fixup! Add OfferId to Bolt12Invoice and tests for offer_id correctness

Signed-off-by: Vincenzo Palazzo <[email protected]>

Author: vincenzopalazzo

lightning/src/offers/invoice.rs

@@ -666,16 +666,14 @@ impl UnsignedBolt12Invoice {
 		&self.tagged_hash
 	}
 
-	/// Computes the offer ID if this invoice corresponds to an offer.
+	/// Computes the [`OfferId`] if this invoice corresponds to an [`Offer`].
 	fn compute_offer_id(&self) -> Option<OfferId> {
 		match &self.contents {
 			InvoiceContents::ForOffer { .. } => {
-				// Extract offer TLV records from the invoice bytes
-				let offer_tlv_stream = TlvStream::new(&self.bytes).range(OFFER_TYPES);
-				let experimental_offer_tlv_stream = TlvStream::new(&self.experimental_bytes).range(EXPERIMENTAL_OFFER_TYPES);
-				let combined_tlv_stream = offer_tlv_stream.chain(experimental_offer_tlv_stream);
-				let tagged_hash = TaggedHash::from_tlv_stream("LDK Offer ID", combined_tlv_stream);
-				Some(OfferId(tagged_hash.to_bytes()))
+				// Create a temporary concatenated array for offer ID computation
+				let mut combined_bytes = self.bytes.clone();
+				combined_bytes.extend_from_slice(&self.experimental_bytes);
+				Some(OfferId::from_invoice_bytes(&combined_bytes))
 			},
 			InvoiceContents::ForRefund { .. } => None,
 		}
@@ -987,7 +985,7 @@ impl Bolt12Invoice {
 		self.tagged_hash.as_digest().as_ref().clone()
 	}
 
-	/// Returns the offer ID if this invoice corresponds to an offer.
+	/// Returns the [`OfferId`] if this invoice corresponds to an [`Offer`].
 	pub fn offer_id(&self) -> Option<OfferId> {
 		self.offer_id
 	}
@@ -1647,11 +1645,7 @@ impl TryFrom<ParsedMessage<FullInvoiceTlvStream>> for Bolt12Invoice {
 		let pubkey = contents.fields().signing_pubkey;
 		merkle::verify_signature(&signature, &tagged_hash, pubkey)?;
 
-		let offer_tlv_stream = TlvStream::new(&bytes).range(OFFER_TYPES);
-		let experimental_offer_tlv_stream = TlvStream::new(&bytes).range(EXPERIMENTAL_OFFER_TYPES);
-		let combined_tlv_stream = offer_tlv_stream.chain(experimental_offer_tlv_stream);
-		let offer_tagged_hash = TaggedHash::from_tlv_stream("LDK Offer ID", combined_tlv_stream);
-		let offer_id = OfferId::from_tagged_hash(&offer_tagged_hash);
+		let offer_id = OfferId::from_invoice_bytes(&bytes);
 		Ok(Bolt12Invoice { bytes, contents, signature, tagged_hash, offer_id: Some(offer_id) })
 	}
 }
@@ -3595,23 +3589,19 @@ mod tests {
 		let secp_ctx = Secp256k1::new();
 		let payment_id = PaymentId([1; 32]);
 
-		// Create an offer
 		let offer = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build()
 			.unwrap();
 
-		// Get the offer ID
 		let offer_id = offer.id();
 
-		// Create an invoice request from the offer
 		let invoice_request = offer
 			.request_invoice(&expanded_key, nonce, &secp_ctx, payment_id)
 			.unwrap()
 			.build_and_sign()
 			.unwrap();
 
-		// Create an invoice from the invoice request
 		let invoice = invoice_request
 			.respond_with_no_std(payment_paths(), payment_hash(), now())
 			.unwrap()
@@ -3620,19 +3610,16 @@ mod tests {
 			.sign(recipient_sign)
 			.unwrap();
 
-		// Verify that the invoice's offer_id matches the offer's id
 		assert_eq!(invoice.offer_id(), Some(offer_id));
 	}
 
 	#[test]
 	fn refund_invoice_has_no_offer_id() {
-		// Create a refund
 		let refund = RefundBuilder::new(vec![1; 32], payer_pubkey(), 1000)
 			.unwrap()
 			.build()
 			.unwrap();
 
-		// Create an invoice from the refund
 		let invoice = refund
 			.respond_with_no_std(payment_paths(), payment_hash(), recipient_pubkey(), now())
 			.unwrap()
@@ -3641,7 +3628,6 @@ mod tests {
 			.sign(recipient_sign)
 			.unwrap();
 
-		// Verify that the refund invoice has no offer_id
 		assert_eq!(invoice.offer_id(), None);
 	}
 }

lightning/src/offers/offer.rs

@@ -134,7 +134,12 @@ impl OfferId {
 		Self(tagged_hash.to_bytes())
 	}
 
-	pub (crate) fn from_tagged_hash(tagged_hash: &TaggedHash) -> Self {
+	/// Computes the [`OfferId`] from a [`Bolt12Invoice`] bytes.
+	pub(crate) fn from_invoice_bytes(bytes: &[u8]) -> Self {
+		let offer_tlv_stream = TlvStream::new(bytes).range(OFFER_TYPES);
+		let experimental_offer_tlv_stream = TlvStream::new(bytes).range(EXPERIMENTAL_OFFER_TYPES);
+		let combined_tlv_stream = offer_tlv_stream.chain(experimental_offer_tlv_stream);
+		let tagged_hash = TaggedHash::from_tlv_stream(Self::ID_TAG, combined_tlv_stream);
 		Self(tagged_hash.to_bytes())
 	}
 }