Add support for sending to human-readable names that resolve to Bolt12 Offers

BIP 353 introduced human-readable names which has been implemented in LDK (0.1). This commit adds support for sending to HRNs that resolve to Bolt12 Offers by using the LDK pay_for_offer_from_human_readable_name method in ChannelManager.

Author: chuksys

Cargo.toml

@@ -28,7 +28,7 @@ panic = 'abort'     # Abort on panic
 default = []
 
 [dependencies]
-lightning = { version = "0.1.0", features = ["std"] }
+lightning = { version = "0.1.0", features = ["std", "dnssec"] }
 lightning-types = { version = "0.2.0" }
 lightning-invoice = { version = "0.33.0", features = ["std"] }
 lightning-net-tokio = { version = "0.1.0" }

bindings/ldk_node.udl

@@ -302,6 +302,7 @@ enum NodeError {
 	"InsufficientFunds",
 	"LiquiditySourceUnavailable",
 	"LiquidityFeeTooHigh",
+	"HrnParsingFailed",
 };
 
 dictionary NodeStatus {
@@ -854,3 +855,6 @@ typedef string OrderId;
 
 [Custom]
 typedef string DateTime;
+
+[Custom]
+typedef string HumanReadableName;

src/error.rs

@@ -120,6 +120,8 @@ pub enum Error {
 	LiquiditySourceUnavailable,
 	/// The given operation failed due to the LSP's required opening fee being too high.
 	LiquidityFeeTooHigh,
+	/// Parsing a Human-Readable Name has failed
+	HrnParsingFailed,
 }
 
 impl fmt::Display for Error {
@@ -193,6 +195,9 @@ 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::HrnParsingFailed => {
+				write!(f, "Failed to parse a human-readable name.")
+			},
 		}
 	}
 }

src/payment/bolt12.rs

@@ -270,6 +270,72 @@ impl Bolt12Payment {
 		}
 	}
 
+		/// Send a payment to an offer resolved from a human-readable name [BIP 353].
+	///
+	/// Paying to human-readable names makes it more intuitive to make payments for offers
+	/// as users can simply send payments to HRNs such as `user@example.com`.
+	///
+	/// This can be used to pay so-called "zero-amount" offers, i.e., an offer that leaves the
+	/// amount paid to be determined by the user.
+	///
+	/// `dns_resolvers` should be a list of node Destinations that are configured for dns resolution (as outlined in bLIP 32).
+	/// These nodes can be found by running a search through the `NetworkGraph` to find nodes that announce the
+	/// `dns_resolver` feature flag.
+	pub fn send_to_human_readable_name(
+		&self, name: &str, amount_msat: u64, dns_resolvers: Vec<Destination>,
+	) -> Result<PaymentId, Error> {
+		let rt_lock = self.runtime.read().unwrap();
+		if rt_lock.is_none() {
+			return Err(Error::NotRunning);
+		}
+
+		let hrn = HumanReadableName::from_encoded(&name).map_err(|_| Error::HrnParsingFailed)?;
+
+		let mut random_bytes = [0u8; 32];
+		rand::thread_rng().fill_bytes(&mut random_bytes);
+		let payment_id = PaymentId(random_bytes);
+		let retry_strategy = Retry::Timeout(LDK_PAYMENT_RETRY_TIMEOUT);
+		let max_total_routing_fee_msat = None;
+
+		match self.channel_manager.pay_for_offer_from_human_readable_name(
+			hrn.clone(),
+			amount_msat,
+			payment_id,
+			retry_strategy,
+			max_total_routing_fee_msat,
+			dns_resolvers,
+		) {
+			Ok(()) => {
+				log_info!(self.logger, "Initiated sending {} msats to {}", amount_msat, name);
+				let kind = PaymentKind::HrnBolt12Offer { hrn };
+				let payment = PaymentDetails::new(
+					payment_id,
+					kind,
+					Some(amount_msat),
+					None,
+					PaymentDirection::Outbound,
+					PaymentStatus::Pending,
+				);
+				self.payment_store.insert(payment)?;
+				Ok(payment_id)
+			},
+			Err(()) => {
+				log_error!(self.logger, "Failed to send payment to {}", name);
+				let kind = PaymentKind::HrnBolt12Offer { hrn };
+				let payment = PaymentDetails::new(
+					payment_id,
+					kind,
+					Some(amount_msat),
+					None,
+					PaymentDirection::Outbound,
+					PaymentStatus::Pending,
+				);
+				self.payment_store.insert(payment)?;
+				Err(Error::PaymentSendingFailed)
+			},
+		}
+	}
+
 	pub(crate) fn receive_inner(
 		&self, amount_msat: u64, description: &str, expiry_secs: Option<u32>, quantity: Option<u64>,
 	) -> Result<LdkOffer, Error> {