Add SendingParameters to spontaneous send

Added optional SendingParameters to the send method in
SpontaneousPayment. If the user provides sending params
the values will be overridden otherwise they remain the
same.

Author: slanesuke

bindings/ldk_node.udl

@@ -136,7 +136,7 @@ interface Bolt12Payment {
 
 interface SpontaneousPayment {
 	[Throws=NodeError]
-	PaymentId send(u64 amount_msat, PublicKey node_id);
+	PaymentId send(u64 amount_msat, PublicKey node_id, SendingParameters? sending_parameters);
 	[Throws=NodeError]
 	void send_probes(u64 amount_msat, PublicKey node_id);
 };

src/payment/spontaneous.rs

@@ -6,6 +6,7 @@ use crate::logger::{log_error, log_info, FilesystemLogger, Logger};
 use crate::payment::store::{
 	PaymentDetails, PaymentDirection, PaymentKind, PaymentStatus, PaymentStore,
 };
+use crate::payment::SendingParameters;
 use crate::types::{ChannelManager, KeysManager};
 
 use lightning::ln::channelmanager::{PaymentId, RecipientOnionFields, Retry, RetryableSendFailure};
@@ -41,8 +42,15 @@ impl SpontaneousPayment {
 		Self { runtime, channel_manager, keys_manager, payment_store, config, logger }
 	}
 
-	/// Send a spontaneous, aka. "keysend", payment
-	pub fn send(&self, amount_msat: u64, node_id: PublicKey) -> Result<PaymentId, Error> {
+	/// Send a spontaneous aka. "keysend", payment.
+	///
+	/// If [`SendingParameters`] are provided they will override the node's default routing parameters
+	/// on a per-field basis. Each field in `SendingParameters` that is set replaces the corresponding
+	/// default value. Fields that are not set fall back to the node's configured defaults. If no
+	/// `SendingParameters` are provided, the method fully relies on these defaults.
+	pub fn send(
+		&self, amount_msat: u64, node_id: PublicKey, sending_parameters: Option<SendingParameters>,
+	) -> Result<PaymentId, Error> {
 		let rt_lock = self.runtime.read().unwrap();
 		if rt_lock.is_none() {
 			return Err(Error::NotRunning);
@@ -61,10 +69,45 @@ impl SpontaneousPayment {
 			}
 		}
 
-		let route_params = RouteParameters::from_payment_params_and_value(
+		let mut route_params = RouteParameters::from_payment_params_and_value(
 			PaymentParameters::from_node_id(node_id, self.config.default_cltv_expiry_delta),
 			amount_msat,
 		);
+
+		if let Some(user_set_params) = sending_parameters {
+			if let Some(mut default_params) =
+				self.config.sending_parameters_config.as_ref().cloned()
+			{
+				default_params.max_total_routing_fee_msat = user_set_params
+					.max_total_routing_fee_msat
+					.or(default_params.max_total_routing_fee_msat);
+				default_params.max_total_cltv_expiry_delta = user_set_params
+					.max_total_cltv_expiry_delta
+					.or(default_params.max_total_cltv_expiry_delta);
+				default_params.max_path_count =
+					user_set_params.max_path_count.or(default_params.max_path_count);
+				default_params.max_channel_saturation_power_of_half = user_set_params
+					.max_channel_saturation_power_of_half
+					.or(default_params.max_channel_saturation_power_of_half);
+
+				route_params.max_total_routing_fee_msat = default_params.max_total_routing_fee_msat;
+				route_params.payment_params.max_total_cltv_expiry_delta =
+					default_params.max_total_cltv_expiry_delta.unwrap_or_default();
+				route_params.payment_params.max_path_count =
+					default_params.max_path_count.unwrap_or_default();
+				route_params.payment_params.max_channel_saturation_power_of_half =
+					default_params.max_channel_saturation_power_of_half.unwrap_or_default();
+			}
+		} else if let Some(default_params) = &self.config.sending_parameters_config {
+			route_params.max_total_routing_fee_msat = default_params.max_total_routing_fee_msat;
+			route_params.payment_params.max_total_cltv_expiry_delta =
+				default_params.max_total_cltv_expiry_delta.unwrap_or_default();
+			route_params.payment_params.max_path_count =
+				default_params.max_path_count.unwrap_or_default();
+			route_params.payment_params.max_channel_saturation_power_of_half =
+				default_params.max_channel_saturation_power_of_half.unwrap_or_default();
+		}
+
 		let recipient_fields = RecipientOnionFields::spontaneous_empty();
 
 		match self.channel_manager.send_spontaneous_payment_with_retry(

tests/common/mod.rs

@@ -695,7 +695,7 @@ pub(crate) fn do_channel_full_cycle<E: ElectrumApi>(
 	println!("\nA send_spontaneous_payment");
 	let keysend_amount_msat = 2500_000;
 	let keysend_payment_id =
-		node_a.spontaneous_payment().send(keysend_amount_msat, node_b.node_id()).unwrap();
+		node_a.spontaneous_payment().send(keysend_amount_msat, node_b.node_id(), None).unwrap();
 	expect_event!(node_a, PaymentSuccessful);
 	let received_keysend_amount = match node_b.wait_next_event() {
 		ref e @ Event::PaymentReceived { amount_msat, .. } => {