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