Drop default_cltv_expiry_delta

.. as it was used for spontaneous payments only and hence a bit
misleading.

We drop it for now and see if any users would complain. If so, it would
probably be sufficient for it to be an optional parameter on the
spontaneous payments methods.

bindings/ldk_node.udl

@@ -8,7 +8,6 @@ dictionary Config {
 	string? log_dir_path;
 	Network network;
 	sequence<SocketAddress>? listening_addresses;
-	u32 default_cltv_expiry_delta;
 	u64 onchain_wallet_sync_interval_secs;
 	u64 wallet_sync_interval_secs;
 	u64 fee_rate_cache_update_interval_secs;

src/config.rs

@@ -12,7 +12,6 @@ use std::time::Duration;
 // Config defaults
 const DEFAULT_STORAGE_DIR_PATH: &str = "/tmp/ldk_node/";
 const DEFAULT_NETWORK: Network = Network::Bitcoin;
-const DEFAULT_CLTV_EXPIRY_DELTA: u32 = 144;
 const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
@@ -33,6 +32,9 @@ pub(crate) const DEFAULT_ESPLORA_SERVER_URL: &str = "https://blockstream.info/ap
 // The default Esplora client timeout we're using.
 pub(crate) const DEFAULT_ESPLORA_CLIENT_TIMEOUT_SECS: u64 = 10;
 
+// The default `final_cltv_expiry_delta` we apply when not set via the invoice.
+pub(crate) const LDK_DEFAULT_FINAL_CLTV_EXPIRY_DELTA: u32 = 144;
+
 // The timeout after which we abandon retrying failed payments.
 pub(crate) const LDK_PAYMENT_RETRY_TIMEOUT: Duration = Duration::from_secs(10);
 
@@ -104,8 +106,6 @@ pub struct Config {
 	pub network: Network,
 	/// The addresses on which the node will listen for incoming connections.
 	pub listening_addresses: Option<Vec<SocketAddress>>,
-	/// The default CLTV expiry delta to be used for payments.
-	pub default_cltv_expiry_delta: u32,
 	/// The time in-between background sync attempts of the onchain wallet, in seconds.
 	///
 	/// **Note:** A minimum of 10 seconds is always enforced.
@@ -167,7 +167,6 @@ impl Default for Config {
 			log_dir_path: None,
 			network: DEFAULT_NETWORK,
 			listening_addresses: None,
-			default_cltv_expiry_delta: DEFAULT_CLTV_EXPIRY_DELTA,
 			onchain_wallet_sync_interval_secs: DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS,
 			wallet_sync_interval_secs: DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS,
 			fee_rate_cache_update_interval_secs: DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS,

src/payment/spontaneous.rs

@@ -1,6 +1,6 @@
 //! Holds a payment handler allowing to send spontaneous ("keysend") payments.
 
-use crate::config::{Config, LDK_PAYMENT_RETRY_TIMEOUT};
+use crate::config::{Config, LDK_DEFAULT_FINAL_CLTV_EXPIRY_DELTA, LDK_PAYMENT_RETRY_TIMEOUT};
 use crate::error::Error;
 use crate::logger::{log_error, log_info, FilesystemLogger, Logger};
 use crate::payment::store::{
@@ -68,7 +68,7 @@ impl SpontaneousPayment {
 		}
 
 		let mut route_params = RouteParameters::from_payment_params_and_value(
-			PaymentParameters::from_node_id(node_id, self.config.default_cltv_expiry_delta),
+			PaymentParameters::from_node_id(node_id, LDK_DEFAULT_FINAL_CLTV_EXPIRY_DELTA),
 			amount_msat,
 		);
 
@@ -153,13 +153,12 @@ impl SpontaneousPayment {
 		}
 
 		let liquidity_limit_multiplier = Some(self.config.probing_liquidity_limit_multiplier);
-		let cltv_expiry_delta = self.config.default_cltv_expiry_delta;
 
 		self.channel_manager
 			.send_spontaneous_preflight_probes(
 				node_id,
 				amount_msat,
-				cltv_expiry_delta,
+				LDK_DEFAULT_FINAL_CLTV_EXPIRY_DELTA,
 				liquidity_limit_multiplier,
 			)
 			.map_err(|e| {