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", default-features = false, features = [ "rt-multi-thread
 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]
@@ -140,6 +141,13 @@ 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",
@@ -184,6 +192,13 @@ enum NodeError {
 	"InsufficientFunds",
 	"LiquiditySourceUnavailable",
 	"LiquidityFeeTooHigh",
+	"PayjoinSenderUnavailable",
+	"PayjoinUriInvalid",
+	"PayjoinNetworkMismatch",
+	"PayjoinRequestMissingAmount",
+	"PayjoinRequestCreationFailed",
+	"PayjoinResponseProcessingFailed",
+	"PayjoinRequestTimeout",
 };
 
 dictionary NodeStatus {
@@ -215,6 +230,7 @@ enum BuildError {
 	"KVStoreSetupFailed",
 	"WalletSetupFailed",
 	"LoggerSetupFailed",
+	"InvalidPayjoinConfig",
 };
 
 [Enum]
@@ -225,6 +241,8 @@ 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);
+	PayjoinTxSendSuccess(Txid txid);
+	PayjoinTxSendFailed(string reason);
 };
 
 enum PaymentFailureReason {

src/builder.rs

@@ -16,7 +16,7 @@ use crate::peer_store::PeerStore;
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
 	ChainMonitor, ChannelManager, DynStore, GossipSync, Graph, KeysManager, MessageRouter,
-	OnionMessenger, PeerManager,
+	OnionMessenger, PayjoinSender, PeerManager,
 };
 use crate::wallet::Wallet;
 use crate::{LogLevel, Node};
@@ -93,6 +93,15 @@ struct LiquiditySourceConfig {
 	lsps2_service: Option<(SocketAddress, PublicKey, Option<String>)>,
 }
 
+#[derive(Debug, Clone)]
+struct PayjoinConfig {
+	#[allow(dead_code)]
+	payjoin_directory: String,
+	payjoin_relay: String,
+	#[allow(dead_code)]
+	ohttp_keys: Option<String>,
+}
+
 impl Default for LiquiditySourceConfig {
 	fn default() -> Self {
 		Self { lsps2_service: None }
@@ -132,6 +141,8 @@ pub enum BuildError {
 	WalletSetupFailed,
 	/// We failed to setup the logger.
 	LoggerSetupFailed,
+	/// Invalid Payjoin configuration.
+	InvalidPayjoinConfig,
 }
 
 impl fmt::Display for BuildError {
@@ -152,6 +163,10 @@ 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 +187,7 @@ 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 +203,14 @@ 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 +265,14 @@ impl NodeBuilder {
 		self
 	}
 
+	/// Configures the [`Node`] instance to enable payjoin transactions.
+	pub fn set_payjoin_config(
+		&mut self, payjoin_directory: String, payjoin_relay: String, ohttp_keys: Option<String>,
+	) -> &mut Self {
+		self.payjoin_config = Some(PayjoinConfig { payjoin_directory, payjoin_relay, ohttp_keys });
+		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 +391,7 @@ 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 +413,7 @@ 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 +481,17 @@ 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_directory: String, payjoin_relay: String, ohttp_keys: Option<String>,
+	) {
+		self.inner.write().unwrap().set_payjoin_config(
+			payjoin_directory,
+			payjoin_relay,
+			ohttp_keys,
+		);
+	}
+
 	/// 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 +560,9 @@ 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)
@@ -960,6 +1000,26 @@ fn build_with_store_internal(
 
 	let (stop_sender, _) = tokio::sync::watch::channel(());
 
+	let mut payjoin_sender = None;
+	if let Some((_payjoin_directory, payjoin_relay, _ohttp_keys)) = payjoin_config
+		.as_ref()
+		.map(|pc| (pc.payjoin_directory.clone(), pc.payjoin_relay.clone(), pc.ohttp_keys.clone()))
+	{
+		match PayjoinSender::new(
+			Arc::clone(&logger),
+			Arc::clone(&wallet),
+			Arc::clone(&tx_broadcaster),
+			&payjoin_relay,
+		) {
+			Ok(payjoin_sender_) => {
+				payjoin_sender = Some(Arc::new(payjoin_sender_));
+			},
+			Err(_) => {
+				return Err(BuildError::InvalidPayjoinConfig);
+			},
+		}
+	}
+
 	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));
@@ -980,6 +1040,7 @@ fn build_with_store_internal(
 		channel_manager,
 		chain_monitor,
 		output_sweeper,
+		payjoin_sender,
 		peer_manager,
 		connection_manager,
 		keys_manager,

src/config.rs

@@ -37,6 +37,15 @@ 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 request 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_SLEEP_TIME_BETWEEN_REQUESTS: 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(3600);
+
 // The time in-between RGS sync attempts.
 pub(crate) const RGS_SYNC_INTERVAL: Duration = Duration::from_secs(60 * 60);
 

src/error.rs

@@ -87,6 +87,20 @@ pub enum Error {
 	LiquiditySourceUnavailable,
 	/// The given operation failed due to the LSP's required opening fee being too high.
 	LiquidityFeeTooHigh,
+	/// Failed to access Payjoin sender object.
+	PayjoinSenderUnavailable,
+	/// Payjoin URI is invalid.
+	PayjoinUriInvalid,
+	/// Payjoin URI network mismatch.
+	PayjoinNetworkMismatch,
+	/// Amount is neither user-provided nor defined in the URI.
+	PayjoinRequestMissingAmount,
+	/// Failed to build a Payjoin request.
+	PayjoinRequestCreationFailed,
+	/// Payjoin response processing failed.
+	PayjoinResponseProcessingFailed,
+	/// Payjoin request timed out.
+	PayjoinRequestTimeout,
 }
 
 impl fmt::Display for Error {
@@ -148,6 +162,30 @@ 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::PayjoinSenderUnavailable => {
+				write!(f, "Failed to access Payjoin sender object. Make sure you have enabled Payjoin sending 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::PayjoinNetworkMismatch => {
+				write!(f, "The provided Payjoin URI does not match the node network.")
+			},
+			Self::PayjoinResponseProcessingFailed => {
+				write!(f, "Payjoin receiver responded to our request with an invalid response that was ignored")
+			},
+			Self::PayjoinRequestTimeout => {
+				write!(
+					f,
+					"Payjoin receiver did not respond to our request within the timeout period."
+				)
+			},
 		}
 	}
 }

src/event.rs

@@ -121,6 +121,21 @@ pub enum Event {
 		/// This will be `None` for events serialized by LDK Node v0.2.1 and prior.
 		reason: Option<ClosureReason>,
 	},
+	/// 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.
+	PayjoinTxSendSuccess {
+		/// Transaction ID of the successfully sent Payjoin transaction.
+		txid: bitcoin::Txid,
+	},
+	/// Failed to send Payjoin transaction.
+	///
+	/// This event is emitted when our attempt to send Payjoin transaction fail.
+	PayjoinTxSendFailed {
+		/// Reason for the failure.
+		reason: String,
+	},
 }
 
 impl_writeable_tlv_based_enum!(Event,
@@ -156,6 +171,12 @@ impl_writeable_tlv_based_enum!(Event,
 		(1, counterparty_node_id, option),
 		(2, user_channel_id, required),
 		(3, reason, upgradable_option),
+	},
+	(6, PayjoinTxSendSuccess) => {
+		(0, txid, required),
+	},
+	(7, PayjoinTxSendFailed) => {
+		(0, reason, required),
 	};
 );
 

src/io/utils.rs

@@ -511,6 +511,15 @@ pub(crate) fn check_namespace_key_validity(
 	Ok(())
 }
 
+pub(crate) fn ohttp_headers() -> reqwest::header::HeaderMap {
+	let mut headers = reqwest::header::HeaderMap::new();
+	headers.insert(
+		reqwest::header::CONTENT_TYPE,
+		reqwest::header::HeaderValue::from_static("message/ohttp-req"),
+	);
+	headers
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;