Proposal: implement custom TLV records for spontaneous payments

bindings/ldk_node.udl

@@ -72,7 +72,7 @@ interface LDKNode {
 	[Throws=NodeError]
 	PaymentHash send_payment_using_amount([ByRef]Bolt11Invoice invoice, u64 amount_msat);
 	[Throws=NodeError]
-	PaymentHash send_spontaneous_payment(u64 amount_msat, PublicKey node_id);
+	PaymentHash send_spontaneous_payment(u64 amount_msat, PublicKey node_id, sequence<TlvEntry> custom_tlvs);
 	[Throws=NodeError]
 	void send_payment_probes([ByRef]Bolt11Invoice invoice);
 	[Throws=NodeError]
@@ -131,6 +131,7 @@ enum NodeError {
 	"InvalidInvoice",
 	"InvalidChannelId",
 	"InvalidNetwork",
+	"InvalidCustomTlv",
 	"DuplicatePayment",
 	"InsufficientFunds",
 	"LiquiditySourceUnavailable",
@@ -312,6 +313,11 @@ enum LogLevel {
 	"Error",
 };
 
+dictionary TlvEntry {
+	u64 type;
+	sequence<u8> value;
+};
+
 [Custom]
 typedef string Txid;
 

src/error.rs

@@ -61,6 +61,8 @@ pub enum Error {
 	InvalidChannelId,
 	/// The given network is invalid.
 	InvalidNetwork,
+	/// The custom TLVs are invalid.
+	InvalidCustomTlv,
 	/// A payment with the given hash has already been initiated.
 	DuplicatePayment,
 	/// The available funds are insufficient to complete the given operation.
@@ -107,6 +109,7 @@ impl fmt::Display for Error {
 			Self::InvalidInvoice => write!(f, "The given invoice is invalid."),
 			Self::InvalidChannelId => write!(f, "The given channel ID is invalid."),
 			Self::InvalidNetwork => write!(f, "The given network is invalid."),
+			Self::InvalidCustomTlv => write!(f, "The given custom TLVs are invalid."),
 			Self::DuplicatePayment => {
 				write!(f, "A payment with the given hash has already been initiated.")
 			},

src/lib.rs

@@ -134,7 +134,7 @@ use types::{
 	Broadcaster, ChainMonitor, ChannelManager, FeeEstimator, KeysManager, NetworkGraph,
 	PeerManager, Router, Scorer, Sweeper, Wallet,
 };
-pub use types::{ChannelDetails, PeerDetails, UserChannelId};
+pub use types::{ChannelDetails, PeerDetails, TlvEntry, UserChannelId};
 
 use logger::{log_error, log_info, log_trace, FilesystemLogger, Logger};
 
@@ -1222,7 +1222,7 @@ impl<K: KVStore + Sync + Send + 'static> Node<K> {
 
 	/// Send a spontaneous, aka. "keysend", payment
 	pub fn send_spontaneous_payment(
-		&self, amount_msat: u64, node_id: PublicKey,
+		&self, amount_msat: u64, node_id: PublicKey, custom_tlvs: Vec<TlvEntry>,
 	) -> Result<PaymentHash, Error> {
 		let rt_lock = self.runtime.read().unwrap();
 		if rt_lock.is_none() {
@@ -1245,7 +1245,12 @@ impl<K: KVStore + Sync + Send + 'static> Node<K> {
 			PaymentParameters::from_node_id(node_id, self.config.default_cltv_expiry_delta),
 			amount_msat,
 		);
-		let recipient_fields = RecipientOnionFields::spontaneous_empty();
+		let recipient_fields = RecipientOnionFields::spontaneous_empty()
+			.with_custom_tlvs(custom_tlvs.into_iter().map(|tlv| (tlv.r#type, tlv.value)).collect())
+			.map_err(|_| {
+				log_error!(self.logger, "Payment error: invalid custom TLVs.");
+				Error::InvalidCustomTlv
+			})?;
 
 		match self.channel_manager.send_spontaneous_payment_with_retry(
 			Some(payment_preimage),

src/types.rs

@@ -456,3 +456,12 @@ impl Default for ChannelConfig {
 		LdkChannelConfig::default().into()
 	}
 }
+
+/// Custom TLV entry.
+pub struct TlvEntry {
+	/// Type number.
+	pub r#type: u64,
+
+	/// Serialized value.
+	pub value: Vec<u8>,
+}

tests/common.rs

@@ -3,7 +3,7 @@
 
 use ldk_node::io::sqlite_store::SqliteStore;
 use ldk_node::{
-	Builder, Config, Event, LogLevel, Node, NodeError, PaymentDirection, PaymentStatus,
+	Builder, Config, Event, LogLevel, Node, NodeError, PaymentDirection, PaymentStatus, TlvEntry,
 };
 
 use lightning::ln::msgs::SocketAddress;
@@ -490,8 +490,11 @@ pub(crate) fn do_channel_full_cycle<K: KVStore + Sync + Send, E: ElectrumApi>(
 	// Test spontaneous/keysend payments
 	println!("\nA send_spontaneous_payment");
 	let keysend_amount_msat = 2500_000;
-	let keysend_payment_hash =
-		node_a.send_spontaneous_payment(keysend_amount_msat, node_b.node_id()).unwrap();
+	let tlv1 = TlvEntry { r#type: 131073, value: vec![0x00, 0x11, 0x22, 0x33] };
+	let tlv2 = TlvEntry { r#type: 131075, value: vec![0xaa, 0xbb] };
+	let keysend_payment_hash = node_a
+		.send_spontaneous_payment(keysend_amount_msat, node_b.node_id(), vec![tlv1, tlv2])
+		.unwrap();
 	expect_event!(node_a, PaymentSuccessful);
 	let received_keysend_amount = match node_b.wait_next_event() {
 		ref e @ Event::PaymentReceived { amount_msat, .. } => {