f Allow to specify the seed bytes or a seed file location

Author: tnull

src/io_utils.rs

@@ -1,4 +1,4 @@
-use crate::{Config, FilesystemLogger, NetworkGraph, Scorer};
+use crate::{Config, FilesystemLogger, NetworkGraph, Scorer, WALLET_KEYS_SEED_LEN};
 
 use lightning::routing::scoring::{ProbabilisticScorer, ProbabilisticScoringParameters};
 use lightning::util::ser::ReadableArgs;
@@ -10,16 +10,19 @@ use std::io::{BufReader, Write};
 use std::path::Path;
 use std::sync::Arc;
 
-pub(crate) fn read_or_generate_seed_file(config: &Config) -> [u8; 32] {
-	let keys_seed_path = format!("{}/keys_seed", config.storage_dir_path);
+pub(crate) fn read_or_generate_seed_file(keys_seed_path: &str) -> [u8; WALLET_KEYS_SEED_LEN] {
 	if Path::new(&keys_seed_path).exists() {
 		let seed = fs::read(keys_seed_path).expect("Failed to read keys seed file");
-		assert_eq!(seed.len(), 32);
-		let mut key = [0; 32];
+		assert_eq!(
+			seed.len(),
+			WALLET_KEYS_SEED_LEN,
+			"Failed to read keys seed file: unexpected length"
+		);
+		let mut key = [0; WALLET_KEYS_SEED_LEN];
 		key.copy_from_slice(&seed);
 		key
 	} else {
-		let mut key = [0; 32];
+		let mut key = [0; WALLET_KEYS_SEED_LEN];
 		thread_rng().fill_bytes(&mut key);
 
 		let mut f = fs::File::create(keys_seed_path).expect("Failed to create keys seed file");

src/lib.rs

@@ -109,6 +109,9 @@ const LDK_PAYMENT_RETRY_TIMEOUT: Duration = Duration::from_secs(10);
 // The time in between peer reconnection attempts.
 const PEER_RECONNECTION_INTERVAL: Duration = Duration::from_secs(10);
 
+// The length in bytes of our wallets' keys seed.
+const WALLET_KEYS_SEED_LEN: usize = 64;
+
 #[derive(Debug, Clone)]
 /// Represents the configuration of an [`Node`] instance.
 pub struct Config {
@@ -136,24 +139,47 @@ impl Default for Config {
 	}
 }
 
+#[derive(Debug, Clone)]
+enum WalletEntropySource {
+	SeedFile(String),
+	SeedBytes([u8; WALLET_KEYS_SEED_LEN]),
+}
+
 /// A builder for an [`Node`] instance, allowing to set some configuration and module choices from
 /// the getgo.
 #[derive(Debug, Clone)]
 pub struct Builder {
 	config: Config,
+	entropy_source: Option<WalletEntropySource>,
 }
 
 impl Builder {
 	/// Creates a new builder instance with the default configuration.
 	pub fn new() -> Self {
 		let config = Config::default();
-
-		Self { config }
+		let entropy_source = None;
+		Self { config, entropy_source }
 	}
 
 	/// Creates a new builder instance from an [`Config`].
 	pub fn from_config(config: Config) -> Self {
-		Self { config }
+		let entropy_source = None;
+		Self { config, entropy_source }
+	}
+
+	/// Configures the [`Node`] instance to source its wallet entropy from a seed file on disk.
+	///
+	/// If the given file does not exist a new random seed file will be generated and
+	/// stored at the given location.
+	pub fn set_entropy_seed_path(&mut self, seed_path: String) -> &mut Self {
+		self.entropy_source = Some(WalletEntropySource::SeedFile(seed_path));
+		self
+	}
+
+	/// Configures the [`Node`] instance to source its wallet entropy from the given seed bytes.
+	pub fn set_entropy_seed_bytes(&mut self, seed_bytes: [u8; WALLET_KEYS_SEED_LEN]) -> &mut Self {
+		self.entropy_source = Some(WalletEntropySource::SeedBytes(seed_bytes));
+		self
 	}
 
 	/// Sets the used storage directory path.
@@ -213,8 +239,21 @@ impl Builder {
 		let logger = Arc::new(FilesystemLogger::new(log_file_path));
 
 		// Initialize the on-chain wallet and chain access
-		let seed = io_utils::read_or_generate_seed_file(config.as_ref());
-		let xprv = bitcoin::util::bip32::ExtendedPrivKey::new_master(config.network, &seed)
+		let seed_bytes = if let Some(entropy_source) = &self.entropy_source {
+			// Use the configured entropy source, if the user set one.
+			match entropy_source {
+				WalletEntropySource::SeedBytes(bytes) => bytes.clone(),
+				WalletEntropySource::SeedFile(seed_path) => {
+					io_utils::read_or_generate_seed_file(seed_path)
+				}
+			}
+		} else {
+			// Default to read or generate from the default location generate a seed file.
+			let seed_path = format!("{}/keys_seed", config.storage_dir_path);
+			io_utils::read_or_generate_seed_file(&seed_path)
+		};
+
+		let xprv = bitcoin::util::bip32::ExtendedPrivKey::new_master(config.network, &seed_bytes)
 			.expect("Failed to read wallet master key");
 
 		let wallet_name = bdk::wallet::wallet_name_from_descriptor(
@@ -263,8 +302,9 @@ impl Builder {
 		let cur_time = SystemTime::now()
 			.duration_since(SystemTime::UNIX_EPOCH)
 			.expect("System time error: Clock may have gone backwards");
+		let ldk_seed_bytes: [u8; 32] = xprv.private_key.secret_bytes();
 		let keys_manager = Arc::new(KeysManager::new(
-			&seed,
+			&ldk_seed_bytes,
 			cur_time.as_secs(),
 			cur_time.subsec_nanos(),
 			Arc::clone(&wallet),