BOLT 12 refund encoding and building

lightning/src/offers/invoice_request.rs

@@ -9,13 +9,14 @@
 
 //! Data structures and encoding for `invoice_request` messages.
 //!
-//! An [`InvoiceRequest`] can be either built from a parsed [`Offer`] as an "offer to be paid" or
-//! built directly as an "offer for money" (e.g., refund, ATM withdrawal). In the former case, it is
+//! An [`InvoiceRequest`] can be built from a parsed [`Offer`] as an "offer to be paid". It is
 //! typically constructed by a customer and sent to the merchant who had published the corresponding
-//! offer. In the latter case, an offer doesn't exist as a precursor to the request. Rather the
-//! merchant would typically construct the invoice request and present it to the customer.
+//! offer. The recipient of the request responds with an `Invoice`.
 //!
-//! The recipient of the request responds with an `Invoice`.
+//! For an "offer for money" (e.g., refund, ATM withdrawal), where an offer doesn't exist as a
+//! precursor, see [`Refund`].
+//!
+//! [`Refund`]: crate::offers::refund::Refund
 //!
 //! ```ignore
 //! extern crate bitcoin;
@@ -34,7 +35,6 @@
 //! let pubkey = PublicKey::from(keys);
 //! let mut buffer = Vec::new();
 //!
-//! // "offer to be paid" flow
 //! "lno1qcp4256ypq"
 //!     .parse::<Offer>()?
 //!     .request_invoice(vec![42; 64], pubkey)?
@@ -287,7 +287,7 @@ impl InvoiceRequest {
 		self.contents.amount_msats
 	}
 
-	/// Features for paying the invoice.
+	/// Features pertaining to requesting an invoice.
 	pub fn features(&self) -> &InvoiceRequestFeatures {
 		&self.contents.features
 	}
@@ -471,7 +471,7 @@ impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
 
 #[cfg(test)]
 mod tests {
-	use super::InvoiceRequest;
+	use super::{InvoiceRequest, InvoiceRequestTlvStreamRef};
 
 	use bitcoin::blockdata::constants::ChainHash;
 	use bitcoin::network::constants::Network;
@@ -483,9 +483,10 @@ mod tests {
 	use core::time::Duration;
 	use crate::ln::features::InvoiceRequestFeatures;
 	use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
-	use crate::offers::merkle::SignError;
-	use crate::offers::offer::{Amount, OfferBuilder, Quantity};
+	use crate::offers::merkle::{SignError, SignatureTlvStreamRef};
+	use crate::offers::offer::{Amount, OfferBuilder, OfferTlvStreamRef, Quantity};
 	use crate::offers::parse::{ParseError, SemanticError};
+	use crate::offers::payer::PayerTlvStreamRef;
 	use crate::util::ser::{BigSize, Writeable};
 	use crate::util::string::PrintableString;
 
@@ -517,14 +518,13 @@ mod tests {
 
 	#[test]
 	fn builds_invoice_request_with_defaults() {
-		let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
 			.amount_msats(1000)
-			.build().unwrap();
-		let invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
-			.build().unwrap().sign(payer_sign).unwrap();
+			.build().unwrap()
+			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
+			.build().unwrap()
+			.sign(payer_sign).unwrap();
 
-		let (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, signature_tlv_stream) =
-			invoice_request.as_tlv_stream();
 		let mut buffer = Vec::new();
 		invoice_request.write(&mut buffer).unwrap();
 
@@ -538,25 +538,34 @@ mod tests {
 		assert_eq!(invoice_request.payer_note(), None);
 		assert!(invoice_request.signature().is_some());
 
-		assert_eq!(payer_tlv_stream.metadata, Some(&vec![1; 32]));
-		assert_eq!(offer_tlv_stream.chains, None);
-		assert_eq!(offer_tlv_stream.metadata, None);
-		assert_eq!(offer_tlv_stream.currency, None);
-		assert_eq!(offer_tlv_stream.amount, Some(1000));
-		assert_eq!(offer_tlv_stream.description, Some(&String::from("foo")));
-		assert_eq!(offer_tlv_stream.features, None);
-		assert_eq!(offer_tlv_stream.absolute_expiry, None);
-		assert_eq!(offer_tlv_stream.paths, None);
-		assert_eq!(offer_tlv_stream.issuer, None);
-		assert_eq!(offer_tlv_stream.quantity_max, None);
-		assert_eq!(offer_tlv_stream.node_id, Some(&recipient_pubkey()));
-		assert_eq!(invoice_request_tlv_stream.chain, None);
-		assert_eq!(invoice_request_tlv_stream.amount, None);
-		assert_eq!(invoice_request_tlv_stream.features, None);
-		assert_eq!(invoice_request_tlv_stream.quantity, None);
-		assert_eq!(invoice_request_tlv_stream.payer_id, Some(&payer_pubkey()));
-		assert_eq!(invoice_request_tlv_stream.payer_note, None);
-		assert!(signature_tlv_stream.signature.is_some());
+		assert_eq!(
+			invoice_request.as_tlv_stream(),
+			(
+				PayerTlvStreamRef { metadata: Some(&vec![1; 32]) },
+				OfferTlvStreamRef {
+					chains: None,
+					metadata: None,
+					currency: None,
+					amount: Some(1000),
+					description: Some(&String::from("foo")),
+					features: None,
+					absolute_expiry: None,
+					paths: None,
+					issuer: None,
+					quantity_max: None,
+					node_id: Some(&recipient_pubkey()),
+				},
+				InvoiceRequestTlvStreamRef {
+					chain: None,
+					amount: None,
+					features: None,
+					quantity: None,
+					payer_id: Some(&payer_pubkey()),
+					payer_note: None,
+				},
+				SignatureTlvStreamRef { signature: invoice_request.signature().as_ref() },
+			),
+		);
 
 		if let Err(e) = InvoiceRequest::try_from(buffer) {
 			panic!("error parsing invoice request: {:?}", e);

lightning/src/offers/mod.rs

@@ -17,3 +17,4 @@ mod merkle;
 pub mod offer;
 pub mod parse;
 mod payer;
+pub mod refund;

lightning/src/offers/offer.rs

@@ -106,7 +106,7 @@ impl OfferBuilder {
 		let offer = OfferContents {
 			chains: None, metadata: None, amount: None, description,
 			features: OfferFeatures::empty(), absolute_expiry: None, issuer: None, paths: None,
-			supported_quantity: Quantity::one(), signing_pubkey: Some(signing_pubkey),
+			supported_quantity: Quantity::one(), signing_pubkey,
 		};
 		OfferBuilder { offer }
 	}
@@ -263,7 +263,7 @@ pub(super) struct OfferContents {
 	issuer: Option<String>,
 	paths: Option<Vec<BlindedPath>>,
 	supported_quantity: Quantity,
-	signing_pubkey: Option<PublicKey>,
+	signing_pubkey: PublicKey,
 }
 
 impl Offer {
@@ -359,7 +359,7 @@ impl Offer {
 
 	/// The public key used by the recipient to sign invoices.
 	pub fn signing_pubkey(&self) -> PublicKey {
-		self.contents.signing_pubkey.unwrap()
+		self.contents.signing_pubkey
 	}
 
 	/// Creates an [`InvoiceRequest`] for the offer with the given `metadata` and `payer_id`, which
@@ -497,7 +497,7 @@ impl OfferContents {
 			paths: self.paths.as_ref(),
 			issuer: self.issuer.as_ref(),
 			quantity_max: self.supported_quantity.to_tlv_record(),
-			node_id: self.signing_pubkey.as_ref(),
+			node_id: Some(&self.signing_pubkey),
 		}
 	}
 }
@@ -634,13 +634,14 @@ impl TryFrom<OfferTlvStream> for OfferContents {
 			Some(n) => Quantity::Bounded(NonZeroU64::new(n).unwrap()),
 		};
 
-		if node_id.is_none() {
-			return Err(SemanticError::MissingSigningPubkey);
-		}
+		let signing_pubkey = match node_id {
+			None => return Err(SemanticError::MissingSigningPubkey),
+			Some(node_id) => node_id,
+		};
 
 		Ok(OfferContents {
 			chains, metadata, amount, description, features, absolute_expiry, issuer, paths,
-			supported_quantity, signing_pubkey: node_id,
+			supported_quantity, signing_pubkey,
 		})
 	}
 }
@@ -653,7 +654,7 @@ impl core::fmt::Display for Offer {
 
 #[cfg(test)]
 mod tests {
-	use super::{Amount, Offer, OfferBuilder, Quantity};
+	use super::{Amount, Offer, OfferBuilder, OfferTlvStreamRef, Quantity};
 
 	use bitcoin::blockdata::constants::ChainHash;
 	use bitcoin::network::constants::Network;
@@ -680,7 +681,7 @@ mod tests {
 	#[test]
 	fn builds_offer_with_defaults() {
 		let offer = OfferBuilder::new("foo".into(), pubkey(42)).build().unwrap();
-		let tlv_stream = offer.as_tlv_stream();
+
 		let mut buffer = Vec::new();
 		offer.write(&mut buffer).unwrap();
 
@@ -699,17 +700,22 @@ mod tests {
 		assert_eq!(offer.supported_quantity(), Quantity::one());
 		assert_eq!(offer.signing_pubkey(), pubkey(42));
 
-		assert_eq!(tlv_stream.chains, None);
-		assert_eq!(tlv_stream.metadata, None);
-		assert_eq!(tlv_stream.currency, None);
-		assert_eq!(tlv_stream.amount, None);
-		assert_eq!(tlv_stream.description, Some(&String::from("foo")));
-		assert_eq!(tlv_stream.features, None);
-		assert_eq!(tlv_stream.absolute_expiry, None);
-		assert_eq!(tlv_stream.paths, None);
-		assert_eq!(tlv_stream.issuer, None);
-		assert_eq!(tlv_stream.quantity_max, None);
-		assert_eq!(tlv_stream.node_id, Some(&pubkey(42)));
+		assert_eq!(
+			offer.as_tlv_stream(),
+			OfferTlvStreamRef {
+				chains: None,
+				metadata: None,
+				currency: None,
+				amount: None,
+				description: Some(&String::from("foo")),
+				features: None,
+				absolute_expiry: None,
+				paths: None,
+				issuer: None,
+				quantity_max: None,
+				node_id: Some(&pubkey(42)),
+			},
+		);
 
 		if let Err(e) = Offer::try_from(buffer) {
 			panic!("error parsing offer: {:?}", e);
@@ -1121,11 +1127,13 @@ mod tests {
 			panic!("error parsing offer: {:?}", e);
 		}
 
-		let mut builder = OfferBuilder::new("foo".into(), pubkey(42));
-		builder.offer.signing_pubkey = None;
+		let mut tlv_stream = offer.as_tlv_stream();
+		tlv_stream.node_id = None;
 
-		let offer = builder.build().unwrap();
-		match offer.to_string().parse::<Offer>() {
+		let mut encoded_offer = Vec::new();
+		tlv_stream.write(&mut encoded_offer).unwrap();
+
+		match Offer::try_from(encoded_offer) {
 			Ok(_) => panic!("expected error"),
 			Err(e) => {
 				assert_eq!(e, ParseError::InvalidSemantics(SemanticError::MissingSigningPubkey));

lightning/src/offers/parse.rs

@@ -127,20 +127,28 @@ pub enum SemanticError {
 	AlreadyExpired,
 	/// The provided chain hash does not correspond to a supported chain.
 	UnsupportedChain,
+	/// A chain was provided but was not expected.
+	UnexpectedChain,
 	/// An amount was expected but was missing.
 	MissingAmount,
 	/// The amount exceeded the total bitcoin supply.
 	InvalidAmount,
 	/// An amount was provided but was not sufficient in value.
 	InsufficientAmount,
+	/// An amount was provided but was not expected.
+	UnexpectedAmount,
 	/// A currency was provided that is not supported.
 	UnsupportedCurrency,
 	/// A feature was required but is unknown.
 	UnknownRequiredFeatures,
+	/// Features were provided but were not expected.
+	UnexpectedFeatures,
 	/// A required description was not provided.
 	MissingDescription,
 	/// A signing pubkey was not provided.
 	MissingSigningPubkey,
+	/// A signing pubkey was provided but was not expected.
+	UnexpectedSigningPubkey,
 	/// A quantity was expected but was missing.
 	MissingQuantity,
 	/// An unsupported quantity was provided.