Introduce new mandatory NodeEntropy object

Previously, the `Builder` allowed setting different entropy sources via
its `set_entropy...` methods, defaulting to sourcing from an
auto-generated seed file in the storage path. While this allowed for
really easy setup, it spared the user to actually think about where to
store their node secret.

Here, we therefore introduce a mandatory `NodeEntropy` object that, as
before, allows the user to source entropy from BIP39 Mnemonic, seed
bytes, or a seed file. However, it doesn't implement any default and
hence intentionally requires manually setup by the user. Moreover, this
API refactor also allows to reuse the same object outside of the
`Node`'s `Builder` in a future commit.

Author: tnull

README.md

@@ -14,20 +14,26 @@ LDK Node is a self-custodial Lightning node in library form. Its central goal is
 The primary abstraction of the library is the [`Node`][api_docs_node], which can be retrieved by setting up and configuring a [`Builder`][api_docs_builder] to your liking and calling one of the `build` methods. `Node` can then be controlled via commands such as `start`, `stop`, `open_channel`, `send`, etc.
 
 ```rust
-use ldk_node::Builder;
-use ldk_node::lightning_invoice::Bolt11Invoice;
-use ldk_node::lightning::ln::msgs::SocketAddress;
 use ldk_node::bitcoin::secp256k1::PublicKey;
 use ldk_node::bitcoin::Network;
+use ldk_node::entropy::{generate_entropy_mnemonic, NodeEntropy};
+use ldk_node::lightning::ln::msgs::SocketAddress;
+use ldk_node::lightning_invoice::Bolt11Invoice;
+use ldk_node::Builder;
 use std::str::FromStr;
 
 fn main() {
 	let mut builder = Builder::new();
 	builder.set_network(Network::Testnet);
 	builder.set_chain_source_esplora("https://blockstream.info/testnet/api".to_string(), None);
-	builder.set_gossip_source_rgs("https://rapidsync.lightningdevkit.org/testnet/snapshot".to_string());
+	builder.set_gossip_source_rgs(
+		"https://rapidsync.lightningdevkit.org/testnet/snapshot".to_string(),
+	);
+
 
-	let node = builder.build().unwrap();
+	let mnemonic = generate_entropy_mnemonic(None);
+	let node_entropy = NodeEntropy::from_bip39_mnemonic(mnemonic, None);
+	let node = builder.build(node_entropy).unwrap();
 
 	node.start().unwrap();
 

bindings/kotlin/ldk-node-android/lib/src/androidTest/kotlin/org/lightningdevkit/ldknode/AndroidLibTest.kt

@@ -34,8 +34,13 @@ class AndroidLibTest {
         val builder1 = Builder.fromConfig(config1)
         val builder2 = Builder.fromConfig(config2)
 
-        val node1 = builder1.build()
-        val node2 = builder2.build()
+        val mnemonic1 = generateEntropyMnemonic(null)
+        val nodeEntropy1 = NodeEntropy.fromBip39Mnemonic(mnemonic1, null)
+        val node1 = builder1.build(nodeEntropy1)
+
+        val mnemonic2 = generateEntropyMnemonic(null)
+        val nodeEntropy2 = NodeEntropy.fromBip39Mnemonic(mnemonic2, null)
+        val node2 = builder2.build(nodeEntropy2)
 
         node1.start()
         node2.start()

bindings/kotlin/ldk-node-jvm/lib/src/test/kotlin/org/lightningdevkit/ldknode/LibraryTest.kt

@@ -193,8 +193,13 @@ class LibraryTest {
         builder2.setChainSourceEsplora(esploraEndpoint, null)
         builder2.setCustomLogger(logWriter2)
 
-        val node1 = builder1.build()
-        val node2 = builder2.build()
+        val mnemonic1 = generateEntropyMnemonic(null)
+        val nodeEntropy1 = NodeEntropy.fromBip39Mnemonic(mnemonic1, null)
+        val node1 = builder1.build(nodeEntropy1)
+
+        val mnemonic2 = generateEntropyMnemonic(null)
+        val nodeEntropy2 = NodeEntropy.fromBip39Mnemonic(mnemonic2, null)
+        val node2 = builder2.build(nodeEntropy2)
 
         node1.start()
         node2.start()

bindings/ldk_node.udl

@@ -47,6 +47,20 @@ dictionary LSPS2ServiceConfig {
 	boolean client_trusts_lsp;
 };
 
+interface NodeEntropy {
+	[Name=from_bip39_mnemonic]
+	constructor(Mnemonic mnemonic, string? passphrase);
+	[Throws=EntropyError, Name=from_seed_bytes]
+	constructor(bytes seed_bytes);
+	[Throws=EntropyError, Name=from_seed_path]
+	constructor(string seed_path);
+};
+
+enum EntropyError {
+	"InvalidSeedBytes",
+	"InvalidSeedFile",
+};
+
 enum WordCount {
 	"Words12",
 	"Words15",
@@ -80,10 +94,6 @@ interface Builder {
 	constructor();
 	[Name=from_config]
 	constructor(Config config);
-	void set_entropy_seed_path(string seed_path);
-	[Throws=BuildError]
-	void set_entropy_seed_bytes(sequence<u8> seed_bytes);
-	void set_entropy_bip39_mnemonic(Mnemonic mnemonic, string? passphrase);
 	void set_chain_source_esplora(string server_url, EsploraSyncConfig? config);
 	void set_chain_source_electrum(string server_url, ElectrumSyncConfig? config);
 	void set_chain_source_bitcoind_rpc(string rpc_host, u16 rpc_port, string rpc_user, string rpc_password);
@@ -107,15 +117,15 @@ interface Builder {
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
 	[Throws=BuildError]
-	Node build();
+	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]
-	Node build_with_fs_store();
+	Node build_with_fs_store(NodeEntropy node_entropy);
 	[Throws=BuildError]
-	Node build_with_vss_store(string vss_url, string store_id, string lnurl_auth_server_url, record<string, string> fixed_headers);
+	Node build_with_vss_store(NodeEntropy node_entropy, string vss_url, string store_id, string lnurl_auth_server_url, record<string, string> fixed_headers);
 	[Throws=BuildError]
-	Node build_with_vss_store_and_fixed_headers(string vss_url, string store_id, record<string, string> fixed_headers);
+	Node build_with_vss_store_and_fixed_headers(NodeEntropy node_entropy, string vss_url, string store_id, record<string, string> fixed_headers);
 	[Throws=BuildError]
-	Node build_with_vss_store_and_header_provider(string vss_url, string store_id, VssHeaderProvider header_provider);
+	Node build_with_vss_store_and_header_provider(NodeEntropy node_entropy, string vss_url, string store_id, VssHeaderProvider header_provider);
 };
 
 interface Node {
@@ -357,8 +367,6 @@ dictionary BestBlock {
 
 [Error]
 enum BuildError {
-	"InvalidSeedBytes",
-	"InvalidSeedFile",
 	"InvalidSystemTime",
 	"InvalidChannelMonitor",
 	"InvalidListeningAddresses",

bindings/python/src/ldk_node/test_ldk_node.py

@@ -97,13 +97,15 @@ def send_to_address(address, amount_sats):
 
 
 def setup_node(tmp_dir, esplora_endpoint, listening_addresses):
+    mnemonic = generate_entropy_mnemonic(None)
+    node_entropy = NodeEntropy.from_bip39_mnemonic(mnemonic, None)
     config = default_config()
     builder = Builder.from_config(config)
     builder.set_storage_dir_path(tmp_dir)
     builder.set_chain_source_esplora(esplora_endpoint, None)
     builder.set_network(DEFAULT_TEST_NETWORK)
     builder.set_listening_addresses(listening_addresses)
-    return builder.build()
+    return builder.build(node_entropy)
 
 def get_esplora_endpoint():
     if os.environ.get('ESPLORA_ENDPOINT'):