Parse experimental invoice TLV records

The BOLT12 spec defines an experimental TLV range that is allowed in
offer and invoice_request messages. The remaining TLV-space is for
experimental use in invoice messages. Allow this range when parsing an
invoice and include it when signing one.

Author: jkczyz

lightning/src/offers/invoice.rs

@@ -497,7 +497,8 @@ impl UnsignedBolt12Invoice {
 		const EXPERIMENTAL_TYPES: core::ops::Range<u64> =
 			EXPERIMENTAL_OFFER_TYPES.start..EXPERIMENTAL_INVOICE_REQUEST_TYPES.end;
 
-		let (_, _, _, invoice_tlv_stream, _, _) = contents.as_tlv_stream();
+		let (_, _, _, invoice_tlv_stream, _, _, experimental_invoice_tlv_stream) =
+			contents.as_tlv_stream();
 
 		// Allocate enough space for the invoice, which will include:
 		// - all TLV records from `invreq_bytes` except signatures,
@@ -510,6 +511,7 @@ impl UnsignedBolt12Invoice {
 			invreq_bytes.len()
 				+ invoice_tlv_stream.serialized_length()
 				+ if contents.is_for_offer() { 0 } else { SIGNATURE_TLV_RECORD_SIZE }
+				+ experimental_invoice_tlv_stream.serialized_length(),
 		);
 
 		// Use the invoice_request bytes instead of the invoice_request TLV stream as the latter may
@@ -531,12 +533,14 @@ impl UnsignedBolt12Invoice {
 				- experimental_tlv_stream
 					.peek()
 					.map_or(remaining_bytes.len(), |first_record| first_record.start)
+				+ experimental_invoice_tlv_stream.serialized_length(),
 		);
 
 		for record in experimental_tlv_stream {
 			record.write(&mut experimental_bytes).unwrap();
 		}
 
+		experimental_invoice_tlv_stream.write(&mut experimental_bytes).unwrap();
 		debug_assert_eq!(experimental_bytes.len(), experimental_bytes.capacity());
 
 		let tlv_stream = TlvStream::new(&bytes).chain(TlvStream::new(&experimental_bytes));
@@ -904,14 +908,15 @@ impl Bolt12Invoice {
 		let (
 			payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream,
 			experimental_offer_tlv_stream, experimental_invoice_request_tlv_stream,
+			experimental_invoice_tlv_stream,
 		) = self.contents.as_tlv_stream();
 		let signature_tlv_stream = SignatureTlvStreamRef {
 			signature: Some(&self.signature),
 		};
 		(
 			payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream,
 			signature_tlv_stream, experimental_offer_tlv_stream,
-			experimental_invoice_request_tlv_stream,
+			experimental_invoice_request_tlv_stream, experimental_invoice_tlv_stream,
 		)
 	}
 
@@ -1179,9 +1184,12 @@ impl InvoiceContents {
 			InvoiceContents::ForOffer { invoice_request, .. } => invoice_request.as_tlv_stream(),
 			InvoiceContents::ForRefund { refund, .. } => refund.as_tlv_stream(),
 		};
-		let invoice = self.fields().as_tlv_stream();
+		let (invoice, experimental_invoice) = self.fields().as_tlv_stream();
 
-		(payer, offer, invoice_request, invoice, experimental_offer, experimental_invoice_request)
+		(
+			payer, offer, invoice_request, invoice, experimental_offer,
+			experimental_invoice_request, experimental_invoice,
+		)
 	}
 }
 
@@ -1229,24 +1237,27 @@ pub(super) fn filter_fallbacks(
 }
 
 impl InvoiceFields {
-	fn as_tlv_stream(&self) -> InvoiceTlvStreamRef {
+	fn as_tlv_stream(&self) -> (InvoiceTlvStreamRef, ExperimentalInvoiceTlvStreamRef) {
 		let features = {
 			if self.features == Bolt12InvoiceFeatures::empty() { None }
 			else { Some(&self.features) }
 		};
 
-		InvoiceTlvStreamRef {
-			paths: Some(Iterable(self.payment_paths.iter().map(|path| path.inner_blinded_path()))),
-			blindedpay: Some(Iterable(self.payment_paths.iter().map(|path| &path.payinfo))),
-			created_at: Some(self.created_at.as_secs()),
-			relative_expiry: self.relative_expiry.map(|duration| duration.as_secs() as u32),
-			payment_hash: Some(&self.payment_hash),
-			amount: Some(self.amount_msats),
-			fallbacks: self.fallbacks.as_ref(),
-			features,
-			node_id: Some(&self.signing_pubkey),
-			message_paths: None,
-		}
+		(
+			InvoiceTlvStreamRef {
+				paths: Some(Iterable(self.payment_paths.iter().map(|path| path.inner_blinded_path()))),
+				blindedpay: Some(Iterable(self.payment_paths.iter().map(|path| &path.payinfo))),
+				created_at: Some(self.created_at.as_secs()),
+				relative_expiry: self.relative_expiry.map(|duration| duration.as_secs() as u32),
+				payment_hash: Some(&self.payment_hash),
+				amount: Some(self.amount_msats),
+				fallbacks: self.fallbacks.as_ref(),
+				features,
+				node_id: Some(&self.signing_pubkey),
+				message_paths: None,
+			},
+			ExperimentalInvoiceTlvStreamRef {},
+		)
 	}
 }
 
@@ -1321,6 +1332,13 @@ tlv_stream!(InvoiceTlvStream, InvoiceTlvStreamRef<'a>, INVOICE_TYPES, {
 	(236, message_paths: (Vec<BlindedMessagePath>, WithoutLength)),
 });
 
+/// Valid type range for experimental invoice TLV records.
+const EXPERIMENTAL_INVOICE_TYPES: core::ops::RangeFrom<u64> = 3_000_000_000..;
+
+tlv_stream!(
+	ExperimentalInvoiceTlvStream, ExperimentalInvoiceTlvStreamRef, EXPERIMENTAL_INVOICE_TYPES, {}
+);
+
 pub(super) type BlindedPathIter<'a> = core::iter::Map<
 	core::slice::Iter<'a, BlindedPaymentPath>,
 	for<'r> fn(&'r BlindedPaymentPath) -> &'r BlindedPath,
@@ -1342,7 +1360,7 @@ impl_writeable!(FallbackAddress, { version, program });
 
 type FullInvoiceTlvStream =(
 	PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream, InvoiceTlvStream, SignatureTlvStream,
-	ExperimentalOfferTlvStream, ExperimentalInvoiceRequestTlvStream,
+	ExperimentalOfferTlvStream, ExperimentalInvoiceRequestTlvStream, ExperimentalInvoiceTlvStream,
 );
 
 type FullInvoiceTlvStreamRef<'a> = (
@@ -1353,6 +1371,7 @@ type FullInvoiceTlvStreamRef<'a> = (
 	SignatureTlvStreamRef<'a>,
 	ExperimentalOfferTlvStreamRef,
 	ExperimentalInvoiceRequestTlvStreamRef,
+	ExperimentalInvoiceTlvStreamRef,
 );
 
 impl CursorReadable for FullInvoiceTlvStream {
@@ -1364,19 +1383,20 @@ impl CursorReadable for FullInvoiceTlvStream {
 		let signature = CursorReadable::read(r)?;
 		let experimental_offer = CursorReadable::read(r)?;
 		let experimental_invoice_request = CursorReadable::read(r)?;
+		let experimental_invoice = CursorReadable::read(r)?;
 
 		Ok(
 			(
 				payer, offer, invoice_request, invoice, signature, experimental_offer,
-				experimental_invoice_request,
+				experimental_invoice_request, experimental_invoice,
 			)
 		)
 	}
 }
 
 type PartialInvoiceTlvStream = (
 	PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream, InvoiceTlvStream,
-	ExperimentalOfferTlvStream, ExperimentalInvoiceRequestTlvStream,
+	ExperimentalOfferTlvStream, ExperimentalInvoiceRequestTlvStream, ExperimentalInvoiceTlvStream,
 );
 
 type PartialInvoiceTlvStreamRef<'a> = (
@@ -1386,6 +1406,7 @@ type PartialInvoiceTlvStreamRef<'a> = (
 	InvoiceTlvStreamRef<'a>,
 	ExperimentalOfferTlvStreamRef,
 	ExperimentalInvoiceRequestTlvStreamRef,
+	ExperimentalInvoiceTlvStreamRef,
 );
 
 impl CursorReadable for PartialInvoiceTlvStream {
@@ -1396,11 +1417,12 @@ impl CursorReadable for PartialInvoiceTlvStream {
 		let invoice = CursorReadable::read(r)?;
 		let experimental_offer = CursorReadable::read(r)?;
 		let experimental_invoice_request = CursorReadable::read(r)?;
+		let experimental_invoice = CursorReadable::read(r)?;
 
 		Ok(
 			(
 				payer, offer, invoice_request, invoice, experimental_offer,
-				experimental_invoice_request,
+				experimental_invoice_request, experimental_invoice,
 			)
 		)
 	}
@@ -1416,11 +1438,13 @@ impl TryFrom<ParsedMessage<FullInvoiceTlvStream>> for Bolt12Invoice {
 			SignatureTlvStream { signature },
 			experimental_offer_tlv_stream,
 			experimental_invoice_request_tlv_stream,
+			experimental_invoice_tlv_stream,
 		) = tlv_stream;
 		let contents = InvoiceContents::try_from(
 			(
 				payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream,
 				experimental_offer_tlv_stream, experimental_invoice_request_tlv_stream,
+				experimental_invoice_tlv_stream,
 			)
 		)?;
 
@@ -1449,6 +1473,7 @@ impl TryFrom<PartialInvoiceTlvStream> for InvoiceContents {
 			},
 			experimental_offer_tlv_stream,
 			experimental_invoice_request_tlv_stream,
+			ExperimentalInvoiceTlvStream {},
 		) = tlv_stream;
 
 		if message_paths.is_some() { return Err(Bolt12SemanticError::UnexpectedPaths) }
@@ -1545,7 +1570,7 @@ pub(super) fn check_invoice_signing_pubkey(
 
 #[cfg(test)]
 mod tests {
-	use super::{Bolt12Invoice, DEFAULT_RELATIVE_EXPIRY, FallbackAddress, FullInvoiceTlvStreamRef, INVOICE_TYPES, InvoiceTlvStreamRef, SIGNATURE_TAG, UnsignedBolt12Invoice};
+	use super::{Bolt12Invoice, DEFAULT_RELATIVE_EXPIRY, ExperimentalInvoiceTlvStreamRef, FallbackAddress, FullInvoiceTlvStreamRef, INVOICE_TYPES, InvoiceTlvStreamRef, SIGNATURE_TAG, UnsignedBolt12Invoice};
 
 	use bitcoin::{CompressedPublicKey, WitnessProgram, WitnessVersion};
 	use bitcoin::constants::ChainHash;
@@ -1741,6 +1766,7 @@ mod tests {
 				ExperimentalInvoiceRequestTlvStreamRef {
 					experimental_bar: None,
 				},
+				ExperimentalInvoiceTlvStreamRef {},
 			),
 		);
 
@@ -1840,6 +1866,7 @@ mod tests {
 				ExperimentalInvoiceRequestTlvStreamRef {
 					experimental_bar: None,
 				},
+				ExperimentalInvoiceTlvStreamRef {},
 			),
 		);
 
@@ -2036,7 +2063,7 @@ mod tests {
 			.relative_expiry(one_hour.as_secs() as u32)
 			.build().unwrap()
 			.sign(recipient_sign).unwrap();
-		let (_, _, _, tlv_stream, _, _, _) = invoice.as_tlv_stream();
+		let (_, _, _, tlv_stream, _, _, _, _) = invoice.as_tlv_stream();
 		#[cfg(feature = "std")]
 		assert!(!invoice.is_expired());
 		assert_eq!(invoice.relative_expiry(), one_hour);
@@ -2052,7 +2079,7 @@ mod tests {
 			.relative_expiry(one_hour.as_secs() as u32 - 1)
 			.build().unwrap()
 			.sign(recipient_sign).unwrap();
-		let (_, _, _, tlv_stream, _, _, _) = invoice.as_tlv_stream();
+		let (_, _, _, tlv_stream, _, _, _, _) = invoice.as_tlv_stream();
 		#[cfg(feature = "std")]
 		assert!(invoice.is_expired());
 		assert_eq!(invoice.relative_expiry(), one_hour - Duration::from_secs(1));
@@ -2071,7 +2098,7 @@ mod tests {
 			.respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
 			.build().unwrap()
 			.sign(recipient_sign).unwrap();
-		let (_, _, _, tlv_stream, _, _, _) = invoice.as_tlv_stream();
+		let (_, _, _, tlv_stream, _, _, _, _) = invoice.as_tlv_stream();
 		assert_eq!(invoice.amount_msats(), 1001);
 		assert_eq!(tlv_stream.amount, Some(1001));
 	}
@@ -2089,7 +2116,7 @@ mod tests {
 			.respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
 			.build().unwrap()
 			.sign(recipient_sign).unwrap();
-		let (_, _, _, tlv_stream, _, _, _) = invoice.as_tlv_stream();
+		let (_, _, _, tlv_stream, _, _, _, _) = invoice.as_tlv_stream();
 		assert_eq!(invoice.amount_msats(), 2000);
 		assert_eq!(tlv_stream.amount, Some(2000));
 
@@ -2127,7 +2154,7 @@ mod tests {
 			.fallback_v1_p2tr_tweaked(&tweaked_pubkey)
 			.build().unwrap()
 			.sign(recipient_sign).unwrap();
-		let (_, _, _, tlv_stream, _, _, _) = invoice.as_tlv_stream();
+		let (_, _, _, tlv_stream, _, _, _, _) = invoice.as_tlv_stream();
 		assert_eq!(
 			invoice.fallbacks(),
 			vec![
@@ -2170,7 +2197,7 @@ mod tests {
 			.allow_mpp()
 			.build().unwrap()
 			.sign(recipient_sign).unwrap();
-		let (_, _, _, tlv_stream, _, _, _) = invoice.as_tlv_stream();
+		let (_, _, _, tlv_stream, _, _, _, _) = invoice.as_tlv_stream();
 		assert_eq!(invoice.invoice_features(), &features);
 		assert_eq!(tlv_stream.features, Some(&features));
 	}

lightning/src/offers/invoice_request.rs

@@ -1565,7 +1565,7 @@ mod tests {
 		let (
 			payer_tlv_stream, offer_tlv_stream, mut invoice_request_tlv_stream,
 			mut invoice_tlv_stream, mut signature_tlv_stream, experimental_offer_tlv_stream,
-			experimental_invoice_request_tlv_stream,
+			experimental_invoice_request_tlv_stream, experimental_invoice_tlv_stream,
 		) = invoice.as_tlv_stream();
 		invoice_request_tlv_stream.amount = Some(2000);
 		invoice_tlv_stream.amount = Some(2000);
@@ -1574,6 +1574,7 @@ mod tests {
 			(payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream);
 		let experimental_tlv_stream = (
 			experimental_offer_tlv_stream, experimental_invoice_request_tlv_stream,
+			experimental_invoice_tlv_stream,
 		);
 		let mut bytes = Vec::new();
 		(&tlv_stream, &experimental_tlv_stream).write(&mut bytes).unwrap();
@@ -1594,7 +1595,7 @@ mod tests {
 		let (
 			mut payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream,
 			mut signature_tlv_stream, experimental_offer_tlv_stream,
-			experimental_invoice_request_tlv_stream,
+			experimental_invoice_request_tlv_stream, experimental_invoice_tlv_stream,
 		) = invoice.as_tlv_stream();
 		let metadata = payer_tlv_stream.metadata.unwrap().iter().copied().rev().collect();
 		payer_tlv_stream.metadata = Some(&metadata);
@@ -1603,6 +1604,7 @@ mod tests {
 			(payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream);
 		let experimental_tlv_stream = (
 			experimental_offer_tlv_stream, experimental_invoice_request_tlv_stream,
+			experimental_invoice_tlv_stream,
 		);
 		let mut bytes = Vec::new();
 		(&tlv_stream, &experimental_tlv_stream).write(&mut bytes).unwrap();
@@ -1652,7 +1654,7 @@ mod tests {
 		let (
 			payer_tlv_stream, offer_tlv_stream, mut invoice_request_tlv_stream,
 			mut invoice_tlv_stream, mut signature_tlv_stream, experimental_offer_tlv_stream,
-			experimental_invoice_request_tlv_stream,
+			experimental_invoice_request_tlv_stream, experimental_invoice_tlv_stream,
 		) = invoice.as_tlv_stream();
 		invoice_request_tlv_stream.amount = Some(2000);
 		invoice_tlv_stream.amount = Some(2000);
@@ -1661,6 +1663,7 @@ mod tests {
 			(payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream);
 		let experimental_tlv_stream = (
 			experimental_offer_tlv_stream, experimental_invoice_request_tlv_stream,
+			experimental_invoice_tlv_stream,
 		);
 		let mut bytes = Vec::new();
 		(&tlv_stream, &experimental_tlv_stream).write(&mut bytes).unwrap();
@@ -1683,7 +1686,7 @@ mod tests {
 		let (
 			payer_tlv_stream, offer_tlv_stream, mut invoice_request_tlv_stream, invoice_tlv_stream,
 			mut signature_tlv_stream, experimental_offer_tlv_stream,
-			experimental_invoice_request_tlv_stream,
+			experimental_invoice_request_tlv_stream, experimental_invoice_tlv_stream,
 		) = invoice.as_tlv_stream();
 		let payer_id = pubkey(1);
 		invoice_request_tlv_stream.payer_id = Some(&payer_id);
@@ -1692,6 +1695,7 @@ mod tests {
 			(payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream, invoice_tlv_stream);
 		let experimental_tlv_stream = (
 			experimental_offer_tlv_stream, experimental_invoice_request_tlv_stream,
+			experimental_invoice_tlv_stream,
 		);
 		let mut bytes = Vec::new();
 		(&tlv_stream, &experimental_tlv_stream).write(&mut bytes).unwrap();