git.bitcoin.ninja Git - rust-lightning/blob - lightning/src/offers/invoice_request.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 encoding for `invoice_request` messages.
  11 //!
  12 //! An [`InvoiceRequest`] can be built from a parsed [`Offer`] as an "offer to be paid". It is
  13 //! typically constructed by a customer and sent to the merchant who had published the corresponding
  14 //! offer. The recipient of the request responds with a [`Bolt12Invoice`].
  15 //!
  16 //! For an "offer for money" (e.g., refund, ATM withdrawal), where an offer doesn't exist as a
  17 //! precursor, see [`Refund`].
  18 //!
  19 //! [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
  20 //! [`Refund`]: crate::offers::refund::Refund
  21 //!
  22 //! ```
  23 //! extern crate bitcoin;
  24 //! extern crate lightning;
  25 //!
  26 //! use bitcoin::network::constants::Network;
  27 //! use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
  28 //! use core::convert::Infallible;
  29 //! use lightning::ln::features::OfferFeatures;
  30 //! use lightning::offers::offer::Offer;
  31 //! use lightning::util::ser::Writeable;
  32 //!
  33 //! # fn parse() -> Result<(), lightning::offers::parse::Bolt12ParseError> {
  34 //! let secp_ctx = Secp256k1::new();
  35 //! let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32])?);
  36 //! let pubkey = PublicKey::from(keys);
  37 //! let mut buffer = Vec::new();
  38 //!
  39 //! "lno1qcp4256ypq"
  40 //!     .parse::<Offer>()?
  41 //!     .request_invoice(vec![42; 64], pubkey)?
  42 //!     .chain(Network::Testnet)?
  43 //!     .amount_msats(1000)?
  44 //!     .quantity(5)?
  45 //!     .payer_note("foo".to_string())
  46 //!     .build()?
  47 //!     .sign::<_, Infallible>(
  48 //!         |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
  49 //!     )
  50 //!     .expect("failed verifying signature")
  51 //!     .write(&mut buffer)
  52 //!     .unwrap();
  53 //! # Ok(())
  54 //! # }
  55 //! ```
  56
  57 use bitcoin::blockdata::constants::ChainHash;
  58 use bitcoin::network::constants::Network;
  59 use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, self};
  60 use bitcoin::secp256k1::schnorr::Signature;
  61 use core::convert::{AsRef, Infallible, TryFrom};
  62 use core::ops::Deref;
  63 use crate::sign::EntropySource;
  64 use crate::io;
  65 use crate::blinded_path::BlindedPath;
  66 use crate::ln::PaymentHash;
  67 use crate::ln::features::InvoiceRequestFeatures;
  68 use crate::ln::inbound_payment::{ExpandedKey, IV_LEN, Nonce};
  69 use crate::ln::msgs::DecodeError;
  70 use crate::offers::invoice::{BlindedPayInfo, DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder};
  71 use crate::offers::merkle::{SignError, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, self};
  72 use crate::offers::offer::{Offer, OfferContents, OfferTlvStream, OfferTlvStreamRef};
  73 use crate::offers::parse::{Bolt12ParseError, ParsedMessage, Bolt12SemanticError};
  74 use crate::offers::payer::{PayerContents, PayerTlvStream, PayerTlvStreamRef};
  75 use crate::offers::signer::{Metadata, MetadataMaterial};
  76 use crate::util::ser::{HighZeroBytesDroppedBigSize, SeekReadable, WithoutLength, Writeable, Writer};
  77 use crate::util::string::PrintableString;
  78
  79 use crate::prelude::*;
  80
  81 /// Tag for the hash function used when signing an [`InvoiceRequest`]'s merkle root.
  82 pub const SIGNATURE_TAG: &'static str = concat!("lightning", "invoice_request", "signature");
  83
  84 pub(super) const IV_BYTES: &[u8; IV_LEN] = b"LDK Invreq ~~~~~";
  85
  86 /// Builds an [`InvoiceRequest`] from an [`Offer`] for the "offer to be paid" flow.
  87 ///
  88 /// See [module-level documentation] for usage.
  89 ///
  90 /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
  91 ///
  92 /// [module-level documentation]: self
  93 pub struct InvoiceRequestBuilder<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> {
  94         offer: &'a Offer,
  95         invoice_request: InvoiceRequestContentsWithoutPayerId,
  96         payer_id: Option<PublicKey>,
  97         payer_id_strategy: core::marker::PhantomData<P>,
  98         secp_ctx: Option<&'b Secp256k1<T>>,
  99 }
 100
 101 /// Indicates how [`InvoiceRequest::payer_id`] will be set.
 102 ///
 103 /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
 104 pub trait PayerIdStrategy {}
 105
 106 /// [`InvoiceRequest::payer_id`] will be explicitly set.
 107 ///
 108 /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
 109 pub struct ExplicitPayerId {}
 110
 111 /// [`InvoiceRequest::payer_id`] will be derived.
 112 ///
 113 /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
 114 pub struct DerivedPayerId {}
 115
 116 impl PayerIdStrategy for ExplicitPayerId {}
 117 impl PayerIdStrategy for DerivedPayerId {}
 118
 119 impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, ExplicitPayerId, T> {
 120         pub(super) fn new(offer: &'a Offer, metadata: Vec<u8>, payer_id: PublicKey) -> Self {
 121                 Self {
 122                         offer,
 123                         invoice_request: Self::create_contents(offer, Metadata::Bytes(metadata)),
 124                         payer_id: Some(payer_id),
 125                         payer_id_strategy: core::marker::PhantomData,
 126                         secp_ctx: None,
 127                 }
 128         }
 129
 130         pub(super) fn deriving_metadata<ES: Deref>(
 131                 offer: &'a Offer, payer_id: PublicKey, expanded_key: &ExpandedKey, entropy_source: ES
 132         ) -> Self where ES::Target: EntropySource {
 133                 let nonce = Nonce::from_entropy_source(entropy_source);
 134                 let derivation_material = MetadataMaterial::new(nonce, expanded_key, IV_BYTES);
 135                 let metadata = Metadata::Derived(derivation_material);
 136                 Self {
 137                         offer,
 138                         invoice_request: Self::create_contents(offer, metadata),
 139                         payer_id: Some(payer_id),
 140                         payer_id_strategy: core::marker::PhantomData,
 141                         secp_ctx: None,
 142                 }
 143         }
 144 }
 145
 146 impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, DerivedPayerId, T> {
 147         pub(super) fn deriving_payer_id<ES: Deref>(
 148                 offer: &'a Offer, expanded_key: &ExpandedKey, entropy_source: ES, secp_ctx: &'b Secp256k1<T>
 149         ) -> Self where ES::Target: EntropySource {
 150                 let nonce = Nonce::from_entropy_source(entropy_source);
 151                 let derivation_material = MetadataMaterial::new(nonce, expanded_key, IV_BYTES);
 152                 let metadata = Metadata::DerivedSigningPubkey(derivation_material);
 153                 Self {
 154                         offer,
 155                         invoice_request: Self::create_contents(offer, metadata),
 156                         payer_id: None,
 157                         payer_id_strategy: core::marker::PhantomData,
 158                         secp_ctx: Some(secp_ctx),
 159                 }
 160         }
 161 }
 162
 163 impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, P, T> {
 164         fn create_contents(offer: &Offer, metadata: Metadata) -> InvoiceRequestContentsWithoutPayerId {
 165                 let offer = offer.contents.clone();
 166                 InvoiceRequestContentsWithoutPayerId {
 167                         payer: PayerContents(metadata), offer, chain: None, amount_msats: None,
 168                         features: InvoiceRequestFeatures::empty(), quantity: None, payer_note: None,
 169                 }
 170         }
 171
 172         /// Sets the [`InvoiceRequest::chain`] of the given [`Network`] for paying an invoice. If not
 173         /// called, [`Network::Bitcoin`] is assumed. Errors if the chain for `network` is not supported
 174         /// by the offer.
 175         ///
 176         /// Successive calls to this method will override the previous setting.
 177         pub fn chain(mut self, network: Network) -> Result<Self, Bolt12SemanticError> {
 178                 let chain = ChainHash::using_genesis_block(network);
 179                 if !self.offer.supports_chain(chain) {
 180                         return Err(Bolt12SemanticError::UnsupportedChain);
 181                 }
 182
 183                 self.invoice_request.chain = Some(chain);
 184                 Ok(self)
 185         }
 186
 187         /// Sets the [`InvoiceRequest::amount_msats`] for paying an invoice. Errors if `amount_msats` is
 188         /// not at least the expected invoice amount (i.e., [`Offer::amount`] times [`quantity`]).
 189         ///
 190         /// Successive calls to this method will override the previous setting.
 191         ///
 192         /// [`quantity`]: Self::quantity
 193         pub fn amount_msats(mut self, amount_msats: u64) -> Result<Self, Bolt12SemanticError> {
 194                 self.invoice_request.offer.check_amount_msats_for_quantity(
 195                         Some(amount_msats), self.invoice_request.quantity
 196                 )?;
 197                 self.invoice_request.amount_msats = Some(amount_msats);
 198                 Ok(self)
 199         }
 200
 201         /// Sets [`InvoiceRequest::quantity`] of items. If not set, `1` is assumed. Errors if `quantity`
 202         /// does not conform to [`Offer::is_valid_quantity`].
 203         ///
 204         /// Successive calls to this method will override the previous setting.
 205         pub fn quantity(mut self, quantity: u64) -> Result<Self, Bolt12SemanticError> {
 206                 self.invoice_request.offer.check_quantity(Some(quantity))?;
 207                 self.invoice_request.quantity = Some(quantity);
 208                 Ok(self)
 209         }
 210
 211         /// Sets the [`InvoiceRequest::payer_note`].
 212         ///
 213         /// Successive calls to this method will override the previous setting.
 214         pub fn payer_note(mut self, payer_note: String) -> Self {
 215                 self.invoice_request.payer_note = Some(payer_note);
 216                 self
 217         }
 218
 219         fn build_with_checks(mut self) -> Result<
 220                 (UnsignedInvoiceRequest, Option<KeyPair>, Option<&'b Secp256k1<T>>),
 221                 Bolt12SemanticError
 222         > {
 223                 #[cfg(feature = "std")] {
 224                         if self.offer.is_expired() {
 225                                 return Err(Bolt12SemanticError::AlreadyExpired);
 226                         }
 227                 }
 228
 229                 let chain = self.invoice_request.chain();
 230                 if !self.offer.supports_chain(chain) {
 231                         return Err(Bolt12SemanticError::UnsupportedChain);
 232                 }
 233
 234                 if chain == self.offer.implied_chain() {
 235                         self.invoice_request.chain = None;
 236                 }
 237
 238                 if self.offer.amount().is_none() && self.invoice_request.amount_msats.is_none() {
 239                         return Err(Bolt12SemanticError::MissingAmount);
 240                 }
 241
 242                 self.invoice_request.offer.check_quantity(self.invoice_request.quantity)?;
 243                 self.invoice_request.offer.check_amount_msats_for_quantity(
 244                         self.invoice_request.amount_msats, self.invoice_request.quantity
 245                 )?;
 246
 247                 Ok(self.build_without_checks())
 248         }
 249
 250         fn build_without_checks(mut self) ->
 251                 (UnsignedInvoiceRequest, Option<KeyPair>, Option<&'b Secp256k1<T>>)
 252         {
 253                 // Create the metadata for stateless verification of a Bolt12Invoice.
 254                 let mut keys = None;
 255                 let secp_ctx = self.secp_ctx.clone();
 256                 if self.invoice_request.payer.0.has_derivation_material() {
 257                         let mut metadata = core::mem::take(&mut self.invoice_request.payer.0);
 258
 259                         let mut tlv_stream = self.invoice_request.as_tlv_stream();
 260                         debug_assert!(tlv_stream.2.payer_id.is_none());
 261                         tlv_stream.0.metadata = None;
 262                         if !metadata.derives_keys() {
 263                                 tlv_stream.2.payer_id = self.payer_id.as_ref();
 264                         }
 265
 266                         let (derived_metadata, derived_keys) = metadata.derive_from(tlv_stream, self.secp_ctx);
 267                         metadata = derived_metadata;
 268                         keys = derived_keys;
 269                         if let Some(keys) = keys {
 270                                 debug_assert!(self.payer_id.is_none());
 271                                 self.payer_id = Some(keys.public_key());
 272                         }
 273
 274                         self.invoice_request.payer.0 = metadata;
 275                 }
 276
 277                 debug_assert!(self.invoice_request.payer.0.as_bytes().is_some());
 278                 debug_assert!(self.payer_id.is_some());
 279                 let payer_id = self.payer_id.unwrap();
 280
 281                 let invoice_request = InvoiceRequestContents {
 282                         inner: self.invoice_request,
 283                         payer_id,
 284                 };
 285                 let unsigned_invoice_request = UnsignedInvoiceRequest::new(self.offer, invoice_request);
 286
 287                 (unsigned_invoice_request, keys, secp_ctx)
 288         }
 289 }
 290
 291 impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, ExplicitPayerId, T> {
 292         /// Builds an unsigned [`InvoiceRequest`] after checking for valid semantics. It can be signed
 293         /// by [`UnsignedInvoiceRequest::sign`].
 294         pub fn build(self) -> Result<UnsignedInvoiceRequest, Bolt12SemanticError> {
 295                 let (unsigned_invoice_request, keys, _) = self.build_with_checks()?;
 296                 debug_assert!(keys.is_none());
 297                 Ok(unsigned_invoice_request)
 298         }
 299 }
 300
 301 impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, DerivedPayerId, T> {
 302         /// Builds a signed [`InvoiceRequest`] after checking for valid semantics.
 303         pub fn build_and_sign(self) -> Result<InvoiceRequest, Bolt12SemanticError> {
 304                 let (unsigned_invoice_request, keys, secp_ctx) = self.build_with_checks()?;
 305                 debug_assert!(keys.is_some());
 306
 307                 let secp_ctx = secp_ctx.unwrap();
 308                 let keys = keys.unwrap();
 309                 let invoice_request = unsigned_invoice_request
 310                         .sign::<_, Infallible>(
 311                                 |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
 312                         )
 313                         .unwrap();
 314                 Ok(invoice_request)
 315         }
 316 }
 317
 318 #[cfg(test)]
 319 impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, P, T> {
 320         fn chain_unchecked(mut self, network: Network) -> Self {
 321                 let chain = ChainHash::using_genesis_block(network);
 322                 self.invoice_request.chain = Some(chain);
 323                 self
 324         }
 325
 326         fn amount_msats_unchecked(mut self, amount_msats: u64) -> Self {
 327                 self.invoice_request.amount_msats = Some(amount_msats);
 328                 self
 329         }
 330
 331         fn features_unchecked(mut self, features: InvoiceRequestFeatures) -> Self {
 332                 self.invoice_request.features = features;
 333                 self
 334         }
 335
 336         fn quantity_unchecked(mut self, quantity: u64) -> Self {
 337                 self.invoice_request.quantity = Some(quantity);
 338                 self
 339         }
 340
 341         pub(super) fn build_unchecked(self) -> UnsignedInvoiceRequest {
 342                 self.build_without_checks().0
 343         }
 344 }
 345
 346 /// A semantically valid [`InvoiceRequest`] that hasn't been signed.
 347 ///
 348 /// # Serialization
 349 ///
 350 /// This is serialized as a TLV stream, which includes TLV records from the originating message. As
 351 /// such, it may include unknown, odd TLV records.
 352 pub struct UnsignedInvoiceRequest {
 353         bytes: Vec<u8>,
 354         contents: InvoiceRequestContents,
 355         tagged_hash: TaggedHash,
 356 }
 357
 358 impl UnsignedInvoiceRequest {
 359         fn new(offer: &Offer, contents: InvoiceRequestContents) -> Self {
 360                 // Use the offer bytes instead of the offer TLV stream as the offer may have contained
 361                 // unknown TLV records, which are not stored in `OfferContents`.
 362                 let (payer_tlv_stream, _offer_tlv_stream, invoice_request_tlv_stream) =
 363                         contents.as_tlv_stream();
 364                 let offer_bytes = WithoutLength(&offer.bytes);
 365                 let unsigned_tlv_stream = (payer_tlv_stream, offer_bytes, invoice_request_tlv_stream);
 366
 367                 let mut bytes = Vec::new();
 368                 unsigned_tlv_stream.write(&mut bytes).unwrap();
 369
 370                 let tagged_hash = TaggedHash::new(SIGNATURE_TAG, &bytes);
 371
 372                 Self { bytes, contents, tagged_hash }
 373         }
 374
 375         /// Signs the [`TaggedHash`] of the invoice request using the given function.
 376         ///
 377         /// Note: The hash computation may have included unknown, odd TLV records.
 378         ///
 379         /// This is not exported to bindings users as functions are not yet mapped.
 380         pub fn sign<F, E>(mut self, sign: F) -> Result<InvoiceRequest, SignError<E>>
 381         where
 382                 F: FnOnce(&Self) -> Result<Signature, E>
 383         {
 384                 let pubkey = self.contents.payer_id;
 385                 let signature = merkle::sign_message(sign, &self, pubkey)?;
 386
 387                 // Append the signature TLV record to the bytes.
 388                 let signature_tlv_stream = SignatureTlvStreamRef {
 389                         signature: Some(&signature),
 390                 };
 391                 signature_tlv_stream.write(&mut self.bytes).unwrap();
 392
 393                 Ok(InvoiceRequest {
 394                         bytes: self.bytes,
 395                         contents: self.contents,
 396                         signature,
 397                 })
 398         }
 399 }
 400
 401 impl AsRef<TaggedHash> for UnsignedInvoiceRequest {
 402         fn as_ref(&self) -> &TaggedHash {
 403                 &self.tagged_hash
 404         }
 405 }
 406
 407 /// An `InvoiceRequest` is a request for a [`Bolt12Invoice`] formulated from an [`Offer`].
 408 ///
 409 /// An offer may provide choices such as quantity, amount, chain, features, etc. An invoice request
 410 /// specifies these such that its recipient can send an invoice for payment.
 411 ///
 412 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 413 /// [`Offer`]: crate::offers::offer::Offer
 414 #[derive(Clone, Debug)]
 415 #[cfg_attr(test, derive(PartialEq))]
 416 pub struct InvoiceRequest {
 417         pub(super) bytes: Vec<u8>,
 418         pub(super) contents: InvoiceRequestContents,
 419         signature: Signature,
 420 }
 421
 422 /// The contents of an [`InvoiceRequest`], which may be shared with an [`Bolt12Invoice`].
 423 ///
 424 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 425 #[derive(Clone, Debug)]
 426 #[cfg_attr(test, derive(PartialEq))]
 427 pub(super) struct InvoiceRequestContents {
 428         pub(super) inner: InvoiceRequestContentsWithoutPayerId,
 429         payer_id: PublicKey,
 430 }
 431
 432 #[derive(Clone, Debug)]
 433 #[cfg_attr(test, derive(PartialEq))]
 434 pub(super) struct InvoiceRequestContentsWithoutPayerId {
 435         payer: PayerContents,
 436         pub(super) offer: OfferContents,
 437         chain: Option<ChainHash>,
 438         amount_msats: Option<u64>,
 439         features: InvoiceRequestFeatures,
 440         quantity: Option<u64>,
 441         payer_note: Option<String>,
 442 }
 443
 444 impl InvoiceRequest {
 445         /// An unpredictable series of bytes, typically containing information about the derivation of
 446         /// [`payer_id`].
 447         ///
 448         /// [`payer_id`]: Self::payer_id
 449         pub fn metadata(&self) -> &[u8] {
 450                 self.contents.metadata()
 451         }
 452
 453         /// A chain from [`Offer::chains`] that the offer is valid for.
 454         pub fn chain(&self) -> ChainHash {
 455                 self.contents.chain()
 456         }
 457
 458         /// The amount to pay in msats (i.e., the minimum lightning-payable unit for [`chain`]), which
 459         /// must be greater than or equal to [`Offer::amount`], converted if necessary.
 460         ///
 461         /// [`chain`]: Self::chain
 462         pub fn amount_msats(&self) -> Option<u64> {
 463                 self.contents.amount_msats()
 464         }
 465
 466         /// Features pertaining to requesting an invoice.
 467         pub fn features(&self) -> &InvoiceRequestFeatures {
 468                 &self.contents.features()
 469         }
 470
 471         /// The quantity of the offer's item conforming to [`Offer::is_valid_quantity`].
 472         pub fn quantity(&self) -> Option<u64> {
 473                 self.contents.quantity()
 474         }
 475
 476         /// A possibly transient pubkey used to sign the invoice request.
 477         pub fn payer_id(&self) -> PublicKey {
 478                 self.contents.payer_id()
 479         }
 480
 481         /// A payer-provided note which will be seen by the recipient and reflected back in the invoice
 482         /// response.
 483         pub fn payer_note(&self) -> Option<PrintableString> {
 484                 self.contents.payer_note()
 485         }
 486
 487         /// Signature of the invoice request using [`payer_id`].
 488         ///
 489         /// [`payer_id`]: Self::payer_id
 490         pub fn signature(&self) -> Signature {
 491                 self.signature
 492         }
 493
 494         /// Creates an [`InvoiceBuilder`] for the request with the given required fields and using the
 495         /// [`Duration`] since [`std::time::SystemTime::UNIX_EPOCH`] as the creation time.
 496         ///
 497         /// See [`InvoiceRequest::respond_with_no_std`] for further details where the aforementioned
 498         /// creation time is used for the `created_at` parameter.
 499         ///
 500         /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
 501         ///
 502         /// [`Duration`]: core::time::Duration
 503         #[cfg(feature = "std")]
 504         pub fn respond_with(
 505                 &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
 506         ) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
 507                 let created_at = std::time::SystemTime::now()
 508                         .duration_since(std::time::SystemTime::UNIX_EPOCH)
 509                         .expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");
 510
 511                 self.respond_with_no_std(payment_paths, payment_hash, created_at)
 512         }
 513
 514         /// Creates an [`InvoiceBuilder`] for the request with the given required fields.
 515         ///
 516         /// Unless [`InvoiceBuilder::relative_expiry`] is set, the invoice will expire two hours after
 517         /// `created_at`, which is used to set [`Bolt12Invoice::created_at`]. Useful for `no-std` builds
 518         /// where [`std::time::SystemTime`] is not available.
 519         ///
 520         /// The caller is expected to remember the preimage of `payment_hash` in order to claim a payment
 521         /// for the invoice.
 522         ///
 523         /// The `payment_paths` parameter is useful for maintaining the payment recipient's privacy. It
 524         /// must contain one or more elements ordered from most-preferred to least-preferred, if there's
 525         /// a preference. Note, however, that any privacy is lost if a public node id was used for
 526         /// [`Offer::signing_pubkey`].
 527         ///
 528         /// Errors if the request contains unknown required features.
 529         ///
 530         /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
 531         ///
 532         /// [`Bolt12Invoice::created_at`]: crate::offers::invoice::Bolt12Invoice::created_at
 533         pub fn respond_with_no_std(
 534                 &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
 535                 created_at: core::time::Duration
 536         ) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
 537                 if self.features().requires_unknown_bits() {
 538                         return Err(Bolt12SemanticError::UnknownRequiredFeatures);
 539                 }
 540
 541                 InvoiceBuilder::for_offer(self, payment_paths, created_at, payment_hash)
 542         }
 543
 544         /// Creates an [`InvoiceBuilder`] for the request using the given required fields and that uses
 545         /// derived signing keys from the originating [`Offer`] to sign the [`Bolt12Invoice`]. Must use
 546         /// the same [`ExpandedKey`] as the one used to create the offer.
 547         ///
 548         /// See [`InvoiceRequest::respond_with`] for further details.
 549         ///
 550         /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
 551         ///
 552         /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 553         #[cfg(feature = "std")]
 554         pub fn verify_and_respond_using_derived_keys<T: secp256k1::Signing>(
 555                 &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
 556                 expanded_key: &ExpandedKey, secp_ctx: &Secp256k1<T>
 557         ) -> Result<InvoiceBuilder<DerivedSigningPubkey>, Bolt12SemanticError> {
 558                 let created_at = std::time::SystemTime::now()
 559                         .duration_since(std::time::SystemTime::UNIX_EPOCH)
 560                         .expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");
 561
 562                 self.verify_and_respond_using_derived_keys_no_std(
 563                         payment_paths, payment_hash, created_at, expanded_key, secp_ctx
 564                 )
 565         }
 566
 567         /// Creates an [`InvoiceBuilder`] for the request using the given required fields and that uses
 568         /// derived signing keys from the originating [`Offer`] to sign the [`Bolt12Invoice`]. Must use
 569         /// the same [`ExpandedKey`] as the one used to create the offer.
 570         ///
 571         /// See [`InvoiceRequest::respond_with_no_std`] for further details.
 572         ///
 573         /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
 574         ///
 575         /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 576         pub fn verify_and_respond_using_derived_keys_no_std<T: secp256k1::Signing>(
 577                 &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
 578                 created_at: core::time::Duration, expanded_key: &ExpandedKey, secp_ctx: &Secp256k1<T>
 579         ) -> Result<InvoiceBuilder<DerivedSigningPubkey>, Bolt12SemanticError> {
 580                 if self.features().requires_unknown_bits() {
 581                         return Err(Bolt12SemanticError::UnknownRequiredFeatures);
 582                 }
 583
 584                 let keys = match self.verify(expanded_key, secp_ctx) {
 585                         Err(()) => return Err(Bolt12SemanticError::InvalidMetadata),
 586                         Ok(None) => return Err(Bolt12SemanticError::InvalidMetadata),
 587                         Ok(Some(keys)) => keys,
 588                 };
 589
 590                 InvoiceBuilder::for_offer_using_keys(self, payment_paths, created_at, payment_hash, keys)
 591         }
 592
 593         /// Verifies that the request was for an offer created using the given key. Returns the derived
 594         /// keys need to sign an [`Bolt12Invoice`] for the request if they could be extracted from the
 595         /// metadata.
 596         ///
 597         /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 598         pub fn verify<T: secp256k1::Signing>(
 599                 &self, key: &ExpandedKey, secp_ctx: &Secp256k1<T>
 600         ) -> Result<Option<KeyPair>, ()> {
 601                 self.contents.inner.offer.verify(&self.bytes, key, secp_ctx)
 602         }
 603
 604         #[cfg(test)]
 605         fn as_tlv_stream(&self) -> FullInvoiceRequestTlvStreamRef {
 606                 let (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream) =
 607                         self.contents.as_tlv_stream();
 608                 let signature_tlv_stream = SignatureTlvStreamRef {
 609                         signature: Some(&self.signature),
 610                 };
 611                 (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, signature_tlv_stream)
 612         }
 613 }
 614
 615 impl InvoiceRequestContents {
 616         pub(super) fn metadata(&self) -> &[u8] {
 617                 self.inner.metadata()
 618         }
 619
 620         pub(super) fn derives_keys(&self) -> bool {
 621                 self.inner.payer.0.derives_keys()
 622         }
 623
 624         pub(super) fn chain(&self) -> ChainHash {
 625                 self.inner.chain()
 626         }
 627
 628         fn amount_msats(&self) -> Option<u64> {
 629                 self.inner.amount_msats
 630         }
 631
 632         fn features(&self) -> &InvoiceRequestFeatures {
 633                 &self.inner.features
 634         }
 635
 636         fn quantity(&self) -> Option<u64> {
 637                 self.inner.quantity
 638         }
 639
 640         pub(super) fn payer_id(&self) -> PublicKey {
 641                 self.payer_id
 642         }
 643
 644         fn payer_note(&self) -> Option<PrintableString> {
 645                 self.inner.payer_note.as_ref()
 646                         .map(|payer_note| PrintableString(payer_note.as_str()))
 647         }
 648
 649         pub(super) fn as_tlv_stream(&self) -> PartialInvoiceRequestTlvStreamRef {
 650                 let (payer, offer, mut invoice_request) = self.inner.as_tlv_stream();
 651                 invoice_request.payer_id = Some(&self.payer_id);
 652                 (payer, offer, invoice_request)
 653         }
 654 }
 655
 656 impl InvoiceRequestContentsWithoutPayerId {
 657         pub(super) fn metadata(&self) -> &[u8] {
 658                 self.payer.0.as_bytes().map(|bytes| bytes.as_slice()).unwrap_or(&[])
 659         }
 660
 661         pub(super) fn chain(&self) -> ChainHash {
 662                 self.chain.unwrap_or_else(|| self.offer.implied_chain())
 663         }
 664
 665         pub(super) fn as_tlv_stream(&self) -> PartialInvoiceRequestTlvStreamRef {
 666                 let payer = PayerTlvStreamRef {
 667                         metadata: self.payer.0.as_bytes(),
 668                 };
 669
 670                 let offer = self.offer.as_tlv_stream();
 671
 672                 let features = {
 673                         if self.features == InvoiceRequestFeatures::empty() { None }
 674                         else { Some(&self.features) }
 675                 };
 676
 677                 let invoice_request = InvoiceRequestTlvStreamRef {
 678                         chain: self.chain.as_ref(),
 679                         amount: self.amount_msats,
 680                         features,
 681                         quantity: self.quantity,
 682                         payer_id: None,
 683                         payer_note: self.payer_note.as_ref(),
 684                 };
 685
 686                 (payer, offer, invoice_request)
 687         }
 688 }
 689
 690 impl Writeable for UnsignedInvoiceRequest {
 691         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 692                 WithoutLength(&self.bytes).write(writer)
 693         }
 694 }
 695
 696 impl Writeable for InvoiceRequest {
 697         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 698                 WithoutLength(&self.bytes).write(writer)
 699         }
 700 }
 701
 702 impl Writeable for InvoiceRequestContents {
 703         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 704                 self.as_tlv_stream().write(writer)
 705         }
 706 }
 707
 708 /// Valid type range for invoice_request TLV records.
 709 pub(super) const INVOICE_REQUEST_TYPES: core::ops::Range<u64> = 80..160;
 710
 711 /// TLV record type for [`InvoiceRequest::payer_id`] and [`Refund::payer_id`].
 712 ///
 713 /// [`Refund::payer_id`]: crate::offers::refund::Refund::payer_id
 714 pub(super) const INVOICE_REQUEST_PAYER_ID_TYPE: u64 = 88;
 715
 716 tlv_stream!(InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef, INVOICE_REQUEST_TYPES, {
 717         (80, chain: ChainHash),
 718         (82, amount: (u64, HighZeroBytesDroppedBigSize)),
 719         (84, features: (InvoiceRequestFeatures, WithoutLength)),
 720         (86, quantity: (u64, HighZeroBytesDroppedBigSize)),
 721         (INVOICE_REQUEST_PAYER_ID_TYPE, payer_id: PublicKey),
 722         (89, payer_note: (String, WithoutLength)),
 723 });
 724
 725 type FullInvoiceRequestTlvStream =
 726         (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream, SignatureTlvStream);
 727
 728 #[cfg(test)]
 729 type FullInvoiceRequestTlvStreamRef<'a> = (
 730         PayerTlvStreamRef<'a>,
 731         OfferTlvStreamRef<'a>,
 732         InvoiceRequestTlvStreamRef<'a>,
 733         SignatureTlvStreamRef<'a>,
 734 );
 735
 736 impl SeekReadable for FullInvoiceRequestTlvStream {
 737         fn read<R: io::Read + io::Seek>(r: &mut R) -> Result<Self, DecodeError> {
 738                 let payer = SeekReadable::read(r)?;
 739                 let offer = SeekReadable::read(r)?;
 740                 let invoice_request = SeekReadable::read(r)?;
 741                 let signature = SeekReadable::read(r)?;
 742
 743                 Ok((payer, offer, invoice_request, signature))
 744         }
 745 }
 746
 747 type PartialInvoiceRequestTlvStream = (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream);
 748
 749 type PartialInvoiceRequestTlvStreamRef<'a> = (
 750         PayerTlvStreamRef<'a>,
 751         OfferTlvStreamRef<'a>,
 752         InvoiceRequestTlvStreamRef<'a>,
 753 );
 754
 755 impl TryFrom<Vec<u8>> for UnsignedInvoiceRequest {
 756         type Error = Bolt12ParseError;
 757
 758         fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
 759                 let invoice_request = ParsedMessage::<PartialInvoiceRequestTlvStream>::try_from(bytes)?;
 760                 let ParsedMessage { bytes, tlv_stream } = invoice_request;
 761                 let (
 762                         payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream,
 763                 ) = tlv_stream;
 764                 let contents = InvoiceRequestContents::try_from(
 765                         (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream)
 766                 )?;
 767
 768                 let tagged_hash = TaggedHash::new(SIGNATURE_TAG, &bytes);
 769
 770                 Ok(UnsignedInvoiceRequest { bytes, contents, tagged_hash })
 771         }
 772 }
 773
 774 impl TryFrom<Vec<u8>> for InvoiceRequest {
 775         type Error = Bolt12ParseError;
 776
 777         fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
 778                 let invoice_request = ParsedMessage::<FullInvoiceRequestTlvStream>::try_from(bytes)?;
 779                 let ParsedMessage { bytes, tlv_stream } = invoice_request;
 780                 let (
 781                         payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream,
 782                         SignatureTlvStream { signature },
 783                 ) = tlv_stream;
 784                 let contents = InvoiceRequestContents::try_from(
 785                         (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream)
 786                 )?;
 787
 788                 let signature = match signature {
 789                         None => return Err(Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingSignature)),
 790                         Some(signature) => signature,
 791                 };
 792                 merkle::verify_signature(&signature, SIGNATURE_TAG, &bytes, contents.payer_id)?;
 793
 794                 Ok(InvoiceRequest { bytes, contents, signature })
 795         }
 796 }
 797
 798 impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
 799         type Error = Bolt12SemanticError;
 800
 801         fn try_from(tlv_stream: PartialInvoiceRequestTlvStream) -> Result<Self, Self::Error> {
 802                 let (
 803                         PayerTlvStream { metadata },
 804                         offer_tlv_stream,
 805                         InvoiceRequestTlvStream { chain, amount, features, quantity, payer_id, payer_note },
 806                 ) = tlv_stream;
 807
 808                 let payer = match metadata {
 809                         None => return Err(Bolt12SemanticError::MissingPayerMetadata),
 810                         Some(metadata) => PayerContents(Metadata::Bytes(metadata)),
 811                 };
 812                 let offer = OfferContents::try_from(offer_tlv_stream)?;
 813
 814                 if !offer.supports_chain(chain.unwrap_or_else(|| offer.implied_chain())) {
 815                         return Err(Bolt12SemanticError::UnsupportedChain);
 816                 }
 817
 818                 if offer.amount().is_none() && amount.is_none() {
 819                         return Err(Bolt12SemanticError::MissingAmount);
 820                 }
 821
 822                 offer.check_quantity(quantity)?;
 823                 offer.check_amount_msats_for_quantity(amount, quantity)?;
 824
 825                 let features = features.unwrap_or_else(InvoiceRequestFeatures::empty);
 826
 827                 let payer_id = match payer_id {
 828                         None => return Err(Bolt12SemanticError::MissingPayerId),
 829                         Some(payer_id) => payer_id,
 830                 };
 831
 832                 Ok(InvoiceRequestContents {
 833                         inner: InvoiceRequestContentsWithoutPayerId {
 834                                 payer, offer, chain, amount_msats: amount, features, quantity, payer_note,
 835                         },
 836                         payer_id,
 837                 })
 838         }
 839 }
 840
 841 #[cfg(test)]
 842 mod tests {
 843         use super::{InvoiceRequest, InvoiceRequestTlvStreamRef, SIGNATURE_TAG, UnsignedInvoiceRequest};
 844
 845         use bitcoin::blockdata::constants::ChainHash;
 846         use bitcoin::network::constants::Network;
 847         use bitcoin::secp256k1::{KeyPair, Secp256k1, SecretKey, self};
 848         use core::convert::{Infallible, TryFrom};
 849         use core::num::NonZeroU64;
 850         #[cfg(feature = "std")]
 851         use core::time::Duration;
 852         use crate::sign::KeyMaterial;
 853         use crate::ln::features::InvoiceRequestFeatures;
 854         use crate::ln::inbound_payment::ExpandedKey;
 855         use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
 856         use crate::offers::invoice::{Bolt12Invoice, SIGNATURE_TAG as INVOICE_SIGNATURE_TAG};
 857         use crate::offers::merkle::{SignError, SignatureTlvStreamRef, TaggedHash, self};
 858         use crate::offers::offer::{Amount, OfferBuilder, OfferTlvStreamRef, Quantity};
 859         use crate::offers::parse::{Bolt12ParseError, Bolt12SemanticError};
 860         use crate::offers::payer::PayerTlvStreamRef;
 861         use crate::offers::test_utils::*;
 862         use crate::util::ser::{BigSize, Writeable};
 863         use crate::util::string::PrintableString;
 864
 865         #[test]
 866         fn builds_invoice_request_with_defaults() {
 867                 let unsigned_invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
 868                         .amount_msats(1000)
 869                         .build().unwrap()
 870                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 871                         .build().unwrap();
 872
 873                 let mut buffer = Vec::new();
 874                 unsigned_invoice_request.write(&mut buffer).unwrap();
 875
 876                 match UnsignedInvoiceRequest::try_from(buffer) {
 877                         Err(e) => panic!("error parsing unsigned invoice request: {:?}", e),
 878                         Ok(parsed) => {
 879                                 assert_eq!(parsed.bytes, unsigned_invoice_request.bytes);
 880                                 assert_eq!(parsed.tagged_hash, unsigned_invoice_request.tagged_hash);
 881                         },
 882                 }
 883
 884                 let invoice_request = unsigned_invoice_request.sign(payer_sign).unwrap();
 885
 886                 let mut buffer = Vec::new();
 887                 invoice_request.write(&mut buffer).unwrap();
 888
 889                 assert_eq!(invoice_request.bytes, buffer.as_slice());
 890                 assert_eq!(invoice_request.metadata(), &[1; 32]);
 891                 assert_eq!(invoice_request.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
 892                 assert_eq!(invoice_request.amount_msats(), None);
 893                 assert_eq!(invoice_request.features(), &InvoiceRequestFeatures::empty());
 894                 assert_eq!(invoice_request.quantity(), None);
 895                 assert_eq!(invoice_request.payer_id(), payer_pubkey());
 896                 assert_eq!(invoice_request.payer_note(), None);
 897                 assert!(
 898                         merkle::verify_signature(
 899                                 &invoice_request.signature, SIGNATURE_TAG, &invoice_request.bytes, payer_pubkey()
 900                         ).is_ok()
 901                 );
 902
 903                 assert_eq!(
 904                         invoice_request.as_tlv_stream(),
 905                         (
 906                                 PayerTlvStreamRef { metadata: Some(&vec![1; 32]) },
 907                                 OfferTlvStreamRef {
 908                                         chains: None,
 909                                         metadata: None,
 910                                         currency: None,
 911                                         amount: Some(1000),
 912                                         description: Some(&String::from("foo")),
 913                                         features: None,
 914                                         absolute_expiry: None,
 915                                         paths: None,
 916                                         issuer: None,
 917                                         quantity_max: None,
 918                                         node_id: Some(&recipient_pubkey()),
 919                                 },
 920                                 InvoiceRequestTlvStreamRef {
 921                                         chain: None,
 922                                         amount: None,
 923                                         features: None,
 924                                         quantity: None,
 925                                         payer_id: Some(&payer_pubkey()),
 926                                         payer_note: None,
 927                                 },
 928                                 SignatureTlvStreamRef { signature: Some(&invoice_request.signature()) },
 929                         ),
 930                 );
 931
 932                 if let Err(e) = InvoiceRequest::try_from(buffer) {
 933                         panic!("error parsing invoice request: {:?}", e);
 934                 }
 935         }
 936
 937         #[cfg(feature = "std")]
 938         #[test]
 939         fn builds_invoice_request_from_offer_with_expiration() {
 940                 let future_expiry = Duration::from_secs(u64::max_value());
 941                 let past_expiry = Duration::from_secs(0);
 942
 943                 if let Err(e) = OfferBuilder::new("foo".into(), recipient_pubkey())
 944                         .amount_msats(1000)
 945                         .absolute_expiry(future_expiry)
 946                         .build().unwrap()
 947                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 948                         .build()
 949                 {
 950                         panic!("error building invoice_request: {:?}", e);
 951                 }
 952
 953                 match OfferBuilder::new("foo".into(), recipient_pubkey())
 954                         .amount_msats(1000)
 955                         .absolute_expiry(past_expiry)
 956                         .build().unwrap()
 957                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 958                         .build()
 959                 {
 960                         Ok(_) => panic!("expected error"),
 961                         Err(e) => assert_eq!(e, Bolt12SemanticError::AlreadyExpired),
 962                 }
 963         }
 964
 965         #[test]
 966         fn builds_invoice_request_with_derived_metadata() {
 967                 let payer_id = payer_pubkey();
 968                 let expanded_key = ExpandedKey::new(&KeyMaterial([42; 32]));
 969                 let entropy = FixedEntropy {};
 970                 let secp_ctx = Secp256k1::new();
 971
 972                 let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
 973                         .amount_msats(1000)
 974                         .build().unwrap();
 975                 let invoice_request = offer
 976                         .request_invoice_deriving_metadata(payer_id, &expanded_key, &entropy)
 977                         .unwrap()
 978                         .build().unwrap()
 979                         .sign(payer_sign).unwrap();
 980                 assert_eq!(invoice_request.payer_id(), payer_pubkey());
 981
 982                 let invoice = invoice_request.respond_with_no_std(payment_paths(), payment_hash(), now())
 983                         .unwrap()
 984                         .build().unwrap()
 985                         .sign(recipient_sign).unwrap();
 986                 assert!(invoice.verify(&expanded_key, &secp_ctx));
 987
 988                 // Fails verification with altered fields
 989                 let (
 990                         payer_tlv_stream, offer_tlv_stream, mut invoice_request_tlv_stream,
 991                         mut invoice_tlv_stream, mut signature_tlv_stream
 992                 ) = invoice.as_tlv_stream();
 993                 invoice_request_tlv_stream.amount = Some(2000);
 994                 invoice_tlv_stream.amount = Some(2000);
 995
 996                 let tlv_stream =
 997                         (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream);
 998                 let mut bytes = Vec::new();
 999                 tlv_stream.write(&mut bytes).unwrap();
1000
1001                 let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
1002                 let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
1003                 signature_tlv_stream.signature = Some(&signature);
1004
1005                 let mut encoded_invoice = bytes;
1006                 signature_tlv_stream.write(&mut encoded_invoice).unwrap();
1007
1008                 let invoice = Bolt12Invoice::try_from(encoded_invoice).unwrap();
1009                 assert!(!invoice.verify(&expanded_key, &secp_ctx));
1010
1011                 // Fails verification with altered metadata
1012                 let (
1013                         mut payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream,
1014                         mut signature_tlv_stream
1015                 ) = invoice.as_tlv_stream();
1016                 let metadata = payer_tlv_stream.metadata.unwrap().iter().copied().rev().collect();
1017                 payer_tlv_stream.metadata = Some(&metadata);
1018
1019                 let tlv_stream =
1020                         (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream);
1021                 let mut bytes = Vec::new();
1022                 tlv_stream.write(&mut bytes).unwrap();
1023
1024                 let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
1025                 let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
1026                 signature_tlv_stream.signature = Some(&signature);
1027
1028                 let mut encoded_invoice = bytes;
1029                 signature_tlv_stream.write(&mut encoded_invoice).unwrap();
1030
1031                 let invoice = Bolt12Invoice::try_from(encoded_invoice).unwrap();
1032                 assert!(!invoice.verify(&expanded_key, &secp_ctx));
1033         }
1034
1035         #[test]
1036         fn builds_invoice_request_with_derived_payer_id() {
1037                 let expanded_key = ExpandedKey::new(&KeyMaterial([42; 32]));
1038                 let entropy = FixedEntropy {};
1039                 let secp_ctx = Secp256k1::new();
1040
1041                 let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
1042                         .amount_msats(1000)
1043                         .build().unwrap();
1044                 let invoice_request = offer
1045                         .request_invoice_deriving_payer_id(&expanded_key, &entropy, &secp_ctx)
1046                         .unwrap()
1047                         .build_and_sign()
1048                         .unwrap();
1049
1050                 let invoice = invoice_request.respond_with_no_std(payment_paths(), payment_hash(), now())
1051                         .unwrap()
1052                         .build().unwrap()
1053                         .sign(recipient_sign).unwrap();
1054                 assert!(invoice.verify(&expanded_key, &secp_ctx));
1055
1056                 // Fails verification with altered fields
1057                 let (
1058                         payer_tlv_stream, offer_tlv_stream, mut invoice_request_tlv_stream,
1059                         mut invoice_tlv_stream, mut signature_tlv_stream
1060                 ) = invoice.as_tlv_stream();
1061                 invoice_request_tlv_stream.amount = Some(2000);
1062                 invoice_tlv_stream.amount = Some(2000);
1063
1064                 let tlv_stream =
1065                         (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream);
1066                 let mut bytes = Vec::new();
1067                 tlv_stream.write(&mut bytes).unwrap();
1068
1069                 let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
1070                 let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
1071                 signature_tlv_stream.signature = Some(&signature);
1072
1073                 let mut encoded_invoice = bytes;
1074                 signature_tlv_stream.write(&mut encoded_invoice).unwrap();
1075
1076                 let invoice = Bolt12Invoice::try_from(encoded_invoice).unwrap();
1077                 assert!(!invoice.verify(&expanded_key, &secp_ctx));
1078
1079                 // Fails verification with altered payer id
1080                 let (
1081                         payer_tlv_stream, offer_tlv_stream, mut invoice_request_tlv_stream, invoice_tlv_stream,
1082                         mut signature_tlv_stream
1083                 ) = invoice.as_tlv_stream();
1084                 let payer_id = pubkey(1);
1085                 invoice_request_tlv_stream.payer_id = Some(&payer_id);
1086
1087                 let tlv_stream =
1088                         (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream);
1089                 let mut bytes = Vec::new();
1090                 tlv_stream.write(&mut bytes).unwrap();
1091
1092                 let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
1093                 let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
1094                 signature_tlv_stream.signature = Some(&signature);
1095
1096                 let mut encoded_invoice = bytes;
1097                 signature_tlv_stream.write(&mut encoded_invoice).unwrap();
1098
1099                 let invoice = Bolt12Invoice::try_from(encoded_invoice).unwrap();
1100                 assert!(!invoice.verify(&expanded_key, &secp_ctx));
1101         }
1102
1103         #[test]
1104         fn builds_invoice_request_with_chain() {
1105                 let mainnet = ChainHash::using_genesis_block(Network::Bitcoin);
1106                 let testnet = ChainHash::using_genesis_block(Network::Testnet);
1107
1108                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1109                         .amount_msats(1000)
1110                         .build().unwrap()
1111                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1112                         .chain(Network::Bitcoin).unwrap()
1113                         .build().unwrap()
1114                         .sign(payer_sign).unwrap();
1115                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1116                 assert_eq!(invoice_request.chain(), mainnet);
1117                 assert_eq!(tlv_stream.chain, None);
1118
1119                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1120                         .amount_msats(1000)
1121                         .chain(Network::Testnet)
1122                         .build().unwrap()
1123                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1124                         .chain(Network::Testnet).unwrap()
1125                         .build().unwrap()
1126                         .sign(payer_sign).unwrap();
1127                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1128                 assert_eq!(invoice_request.chain(), testnet);
1129                 assert_eq!(tlv_stream.chain, Some(&testnet));
1130
1131                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1132                         .amount_msats(1000)
1133                         .chain(Network::Bitcoin)
1134                         .chain(Network::Testnet)
1135                         .build().unwrap()
1136                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1137                         .chain(Network::Bitcoin).unwrap()
1138                         .build().unwrap()
1139                         .sign(payer_sign).unwrap();
1140                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1141                 assert_eq!(invoice_request.chain(), mainnet);
1142                 assert_eq!(tlv_stream.chain, None);
1143
1144                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1145                         .amount_msats(1000)
1146                         .chain(Network::Bitcoin)
1147                         .chain(Network::Testnet)
1148                         .build().unwrap()
1149                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1150                         .chain(Network::Bitcoin).unwrap()
1151                         .chain(Network::Testnet).unwrap()
1152                         .build().unwrap()
1153                         .sign(payer_sign).unwrap();
1154                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1155                 assert_eq!(invoice_request.chain(), testnet);
1156                 assert_eq!(tlv_stream.chain, Some(&testnet));
1157
1158                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1159                         .amount_msats(1000)
1160                         .chain(Network::Testnet)
1161                         .build().unwrap()
1162                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1163                         .chain(Network::Bitcoin)
1164                 {
1165                         Ok(_) => panic!("expected error"),
1166                         Err(e) => assert_eq!(e, Bolt12SemanticError::UnsupportedChain),
1167                 }
1168
1169                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1170                         .amount_msats(1000)
1171                         .chain(Network::Testnet)
1172                         .build().unwrap()
1173                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1174                         .build()
1175                 {
1176                         Ok(_) => panic!("expected error"),
1177                         Err(e) => assert_eq!(e, Bolt12SemanticError::UnsupportedChain),
1178                 }
1179         }
1180
1181         #[test]
1182         fn builds_invoice_request_with_amount() {
1183                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1184                         .amount_msats(1000)
1185                         .build().unwrap()
1186                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1187                         .amount_msats(1000).unwrap()
1188                         .build().unwrap()
1189                         .sign(payer_sign).unwrap();
1190                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1191                 assert_eq!(invoice_request.amount_msats(), Some(1000));
1192                 assert_eq!(tlv_stream.amount, Some(1000));
1193
1194                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1195                         .amount_msats(1000)
1196                         .build().unwrap()
1197                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1198                         .amount_msats(1001).unwrap()
1199                         .amount_msats(1000).unwrap()
1200                         .build().unwrap()
1201                         .sign(payer_sign).unwrap();
1202                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1203                 assert_eq!(invoice_request.amount_msats(), Some(1000));
1204                 assert_eq!(tlv_stream.amount, Some(1000));
1205
1206                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1207                         .amount_msats(1000)
1208                         .build().unwrap()
1209                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1210                         .amount_msats(1001).unwrap()
1211                         .build().unwrap()
1212                         .sign(payer_sign).unwrap();
1213                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1214                 assert_eq!(invoice_request.amount_msats(), Some(1001));
1215                 assert_eq!(tlv_stream.amount, Some(1001));
1216
1217                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1218                         .amount_msats(1000)
1219                         .build().unwrap()
1220                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1221                         .amount_msats(999)
1222                 {
1223                         Ok(_) => panic!("expected error"),
1224                         Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
1225                 }
1226
1227                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1228                         .amount_msats(1000)
1229                         .supported_quantity(Quantity::Unbounded)
1230                         .build().unwrap()
1231                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1232                         .quantity(2).unwrap()
1233                         .amount_msats(1000)
1234                 {
1235                         Ok(_) => panic!("expected error"),
1236                         Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
1237                 }
1238
1239                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1240                         .amount_msats(1000)
1241                         .build().unwrap()
1242                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1243                         .amount_msats(MAX_VALUE_MSAT + 1)
1244                 {
1245                         Ok(_) => panic!("expected error"),
1246                         Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidAmount),
1247                 }
1248
1249                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1250                         .amount_msats(1000)
1251                         .supported_quantity(Quantity::Unbounded)
1252                         .build().unwrap()
1253                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1254                         .amount_msats(1000).unwrap()
1255                         .quantity(2).unwrap()
1256                         .build()
1257                 {
1258                         Ok(_) => panic!("expected error"),
1259                         Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
1260                 }
1261
1262                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1263                         .build().unwrap()
1264                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1265                         .build()
1266                 {
1267                         Ok(_) => panic!("expected error"),
1268                         Err(e) => assert_eq!(e, Bolt12SemanticError::MissingAmount),
1269                 }
1270
1271                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1272                         .amount_msats(1000)
1273                         .supported_quantity(Quantity::Unbounded)
1274                         .build().unwrap()
1275                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1276                         .quantity(u64::max_value()).unwrap()
1277                         .build()
1278                 {
1279                         Ok(_) => panic!("expected error"),
1280                         Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidAmount),
1281                 }
1282         }
1283
1284         #[test]
1285         fn builds_invoice_request_with_features() {
1286                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1287                         .amount_msats(1000)
1288                         .build().unwrap()
1289                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1290                         .features_unchecked(InvoiceRequestFeatures::unknown())
1291                         .build().unwrap()
1292                         .sign(payer_sign).unwrap();
1293                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1294                 assert_eq!(invoice_request.features(), &InvoiceRequestFeatures::unknown());
1295                 assert_eq!(tlv_stream.features, Some(&InvoiceRequestFeatures::unknown()));
1296
1297                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1298                         .amount_msats(1000)
1299                         .build().unwrap()
1300                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1301                         .features_unchecked(InvoiceRequestFeatures::unknown())
1302                         .features_unchecked(InvoiceRequestFeatures::empty())
1303                         .build().unwrap()
1304                         .sign(payer_sign).unwrap();
1305                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1306                 assert_eq!(invoice_request.features(), &InvoiceRequestFeatures::empty());
1307                 assert_eq!(tlv_stream.features, None);
1308         }
1309
1310         #[test]
1311         fn builds_invoice_request_with_quantity() {
1312                 let one = NonZeroU64::new(1).unwrap();
1313                 let ten = NonZeroU64::new(10).unwrap();
1314
1315                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1316                         .amount_msats(1000)
1317                         .supported_quantity(Quantity::One)
1318                         .build().unwrap()
1319                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1320                         .build().unwrap()
1321                         .sign(payer_sign).unwrap();
1322                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1323                 assert_eq!(invoice_request.quantity(), None);
1324                 assert_eq!(tlv_stream.quantity, None);
1325
1326                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1327                         .amount_msats(1000)
1328                         .supported_quantity(Quantity::One)
1329                         .build().unwrap()
1330                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1331                         .amount_msats(2_000).unwrap()
1332                         .quantity(2)
1333                 {
1334                         Ok(_) => panic!("expected error"),
1335                         Err(e) => assert_eq!(e, Bolt12SemanticError::UnexpectedQuantity),
1336                 }
1337
1338                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1339                         .amount_msats(1000)
1340                         .supported_quantity(Quantity::Bounded(ten))
1341                         .build().unwrap()
1342                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1343                         .amount_msats(10_000).unwrap()
1344                         .quantity(10).unwrap()
1345                         .build().unwrap()
1346                         .sign(payer_sign).unwrap();
1347                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1348                 assert_eq!(invoice_request.amount_msats(), Some(10_000));
1349                 assert_eq!(tlv_stream.amount, Some(10_000));
1350
1351                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1352                         .amount_msats(1000)
1353                         .supported_quantity(Quantity::Bounded(ten))
1354                         .build().unwrap()
1355                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1356                         .amount_msats(11_000).unwrap()
1357                         .quantity(11)
1358                 {
1359                         Ok(_) => panic!("expected error"),
1360                         Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidQuantity),
1361                 }
1362
1363                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1364                         .amount_msats(1000)
1365                         .supported_quantity(Quantity::Unbounded)
1366                         .build().unwrap()
1367                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1368                         .amount_msats(2_000).unwrap()
1369                         .quantity(2).unwrap()
1370                         .build().unwrap()
1371                         .sign(payer_sign).unwrap();
1372                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1373                 assert_eq!(invoice_request.amount_msats(), Some(2_000));
1374                 assert_eq!(tlv_stream.amount, Some(2_000));
1375
1376                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1377                         .amount_msats(1000)
1378                         .supported_quantity(Quantity::Unbounded)
1379                         .build().unwrap()
1380                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1381                         .build()
1382                 {
1383                         Ok(_) => panic!("expected error"),
1384                         Err(e) => assert_eq!(e, Bolt12SemanticError::MissingQuantity),
1385                 }
1386
1387                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1388                         .amount_msats(1000)
1389                         .supported_quantity(Quantity::Bounded(one))
1390                         .build().unwrap()
1391                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1392                         .build()
1393                 {
1394                         Ok(_) => panic!("expected error"),
1395                         Err(e) => assert_eq!(e, Bolt12SemanticError::MissingQuantity),
1396                 }
1397         }
1398
1399         #[test]
1400         fn builds_invoice_request_with_payer_note() {
1401                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1402                         .amount_msats(1000)
1403                         .build().unwrap()
1404                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1405                         .payer_note("bar".into())
1406                         .build().unwrap()
1407                         .sign(payer_sign).unwrap();
1408                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1409                 assert_eq!(invoice_request.payer_note(), Some(PrintableString("bar")));
1410                 assert_eq!(tlv_stream.payer_note, Some(&String::from("bar")));
1411
1412                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1413                         .amount_msats(1000)
1414                         .build().unwrap()
1415                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1416                         .payer_note("bar".into())
1417                         .payer_note("baz".into())
1418                         .build().unwrap()
1419                         .sign(payer_sign).unwrap();
1420                 let (_, _, tlv_stream, _) = invoice_request.as_tlv_stream();
1421                 assert_eq!(invoice_request.payer_note(), Some(PrintableString("baz")));
1422                 assert_eq!(tlv_stream.payer_note, Some(&String::from("baz")));
1423         }
1424
1425         #[test]
1426         fn fails_signing_invoice_request() {
1427                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1428                         .amount_msats(1000)
1429                         .build().unwrap()
1430                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1431                         .build().unwrap()
1432                         .sign(|_| Err(()))
1433                 {
1434                         Ok(_) => panic!("expected error"),
1435                         Err(e) => assert_eq!(e, SignError::Signing(())),
1436                 }
1437
1438                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1439                         .amount_msats(1000)
1440                         .build().unwrap()
1441                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1442                         .build().unwrap()
1443                         .sign(recipient_sign)
1444                 {
1445                         Ok(_) => panic!("expected error"),
1446                         Err(e) => assert_eq!(e, SignError::Verification(secp256k1::Error::InvalidSignature)),
1447                 }
1448         }
1449
1450         #[test]
1451         fn fails_responding_with_unknown_required_features() {
1452                 match OfferBuilder::new("foo".into(), recipient_pubkey())
1453                         .amount_msats(1000)
1454                         .build().unwrap()
1455                         .request_invoice(vec![42; 32], payer_pubkey()).unwrap()
1456                         .features_unchecked(InvoiceRequestFeatures::unknown())
1457                         .build().unwrap()
1458                         .sign(payer_sign).unwrap()
1459                         .respond_with_no_std(payment_paths(), payment_hash(), now())
1460                 {
1461                         Ok(_) => panic!("expected error"),
1462                         Err(e) => assert_eq!(e, Bolt12SemanticError::UnknownRequiredFeatures),
1463                 }
1464         }
1465
1466         #[test]
1467         fn parses_invoice_request_with_metadata() {
1468                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1469                         .amount_msats(1000)
1470                         .build().unwrap()
1471                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1472                         .build().unwrap()
1473                         .sign(payer_sign).unwrap();
1474
1475                 let mut buffer = Vec::new();
1476                 invoice_request.write(&mut buffer).unwrap();
1477
1478                 if let Err(e) = InvoiceRequest::try_from(buffer) {
1479                         panic!("error parsing invoice_request: {:?}", e);
1480                 }
1481         }
1482
1483         #[test]
1484         fn parses_invoice_request_with_chain() {
1485                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1486                         .amount_msats(1000)
1487                         .build().unwrap()
1488                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1489                         .chain(Network::Bitcoin).unwrap()
1490                         .build().unwrap()
1491                         .sign(payer_sign).unwrap();
1492
1493                 let mut buffer = Vec::new();
1494                 invoice_request.write(&mut buffer).unwrap();
1495
1496                 if let Err(e) = InvoiceRequest::try_from(buffer) {
1497                         panic!("error parsing invoice_request: {:?}", e);
1498                 }
1499
1500                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1501                         .amount_msats(1000)
1502                         .build().unwrap()
1503                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1504                         .chain_unchecked(Network::Testnet)
1505                         .build_unchecked()
1506                         .sign(payer_sign).unwrap();
1507
1508                 let mut buffer = Vec::new();
1509                 invoice_request.write(&mut buffer).unwrap();
1510
1511                 match InvoiceRequest::try_from(buffer) {
1512                         Ok(_) => panic!("expected error"),
1513                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::UnsupportedChain)),
1514                 }
1515         }
1516
1517         #[test]
1518         fn parses_invoice_request_with_amount() {
1519                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1520                         .amount_msats(1000)
1521                         .build().unwrap()
1522                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1523                         .build().unwrap()
1524                         .sign(payer_sign).unwrap();
1525
1526                 let mut buffer = Vec::new();
1527                 invoice_request.write(&mut buffer).unwrap();
1528
1529                 if let Err(e) = InvoiceRequest::try_from(buffer) {
1530                         panic!("error parsing invoice_request: {:?}", e);
1531                 }
1532
1533                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1534                         .build().unwrap()
1535                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1536                         .amount_msats(1000).unwrap()
1537                         .build().unwrap()
1538                         .sign(payer_sign).unwrap();
1539
1540                 let mut buffer = Vec::new();
1541                 invoice_request.write(&mut buffer).unwrap();
1542
1543                 if let Err(e) = InvoiceRequest::try_from(buffer) {
1544                         panic!("error parsing invoice_request: {:?}", e);
1545                 }
1546
1547                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1548                         .build().unwrap()
1549                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1550                         .build_unchecked()
1551                         .sign(payer_sign).unwrap();
1552
1553                 let mut buffer = Vec::new();
1554                 invoice_request.write(&mut buffer).unwrap();
1555
1556                 match InvoiceRequest::try_from(buffer) {
1557                         Ok(_) => panic!("expected error"),
1558                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingAmount)),
1559                 }
1560
1561                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1562                         .amount_msats(1000)
1563                         .build().unwrap()
1564                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1565                         .amount_msats_unchecked(999)
1566                         .build_unchecked()
1567                         .sign(payer_sign).unwrap();
1568
1569                 let mut buffer = Vec::new();
1570                 invoice_request.write(&mut buffer).unwrap();
1571
1572                 match InvoiceRequest::try_from(buffer) {
1573                         Ok(_) => panic!("expected error"),
1574                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InsufficientAmount)),
1575                 }
1576
1577                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1578                         .amount(Amount::Currency { iso4217_code: *b"USD", amount: 1000 })
1579                         .build_unchecked()
1580                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1581                         .build_unchecked()
1582                         .sign(payer_sign).unwrap();
1583
1584                 let mut buffer = Vec::new();
1585                 invoice_request.write(&mut buffer).unwrap();
1586
1587                 match InvoiceRequest::try_from(buffer) {
1588                         Ok(_) => panic!("expected error"),
1589                         Err(e) => {
1590                                 assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::UnsupportedCurrency));
1591                         },
1592                 }
1593
1594                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1595                         .amount_msats(1000)
1596                         .supported_quantity(Quantity::Unbounded)
1597                         .build().unwrap()
1598                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1599                         .quantity(u64::max_value()).unwrap()
1600                         .build_unchecked()
1601                         .sign(payer_sign).unwrap();
1602
1603                 let mut buffer = Vec::new();
1604                 invoice_request.write(&mut buffer).unwrap();
1605
1606                 match InvoiceRequest::try_from(buffer) {
1607                         Ok(_) => panic!("expected error"),
1608                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InvalidAmount)),
1609                 }
1610         }
1611
1612         #[test]
1613         fn parses_invoice_request_with_quantity() {
1614                 let one = NonZeroU64::new(1).unwrap();
1615                 let ten = NonZeroU64::new(10).unwrap();
1616
1617                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1618                         .amount_msats(1000)
1619                         .supported_quantity(Quantity::One)
1620                         .build().unwrap()
1621                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1622                         .build().unwrap()
1623                         .sign(payer_sign).unwrap();
1624
1625                 let mut buffer = Vec::new();
1626                 invoice_request.write(&mut buffer).unwrap();
1627
1628                 if let Err(e) = InvoiceRequest::try_from(buffer) {
1629                         panic!("error parsing invoice_request: {:?}", e);
1630                 }
1631
1632                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1633                         .amount_msats(1000)
1634                         .supported_quantity(Quantity::One)
1635                         .build().unwrap()
1636                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1637                         .amount_msats(2_000).unwrap()
1638                         .quantity_unchecked(2)
1639                         .build_unchecked()
1640                         .sign(payer_sign).unwrap();
1641
1642                 let mut buffer = Vec::new();
1643                 invoice_request.write(&mut buffer).unwrap();
1644
1645                 match InvoiceRequest::try_from(buffer) {
1646                         Ok(_) => panic!("expected error"),
1647                         Err(e) => {
1648                                 assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::UnexpectedQuantity));
1649                         },
1650                 }
1651
1652                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1653                         .amount_msats(1000)
1654                         .supported_quantity(Quantity::Bounded(ten))
1655                         .build().unwrap()
1656                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1657                         .amount_msats(10_000).unwrap()
1658                         .quantity(10).unwrap()
1659                         .build().unwrap()
1660                         .sign(payer_sign).unwrap();
1661
1662                 let mut buffer = Vec::new();
1663                 invoice_request.write(&mut buffer).unwrap();
1664
1665                 if let Err(e) = InvoiceRequest::try_from(buffer) {
1666                         panic!("error parsing invoice_request: {:?}", e);
1667                 }
1668
1669                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1670                         .amount_msats(1000)
1671                         .supported_quantity(Quantity::Bounded(ten))
1672                         .build().unwrap()
1673                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1674                         .amount_msats(11_000).unwrap()
1675                         .quantity_unchecked(11)
1676                         .build_unchecked()
1677                         .sign(payer_sign).unwrap();
1678
1679                 let mut buffer = Vec::new();
1680                 invoice_request.write(&mut buffer).unwrap();
1681
1682                 match InvoiceRequest::try_from(buffer) {
1683                         Ok(_) => panic!("expected error"),
1684                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InvalidQuantity)),
1685                 }
1686
1687                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1688                         .amount_msats(1000)
1689                         .supported_quantity(Quantity::Unbounded)
1690                         .build().unwrap()
1691                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1692                         .amount_msats(2_000).unwrap()
1693                         .quantity(2).unwrap()
1694                         .build().unwrap()
1695                         .sign(payer_sign).unwrap();
1696
1697                 let mut buffer = Vec::new();
1698                 invoice_request.write(&mut buffer).unwrap();
1699
1700                 if let Err(e) = InvoiceRequest::try_from(buffer) {
1701                         panic!("error parsing invoice_request: {:?}", e);
1702                 }
1703
1704                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1705                         .amount_msats(1000)
1706                         .supported_quantity(Quantity::Unbounded)
1707                         .build().unwrap()
1708                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1709                         .build_unchecked()
1710                         .sign(payer_sign).unwrap();
1711
1712                 let mut buffer = Vec::new();
1713                 invoice_request.write(&mut buffer).unwrap();
1714
1715                 match InvoiceRequest::try_from(buffer) {
1716                         Ok(_) => panic!("expected error"),
1717                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingQuantity)),
1718                 }
1719
1720                 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1721                         .amount_msats(1000)
1722                         .supported_quantity(Quantity::Bounded(one))
1723                         .build().unwrap()
1724                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1725                         .build_unchecked()
1726                         .sign(payer_sign).unwrap();
1727
1728                 let mut buffer = Vec::new();
1729                 invoice_request.write(&mut buffer).unwrap();
1730
1731                 match InvoiceRequest::try_from(buffer) {
1732                         Ok(_) => panic!("expected error"),
1733                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingQuantity)),
1734                 }
1735         }
1736
1737         #[test]
1738         fn fails_parsing_invoice_request_without_metadata() {
1739                 let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
1740                         .amount_msats(1000)
1741                         .build().unwrap();
1742                 let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1743                         .build().unwrap();
1744                 let mut tlv_stream = unsigned_invoice_request.contents.as_tlv_stream();
1745                 tlv_stream.0.metadata = None;
1746
1747                 let mut buffer = Vec::new();
1748                 tlv_stream.write(&mut buffer).unwrap();
1749
1750                 match InvoiceRequest::try_from(buffer) {
1751                         Ok(_) => panic!("expected error"),
1752                         Err(e) => {
1753                                 assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingPayerMetadata));
1754                         },
1755                 }
1756         }
1757
1758         #[test]
1759         fn fails_parsing_invoice_request_without_payer_id() {
1760                 let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
1761                         .amount_msats(1000)
1762                         .build().unwrap();
1763                 let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1764                         .build().unwrap();
1765                 let mut tlv_stream = unsigned_invoice_request.contents.as_tlv_stream();
1766                 tlv_stream.2.payer_id = None;
1767
1768                 let mut buffer = Vec::new();
1769                 tlv_stream.write(&mut buffer).unwrap();
1770
1771                 match InvoiceRequest::try_from(buffer) {
1772                         Ok(_) => panic!("expected error"),
1773                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingPayerId)),
1774                 }
1775         }
1776
1777         #[test]
1778         fn fails_parsing_invoice_request_without_node_id() {
1779                 let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
1780                         .amount_msats(1000)
1781                         .build().unwrap();
1782                 let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1783                         .build().unwrap();
1784                 let mut tlv_stream = unsigned_invoice_request.contents.as_tlv_stream();
1785                 tlv_stream.1.node_id = None;
1786
1787                 let mut buffer = Vec::new();
1788                 tlv_stream.write(&mut buffer).unwrap();
1789
1790                 match InvoiceRequest::try_from(buffer) {
1791                         Ok(_) => panic!("expected error"),
1792                         Err(e) => {
1793                                 assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingSigningPubkey));
1794                         },
1795                 }
1796         }
1797
1798         #[test]
1799         fn fails_parsing_invoice_request_without_signature() {
1800                 let mut buffer = Vec::new();
1801                 OfferBuilder::new("foo".into(), recipient_pubkey())
1802                         .amount_msats(1000)
1803                         .build().unwrap()
1804                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1805                         .build().unwrap()
1806                         .contents
1807                         .write(&mut buffer).unwrap();
1808
1809                 match InvoiceRequest::try_from(buffer) {
1810                         Ok(_) => panic!("expected error"),
1811                         Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingSignature)),
1812                 }
1813         }
1814
1815         #[test]
1816         fn fails_parsing_invoice_request_with_invalid_signature() {
1817                 let mut invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
1818                         .amount_msats(1000)
1819                         .build().unwrap()
1820                         .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
1821                         .build().unwrap()
1822                         .sign(payer_sign).unwrap();
1823                 let last_signature_byte = invoice_request.bytes.last_mut().unwrap();
1824                 *last_signature_byte = last_signature_byte.wrapping_add(1);
1825
1826                 let mut buffer = Vec::new();
1827                 invoice_request.write(&mut buffer).unwrap();
1828
1829                 match InvoiceRequest::try_from(buffer) {
1830                         Ok(_) => panic!("expected error"),
1831                         Err(e) => {
1832                                 assert_eq!(e, Bolt12ParseError::InvalidSignature(secp256k1::Error::InvalidSignature));
1833                         },
1834                 }
1835         }
1836
1837         #[test]
1838         fn fails_parsing_invoice_request_with_extra_tlv_records() {
1839                 let secp_ctx = Secp256k1::new();
1840                 let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
1841                 let invoice_request = OfferBuilder::new("foo".into(), keys.public_key())
1842                         .amount_msats(1000)
1843                         .build().unwrap()
1844                         .request_invoice(vec![1; 32], keys.public_key()).unwrap()
1845                         .build().unwrap()
1846                         .sign::<_, Infallible>(
1847                                 |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
1848                         )
1849                         .unwrap();
1850
1851                 let mut encoded_invoice_request = Vec::new();
1852                 invoice_request.write(&mut encoded_invoice_request).unwrap();
1853                 BigSize(1002).write(&mut encoded_invoice_request).unwrap();
1854                 BigSize(32).write(&mut encoded_invoice_request).unwrap();
1855                 [42u8; 32].write(&mut encoded_invoice_request).unwrap();
1856
1857                 match InvoiceRequest::try_from(encoded_invoice_request) {
1858                         Ok(_) => panic!("expected error"),
1859                         Err(e) => assert_eq!(e, Bolt12ParseError::Decode(DecodeError::InvalidValue)),
1860                 }
1861         }
1862 }