_ 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 either built from a parsed [`Offer`] as an "offer to be paid" or
  13 //! built directly as an "offer for money" (e.g., refund, ATM withdrawal). In the former case, it is
  14 //! typically constructed by a customer and sent to the merchant who had published the corresponding
  15 //! offer. In the latter case, an offer doesn't exist as a precursor to the request. Rather the
  16 //! merchant would typically construct the invoice request and present it to the customer.
  17 //!
  18 //! The recipient of the request responds with an `Invoice`.
  19 //!
  20 //! ```ignore
  21 //! extern crate bitcoin;
  22 //! extern crate lightning;
  23 //!
  24 //! use bitcoin::network::constants::Network;
  25 //! use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
  26 //! use core::convert::Infallible;
  27 //! use lightning::ln::features::OfferFeatures;
  28 //! use lightning::offers::offer::Offer;
  29 //! use lightning::util::ser::Writeable;
  30 //!
  31 //! # fn parse() -> Result<(), lightning::offers::parse::ParseError> {
  32 //! let secp_ctx = Secp256k1::new();
  33 //! let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32])?);
  34 //! let pubkey = PublicKey::from(keys);
  35 //! let mut buffer = Vec::new();
  36 //!
  37 //! // "offer to be paid" flow
  38 //! "lno1qcp4256ypq"
  39 //!     .parse::<Offer>()?
  40 //!     .request_invoice(vec![42; 64], pubkey)?
  41 //!     .chain(Network::Testnet)?
  42 //!     .amount_msats(1000)?
  43 //!     .quantity(5)?
  44 //!     .payer_note("foo".to_string())
  45 //!     .build()?
  46 //!     .sign::<_, Infallible>(|digest| Ok(secp_ctx.sign_schnorr_no_aux_rand(digest, &keys)))
  47 //!     .expect("failed verifying signature")
  48 //!     .write(&mut buffer)
  49 //!     .unwrap();
  50 //! # Ok(())
  51 //! # }
  52 //! ```
  53
  54 use bitcoin::blockdata::constants::ChainHash;
  55 use bitcoin::network::constants::Network;
  56 use bitcoin::secp256k1::{Message, PublicKey};
  57 use bitcoin::secp256k1::schnorr::Signature;
  58 use core::convert::TryFrom;
  59 use crate::io;
  60 use crate::ln::features::InvoiceRequestFeatures;
  61 use crate::ln::msgs::DecodeError;
  62 use crate::offers::merkle::{SignError, SignatureTlvStream, SignatureTlvStreamRef, self};
  63 use crate::offers::offer::{Offer, OfferContents, OfferTlvStream, OfferTlvStreamRef};
  64 use crate::offers::parse::{ParseError, ParsedMessage, SemanticError};
  65 use crate::offers::payer::{PayerContents, PayerTlvStream, PayerTlvStreamRef};
  66 use crate::util::ser::{HighZeroBytesDroppedBigSize, SeekReadable, WithoutLength, Writeable, Writer};
  67 use crate::util::string::PrintableString;
  68
  69 use crate::prelude::*;
  70
  71 const SIGNATURE_TAG: &'static str = concat!("lightning", "invoice_request", "signature");
  72
  73 /// Builds an [`InvoiceRequest`] from an [`Offer`] for the "offer to be paid" flow.
  74 ///
  75 /// See [module-level documentation] for usage.
  76 ///
  77 /// [module-level documentation]: self
  78 pub struct InvoiceRequestBuilder<'a> {
  79         offer: &'a Offer,
  80         invoice_request: InvoiceRequestContents,
  81 }
  82
  83 impl<'a> InvoiceRequestBuilder<'a> {
  84         pub(super) fn new(offer: &'a Offer, metadata: Vec<u8>, payer_id: PublicKey) -> Self {
  85                 Self {
  86                         offer,
  87                         invoice_request: InvoiceRequestContents {
  88                                 payer: PayerContents(metadata), offer: offer.contents.clone(), chain: None,
  89                                 amount_msats: None, features: InvoiceRequestFeatures::empty(), quantity: None,
  90                                 payer_id, payer_note: None,
  91                         },
  92                 }
  93         }
  94
  95         /// Sets the [`InvoiceRequest::chain`] of the given [`Network`] for paying an invoice. If not
  96         /// called, [`Network::Bitcoin`] is assumed. Errors if the chain for `network` is not supported
  97         /// by the offer.
  98         ///
  99         /// Successive calls to this method will override the previous setting.
 100         pub fn chain(mut self, network: Network) -> Result<Self, SemanticError> {
 101                 let chain = ChainHash::using_genesis_block(network);
 102                 if !self.offer.supports_chain(chain) {
 103                         return Err(SemanticError::UnsupportedChain);
 104                 }
 105
 106                 self.invoice_request.chain = Some(chain);
 107                 Ok(self)
 108         }
 109
 110         /// Sets the [`InvoiceRequest::amount_msats`] for paying an invoice. Errors if `amount_msats` is
 111         /// not at least the expected invoice amount (i.e., [`Offer::amount`] times [`quantity`]).
 112         ///
 113         /// Successive calls to this method will override the previous setting.
 114         ///
 115         /// [`quantity`]: Self::quantity
 116         pub fn amount_msats(mut self, amount_msats: u64) -> Result<Self, SemanticError> {
 117                 self.invoice_request.offer.check_amount_msats_for_quantity(
 118                         Some(amount_msats), self.invoice_request.quantity
 119                 )?;
 120                 self.invoice_request.amount_msats = Some(amount_msats);
 121                 Ok(self)
 122         }
 123
 124         /// Sets [`InvoiceRequest::quantity`] of items. If not set, `1` is assumed. Errors if `quantity`
 125         /// does not conform to [`Offer::is_valid_quantity`].
 126         ///
 127         /// Successive calls to this method will override the previous setting.
 128         pub fn quantity(mut self, quantity: u64) -> Result<Self, SemanticError> {
 129                 self.invoice_request.offer.check_quantity(Some(quantity))?;
 130                 self.invoice_request.quantity = Some(quantity);
 131                 Ok(self)
 132         }
 133
 134         /// Sets the [`InvoiceRequest::payer_note`].
 135         ///
 136         /// Successive calls to this method will override the previous setting.
 137         pub fn payer_note(mut self, payer_note: String) -> Self {
 138                 self.invoice_request.payer_note = Some(payer_note);
 139                 self
 140         }
 141
 142         /// Builds an unsigned [`InvoiceRequest`] after checking for valid semantics. It can be signed
 143         /// by [`UnsignedInvoiceRequest::sign`].
 144         pub fn build(mut self) -> Result<UnsignedInvoiceRequest<'a>, SemanticError> {
 145                 #[cfg(feature = "std")] {
 146                         if self.offer.is_expired() {
 147                                 return Err(SemanticError::AlreadyExpired);
 148                         }
 149                 }
 150
 151                 let chain = self.invoice_request.chain();
 152                 if !self.offer.supports_chain(chain) {
 153                         return Err(SemanticError::UnsupportedChain);
 154                 }
 155
 156                 if chain == self.offer.implied_chain() {
 157                         self.invoice_request.chain = None;
 158                 }
 159
 160                 if self.offer.amount().is_none() && self.invoice_request.amount_msats.is_none() {
 161                         return Err(SemanticError::MissingAmount);
 162                 }
 163
 164                 self.invoice_request.offer.check_quantity(self.invoice_request.quantity)?;
 165                 self.invoice_request.offer.check_amount_msats_for_quantity(
 166                         self.invoice_request.amount_msats, self.invoice_request.quantity
 167                 )?;
 168
 169                 let InvoiceRequestBuilder { offer, invoice_request } = self;
 170                 Ok(UnsignedInvoiceRequest { offer, invoice_request })
 171         }
 172 }
 173
 174 /// A semantically valid [`InvoiceRequest`] that hasn't been signed.
 175 pub struct UnsignedInvoiceRequest<'a> {
 176         offer: &'a Offer,
 177         invoice_request: InvoiceRequestContents,
 178 }
 179
 180 impl<'a> UnsignedInvoiceRequest<'a> {
 181         /// Signs the invoice request using the given function.
 182         pub fn sign<F, E>(self, sign: F) -> Result<InvoiceRequest, SignError<E>>
 183         where
 184                 F: FnOnce(&Message) -> Result<Signature, E>
 185         {
 186                 // Use the offer bytes instead of the offer TLV stream as the offer may have contained
 187                 // unknown TLV records, which are not stored in `OfferContents`.
 188                 let (payer_tlv_stream, _offer_tlv_stream, invoice_request_tlv_stream) =
 189                         self.invoice_request.as_tlv_stream();
 190                 let offer_bytes = WithoutLength(&self.offer.bytes);
 191                 let unsigned_tlv_stream = (payer_tlv_stream, offer_bytes, invoice_request_tlv_stream);
 192
 193                 let mut bytes = Vec::new();
 194                 unsigned_tlv_stream.write(&mut bytes).unwrap();
 195
 196                 let pubkey = self.invoice_request.payer_id;
 197                 let signature = Some(merkle::sign_message(sign, SIGNATURE_TAG, &bytes, pubkey)?);
 198
 199                 // Append the signature TLV record to the bytes.
 200                 let signature_tlv_stream = SignatureTlvStreamRef {
 201                         signature: signature.as_ref(),
 202                 };
 203                 signature_tlv_stream.write(&mut bytes).unwrap();
 204
 205                 Ok(InvoiceRequest {
 206                         bytes,
 207                         contents: self.invoice_request,
 208                         signature,
 209                 })
 210         }
 211 }
 212
 213 /// An `InvoiceRequest` is a request for an `Invoice` formulated from an [`Offer`].
 214 ///
 215 /// An offer may provide choices such as quantity, amount, chain, features, etc. An invoice request
 216 /// specifies these such that its recipient can send an invoice for payment.
 217 ///
 218 /// [`Offer`]: crate::offers::offer::Offer
 219 #[derive(Clone, Debug)]
 220 pub struct InvoiceRequest {
 221         bytes: Vec<u8>,
 222         contents: InvoiceRequestContents,
 223         signature: Option<Signature>,
 224 }
 225
 226 /// The contents of an [`InvoiceRequest`], which may be shared with an `Invoice`.
 227 #[derive(Clone, Debug)]
 228 pub(super) struct InvoiceRequestContents {
 229         payer: PayerContents,
 230         offer: OfferContents,
 231         chain: Option<ChainHash>,
 232         amount_msats: Option<u64>,
 233         features: InvoiceRequestFeatures,
 234         quantity: Option<u64>,
 235         payer_id: PublicKey,
 236         payer_note: Option<String>,
 237 }
 238
 239 impl InvoiceRequest {
 240         /// An unpredictable series of bytes, typically containing information about the derivation of
 241         /// [`payer_id`].
 242         ///
 243         /// [`payer_id`]: Self::payer_id
 244         pub fn metadata(&self) -> &[u8] {
 245                 &self.contents.payer.0[..]
 246         }
 247
 248         /// A chain from [`Offer::chains`] that the offer is valid for.
 249         pub fn chain(&self) -> ChainHash {
 250                 self.contents.chain()
 251         }
 252
 253         /// The amount to pay in msats (i.e., the minimum lightning-payable unit for [`chain`]), which
 254         /// must be greater than or equal to [`Offer::amount`], converted if necessary.
 255         ///
 256         /// [`chain`]: Self::chain
 257         pub fn amount_msats(&self) -> Option<u64> {
 258                 self.contents.amount_msats
 259         }
 260
 261         /// Features for paying the invoice.
 262         pub fn features(&self) -> &InvoiceRequestFeatures {
 263                 &self.contents.features
 264         }
 265
 266         /// The quantity of the offer's item conforming to [`Offer::is_valid_quantity`].
 267         pub fn quantity(&self) -> Option<u64> {
 268                 self.contents.quantity
 269         }
 270
 271         /// A possibly transient pubkey used to sign the invoice request.
 272         pub fn payer_id(&self) -> PublicKey {
 273                 self.contents.payer_id
 274         }
 275
 276         /// A payer-provided note which will be seen by the recipient and reflected back in the invoice
 277         /// response.
 278         pub fn payer_note(&self) -> Option<PrintableString> {
 279                 self.contents.payer_note.as_ref().map(|payer_note| PrintableString(payer_note.as_str()))
 280         }
 281
 282         /// Signature of the invoice request using [`payer_id`].
 283         ///
 284         /// [`payer_id`]: Self::payer_id
 285         pub fn signature(&self) -> Option<Signature> {
 286                 self.signature
 287         }
 288 }
 289
 290 impl InvoiceRequestContents {
 291         fn chain(&self) -> ChainHash {
 292                 self.chain.unwrap_or_else(|| self.offer.implied_chain())
 293         }
 294
 295         pub(super) fn as_tlv_stream(&self) -> PartialInvoiceRequestTlvStreamRef {
 296                 let payer = PayerTlvStreamRef {
 297                         metadata: Some(&self.payer.0),
 298                 };
 299
 300                 let offer = self.offer.as_tlv_stream();
 301
 302                 let features = {
 303                         if self.features == InvoiceRequestFeatures::empty() { None }
 304                         else { Some(&self.features) }
 305                 };
 306
 307                 let invoice_request = InvoiceRequestTlvStreamRef {
 308                         chain: self.chain.as_ref(),
 309                         amount: self.amount_msats,
 310                         features,
 311                         quantity: self.quantity,
 312                         payer_id: Some(&self.payer_id),
 313                         payer_note: self.payer_note.as_ref(),
 314                 };
 315
 316                 (payer, offer, invoice_request)
 317         }
 318 }
 319
 320 impl Writeable for InvoiceRequest {
 321         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 322                 WithoutLength(&self.bytes).write(writer)
 323         }
 324 }
 325
 326 impl Writeable for InvoiceRequestContents {
 327         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 328                 self.as_tlv_stream().write(writer)
 329         }
 330 }
 331
 332 tlv_stream!(InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef, 80..160, {
 333         (80, chain: ChainHash),
 334         (82, amount: (u64, HighZeroBytesDroppedBigSize)),
 335         (84, features: InvoiceRequestFeatures),
 336         (86, quantity: (u64, HighZeroBytesDroppedBigSize)),
 337         (88, payer_id: PublicKey),
 338         (89, payer_note: (String, WithoutLength)),
 339 });
 340
 341 type FullInvoiceRequestTlvStream =
 342         (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream, SignatureTlvStream);
 343
 344 impl SeekReadable for FullInvoiceRequestTlvStream {
 345         fn read<R: io::Read + io::Seek>(r: &mut R) -> Result<Self, DecodeError> {
 346                 let payer = SeekReadable::read(r)?;
 347                 let offer = SeekReadable::read(r)?;
 348                 let invoice_request = SeekReadable::read(r)?;
 349                 let signature = SeekReadable::read(r)?;
 350
 351                 Ok((payer, offer, invoice_request, signature))
 352         }
 353 }
 354
 355 type PartialInvoiceRequestTlvStream = (PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream);
 356
 357 type PartialInvoiceRequestTlvStreamRef<'a> = (
 358         PayerTlvStreamRef<'a>,
 359         OfferTlvStreamRef<'a>,
 360         InvoiceRequestTlvStreamRef<'a>,
 361 );
 362
 363 impl TryFrom<Vec<u8>> for InvoiceRequest {
 364         type Error = ParseError;
 365
 366         fn try_from(bytes: Vec<u8>) -> Result<Self, Self::Error> {
 367                 let invoice_request = ParsedMessage::<FullInvoiceRequestTlvStream>::try_from(bytes)?;
 368                 let ParsedMessage { bytes, tlv_stream } = invoice_request;
 369                 let (
 370                         payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream,
 371                         SignatureTlvStream { signature },
 372                 ) = tlv_stream;
 373                 let contents = InvoiceRequestContents::try_from(
 374                         (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream)
 375                 )?;
 376
 377                 if let Some(signature) = &signature {
 378                         merkle::verify_signature(signature, SIGNATURE_TAG, &bytes, contents.payer_id)?;
 379                 }
 380
 381                 Ok(InvoiceRequest { bytes, contents, signature })
 382         }
 383 }
 384
 385 impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
 386         type Error = SemanticError;
 387
 388         fn try_from(tlv_stream: PartialInvoiceRequestTlvStream) -> Result<Self, Self::Error> {
 389                 let (
 390                         PayerTlvStream { metadata },
 391                         offer_tlv_stream,
 392                         InvoiceRequestTlvStream { chain, amount, features, quantity, payer_id, payer_note },
 393                 ) = tlv_stream;
 394
 395                 let payer = match metadata {
 396                         None => return Err(SemanticError::MissingPayerMetadata),
 397                         Some(metadata) => PayerContents(metadata),
 398                 };
 399                 let offer = OfferContents::try_from(offer_tlv_stream)?;
 400
 401                 if !offer.supports_chain(chain.unwrap_or_else(|| offer.implied_chain())) {
 402                         return Err(SemanticError::UnsupportedChain);
 403                 }
 404
 405                 if offer.amount().is_none() && amount.is_none() {
 406                         return Err(SemanticError::MissingAmount);
 407                 }
 408
 409                 offer.check_quantity(quantity)?;
 410                 offer.check_amount_msats_for_quantity(amount, quantity)?;
 411
 412                 let features = features.unwrap_or_else(InvoiceRequestFeatures::empty);
 413
 414                 let payer_id = match payer_id {
 415                         None => return Err(SemanticError::MissingPayerId),
 416                         Some(payer_id) => payer_id,
 417                 };
 418
 419                 Ok(InvoiceRequestContents {
 420                         payer, offer, chain, amount_msats: amount, features, quantity, payer_id, payer_note,
 421                 })
 422         }
 423 }
 424
 425 #[cfg(test)]
 426 mod tests {
 427         use super::InvoiceRequest;
 428
 429         use bitcoin::secp256k1::{KeyPair, Secp256k1, SecretKey};
 430         use core::convert::{Infallible, TryFrom};
 431         use crate::ln::msgs::DecodeError;
 432         use crate::offers::offer::OfferBuilder;
 433         use crate::offers::parse::ParseError;
 434         use crate::util::ser::{BigSize, Writeable};
 435
 436         #[test]
 437         fn fails_parsing_invoice_request_with_extra_tlv_records() {
 438                 let secp_ctx = Secp256k1::new();
 439                 let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
 440                 let invoice_request = OfferBuilder::new("foo".into(), keys.public_key())
 441                         .amount_msats(1000)
 442                         .build().unwrap()
 443                         .request_invoice(vec![1; 32], keys.public_key()).unwrap()
 444                         .build().unwrap()
 445                         .sign::<_, Infallible>(|digest| Ok(secp_ctx.sign_schnorr_no_aux_rand(digest, &keys)))
 446                         .unwrap();
 447
 448                 let mut encoded_invoice_request = Vec::new();
 449                 invoice_request.write(&mut encoded_invoice_request).unwrap();
 450                 BigSize(1002).write(&mut encoded_invoice_request).unwrap();
 451                 BigSize(32).write(&mut encoded_invoice_request).unwrap();
 452                 [42u8; 32].write(&mut encoded_invoice_request).unwrap();
 453
 454                 match InvoiceRequest::try_from(encoded_invoice_request) {
 455                         Ok(_) => panic!("expected error"),
 456                         Err(e) => assert_eq!(e, ParseError::Decode(DecodeError::InvalidValue)),
 457                 }
 458         }
 459 }