Allow to send payjoin transactions

Implements the payjoin sender as describe in BIP77.

This would allow the on chain wallet linked to LDK node to send payjoin
transactions.

Author: jbesraa

Cargo.toml

@@ -68,6 +68,7 @@ tokio = { version = "1.37", default-features = false, features = [ "rt-multi-thr
 esplora-client = { version = "0.6", default-features = false }
 libc = "0.2"
 uniffi = { version = "0.26.0", features = ["build"], optional = true }
+payjoin = { version = "0.16.0", default-features = false, features = ["send", "v2"] }
 
 [target.'cfg(vss)'.dependencies]
 vss-client = "0.2"

bindings/ldk_node.udl

@@ -63,6 +63,7 @@ interface Node {
 	Bolt12Payment bolt12_payment();
 	SpontaneousPayment spontaneous_payment();
 	OnchainPayment onchain_payment();
+	PayjoinPayment payjoin_payment();
 	[Throws=NodeError]
 	void connect(PublicKey node_id, SocketAddress address, boolean persist);
 	[Throws=NodeError]
@@ -148,6 +149,13 @@ interface OnchainPayment {
 	Txid send_all_to_address([ByRef]Address address);
 };
 
+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",
@@ -196,6 +204,12 @@ enum NodeError {
 	"InsufficientFunds",
 	"LiquiditySourceUnavailable",
 	"LiquidityFeeTooHigh",
+	"PayjoinUnavailable",
+	"PayjoinUriInvalid",
+	"PayjoinRequestMissingAmount",
+	"PayjoinRequestCreationFailed",
+	"PayjoinRequestSendingFailed",
+	"PayjoinResponseProcessingFailed",
 };
 
 dictionary NodeStatus {
@@ -227,6 +241,7 @@ enum BuildError {
 	"KVStoreSetupFailed",
 	"WalletSetupFailed",
 	"LoggerSetupFailed",
+	"InvalidPayjoinConfig",
 };
 
 [Enum]
@@ -238,6 +253,9 @@ 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);
+	PayjoinPaymentPending(Txid txid, u64 amount, ScriptBuf receipient);
+	PayjoinPaymentSuccess(Txid txid, u64 amount, ScriptBuf receipient);
+	PayjoinPaymentFailed(Txid? txid, u64 amount, ScriptBuf receipient, PayjoinPaymentFailureReason reason);
 };
 
 enum PaymentFailureReason {
@@ -249,6 +267,12 @@ enum PaymentFailureReason {
 	"UnexpectedError",
 };
 
+enum PayjoinPaymentFailureReason {
+	"Timeout",
+	"TransactionFinalisationFailed",
+	"InvalidReceiverResponse",
+};
+
 [Enum]
 interface ClosureReason {
 	CounterpartyForceClosed(UntrustedString peer_msg);
@@ -274,6 +298,7 @@ interface PaymentKind {
 	Bolt12Offer(PaymentHash? hash, PaymentPreimage? preimage, PaymentSecret? secret, OfferId offer_id);
 	Bolt12Refund(PaymentHash? hash, PaymentPreimage? preimage, PaymentSecret? secret);
 	Spontaneous(PaymentHash hash, PaymentPreimage? preimage);
+	Payjoin();
 };
 
 enum PaymentDirection {
@@ -499,3 +524,6 @@ typedef string Mnemonic;
 
 [Custom]
 typedef string UntrustedString;
+
+[Custom]
+typedef string ScriptBuf;

src/builder.rs

@@ -11,6 +11,7 @@ use crate::io::sqlite_store::SqliteStore;
 use crate::liquidity::LiquiditySource;
 use crate::logger::{log_error, log_info, FilesystemLogger, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
+use crate::payment::payjoin::handler::PayjoinHandler;
 use crate::payment::store::PaymentStore;
 use crate::peer_store::PeerStore;
 use crate::tx_broadcaster::TransactionBroadcaster;
@@ -93,6 +94,11 @@ 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 }
@@ -132,6 +138,8 @@ pub enum BuildError {
 	WalletSetupFailed,
 	/// We failed to setup the logger.
 	LoggerSetupFailed,
+	/// Invalid Payjoin configuration.
+	InvalidPayjoinConfig,
 }
 
 impl fmt::Display for BuildError {
@@ -152,6 +160,10 @@ impl fmt::Display for BuildError {
 			Self::KVStoreSetupFailed => write!(f, "Failed to setup KVStore."),
 			Self::WalletSetupFailed => write!(f, "Failed to setup onchain wallet."),
 			Self::LoggerSetupFailed => write!(f, "Failed to setup the logger."),
+			Self::InvalidPayjoinConfig => write!(
+				f,
+				"Invalid Payjoin configuration. Make sure the provided arguments are valid URLs."
+			),
 		}
 	}
 }
@@ -172,6 +184,7 @@ 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 {
@@ -187,12 +200,14 @@ 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,
 		}
 	}
 
@@ -247,6 +262,14 @@ 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.
@@ -365,6 +388,7 @@ 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,
 			vss_store,
@@ -386,6 +410,7 @@ 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,
@@ -453,6 +478,11 @@ 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) {
@@ -521,8 +551,9 @@ 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 on-chain wallet and chain access
 	let xprv = bitcoin::bip32::ExtendedPrivKey::new_master(config.network.into(), &seed_bytes)
@@ -966,6 +997,16 @@ 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(&tx_sync),
+			Arc::clone(&event_queue),
+			pj_config.payjoin_relay.clone(),
+			Arc::clone(&payment_store),
+			Arc::clone(&wallet),
+		))
+	});
+
 	let is_listening = Arc::new(AtomicBool::new(false));
 	let latest_wallet_sync_timestamp = Arc::new(RwLock::new(None));
 	let latest_onchain_wallet_sync_timestamp = Arc::new(RwLock::new(None));
@@ -987,6 +1028,7 @@ fn build_with_store_internal(
 		channel_manager,
 		chain_monitor,
 		output_sweeper,
+		payjoin_handler,
 		peer_manager,
 		connection_manager,
 		keys_manager,

src/config.rs

@@ -40,6 +40,15 @@ 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 payjoin sender requests timeout.
+pub(crate) const PAYJOIN_REQUEST_TIMEOUT: Duration = Duration::from_secs(30);
+
+// The time before payjoin sender try to send the next request.
+pub(crate) const PAYJOIN_RETRY_INTERVAL: Duration = Duration::from_secs(3);
+
+// The total time payjoin sender try to send a 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

@@ -95,6 +95,18 @@ 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 {
@@ -162,6 +174,27 @@ 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 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 that was ignored")
+			},
 		}
 	}
 }

src/event.rs

@@ -24,6 +24,7 @@ use lightning::events::{ClosureReason, PaymentPurpose};
 use lightning::events::{Event as LdkEvent, PaymentFailureReason};
 use lightning::impl_writeable_tlv_based_enum;
 use lightning::ln::channelmanager::PaymentId;
+use lightning::ln::msgs::DecodeError;
 use lightning::ln::{ChannelId, PaymentHash};
 use lightning::routing::gossip::NodeId;
 use lightning::util::errors::APIError;
@@ -143,6 +144,73 @@ pub enum Event {
 		/// This will be `None` for events serialized by LDK Node v0.2.1 and prior.
 		reason: Option<ClosureReason>,
 	},
+	/// Failed to send Payjoin transaction.
+	///
+	/// This event is emitted when our attempt to send Payjoin transaction fail.
+	PayjoinPaymentPending {
+		/// Transaction ID of the successfully sent Payjoin transaction.
+		txid: bitcoin::Txid,
+		/// docs
+		amount: u64,
+		/// docs
+		receipient: bitcoin::ScriptBuf,
+	},
+	/// A Payjoin transaction has been successfully sent.
+	///
+	/// This event is emitted when we send a Payjoin transaction and it was accepted by the
+	/// receiver, and then finalised and broadcasted by us.
+	PayjoinPaymentSuccess {
+		/// Transaction ID of the successfully sent Payjoin transaction.
+		txid: bitcoin::Txid,
+		/// docs
+		amount: u64,
+		/// docs
+		receipient: bitcoin::ScriptBuf,
+	},
+	/// Failed to send Payjoin transaction.
+	///
+	/// This event is emitted when our attempt to send Payjoin transaction fail.
+	PayjoinPaymentFailed {
+		/// Transaction ID of the successfully sent Payjoin transaction.
+		txid: Option<bitcoin::Txid>,
+		/// docs
+		amount: u64,
+		/// docs
+		receipient: bitcoin::ScriptBuf,
+		/// Reason for the failure.
+		reason: PayjoinPaymentFailureReason,
+	},
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum PayjoinPaymentFailureReason {
+	Timeout,
+	TransactionFinalisationFailed,
+	InvalidReceiverResponse,
+	RequestFailed,
+}
+
+impl Readable for PayjoinPaymentFailureReason {
+	fn read<R: std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+		match u8::read(reader)? {
+			0 => Ok(Self::Timeout),
+			1 => Ok(Self::TransactionFinalisationFailed),
+			2 => Ok(Self::InvalidReceiverResponse),
+			3 => Ok(Self::RequestFailed),
+			_ => Err(DecodeError::InvalidValue),
+		}
+	}
+}
+
+impl Writeable for PayjoinPaymentFailureReason {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), std::io::Error> {
+		match *self {
+			Self::Timeout => 0u8.write(writer),
+			Self::TransactionFinalisationFailed => 1u8.write(writer),
+			Self::InvalidReceiverResponse => 2u8.write(writer),
+			Self::RequestFailed => 3u8.write(writer),
+		}
+	}
 }
 
 impl_writeable_tlv_based_enum!(Event,
@@ -184,6 +252,22 @@ impl_writeable_tlv_based_enum!(Event,
 		(2, payment_id, required),
 		(4, claimable_amount_msat, required),
 		(6, claim_deadline, option),
+	},
+	(7, PayjoinPaymentPending) => {
+		(0, txid, required),
+		(2, amount, required),
+		(4, receipient, required),
+	},
+	(8, PayjoinPaymentSuccess) => {
+		(0, txid, required),
+		(2, amount, required),
+		(4, receipient, required),
+	},
+	(9, PayjoinPaymentFailed) => {
+		(0, amount, required),
+		(1, txid, option),
+		(2, receipient, required),
+		(4, reason, required),
 	};
 );