Allow LDK node to send payjoin transactions

Cargo.toml

@@ -75,6 +75,7 @@ libc = "0.2"
 uniffi = { version = "0.27.3", features = ["build"], optional = true }
 serde = { version = "1.0.210", default-features = false, features = ["std", "derive"] }
 serde_json = { version = "1.0.128", default-features = false, features = ["std"] }
+payjoin = { version = "0.21.0", default-features = false, features = ["send", "v2"] }
 
 vss-client = "0.3"
 prost = { version = "0.11.6", default-features = false}
@@ -89,6 +90,8 @@ electrum-client = { version = "0.21.0", default-features = true }
 bitcoincore-rpc = { version = "0.19.0", default-features = false }
 proptest = "1.0.0"
 regex = "1.5.6"
+payjoin = { version = "0.21.0", default-features = false, features = ["send", "v2", "receive"] }
+reqwest = { version = "0.11", default-features = false, features = ["json", "rustls-tls", "blocking"] }
 
 [target.'cfg(not(no_download))'.dev-dependencies]
 electrsd = { version = "0.29.0", features = ["legacy", "esplora_a33e97e1", "bitcoind_25_0"] }

bindings/ldk_node.udl

@@ -78,6 +78,7 @@ interface Node {
 	SpontaneousPayment spontaneous_payment();
 	OnchainPayment onchain_payment();
 	UnifiedQrPayment unified_qr_payment();
+	PayjoinPayment payjoin_payment();
 	[Throws=NodeError]
 	void connect(PublicKey node_id, SocketAddress address, boolean persist);
 	[Throws=NodeError]
@@ -171,6 +172,13 @@ interface UnifiedQrPayment {
 	QrPaymentResult send([ByRef]string uri_str);
 };
 
+interface PayjoinPayment {
+	[Throws=NodeError]
+	void send(string payjoin_uri);
+	[Throws=NodeError]
+	void send_with_amount(string payjoin_uri, u64 amount_sats);
+};
+
 [Error]
 enum NodeError {
 	"AlreadyRunning",
@@ -222,6 +230,12 @@ enum NodeError {
 	"InsufficientFunds",
 	"LiquiditySourceUnavailable",
 	"LiquidityFeeTooHigh",
+	"PayjoinUnavailable",
+	"PayjoinUriInvalid",
+	"PayjoinRequestMissingAmount",
+	"PayjoinRequestCreationFailed",
+	"PayjoinRequestSendingFailed",
+	"PayjoinResponseProcessingFailed",
 };
 
 dictionary NodeStatus {
@@ -249,6 +263,7 @@ enum BuildError {
 	"InvalidChannelMonitor",
 	"InvalidListeningAddresses",
 	"InvalidNodeAlias",
+	"InvalidPayjoinConfig",
 	"ReadFailed",
 	"WriteFailed",
 	"StoragePathAccessFailed",
@@ -281,6 +296,9 @@ interface Event {
 	ChannelPending(ChannelId channel_id, UserChannelId user_channel_id, ChannelId former_temporary_channel_id, PublicKey counterparty_node_id, OutPoint funding_txo);
 	ChannelReady(ChannelId channel_id, UserChannelId user_channel_id, PublicKey? counterparty_node_id);
 	ChannelClosed(ChannelId channel_id, UserChannelId user_channel_id, PublicKey? counterparty_node_id, ClosureReason? reason);
+	PayjoinPaymentAwaitingConfirmation(Txid txid, u64 amount_sats);
+	PayjoinPaymentSuccessful(Txid txid, u64 amount_sats, boolean is_original_psbt_modified);
+	PayjoinPaymentFailed(Txid txid, u64 amount_sats, PayjoinPaymentFailureReason reason);
 };
 
 enum PaymentFailureReason {
@@ -295,6 +313,12 @@ enum PaymentFailureReason {
 	"InvoiceRequestRejected",
 };
 
+enum PayjoinPaymentFailureReason {
+	"Timeout",
+	"RequestSendingFailed",
+	"ResponseProcessingFailed",
+};
+
 [Enum]
 interface ClosureReason {
 	CounterpartyForceClosed(UntrustedString peer_msg);
@@ -321,6 +345,7 @@ interface PaymentKind {
 	Bolt12Offer(PaymentHash? hash, PaymentPreimage? preimage, PaymentSecret? secret, OfferId offer_id, UntrustedString? payer_note, u64? quantity);
 	Bolt12Refund(PaymentHash? hash, PaymentPreimage? preimage, PaymentSecret? secret, UntrustedString? payer_note, u64? quantity);
 	Spontaneous(PaymentHash hash, PaymentPreimage? preimage);
+	Payjoin();
 };
 
 [Enum]
@@ -353,6 +378,8 @@ dictionary PaymentDetails {
 	PaymentDirection direction;
 	PaymentStatus status;
 	u64 latest_update_timestamp;
+	Txid? txid;
+	BestBlock? best_block;
 };
 
 dictionary SendingParameters {

src/builder.rs

@@ -28,6 +28,7 @@ use crate::types::{
 use crate::wallet::persist::KVStoreWalletPersister;
 use crate::wallet::Wallet;
 use crate::{io, NodeMetrics};
+use crate::PayjoinHandler;
 use crate::{LogLevel, Node};
 
 use lightning::chain::{chainmonitor, BestBlock, Watch};
@@ -100,6 +101,11 @@ struct LiquiditySourceConfig {
 	lsps2_service: Option<(SocketAddress, PublicKey, Option<String>)>,
 }
 
+#[derive(Debug, Clone)]
+struct PayjoinConfig {
+	payjoin_relay: payjoin::Url,
+}
+
 impl Default for LiquiditySourceConfig {
 	fn default() -> Self {
 		Self { lsps2_service: None }
@@ -141,6 +147,8 @@ pub enum BuildError {
 	WalletSetupFailed,
 	/// We failed to setup the logger.
 	LoggerSetupFailed,
+	/// Invalid Payjoin configuration.
+	InvalidPayjoinConfig,
 }
 
 impl fmt::Display for BuildError {
@@ -162,6 +170,10 @@ impl fmt::Display for BuildError {
 			Self::WalletSetupFailed => write!(f, "Failed to setup onchain wallet."),
 			Self::LoggerSetupFailed => write!(f, "Failed to setup the logger."),
 			Self::InvalidNodeAlias => write!(f, "Given node alias is invalid."),
+			Self::InvalidPayjoinConfig => write!(
+				f,
+				"Invalid Payjoin configuration. Make sure the provided arguments are valid URLs."
+			),
 		}
 	}
 }
@@ -182,6 +194,7 @@ pub struct NodeBuilder {
 	chain_data_source_config: Option<ChainDataSourceConfig>,
 	gossip_source_config: Option<GossipSourceConfig>,
 	liquidity_source_config: Option<LiquiditySourceConfig>,
+	payjoin_config: Option<PayjoinConfig>,
 }
 
 impl NodeBuilder {
@@ -197,12 +210,14 @@ impl NodeBuilder {
 		let chain_data_source_config = None;
 		let gossip_source_config = None;
 		let liquidity_source_config = None;
+		let payjoin_config = None;
 		Self {
 			config,
 			entropy_source_config,
 			chain_data_source_config,
 			gossip_source_config,
 			liquidity_source_config,
+			payjoin_config,
 		}
 	}
 
@@ -273,6 +288,14 @@ impl NodeBuilder {
 		self
 	}
 
+	/// Configures the [`Node`] instance to enable payjoin transactions.
+	pub fn set_payjoin_config(&mut self, payjoin_relay: String) -> Result<&mut Self, BuildError> {
+		let payjoin_relay =
+			payjoin::Url::parse(&payjoin_relay).map_err(|_| BuildError::InvalidPayjoinConfig)?;
+		self.payjoin_config = Some(PayjoinConfig { payjoin_relay });
+		Ok(self)
+	}
+
 	/// Configures the [`Node`] instance to source its inbound liquidity from the given
 	/// [LSPS2](https://github.com/BitcoinAndLightningLayerSpecs/lsp/blob/main/LSPS2/README.md)
 	/// service.
@@ -480,6 +503,7 @@ impl NodeBuilder {
 			self.chain_data_source_config.as_ref(),
 			self.gossip_source_config.as_ref(),
 			self.liquidity_source_config.as_ref(),
+			self.payjoin_config.as_ref(),
 			seed_bytes,
 			logger,
 			Arc::new(vss_store),
@@ -501,6 +525,7 @@ impl NodeBuilder {
 			self.chain_data_source_config.as_ref(),
 			self.gossip_source_config.as_ref(),
 			self.liquidity_source_config.as_ref(),
+			self.payjoin_config.as_ref(),
 			seed_bytes,
 			logger,
 			kv_store,
@@ -586,6 +611,11 @@ impl ArcedNodeBuilder {
 		self.inner.write().unwrap().set_gossip_source_p2p();
 	}
 
+	/// Configures the [`Node`] instance to enable payjoin transactions.
+	pub fn set_payjoin_config(&self, payjoin_relay: String) -> Result<(), BuildError> {
+		self.inner.write().unwrap().set_payjoin_config(payjoin_relay).map(|_| ())
+	}
+
 	/// Configures the [`Node`] instance to source its gossip data from the given RapidGossipSync
 	/// server.
 	pub fn set_gossip_source_rgs(&self, rgs_server_url: String) {
@@ -733,8 +763,9 @@ impl ArcedNodeBuilder {
 fn build_with_store_internal(
 	config: Arc<Config>, chain_data_source_config: Option<&ChainDataSourceConfig>,
 	gossip_source_config: Option<&GossipSourceConfig>,
-	liquidity_source_config: Option<&LiquiditySourceConfig>, seed_bytes: [u8; 64],
-	logger: Arc<FilesystemLogger>, kv_store: Arc<DynStore>,
+	liquidity_source_config: Option<&LiquiditySourceConfig>,
+	payjoin_config: Option<&PayjoinConfig>, seed_bytes: [u8; 64], logger: Arc<FilesystemLogger>,
+	kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	// Initialize the status fields.
 	let is_listening = Arc::new(AtomicBool::new(false));
@@ -1201,6 +1232,16 @@ fn build_with_store_internal(
 	let (stop_sender, _) = tokio::sync::watch::channel(());
 	let (event_handling_stopped_sender, _) = tokio::sync::watch::channel(());
 
+	let payjoin_handler = payjoin_config.map(|pj_config| {
+		Arc::new(PayjoinHandler::new(
+			Arc::clone(&event_queue),
+			Arc::clone(&logger),
+			pj_config.payjoin_relay.clone(),
+			Arc::clone(&payment_store),
+			Arc::clone(&wallet),
+		))
+	});
+
 	Ok(Node {
 		runtime,
 		stop_sender,
@@ -1213,6 +1254,7 @@ fn build_with_store_internal(
 		channel_manager,
 		chain_monitor,
 		output_sweeper,
+		payjoin_handler,
 		peer_manager,
 		onion_messenger,
 		connection_manager,

src/config.rs

@@ -47,6 +47,15 @@ pub(crate) const RESOLVED_CHANNEL_MONITOR_ARCHIVAL_INTERVAL: u32 = 6;
 // The time in-between peer reconnection attempts.
 pub(crate) const PEER_RECONNECTION_INTERVAL: Duration = Duration::from_secs(10);
 
+// The time before a payjoin http request is considered timed out.
+pub(crate) const PAYJOIN_REQUEST_TIMEOUT: Duration = Duration::from_secs(30);
+
+// The duration between retries of a payjoin http request.
+pub(crate) const PAYJOIN_RETRY_INTERVAL: Duration = Duration::from_secs(3);
+
+// The total duration of retrying to send a payjoin http request.
+pub(crate) const PAYJOIN_REQUEST_TOTAL_DURATION: Duration = Duration::from_secs(24 * 60 * 60);
+
 // The time in-between RGS sync attempts.
 pub(crate) const RGS_SYNC_INTERVAL: Duration = Duration::from_secs(60 * 60);
 

src/error.rs

@@ -114,6 +114,18 @@ pub enum Error {
 	LiquiditySourceUnavailable,
 	/// The given operation failed due to the LSP's required opening fee being too high.
 	LiquidityFeeTooHigh,
+	/// Failed to access Payjoin object.
+	PayjoinUnavailable,
+	/// Payjoin URI is invalid.
+	PayjoinUriInvalid,
+	/// Amount is neither user-provided nor defined in the URI.
+	PayjoinRequestMissingAmount,
+	/// Failed to build a Payjoin request.
+	PayjoinRequestCreationFailed,
+	/// Failed to send Payjoin request.
+	PayjoinRequestSendingFailed,
+	/// Payjoin response processing failed.
+	PayjoinResponseProcessingFailed,
 }
 
 impl fmt::Display for Error {
@@ -184,6 +196,30 @@ impl fmt::Display for Error {
 			Self::LiquidityFeeTooHigh => {
 				write!(f, "The given operation failed due to the LSP's required opening fee being too high.")
 			},
+			Self::PayjoinUnavailable => {
+				write!(
+					f,
+					"Failed to access Payjoin object. Make sure you have enabled Payjoin support."
+				)
+			},
+			Self::PayjoinRequestMissingAmount => {
+				write!(
+					f,
+					"Amount is neither user-provided nor defined in the provided Payjoin URI."
+				)
+			},
+			Self::PayjoinRequestCreationFailed => {
+				write!(f, "Failed construct a Payjoin request")
+			},
+			Self::PayjoinUriInvalid => {
+				write!(f, "The provided Payjoin URI is invalid")
+			},
+			Self::PayjoinRequestSendingFailed => {
+				write!(f, "Failed to send Payjoin request")
+			},
+			Self::PayjoinResponseProcessingFailed => {
+				write!(f, "Payjoin receiver responded to our request with an invalid response")
+			},
 		}
 	}
 }