Add timeout for fee rate cache updates

.. even though we don't expect this to block, we're better safe than
sorry and start to introduce timeouts for any calls we make to remote
servers.

Author: tnull

bindings/ldk_node.udl

@@ -135,6 +135,7 @@ enum NodeError {
 	"ChannelConfigUpdateFailed",
 	"PersistenceFailed",
 	"FeerateEstimationUpdateFailed",
+	"FeerateEstimationUpdateTimeout",
 	"WalletOperationFailed",
 	"WalletOperationTimeout",
 	"OnchainTxSigningFailed",

src/config.rs

@@ -48,6 +48,9 @@ pub(crate) const BDK_WALLET_SYNC_TIMEOUT_SECS: u64 = 90;
 // The timeout after which we abort a wallet syncing operation.
 pub(crate) const LDK_WALLET_SYNC_TIMEOUT_SECS: u64 = 30;
 
+// The timeout after which we abort a fee rate cache update operation.
+pub(crate) const FEE_RATE_CACHE_UPDATE_TIMEOUT_SECS: u64 = 5;
+
 // The length in bytes of our wallets' keys seed.
 pub(crate) const WALLET_KEYS_SEED_LEN: usize = 64;
 

src/error.rs

@@ -27,6 +27,8 @@ pub enum Error {
 	PersistenceFailed,
 	/// A fee rate estimation update failed.
 	FeerateEstimationUpdateFailed,
+	/// A fee rate estimation update timed out.
+	FeerateEstimationUpdateTimeout,
 	/// A wallet operation failed.
 	WalletOperationFailed,
 	/// A wallet operation timed out.
@@ -94,6 +96,9 @@ impl fmt::Display for Error {
 			Self::FeerateEstimationUpdateFailed => {
 				write!(f, "Failed to update fee rate estimates.")
 			},
+			Self::FeerateEstimationUpdateTimeout => {
+				write!(f, "Updating fee rate estimates timed out.")
+			},
 			Self::WalletOperationFailed => write!(f, "Failed to conduct wallet operation."),
 			Self::WalletOperationTimeout => write!(f, "A wallet operation timed out."),
 			Self::OnchainTxSigningFailed => write!(f, "Failed to sign given transaction."),

src/fee_estimator.rs

@@ -1,3 +1,4 @@
+use crate::config::FEE_RATE_CACHE_UPDATE_TIMEOUT_SECS;
 use crate::logger::{log_error, log_trace, Logger};
 use crate::{Config, Error};
 
@@ -14,6 +15,7 @@ use bitcoin::Network;
 use std::collections::HashMap;
 use std::ops::Deref;
 use std::sync::{Arc, RwLock};
+use std::time::Duration;
 
 pub(crate) struct OnchainFeeEstimator<L: Deref>
 where
@@ -55,7 +57,21 @@ where
 				ConfirmationTarget::OutputSpendingFee => 12,
 			};
 
-			let estimates = self.esplora_client.get_fee_estimates().await.map_err(|e| {
+			let estimates = tokio::time::timeout(
+				Duration::from_secs(FEE_RATE_CACHE_UPDATE_TIMEOUT_SECS),
+				self.esplora_client.get_fee_estimates(),
+			)
+			.await
+			.map_err(|e| {
+				log_error!(
+					self.logger,
+					"Updating fee rate estimates for {:?} timed out: {}",
+					target,
+					e
+				);
+				Error::FeerateEstimationUpdateTimeout
+			})?
+			.map_err(|e| {
 				log_error!(
 					self.logger,
 					"Failed to retrieve fee rate estimates for {:?}: {}",