f allow explicit min of 21 blocks for delta in invoice

Author: dunxen

lightning-invoice/src/utils.rs

@@ -42,6 +42,11 @@ use core::time::Duration;
 /// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
 /// in excess of the current time.
 ///
+/// You can specify a custom `min_final_cltv_expiry_delta`, or let LDK default it to
+/// [`MIN_FINAL_CLTV_EXPIRY_DELTA`]. The provided expiry must be at least [`MIN_FINAL_CLTV_EXPIRY_DELTA`].
+/// Note that LDK will add a buffer of 3 blocks to the delta to allow for up to a few new block
+/// confirmations during routing.
+///
 /// Note that the provided `keys_manager`'s `NodeSigner` implementation must support phantom
 /// invoices in its `sign_invoice` implementation ([`PhantomKeysManager`] satisfies this
 /// requirement).
@@ -51,6 +56,7 @@ use core::time::Duration;
 /// [`ChannelManager::create_inbound_payment`]: lightning::ln::channelmanager::ChannelManager::create_inbound_payment
 /// [`ChannelManager::create_inbound_payment_for_hash`]: lightning::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash
 /// [`PhantomRouteHints::channels`]: lightning::ln::channelmanager::PhantomRouteHints::channels
+/// [`MIN_FINAL_CLTV_EXPIRY_DETLA`]: lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA
 pub fn create_phantom_invoice<ES: Deref, NS: Deref, L: Deref>(
 	amt_msat: Option<u64>, payment_hash: Option<PaymentHash>, description: String,
 	invoice_expiry_delta_secs: u32, phantom_route_hints: Vec<PhantomRouteHints>, entropy_source: ES,
@@ -137,7 +143,7 @@ where
 		));
 	}
 
-	if min_final_cltv_expiry_delta.is_some() && min_final_cltv_expiry_delta.unwrap() < MIN_FINAL_CLTV_EXPIRY_DELTA {
+	if min_final_cltv_expiry_delta.is_some() && min_final_cltv_expiry_delta.unwrap() + 3 < MIN_FINAL_CLTV_EXPIRY_DELTA {
 		return Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort));
 	}
 
@@ -245,6 +251,8 @@ where
 ///
 /// You can specify a custom `min_final_cltv_expiry_delta`, or let LDK default it to
 /// [`MIN_FINAL_CLTV_EXPIRY_DELTA`]. The provided expiry must be at least [`MIN_FINAL_CLTV_EXPIRY_DELTA`].
+/// Note that LDK will add a buffer of 3 blocks to the delta to allow for up to a few new block
+/// confirmations during routing.
 ///
 /// [`MIN_FINAL_CLTV_EXPIRY_DETLA`]: lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA
 pub fn create_invoice_from_channelmanager<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
@@ -281,6 +289,13 @@ where
 ///
 /// `invoice_expiry_delta_secs` describes the number of seconds that the invoice is valid for
 /// in excess of the current time.
+///
+/// You can specify a custom `min_final_cltv_expiry_delta`, or let LDK default it to
+/// [`MIN_FINAL_CLTV_EXPIRY_DELTA`]. The provided expiry must be at least [`MIN_FINAL_CLTV_EXPIRY_DELTA`].
+/// Note that LDK will add a buffer of 3 blocks to the delta to allow for up to a few new block
+/// confirmations during routing.
+///
+/// [`MIN_FINAL_CLTV_EXPIRY_DETLA`]: lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA
 pub fn create_invoice_from_channelmanager_with_description_hash<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref>(
 	channelmanager: &ChannelManager<M, T, ES, NS, SP, F, R, L>, node_signer: NS, logger: L,
 	network: Currency, amt_msat: Option<u64>, description_hash: Sha256,
@@ -375,7 +390,7 @@ fn _create_invoice_from_channelmanager_and_duration_since_epoch<M: Deref, T: Der
 			R::Target: Router,
 			L::Target: Logger,
 {
-	if min_final_cltv_expiry_delta.is_some() && min_final_cltv_expiry_delta.unwrap() < MIN_FINAL_CLTV_EXPIRY_DELTA {
+	if min_final_cltv_expiry_delta.is_some() && min_final_cltv_expiry_delta.unwrap().saturating_add(3) < MIN_FINAL_CLTV_EXPIRY_DELTA {
 		return Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort));
 	}
 
@@ -440,6 +455,10 @@ fn _create_invoice_from_channelmanager_and_duration_since_epoch_with_payment_has
 	let our_node_pubkey = channelmanager.get_our_node_id();
 	let channels = channelmanager.list_channels();
 
+	if min_final_cltv_expiry_delta.is_some() && min_final_cltv_expiry_delta.unwrap().saturating_add(3) < MIN_FINAL_CLTV_EXPIRY_DELTA {
+		return Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort));
+	}
+
 	log_trace!(logger, "Creating invoice with payment hash {}", log_bytes!(payment_hash.0));
 
 	let invoice = match description {
@@ -742,6 +761,44 @@ mod test {
 		assert_eq!(events.len(), 2);
 	}
 
+	fn do_create_invoice_min_final_cltv_delta(with_custom_delta: bool) {
+		let chanmon_cfgs = create_chanmon_cfgs(2);
+		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+		let custom_min_final_cltv_expiry_delta = Some(50);
+
+		let invoice = crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch(
+			&nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
+			Some(10_000), "".into(), Duration::from_secs(1234567), 3600,
+			if with_custom_delta { custom_min_final_cltv_expiry_delta } else { None },
+		).unwrap();
+		assert_eq!(invoice.min_final_cltv_expiry_delta(), if with_custom_delta {
+			custom_min_final_cltv_expiry_delta.unwrap() + 3 /* Buffer */} else { MIN_FINAL_CLTV_EXPIRY_DELTA } as u64);
+	}
+
+	#[test]
+	fn test_create_invoice_custom_min_final_cltv_delta() {
+		do_create_invoice_min_final_cltv_delta(true);
+		do_create_invoice_min_final_cltv_delta(false);
+	}
+
+	#[test]
+	fn create_invoice_min_final_cltv_delta_equals_htlc_fail_buffer() {
+		let chanmon_cfgs = create_chanmon_cfgs(2);
+		let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+		let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+		let custom_min_final_cltv_expiry_delta = Some(21);
+
+		let invoice = crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch(
+			&nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
+			Some(10_000), "".into(), Duration::from_secs(1234567), 3600,
+			custom_min_final_cltv_expiry_delta,
+		).unwrap();
+		assert_eq!(invoice.min_final_cltv_expiry_delta(), MIN_FINAL_CLTV_EXPIRY_DELTA as u64);
+	}
+
 	#[test]
 	fn test_create_invoice_with_description_hash() {
 		let chanmon_cfgs = create_chanmon_cfgs(2);
@@ -1542,7 +1599,7 @@ mod test {
 		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 		let result = crate::utils::create_invoice_from_channelmanager_and_duration_since_epoch(
 			&nodes[1].node, nodes[1].keys_manager, nodes[1].logger, Currency::BitcoinTestnet,
-			Some(10_000), "Some description".into(), Duration::from_secs(1234567), 3600, Some(MIN_FINAL_CLTV_EXPIRY_DELTA - 1),
+			Some(10_000), "Some description".into(), Duration::from_secs(1234567), 3600, Some(MIN_FINAL_CLTV_EXPIRY_DELTA - 4),
 		);
 		match result {
 			Err(SignOrCreationError::CreationError(CreationError::MinFinalCltvExpiryDeltaTooShort)) => {},