, 4242, TEST_FINAL_CLTV as u16).unwrap();
 551                 assert_eq!(blinded_payinfo.fee_base_msat, 0);
 552                 assert_eq!(blinded_payinfo.fee_proportional_millionths, 0);
 553                 assert_eq!(blinded_payinfo.cltv_expiry_delta, TEST_FINAL_CLTV as u16);
 554                 assert_eq!(blinded_payinfo.htlc_minimum_msat, 1);
 555                 assert_eq!(blinded_payinfo.htlc_maximum_msat, 4242);
 556         }
 557
 558         #[test]
 559         fn simple_aggregated_htlc_min() {
 560                 // If no hops charge fees, the htlc_minimum_msat should just be the maximum htlc_minimum_msat
 561                 // along the path.
 562                 let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap();
 563                 let intermediate_nodes = vec![ForwardNode {
 564                         node_id: dummy_pk,
 565                         tlvs: ForwardTlvs {
 566                                 short_channel_id: 0,
 567                                 payment_relay: PaymentRelay {
 568                                         cltv_expiry_delta: 0,
 569                                         fee_proportional_millionths: 0,
 570                                         fee_base_msat: 0,
 571                                 },
 572                                 payment_constraints: PaymentConstraints {
 573                                         max_cltv_expiry: 0,
 574                                         htlc_minimum_msat: 1,
 575                                 },
 576                                 features: BlindedHopFeatures::empty(),
 577                         },
 578                         htlc_maximum_msat: u64::max_value()
 579                 }, ForwardNode {
 580                         node_id: dummy_pk,
 581                         tlvs: ForwardTlvs {
 582                                 short_channel_id: 0,
 583                                 payment_relay: PaymentRelay {
 584                                         cltv_expiry_delta: 0,
 585                                         fee_proportional_millionths: 0,
 586                                         fee_base_msat: 0,
 587                                 },
 588                                 payment_constraints: PaymentConstraints {
 589                                         max_cltv_expiry: 0,
 590                                         htlc_minimum_msat: 2_000,
 591                                 },
 592                                 features: BlindedHopFeatures::empty(),
 593                         },
 594                         htlc_maximum_msat: u64::max_value()
 595                 }];
 596                 let recv_tlvs = ReceiveTlvs {
 597                         payment_secret: PaymentSecret([0; 32]),
 598                         payment_constraints: PaymentConstraints {
 599                                 max_cltv_expiry: 0,
 600                                 htlc_minimum_msat: 3,
 601                         },
 602                         payment_context: PaymentContext::unknown(),
 603                 };
 604                 let htlc_maximum_msat = 100_000;
 605                 let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, TEST_FINAL_CLTV as u16).unwrap();
 606                 assert_eq!(blinded_payinfo.htlc_minimum_msat, 2_000);
 607         }
 608
 609         #[test]
 610         fn aggregated_htlc_min() {
 611                 // Create a path with varying fees and htlc_mins, and make sure htlc_minimum_msat ends up as the
 612                 // max (htlc_min - following_fees) along the path.
 613                 let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap();
 614                 let intermediate_nodes = vec![ForwardNode {
 615                         node_id: dummy_pk,
 616                         tlvs: ForwardTlvs {
 617                                 short_channel_id: 0,
 618                                 payment_relay: PaymentRelay {
 619                                         cltv_expiry_delta: 0,
 620                                         fee_proportional_millionths: 500,
 621                                         fee_base_msat: 1_000,
 622                                 },
 623                                 payment_constraints: PaymentConstraints {
 624                                         max_cltv_expiry: 0,
 625                                         htlc_minimum_msat: 5_000,
 626                                 },
 627                                 features: BlindedHopFeatures::empty(),
 628                         },
 629                         htlc_maximum_msat: u64::max_value()
 630                 }, ForwardNode {
 631                         node_id: dummy_pk,
 632                         tlvs: ForwardTlvs {
 633                                 short_channel_id: 0,
 634                                 payment_relay: PaymentRelay {
 635                                         cltv_expiry_delta: 0,
 636                                         fee_proportional_millionths: 500,
 637                                         fee_base_msat: 200,
 638                                 },
 639                                 payment_constraints: PaymentConstraints {
 640                                         max_cltv_expiry: 0,
 641                                         htlc_minimum_msat: 2_000,
 642                                 },
 643                                 features: BlindedHopFeatures::empty(),
 644                         },
 645                         htlc_maximum_msat: u64::max_value()
 646                 }];
 647                 let recv_tlvs = ReceiveTlvs {
 648                         payment_secret: PaymentSecret([0; 32]),
 649                         payment_constraints: PaymentConstraints {
 650                                 max_cltv_expiry: 0,
 651                                 htlc_minimum_msat: 1,
 652                         },
 653                         payment_context: PaymentContext::unknown(),
 654                 };
 655                 let htlc_minimum_msat = 3798;
 656                 assert!(super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_minimum_msat - 1, TEST_FINAL_CLTV as u16).is_err());
 657
 658                 let htlc_maximum_msat = htlc_minimum_msat + 1;
 659                 let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, TEST_FINAL_CLTV as u16).unwrap();
 660                 assert_eq!(blinded_payinfo.htlc_minimum_msat, htlc_minimum_msat);
 661                 assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat);
 662         }
 663
 664         #[test]
 665         fn aggregated_htlc_max() {
 666                 // Create a path with varying fees and `htlc_maximum_msat`s, and make sure the aggregated max
 667                 // htlc ends up as the min (htlc_max - following_fees) along the path.
 668                 let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap();
 669                 let intermediate_nodes = vec![ForwardNode {
 670                         node_id: dummy_pk,
 671                         tlvs: ForwardTlvs {
 672                                 short_channel_id: 0,
 673                                 payment_relay: PaymentRelay {
 674                                         cltv_expiry_delta: 0,
 675                                         fee_proportional_millionths: 500,
 676                                         fee_base_msat: 1_000,
 677                                 },
 678                                 payment_constraints: PaymentConstraints {
 679                                         max_cltv_expiry: 0,
 680                                         htlc_minimum_msat: 1,
 681                                 },
 682                                 features: BlindedHopFeatures::empty(),
 683                         },
 684                         htlc_maximum_msat: 5_000,
 685                 }, ForwardNode {
 686                         node_id: dummy_pk,
 687                         tlvs: ForwardTlvs {
 688                                 short_channel_id: 0,
 689                                 payment_relay: PaymentRelay {
 690                                         cltv_expiry_delta: 0,
 691                                         fee_proportional_millionths: 500,
 692                                         fee_base_msat: 1,
 693                                 },
 694                                 payment_constraints: PaymentConstraints {
 695                                         max_cltv_expiry: 0,
 696                                         htlc_minimum_msat: 1,
 697                                 },
 698                                 features: BlindedHopFeatures::empty(),
 699                         },
 700                         htlc_maximum_msat: 10_000
 701                 }];
 702                 let recv_tlvs = ReceiveTlvs {
 703                         payment_secret: PaymentSecret([0; 32]),
 704                         payment_constraints: PaymentConstraints {
 705                                 max_cltv_expiry: 0,
 706                                 htlc_minimum_msat: 1,
 707                         },
 708                         payment_context: PaymentContext::unknown(),
 709                 };
 710
 711                 let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, 10_000, TEST_FINAL_CLTV as u16).unwrap();
 712                 assert_eq!(blinded_payinfo.htlc_maximum_msat, 3997);
 713         }
 714 }