_ 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::features::BlindedHopFeatures;
  12 use crate::ln::msgs::DecodeError;
  13 use crate::offers::invoice::BlindedPayInfo;
  14 use crate::prelude::*;
  15 use crate::util::ser::{Readable, Writeable, Writer};
  16
  17 use core::convert::TryFrom;
  18
  19 /// An intermediate node, its outbound channel, and relay parameters.
  20 #[derive(Clone, Debug)]
  21 pub struct ForwardNode {
  22         /// The TLVs for this node's [`BlindedHop`], where the fee parameters contained within are also
  23         /// used for [`BlindedPayInfo`] construction.
  24         pub tlvs: ForwardTlvs,
  25         /// This node's pubkey.
  26         pub node_id: PublicKey,
  27         /// The maximum value, in msat, that may be accepted by this node.
  28         pub htlc_maximum_msat: u64,
  29 }
  30
  31 /// Data to construct a [`BlindedHop`] for forwarding a payment.
  32 #[derive(Clone, Debug)]
  33 pub struct ForwardTlvs {
  34         /// The short channel id this payment should be forwarded out over.
  35         pub short_channel_id: u64,
  36         /// Payment parameters for relaying over [`Self::short_channel_id`].
  37         pub payment_relay: PaymentRelay,
  38         /// Payment constraints for relaying over [`Self::short_channel_id`].
  39         pub payment_constraints: PaymentConstraints,
  40         /// Supported and required features when relaying a payment onion containing this object's
  41         /// corresponding [`BlindedHop::encrypted_payload`].
  42         ///
  43         /// [`BlindedHop::encrypted_payload`]: crate::blinded_path::BlindedHop::encrypted_payload
  44         pub features: BlindedHopFeatures,
  45 }
  46
  47 /// Data to construct a [`BlindedHop`] for receiving a payment. This payload is custom to LDK and
  48 /// may not be valid if received by another lightning implementation.
  49 #[derive(Clone, Debug)]
  50 pub struct ReceiveTlvs {
  51         /// Used to authenticate the sender of a payment to the receiver and tie MPP HTLCs together.
  52         pub payment_secret: PaymentSecret,
  53         /// Constraints for the receiver of this payment.
  54         pub payment_constraints: PaymentConstraints,
  55 }
  56
  57 /// Data to construct a [`BlindedHop`] for sending a payment over.
  58 ///
  59 /// [`BlindedHop`]: crate::blinded_path::BlindedHop
  60 pub(crate) enum BlindedPaymentTlvs {
  61         /// This blinded payment data is for a forwarding node.
  62         Forward(ForwardTlvs),
  63         /// This blinded payment data is for the receiving node.
  64         Receive(ReceiveTlvs),
  65 }
  66
  67 // Used to include forward and receive TLVs in the same iterator for encoding.
  68 enum BlindedPaymentTlvsRef<'a> {
  69         Forward(&'a ForwardTlvs),
  70         Receive(&'a ReceiveTlvs),
  71 }
  72
  73 /// Parameters for relaying over a given [`BlindedHop`].
  74 ///
  75 /// [`BlindedHop`]: crate::blinded_path::BlindedHop
  76 #[derive(Clone, Debug)]
  77 pub struct PaymentRelay {
  78         /// Number of blocks subtracted from an incoming HTLC's `cltv_expiry` for this [`BlindedHop`].
  79         pub cltv_expiry_delta: u16,
  80         /// Liquidity fee charged (in millionths of the amount transferred) for relaying a payment over
  81         /// this [`BlindedHop`], (i.e., 10,000 is 1%).
  82         pub fee_proportional_millionths: u32,
  83         /// Base fee charged (in millisatoshi) for relaying a payment over this [`BlindedHop`].
  84         pub fee_base_msat: u32,
  85 }
  86
  87 /// Constraints for relaying over a given [`BlindedHop`].
  88 ///
  89 /// [`BlindedHop`]: crate::blinded_path::BlindedHop
  90 #[derive(Clone, Debug)]
  91 pub struct PaymentConstraints {
  92         /// The maximum total CLTV delta that is acceptable when relaying a payment over this
  93         /// [`BlindedHop`].
  94         pub max_cltv_expiry: u32,
  95         /// The minimum value, in msat, that may be accepted by the node corresponding to this
  96         /// [`BlindedHop`].
  97         pub htlc_minimum_msat: u64,
  98 }
  99
 100 impl Writeable for ForwardTlvs {
 101         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 102                 encode_tlv_stream!(w, {
 103                         (2, self.short_channel_id, required),
 104                         (10, self.payment_relay, required),
 105                         (12, self.payment_constraints, required),
 106                         (14, self.features, required)
 107                 });
 108                 Ok(())
 109         }
 110 }
 111
 112 impl Writeable for ReceiveTlvs {
 113         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 114                 encode_tlv_stream!(w, {
 115                         (12, self.payment_constraints, required),
 116                         (65536, self.payment_secret, required)
 117                 });
 118                 Ok(())
 119         }
 120 }
 121
 122 impl<'a> Writeable for BlindedPaymentTlvsRef<'a> {
 123         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 124                 // TODO: write padding
 125                 match self {
 126                         Self::Forward(tlvs) => tlvs.write(w)?,
 127                         Self::Receive(tlvs) => tlvs.write(w)?,
 128                 }
 129                 Ok(())
 130         }
 131 }
 132
 133 impl Readable for BlindedPaymentTlvs {
 134         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
 135                 _init_and_read_tlv_stream!(r, {
 136                         (1, _padding, option),
 137                         (2, scid, option),
 138                         (10, payment_relay, option),
 139                         (12, payment_constraints, required),
 140                         (14, features, option),
 141                         (65536, payment_secret, option),
 142                 });
 143                 let _padding: Option<utils::Padding> = _padding;
 144
 145                 if let Some(short_channel_id) = scid {
 146                         if payment_secret.is_some() { return Err(DecodeError::InvalidValue) }
 147                         Ok(BlindedPaymentTlvs::Forward(ForwardTlvs {
 148                                 short_channel_id,
 149                                 payment_relay: payment_relay.ok_or(DecodeError::InvalidValue)?,
 150                                 payment_constraints: payment_constraints.0.unwrap(),
 151                                 features: features.ok_or(DecodeError::InvalidValue)?,
 152                         }))
 153                 } else {
 154                         if payment_relay.is_some() || features.is_some() { return Err(DecodeError::InvalidValue) }
 155                         Ok(BlindedPaymentTlvs::Receive(ReceiveTlvs {
 156                                 payment_secret: payment_secret.ok_or(DecodeError::InvalidValue)?,
 157                                 payment_constraints: payment_constraints.0.unwrap(),
 158                         }))
 159                 }
 160         }
 161 }
 162
 163 /// Construct blinded payment hops for the given `intermediate_nodes` and payee info.
 164 pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 165         secp_ctx: &Secp256k1<T>, intermediate_nodes: &[ForwardNode],
 166         payee_node_id: PublicKey, payee_tlvs: ReceiveTlvs, session_priv: &SecretKey
 167 ) -> Result<Vec<BlindedHop>, secp256k1::Error> {
 168         let pks = intermediate_nodes.iter().map(|node| &node.node_id)
 169                 .chain(core::iter::once(&payee_node_id));
 170         let tlvs = intermediate_nodes.iter().map(|node| BlindedPaymentTlvsRef::Forward(&node.tlvs))
 171                 .chain(core::iter::once(BlindedPaymentTlvsRef::Receive(&payee_tlvs)));
 172         utils::construct_blinded_hops(secp_ctx, pks, tlvs, session_priv)
 173 }
 174
 175 /// `None` if underflow occurs.
 176 fn amt_to_forward_msat(inbound_amt_msat: u64, payment_relay: &PaymentRelay) -> Option<u64> {
 177         let inbound_amt = inbound_amt_msat as u128;
 178         let base = payment_relay.fee_base_msat as u128;
 179         let prop = payment_relay.fee_proportional_millionths as u128;
 180
 181         let post_base_fee_inbound_amt =
 182                 if let Some(amt) = inbound_amt.checked_sub(base) { amt } else { return None };
 183         let mut amt_to_forward =
 184                 (post_base_fee_inbound_amt * 1_000_000 + 1_000_000 + prop - 1) / (prop + 1_000_000);
 185
 186         let fee = ((amt_to_forward * prop) / 1_000_000) + base;
 187         if inbound_amt - fee < amt_to_forward {
 188                 // Rounding up the forwarded amount resulted in underpaying this node, so take an extra 1 msat
 189                 // in fee to compensate.
 190                 amt_to_forward -= 1;
 191         }
 192         debug_assert_eq!(amt_to_forward + fee, inbound_amt);
 193         u64::try_from(amt_to_forward).ok()
 194 }
 195
 196 pub(super) fn compute_payinfo(
 197         intermediate_nodes: &[ForwardNode], payee_tlvs: &ReceiveTlvs, payee_htlc_maximum_msat: u64
 198 ) -> Result<BlindedPayInfo, ()> {
 199         let mut curr_base_fee: u64 = 0;
 200         let mut curr_prop_mil: u64 = 0;
 201         let mut cltv_expiry_delta: u16 = 0;
 202         for tlvs in intermediate_nodes.iter().rev().map(|n| &n.tlvs) {
 203                 // In the future, we'll want to take the intersection of all supported features for the
 204                 // `BlindedPayInfo`, but there are no features in that context right now.
 205                 if tlvs.features.requires_unknown_bits_from(&BlindedHopFeatures::empty()) { return Err(()) }
 206
 207                 let next_base_fee = tlvs.payment_relay.fee_base_msat as u64;
 208                 let next_prop_mil = tlvs.payment_relay.fee_proportional_millionths as u64;
 209                 // Use integer arithmetic to compute `ceil(a/b)` as `(a+b-1)/b`
 210                 // ((curr_base_fee * (1_000_000 + next_prop_mil)) / 1_000_000) + next_base_fee
 211                 curr_base_fee = curr_base_fee.checked_mul(1_000_000 + next_prop_mil)
 212                         .and_then(|f| f.checked_add(1_000_000 - 1))
 213                         .map(|f| f / 1_000_000)
 214                         .and_then(|f| f.checked_add(next_base_fee))
 215                         .ok_or(())?;
 216                 // ceil(((curr_prop_mil + 1_000_000) * (next_prop_mil + 1_000_000)) / 1_000_000) - 1_000_000
 217                 curr_prop_mil = curr_prop_mil.checked_add(1_000_000)
 218                         .and_then(|f1| next_prop_mil.checked_add(1_000_000).and_then(|f2| f2.checked_mul(f1)))
 219                         .and_then(|f| f.checked_add(1_000_000 - 1))
 220                         .map(|f| f / 1_000_000)
 221                         .and_then(|f| f.checked_sub(1_000_000))
 222                         .ok_or(())?;
 223
 224                 cltv_expiry_delta = cltv_expiry_delta.checked_add(tlvs.payment_relay.cltv_expiry_delta).ok_or(())?;
 225         }
 226
 227         let mut htlc_minimum_msat: u64 = 1;
 228         let mut htlc_maximum_msat: u64 = 21_000_000 * 100_000_000 * 1_000; // Total bitcoin supply
 229         for node in intermediate_nodes.iter() {
 230                 // The min htlc for an intermediate node is that node's min minus the fees charged by all of the
 231                 // following hops for forwarding that min, since that fee amount will automatically be included
 232                 // in the amount that this node receives and contribute towards reaching its min.
 233                 htlc_minimum_msat = amt_to_forward_msat(
 234                         core::cmp::max(node.tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat),
 235                         &node.tlvs.payment_relay
 236                 ).unwrap_or(1); // If underflow occurs, we definitely reached this node's min
 237                 htlc_maximum_msat = amt_to_forward_msat(
 238                         core::cmp::min(node.htlc_maximum_msat, htlc_maximum_msat), &node.tlvs.payment_relay
 239                 ).ok_or(())?; // If underflow occurs, we cannot send to this hop without exceeding their max
 240         }
 241         htlc_minimum_msat = core::cmp::max(
 242                 payee_tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat
 243         );
 244         htlc_maximum_msat = core::cmp::min(payee_htlc_maximum_msat, htlc_maximum_msat);
 245
 246         if htlc_maximum_msat < htlc_minimum_msat { return Err(()) }
 247         Ok(BlindedPayInfo {
 248                 fee_base_msat: u32::try_from(curr_base_fee).map_err(|_| ())?,
 249                 fee_proportional_millionths: u32::try_from(curr_prop_mil).map_err(|_| ())?,
 250                 cltv_expiry_delta,
 251                 htlc_minimum_msat,
 252                 htlc_maximum_msat,
 253                 features: BlindedHopFeatures::empty(),
 254         })
 255 }
 256
 257 impl_writeable_msg!(PaymentRelay, {
 258         cltv_expiry_delta,
 259         fee_proportional_millionths,
 260         fee_base_msat
 261 }, {});
 262
 263 impl_writeable_msg!(PaymentConstraints, {
 264         max_cltv_expiry,
 265         htlc_minimum_msat
 266 }, {});
 267
 268 #[cfg(test)]
 269 mod tests {
 270         use bitcoin::secp256k1::PublicKey;
 271         use crate::blinded_path::payment::{ForwardNode, ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentRelay};
 272         use crate::ln::PaymentSecret;
 273         use crate::ln::features::BlindedHopFeatures;
 274
 275         #[test]
 276         fn compute_payinfo() {
 277                 // Taken from the spec example for aggregating blinded payment info. See
 278                 // https://github.com/lightning/bolts/blob/master/proposals/route-blinding.md#blinded-payments
 279                 let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap();
 280                 let intermediate_nodes = vec![ForwardNode {
 281                         node_id: dummy_pk,
 282                         tlvs: ForwardTlvs {
 283                                 short_channel_id: 0,
 284                                 payment_relay: PaymentRelay {
 285                                         cltv_expiry_delta: 144,
 286                                         fee_proportional_millionths: 500,
 287                                         fee_base_msat: 100,
 288                                 },
 289                                 payment_constraints: PaymentConstraints {
 290                                         max_cltv_expiry: 0,
 291                                         htlc_minimum_msat: 100,
 292                                 },
 293                                 features: BlindedHopFeatures::empty(),
 294                         },
 295                         htlc_maximum_msat: u64::max_value(),
 296                 }, ForwardNode {
 297                         node_id: dummy_pk,
 298                         tlvs: ForwardTlvs {
 299                                 short_channel_id: 0,
 300                                 payment_relay: PaymentRelay {
 301                                         cltv_expiry_delta: 144,
 302                                         fee_proportional_millionths: 500,
 303                                         fee_base_msat: 100,
 304                                 },
 305                                 payment_constraints: PaymentConstraints {
 306                                         max_cltv_expiry: 0,
 307                                         htlc_minimum_msat: 1_000,
 308                                 },
 309                                 features: BlindedHopFeatures::empty(),
 310                         },
 311                         htlc_maximum_msat: u64::max_value(),
 312                 }];
 313                 let recv_tlvs = ReceiveTlvs {
 314                         payment_secret: PaymentSecret([0; 32]),
 315                         payment_constraints: PaymentConstraints {
 316                                 max_cltv_expiry: 0,
 317                                 htlc_minimum_msat: 1,
 318                         },
 319                 };
 320                 let htlc_maximum_msat = 100_000;
 321                 let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
 322                 assert_eq!(blinded_payinfo.fee_base_msat, 201);
 323                 assert_eq!(blinded_payinfo.fee_proportional_millionths, 1001);
 324                 assert_eq!(blinded_payinfo.cltv_expiry_delta, 288);
 325                 assert_eq!(blinded_payinfo.htlc_minimum_msat, 900);
 326                 assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat);
 327         }
 328
 329         #[test]
 330         fn compute_payinfo_1_hop() {
 331                 let recv_tlvs = ReceiveTlvs {
 332                         payment_secret: PaymentSecret([0; 32]),
 333                         payment_constraints: PaymentConstraints {
 334                                 max_cltv_expiry: 0,
 335                                 htlc_minimum_msat: 1,
 336                         },
 337                 };
 338                 let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs, 4242).unwrap();
 339                 assert_eq!(blinded_payinfo.fee_base_msat, 0);
 340                 assert_eq!(blinded_payinfo.fee_proportional_millionths, 0);
 341                 assert_eq!(blinded_payinfo.cltv_expiry_delta, 0);
 342                 assert_eq!(blinded_payinfo.htlc_minimum_msat, 1);
 343                 assert_eq!(blinded_payinfo.htlc_maximum_msat, 4242);
 344         }
 345
 346         #[test]
 347         fn simple_aggregated_htlc_min() {
 348                 // If no hops charge fees, the htlc_minimum_msat should just be the maximum htlc_minimum_msat
 349                 // along the path.
 350                 let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap();
 351                 let intermediate_nodes = vec![ForwardNode {
 352                         node_id: dummy_pk,
 353                         tlvs: ForwardTlvs {
 354                                 short_channel_id: 0,
 355                                 payment_relay: PaymentRelay {
 356                                         cltv_expiry_delta: 0,
 357                                         fee_proportional_millionths: 0,
 358                                         fee_base_msat: 0,
 359                                 },
 360                                 payment_constraints: PaymentConstraints {
 361                                         max_cltv_expiry: 0,
 362                                         htlc_minimum_msat: 1,
 363                                 },
 364                                 features: BlindedHopFeatures::empty(),
 365                         },
 366                         htlc_maximum_msat: u64::max_value()
 367                 }, ForwardNode {
 368                         node_id: dummy_pk,
 369                         tlvs: ForwardTlvs {
 370                                 short_channel_id: 0,
 371                                 payment_relay: PaymentRelay {
 372                                         cltv_expiry_delta: 0,
 373                                         fee_proportional_millionths: 0,
 374                                         fee_base_msat: 0,
 375                                 },
 376                                 payment_constraints: PaymentConstraints {
 377                                         max_cltv_expiry: 0,
 378                                         htlc_minimum_msat: 2_000,
 379                                 },
 380                                 features: BlindedHopFeatures::empty(),
 381                         },
 382                         htlc_maximum_msat: u64::max_value()
 383                 }];
 384                 let recv_tlvs = ReceiveTlvs {
 385                         payment_secret: PaymentSecret([0; 32]),
 386                         payment_constraints: PaymentConstraints {
 387                                 max_cltv_expiry: 0,
 388                                 htlc_minimum_msat: 3,
 389                         },
 390                 };
 391                 let htlc_maximum_msat = 100_000;
 392                 let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
 393                 assert_eq!(blinded_payinfo.htlc_minimum_msat, 2_000);
 394         }
 395
 396         #[test]
 397         fn aggregated_htlc_min() {
 398                 // Create a path with varying fees and htlc_mins, and make sure htlc_minimum_msat ends up as the
 399                 // max (htlc_min - following_fees) along the path.
 400                 let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap();
 401                 let intermediate_nodes = vec![ForwardNode {
 402                         node_id: dummy_pk,
 403                         tlvs: ForwardTlvs {
 404                                 short_channel_id: 0,
 405                                 payment_relay: PaymentRelay {
 406                                         cltv_expiry_delta: 0,
 407                                         fee_proportional_millionths: 500,
 408                                         fee_base_msat: 1_000,
 409                                 },
 410                                 payment_constraints: PaymentConstraints {
 411                                         max_cltv_expiry: 0,
 412                                         htlc_minimum_msat: 5_000,
 413                                 },
 414                                 features: BlindedHopFeatures::empty(),
 415                         },
 416                         htlc_maximum_msat: u64::max_value()
 417                 }, ForwardNode {
 418                         node_id: dummy_pk,
 419                         tlvs: ForwardTlvs {
 420                                 short_channel_id: 0,
 421                                 payment_relay: PaymentRelay {
 422                                         cltv_expiry_delta: 0,
 423                                         fee_proportional_millionths: 500,
 424                                         fee_base_msat: 200,
 425                                 },
 426                                 payment_constraints: PaymentConstraints {
 427                                         max_cltv_expiry: 0,
 428                                         htlc_minimum_msat: 2_000,
 429                                 },
 430                                 features: BlindedHopFeatures::empty(),
 431                         },
 432                         htlc_maximum_msat: u64::max_value()
 433                 }];
 434                 let recv_tlvs = ReceiveTlvs {
 435                         payment_secret: PaymentSecret([0; 32]),
 436                         payment_constraints: PaymentConstraints {
 437                                 max_cltv_expiry: 0,
 438                                 htlc_minimum_msat: 1,
 439                         },
 440                 };
 441                 let htlc_minimum_msat = 3798;
 442                 assert!(super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_minimum_msat - 1).is_err());
 443
 444                 let htlc_maximum_msat = htlc_minimum_msat + 1;
 445                 let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
 446                 assert_eq!(blinded_payinfo.htlc_minimum_msat, htlc_minimum_msat);
 447                 assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat);
 448         }
 449
 450         #[test]
 451         fn aggregated_htlc_max() {
 452                 // Create a path with varying fees and `htlc_maximum_msat`s, and make sure the aggregated max
 453                 // htlc ends up as the min (htlc_max - following_fees) along the path.
 454                 let dummy_pk = PublicKey::from_slice(&[2; 33]).unwrap();
 455                 let intermediate_nodes = vec![ForwardNode {
 456                         node_id: dummy_pk,
 457                         tlvs: ForwardTlvs {
 458                                 short_channel_id: 0,
 459                                 payment_relay: PaymentRelay {
 460                                         cltv_expiry_delta: 0,
 461                                         fee_proportional_millionths: 500,
 462                                         fee_base_msat: 1_000,
 463                                 },
 464                                 payment_constraints: PaymentConstraints {
 465                                         max_cltv_expiry: 0,
 466                                         htlc_minimum_msat: 1,
 467                                 },
 468                                 features: BlindedHopFeatures::empty(),
 469                         },
 470                         htlc_maximum_msat: 5_000,
 471                 }, ForwardNode {
 472                         node_id: dummy_pk,
 473                         tlvs: ForwardTlvs {
 474                                 short_channel_id: 0,
 475                                 payment_relay: PaymentRelay {
 476                                         cltv_expiry_delta: 0,
 477                                         fee_proportional_millionths: 500,
 478                                         fee_base_msat: 1,
 479                                 },
 480                                 payment_constraints: PaymentConstraints {
 481                                         max_cltv_expiry: 0,
 482                                         htlc_minimum_msat: 1,
 483                                 },
 484                                 features: BlindedHopFeatures::empty(),
 485                         },
 486                         htlc_maximum_msat: 10_000
 487                 }];
 488                 let recv_tlvs = ReceiveTlvs {
 489                         payment_secret: PaymentSecret([0; 32]),
 490                         payment_constraints: PaymentConstraints {
 491                                 max_cltv_expiry: 0,
 492                                 htlc_minimum_msat: 1,
 493                         },
 494                 };
 495
 496                 let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, 10_000).unwrap();
 497                 assert_eq!(blinded_payinfo.htlc_maximum_msat, 3997);
 498         }
 499 }