WIP Introduce AnchorChannelsConfig

Author: tnull

bindings/ldk_node.udl

@@ -15,6 +15,12 @@ dictionary Config {
 	sequence<PublicKey> trusted_peers_0conf;
 	u64 probing_liquidity_limit_multiplier;
 	LogLevel log_level;
+	AnchorChannelsConfig? anchor_channels_config;
+};
+
+dictionary AnchorChannelsConfig {
+	sequence<PublicKey> trusted_peers_no_reserve;
+	u64 per_channel_reserve_sats;
 };
 
 interface Builder {

src/config.rs

@@ -15,6 +15,7 @@ const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
 const DEFAULT_LOG_LEVEL: LogLevel = LogLevel::Debug;
+const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The 'stop gap' parameter used by BDK's wallet sync. This seems to configure the threshold
 // number of derivation indexes after which BDK stops looking for new scripts belonging to the wallet.
@@ -104,6 +105,17 @@ pub struct Config {
 	///
 	/// Any messages below this level will be excluded from the logs.
 	pub log_level: LogLevel,
+	/// Configuration options pertaining to 'Anchor' channels, i.e., channels for which the
+	/// `option_anchors_zero_fee_htlc_tx` channel type is negotiated.
+	///
+	/// If set to `None`, new channels will be negotiated with the legacy `option_static_remotekey` channel type.
+	///
+	/// TODO: improve docs/explanation of Anchor channels.
+	///
+	/// See [`BOLT 3`] for more information.
+	///
+	/// [`BOLT3`]: https://github.com/lightning/bolts/blob/master/03-transactions.md#htlc-timeout-and-htlc-success-transactions
+	pub anchor_channels_config: Option<AnchorChannelsConfig>,
 }
 
 impl Default for Config {
@@ -120,6 +132,44 @@ impl Default for Config {
 			trusted_peers_0conf: Vec::new(),
 			probing_liquidity_limit_multiplier: DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER,
 			log_level: DEFAULT_LOG_LEVEL,
+			anchor_channels_config: Some(AnchorChannelsConfig::default()),
+		}
+	}
+}
+
+/// Configuration options pertaining to 'Anchor' channels, i.e., channels for which the
+/// `option_anchors_zero_fee_htlc_tx` channel type is negotiated.
+///
+/// ### Defaults
+///
+/// | Parameter                | Value  |
+/// |--------------------------|--------|
+/// | trusted_peers_no_reserve | []     |
+/// | per_channel_reserve_sats | 25000  |
+///
+#[derive(Debug, Clone)]
+pub struct AnchorChannelsConfig {
+	/// A list of peers which we trust to spend the anchor output *for us* on channel closing.
+	///
+	/// Channels with these peers won't count towards the retained on-chain reserve.
+	///
+	/// **Note:** Trusting the channel counterparty to spend the anchor output is potentially
+	/// insecure as the channel may not be closed if they refuse to do so, potentially leaving the
+	/// user funds stuck.
+	pub trusted_peers_no_reserve: Vec<PublicKey>,
+	/// The amount of satoshis we keep as an emergency reserve in our on-chain wallet in order to
+	/// be able to spend the Anchor output on channel close.
+	///
+	/// Note that, depending on the fee market at the time of closure, this amount might or might
+	/// not suffice to successfully spend the Anchor output.
+	pub per_channel_reserve_sats: u64,
+}
+
+impl Default for AnchorChannelsConfig {
+	fn default() -> Self {
+		Self {
+			trusted_peers_no_reserve: Vec::new(),
+			per_channel_reserve_sats: DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS,
 		}
 	}
 }

src/lib.rs

@@ -100,7 +100,7 @@ pub use lightning;
 pub use lightning_invoice;
 
 pub use balance::{BalanceDetails, LightningBalance, PendingSweepBalance};
-pub use config::{default_config, Config};
+pub use config::{default_config, AnchorChannelsConfig, Config};
 pub use error::Error as NodeError;
 use error::Error;