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

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