Allow setting default DNS resolvers for HRNs

Author: chuksys

src/builder.rs

@@ -45,6 +45,7 @@ use lightning::routing::scoring::{
 	ProbabilisticScorer, ProbabilisticScoringDecayParameters, ProbabilisticScoringFeeParameters,
 };
 use lightning::sign::EntropySource;
+use lightning::onion_message::messenger::Destination;
 
 use lightning::util::persist::{
 	read_channel_monitors, CHANNEL_MANAGER_PERSISTENCE_KEY,
@@ -457,6 +458,12 @@ impl NodeBuilder {
 		Ok(self)
 	}
 
+	/// Sets the default dns_resolvers to be used when sending payments to HRNs.
+	pub fn set_dns_resolvers(&mut self, dns_resolvers: Vec<Destination>) -> Result<&mut Self, BuildError> {
+		self.config.dns_resolvers = Some(dns_resolvers);
+		Ok(self)
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self) -> Result<Node, BuildError> {

src/config.rs

@@ -11,6 +11,7 @@ use crate::logger::LogLevel;
 use crate::payment::SendingParameters;
 
 use lightning::ln::msgs::SocketAddress;
+use lightning::onion_message::messenger::Destination;
 use lightning::routing::gossip::NodeAlias;
 use lightning::util::config::ChannelConfig as LdkChannelConfig;
 use lightning::util::config::MaxDustHTLCExposure as LdkMaxDustHTLCExposure;
@@ -103,7 +104,8 @@ pub const WALLET_KEYS_SEED_LEN: usize = 64;
 /// | `log_level`                            | Debug              |
 /// | `anchor_channels_config`               | Some(..)           |
 /// | `sending_parameters`                   | None               |
-///
+/// | `dns_resolvers`                        | None               |
+/// 
 /// See [`AnchorChannelsConfig`] and [`SendingParameters`] for more information regarding their
 /// respective default values.
 ///
@@ -167,6 +169,11 @@ pub struct Config {
 	/// **Note:** If unset, default parameters will be used, and you will be able to override the
 	/// parameters on a per-payment basis in the corresponding method calls.
 	pub sending_parameters: Option<SendingParameters>,
+	/// The dns_resolver nodes (Destinations) to be used for resolving Human-readable Names.
+	/// 
+	/// If set to `Some`, the values set will be used as dns_resolvers when sending to HRNs.
+	/// **Note:** If set to `None`, payments to HRNs will fail.
+	pub dns_resolvers: Option<Vec<Destination>>,
 }
 
 impl Default for Config {
@@ -181,6 +188,7 @@ impl Default for Config {
 			anchor_channels_config: Some(AnchorChannelsConfig::default()),
 			sending_parameters: None,
 			node_alias: None,
+			dns_resolvers: None,
 		}
 	}
 }

src/error.rs

@@ -122,6 +122,8 @@ pub enum Error {
 	LiquidityFeeTooHigh,
 	/// Parsing a Human-Readable Name has failed
 	HrnParsingFailed,
+	/// The given operation failed due to `dns-resolvers` not being configured in builder.
+	DnsResolversNotConfigured,
 }
 
 impl fmt::Display for Error {
@@ -198,6 +200,9 @@ impl fmt::Display for Error {
 			Self::HrnParsingFailed => {
 				write!(f, "Failed to parse a human-readable name.")
 			},
+			Self::DnsResolversNotConfigured => {
+				write!(f, "The given operation failed due to `dns-resolvers` not being configured in builder.")
+			},
 		}
 	}
 }