Make cltv_expiry_delta u16

The BOLT 7 wire format defines `cltv_expiry_delta` as a 2-byte field,
and LDK uses u16 for it everywhere (`RouteHintHop`, `ChannelUpdateInfo`,
`UnsignedChannelUpdate`). Align the LSPS2 types accordingly.

serde_json will reject values exceeding `u16::MAX` during
deserialization, so a counterparty sending an out-of-range value is
handled gracefully.

Co-Authored-By: HAL 9000
Signed-off-by: Elias Rohrer <dev@tnull.de>

Author: tnull

lightning-liquidity/src/lsps2/event.rs

@@ -73,7 +73,7 @@ pub enum LSPS2ClientEvent {
 		/// The intercept short channel id to use in the route hint.
 		intercept_scid: u64,
 		/// The `cltv_expiry_delta` to use in the route hint.
-		cltv_expiry_delta: u32,
+		cltv_expiry_delta: u16,
 		/// The initial payment size you specified.
 		payment_size_msat: Option<u64>,
 	},

lightning-liquidity/src/lsps2/msgs.rs

@@ -182,7 +182,7 @@ pub struct LSPS2BuyResponse {
 	/// The intercept short channel id used by LSP to identify need to open channel.
 	pub jit_channel_scid: LSPS2InterceptScid,
 	/// The locktime expiry delta the lsp requires.
-	pub lsp_cltv_expiry_delta: u32,
+	pub lsp_cltv_expiry_delta: u16,
 	/// Trust model flag (default: false).
 	///
 	/// false => "LSP trusts client": LSP immediately (or as soon as safe) broadcasts the

lightning-liquidity/src/lsps2/router.rs

@@ -35,7 +35,7 @@ pub struct LSPS2Bolt12InvoiceParameters {
 	/// The LSPS2 intercept short channel id.
 	pub intercept_scid: u64,
 	/// The CLTV expiry delta the LSP requires for forwarding over `intercept_scid`.
-	pub cltv_expiry_delta: u32,
+	pub cltv_expiry_delta: u16,
 }
 
 /// A router wrapper that injects LSPS2-specific BOLT12 blinded payment paths for registered
@@ -160,19 +160,16 @@ impl<R: Router, ES: EntropySource> Router for LSPS2BOLT12Router<R, ES> {
 		// the paths in this exact order.
 		let mut paths = inner_res.unwrap_or_default();
 		for lsps2_invoice_params in all_params {
-			let payment_relay = match u16::try_from(lsps2_invoice_params.cltv_expiry_delta) {
-				Ok(cltv_expiry_delta) => PaymentRelay {
-					cltv_expiry_delta,
-					fee_proportional_millionths: 0,
-					fee_base_msat: 0,
-				},
-				Err(_) => continue,
+			let payment_relay = PaymentRelay {
+				cltv_expiry_delta: lsps2_invoice_params.cltv_expiry_delta,
+				fee_proportional_millionths: 0,
+				fee_base_msat: 0,
 			};
 			let payment_constraints = PaymentConstraints {
 				max_cltv_expiry: tlvs
 					.payment_constraints
 					.max_cltv_expiry
-					.saturating_add(lsps2_invoice_params.cltv_expiry_delta),
+					.saturating_add(lsps2_invoice_params.cltv_expiry_delta as u32),
 				htlc_minimum_msat: 0,
 			};
 
@@ -376,7 +373,7 @@ mod tests {
 		assert_eq!(path.payinfo.fee_proportional_millionths, 0);
 		assert_eq!(
 			path.payinfo.cltv_expiry_delta,
-			expected_cltv_delta as u16 + MIN_FINAL_CLTV_EXPIRY_DELTA
+			expected_cltv_delta + MIN_FINAL_CLTV_EXPIRY_DELTA
 		);
 
 		let lookup =
@@ -427,62 +424,6 @@ mod tests {
 		assert_eq!(router.inner_router.create_blinded_payment_paths_calls(), 1);
 	}
 
-	#[test]
-	fn skips_out_of_range_cltv_delta_and_keeps_valid_paths() {
-		let inner_router = MockRouter::new();
-		let recipient = pubkey(13);
-		let secp_ctx = Secp256k1::new();
-
-		let existing_tlvs = bolt12_offer_tlvs(OfferId([11; 32]));
-		let existing_path = lightning::blinded_path::payment::BlindedPaymentPath::new(
-			&[],
-			recipient,
-			ReceiveAuthKey([3; 32]),
-			existing_tlvs,
-			u64::MAX,
-			MIN_FINAL_CLTV_EXPIRY_DELTA,
-			&TestEntropy,
-			&secp_ctx,
-		)
-		.unwrap();
-		*inner_router.paths_to_return.lock().unwrap() = Some(vec![existing_path]);
-
-		let entropy_source = TestEntropy;
-		let router = LSPS2BOLT12Router::new(inner_router, entropy_source);
-
-		let valid_scid = 21;
-		router.register_intercept_scid(
-			valid_scid,
-			LSPS2Bolt12InvoiceParameters {
-				counterparty_node_id: pubkey(12),
-				intercept_scid: valid_scid,
-				cltv_expiry_delta: 48,
-			},
-		);
-		router.register_intercept_scid(
-			22,
-			LSPS2Bolt12InvoiceParameters {
-				counterparty_node_id: pubkey(14),
-				intercept_scid: 22,
-				cltv_expiry_delta: u32::from(u16::MAX) + 1,
-			},
-		);
-
-		let paths = router
-			.create_blinded_payment_paths(
-				recipient,
-				ReceiveAuthKey([3; 32]),
-				Vec::new(),
-				bolt12_offer_tlvs(OfferId([11; 32])),
-				Some(1_000),
-				&secp_ctx,
-			)
-			.unwrap();
-
-		assert_eq!(paths.len(), 2);
-		assert_eq!(router.inner_router.create_blinded_payment_paths_calls(), 1);
-	}
-
 	#[test]
 	fn can_deregister_intercept_scid() {
 		let inner_router = MockRouter::new();

lightning-liquidity/src/lsps2/service.rs

@@ -904,7 +904,7 @@ where
 	/// [`LSPS2ServiceEvent::BuyRequest`]: crate::lsps2::event::LSPS2ServiceEvent::BuyRequest
 	pub async fn invoice_parameters_generated(
 		&self, counterparty_node_id: &PublicKey, request_id: LSPSRequestId, intercept_scid: u64,
-		cltv_expiry_delta: u32, client_trusts_lsp: bool, user_channel_id: u128,
+		cltv_expiry_delta: u16, client_trusts_lsp: bool, user_channel_id: u128,
 	) -> Result<(), APIError> {
 		let mut message_queue_notifier = self.pending_messages.notifier();
 		let mut should_persist = false;
@@ -2179,7 +2179,7 @@ where
 	/// Wraps [`LSPS2ServiceHandler::invoice_parameters_generated`].
 	pub fn invoice_parameters_generated(
 		&self, counterparty_node_id: &PublicKey, request_id: LSPSRequestId, intercept_scid: u64,
-		cltv_expiry_delta: u32, client_trusts_lsp: bool, user_channel_id: u128,
+		cltv_expiry_delta: u16, client_trusts_lsp: bool, user_channel_id: u128,
 	) -> Result<(), APIError> {
 		let mut fut = pin!(self.inner.invoice_parameters_generated(
 			counterparty_node_id,

lightning-liquidity/tests/lsps2_integration_tests.rs

@@ -167,7 +167,7 @@ fn setup_test_lsps2_nodes_with_payer<'a, 'b, 'c>(
 
 fn create_jit_invoice(
 	node: &LiquidityNode<'_, '_, '_>, service_node_id: PublicKey, intercept_scid: u64,
-	cltv_expiry_delta: u32, payment_size_msat: Option<u64>, description: &str, expiry_secs: u32,
+	cltv_expiry_delta: u16, payment_size_msat: Option<u64>, description: &str, expiry_secs: u32,
 ) -> Result<Bolt11Invoice, ()> {
 	// LSPS2 requires min_final_cltv_expiry_delta to be at least 2 more than usual.
 	let min_final_cltv_expiry_delta = MIN_FINAL_CLTV_EXPIRY_DELTA + 2;
@@ -182,7 +182,7 @@ fn create_jit_invoice(
 		src_node_id: service_node_id,
 		short_channel_id: intercept_scid,
 		fees: RoutingFees { base_msat: 0, proportional_millionths: 0 },
-		cltv_expiry_delta: cltv_expiry_delta as u16,
+		cltv_expiry_delta,
 		htlc_minimum_msat: None,
 		htlc_maximum_msat: None,
 	}]);
@@ -1218,7 +1218,7 @@ fn client_trusts_lsp_end_to_end_test() {
 
 	let intercept_scid = service_node.node.get_intercept_scid();
 	let user_channel_id = 42;
-	let cltv_expiry_delta: u32 = 144;
+	let cltv_expiry_delta: u16 = 144;
 	let payment_size_msat = Some(1_000_000);
 
 	let fee_base_msat = 1000;
@@ -1396,7 +1396,7 @@ fn client_trusts_lsp_end_to_end_test() {
 
 fn execute_lsps2_dance(
 	lsps_nodes: &LSPSNodesWithPayer, intercept_scid: u64, user_channel_id: u128,
-	cltv_expiry_delta: u32, promise_secret: [u8; 32], payment_size_msat: Option<u64>,
+	cltv_expiry_delta: u16, promise_secret: [u8; 32], payment_size_msat: Option<u64>,
 	fee_base_msat: u64,
 ) {
 	let service_node = &lsps_nodes.service_node;
@@ -1640,7 +1640,7 @@ fn bolt12_lsps2_end_to_end_test() {
 
 	let intercept_scid = service_node.node.get_intercept_scid();
 	let user_channel_id = 42;
-	let cltv_expiry_delta: u32 = 144;
+	let cltv_expiry_delta: u16 = 144;
 	let payment_size_msat = Some(1_000_000);
 	let fee_base_msat = 1_000;
 
@@ -1904,7 +1904,7 @@ fn bolt12_lsps2_compact_message_path_test() {
 
 	let intercept_scid = service_node.node.get_intercept_scid();
 	let user_channel_id = 42;
-	let cltv_expiry_delta: u32 = 144;
+	let cltv_expiry_delta: u16 = 144;
 	let payment_size_msat = Some(1_000_000);
 	let fee_base_msat = 1_000;
 
@@ -2228,7 +2228,7 @@ fn late_payment_forwarded_and_safe_after_force_close_does_not_broadcast() {
 
 	let intercept_scid = service_node.node.get_intercept_scid();
 	let user_channel_id = 43u128;
-	let cltv_expiry_delta: u32 = 144;
+	let cltv_expiry_delta: u16 = 144;
 	let payment_size_msat = Some(1_000_000);
 	let fee_base_msat: u64 = 10_000;
 
@@ -2417,7 +2417,7 @@ fn htlc_timeout_before_client_claim_results_in_handling_failed() {
 
 	let intercept_scid = service_node.node.get_intercept_scid();
 	let user_channel_id = 44u128;
-	let cltv_expiry_delta: u32 = 144;
+	let cltv_expiry_delta: u16 = 144;
 	let payment_size_msat = Some(1_000_000);
 	let fee_base_msat: u64 = 10_000;
 
@@ -2751,7 +2751,7 @@ fn client_trusts_lsp_partial_fee_does_not_trigger_broadcast() {
 
 	let intercept_scid = service_node.node.get_intercept_scid();
 	let user_channel_id = 42;
-	let cltv_expiry_delta: u32 = 144;
+	let cltv_expiry_delta: u16 = 144;
 	let payment_size_msat = Some(1_000_000);
 
 	let fee_base_msat: u64 = 10_000;