Introduce custom TLVs in pay_for_bolt11_invoice

Custom TLVs let the payer attach arbitrary data to the onion packet,
enabling everything from richer metadata to custom authentication on
the payee's side.

Until now, this flexibility existed only through `send_payment`. The
simpler `pay_for_bolt11_invoice` API offered no way to pass custom
TLVs, limiting its usefulness in flows that rely on additional context.

This commit adds custom TLV support to `pay_for_bolt11_invoice`,
bringing it to feature parity.

Author: shaavan

lightning-liquidity/tests/lsps2_integration_tests.rs

@@ -1221,6 +1221,7 @@ fn client_trusts_lsp_end_to_end_test() {
 			&invoice,
 			PaymentId(invoice.payment_hash().to_byte_array()),
 			None,
+			vec![],
 			Default::default(),
 			Retry::Attempts(3),
 		)
@@ -1694,6 +1695,7 @@ fn late_payment_forwarded_and_safe_after_force_close_does_not_broadcast() {
 			&invoice,
 			PaymentId(invoice.payment_hash().to_byte_array()),
 			None,
+			vec![],
 			Default::default(),
 			Retry::Attempts(3),
 		)
@@ -1885,6 +1887,7 @@ fn htlc_timeout_before_client_claim_results_in_handling_failed() {
 			&invoice,
 			PaymentId(invoice.payment_hash().to_byte_array()),
 			None,
+			vec![],
 			Default::default(),
 			Retry::Attempts(3),
 		)
@@ -2222,6 +2225,7 @@ fn client_trusts_lsp_partial_fee_does_not_trigger_broadcast() {
 			&invoice,
 			PaymentId(invoice.payment_hash().to_byte_array()),
 			None,
+			vec![],
 			Default::default(),
 			Retry::Attempts(3),
 		)

lightning/src/ln/bolt11_payment_tests.rs

@@ -55,6 +55,7 @@ fn payment_metadata_end_to_end_for_invoice_with_amount() {
 		&invoice,
 		PaymentId(payment_hash.0),
 		Some(100),
+		vec![],
 		RouteParametersConfig::default(),
 		Retry::Attempts(0),
 	) {
@@ -68,6 +69,7 @@ fn payment_metadata_end_to_end_for_invoice_with_amount() {
 			&invoice,
 			PaymentId(payment_hash.0),
 			None,
+			vec![],
 			RouteParametersConfig::default(),
 			Retry::Attempts(0),
 		)
@@ -123,6 +125,7 @@ fn payment_metadata_end_to_end_for_invoice_with_no_amount() {
 		&invoice,
 		PaymentId(payment_hash.0),
 		None,
+		vec![],
 		RouteParametersConfig::default(),
 		Retry::Attempts(0),
 	) {
@@ -136,6 +139,7 @@ fn payment_metadata_end_to_end_for_invoice_with_no_amount() {
 			&invoice,
 			PaymentId(payment_hash.0),
 			Some(50_000),
+			vec![],
 			RouteParametersConfig::default(),
 			Retry::Attempts(0),
 		)

lightning/src/ln/channelmanager.rs

@@ -2272,8 +2272,11 @@ where
 /// # let channel_manager = channel_manager.get_cm();
 /// # let payment_id = PaymentId([42; 32]);
 /// # let payment_hash = PaymentHash((*invoice.payment_hash()).to_byte_array());
+/// # let custom_tlvs = vec![
+/// #     (343493u64, b"hello".to_vec()),
+/// # ];
 /// match channel_manager.pay_for_bolt11_invoice(
-///     invoice, payment_id, None, route_params_config, retry
+///     invoice, payment_id, None, custom_tlvs, route_params_config, retry
 /// ) {
 ///     Ok(()) => println!("Sending payment with hash {}", payment_hash),
 ///     Err(e) => println!("Failed sending payment with hash {}: {:?}", payment_hash, e),
@@ -5542,14 +5545,16 @@ where
 	/// To use default settings, call the function with [`RouteParametersConfig::default`].
 	pub fn pay_for_bolt11_invoice(
 		&self, invoice: &Bolt11Invoice, payment_id: PaymentId, amount_msats: Option<u64>,
-		route_params_config: RouteParametersConfig, retry_strategy: Retry,
+		custom_tlvs: Vec<(u64, Vec<u8>)>, route_params_config: RouteParametersConfig,
+		retry_strategy: Retry,
 	) -> Result<(), Bolt11PaymentError> {
 		let best_block_height = self.best_block.read().unwrap().height;
 		let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
 		self.pending_outbound_payments.pay_for_bolt11_invoice(
 			invoice,
 			payment_id,
 			amount_msats,
+			custom_tlvs,
 			route_params_config,
 			retry_strategy,
 			&self.router,

lightning/src/ln/invoice_utils.rs

@@ -710,7 +710,14 @@ mod test {
 		let retry = Retry::Attempts(0);
 		nodes[0]
 			.node
-			.pay_for_bolt11_invoice(&invoice, PaymentId([42; 32]), None, Default::default(), retry)
+			.pay_for_bolt11_invoice(
+				&invoice,
+				PaymentId([42; 32]),
+				None,
+				vec![],
+				Default::default(),
+				retry,
+			)
 			.unwrap();
 		check_added_monitors(&nodes[0], 1);
 

lightning/src/ln/outbound_payment.rs

@@ -543,6 +543,8 @@ pub enum RetryableSendFailure {
 	///
 	/// [`BlindedPaymentPath`]: crate::blinded_path::payment::BlindedPaymentPath
 	OnionPacketSizeExceeded,
+	/// The provided [`RecipientOnionFields::custom_tlvs`] are of invalid range
+	InvalidCustomTlvs,
 }
 
 /// If a payment fails to send to a route, it can be in one of several states. This enum is returned
@@ -919,6 +921,7 @@ where
 	pub(super) fn pay_for_bolt11_invoice<R: Deref, ES: Deref, NS: Deref, IH, SP>(
 		&self, invoice: &Bolt11Invoice, payment_id: PaymentId,
 		amount_msats: Option<u64>,
+		custom_tlvs: Vec<(u64, Vec<u8>)>,
 		route_params_config: RouteParametersConfig,
 		retry_strategy: Retry,
 		router: &R,
@@ -942,7 +945,9 @@ where
 			(None, None) => return Err(Bolt11PaymentError::InvalidAmount),
 		};
 
-		let mut recipient_onion = RecipientOnionFields::secret_only(*invoice.payment_secret());
+		let mut recipient_onion = RecipientOnionFields::secret_only(*invoice.payment_secret())
+			.with_custom_tlvs(custom_tlvs)
+			.map_err(|_| Bolt11PaymentError::SendingFailed(RetryableSendFailure::InvalidCustomTlvs))?;
 		recipient_onion.payment_metadata = invoice.payment_metadata().map(|v| v.clone());
 
 		let payment_params = PaymentParameters::from_bolt11_invoice(invoice)
@@ -1061,6 +1066,7 @@ where
 					RetryableSendFailure::RouteNotFound => PaymentFailureReason::RouteNotFound,
 					RetryableSendFailure::DuplicatePayment => PaymentFailureReason::UnexpectedError,
 					RetryableSendFailure::OnionPacketSizeExceeded => PaymentFailureReason::UnexpectedError,
+					RetryableSendFailure::InvalidCustomTlvs => PaymentFailureReason::UnexpectedError,
 				};
 				self.abandon_payment(payment_id, reason, pending_events);
 				return Err(Bolt12PaymentError::SendingFailed(e));

lightning/src/ln/payment_tests.rs

@@ -5400,7 +5400,10 @@ fn max_out_mpp_path() {
 
 	let id = PaymentId([42; 32]);
 	let retry = Retry::Attempts(0);
-	nodes[0].node.pay_for_bolt11_invoice(&invoice, id, None, route_params_cfg, retry).unwrap();
+	nodes[0]
+		.node
+		.pay_for_bolt11_invoice(&invoice, id, None, vec![], route_params_cfg, retry)
+		.unwrap();
 
 	assert!(nodes[0].node.list_recent_payments().len() == 1);
 	check_added_monitors(&nodes[0], 2); // one monitor update per MPP part