Move commit_upfront_shutdown_pubkey to ChannelHandshakeConfig

As like the previous commit, `commit_upfront_shutdown_pubkey` is another
static field that cannot change after the initial channel handshake. We
therefore move it out from its existing place in `ChannelConfig`.

Author: wpaulino

lightning/src/ln/chanmon_update_fail_tests.rs

@@ -2541,7 +2541,7 @@ fn test_temporary_error_during_shutdown() {
 	// Test that temporary failures when updating the monitor's shutdown script delay cooperative
 	// close.
 	let mut config = test_default_channel_config();
-	config.channel_options.commit_upfront_shutdown_pubkey = false;
+	config.own_channel_config.commit_upfront_shutdown_pubkey = false;
 
 	let chanmon_cfgs = create_chanmon_cfgs(2);
 	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
@@ -2596,7 +2596,7 @@ fn test_permanent_error_during_sending_shutdown() {
 	// Test that permanent failures when updating the monitor's shutdown script result in a force
 	// close when initiating a cooperative close.
 	let mut config = test_default_channel_config();
-	config.channel_options.commit_upfront_shutdown_pubkey = false;
+	config.own_channel_config.commit_upfront_shutdown_pubkey = false;
 
 	let chanmon_cfgs = create_chanmon_cfgs(2);
 	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
@@ -2617,7 +2617,7 @@ fn test_permanent_error_during_handling_shutdown() {
 	// Test that permanent failures when updating the monitor's shutdown script result in a force
 	// close when handling a cooperative close.
 	let mut config = test_default_channel_config();
-	config.channel_options.commit_upfront_shutdown_pubkey = false;
+	config.own_channel_config.commit_upfront_shutdown_pubkey = false;
 
 	let chanmon_cfgs = create_chanmon_cfgs(2);
 	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);

lightning/src/ln/channel.rs

@@ -918,7 +918,7 @@ impl<Signer: Sign> Channel<Signer> {
 		let mut secp_ctx = Secp256k1::new();
 		secp_ctx.seeded_randomize(&keys_provider.get_secure_random_bytes());
 
-		let shutdown_scriptpubkey = if config.channel_options.commit_upfront_shutdown_pubkey {
+		let shutdown_scriptpubkey = if config.own_channel_config.commit_upfront_shutdown_pubkey {
 			Some(keys_provider.get_shutdown_scriptpubkey())
 		} else { None };
 
@@ -1239,7 +1239,7 @@ impl<Signer: Sign> Channel<Signer> {
 			}
 		} else { None };
 
-		let shutdown_scriptpubkey = if config.channel_options.commit_upfront_shutdown_pubkey {
+		let shutdown_scriptpubkey = if config.own_channel_config.commit_upfront_shutdown_pubkey {
 			Some(keys_provider.get_shutdown_scriptpubkey())
 		} else { None };
 

lightning/src/ln/shutdown_tests.rs

@@ -411,7 +411,7 @@ fn test_upfront_shutdown_script() {
 	let mut config = UserConfig::default();
 	config.own_channel_config.announced_channel = true;
 	config.peer_channel_config_limits.force_announced_channel_preference = false;
-	config.channel_options.commit_upfront_shutdown_pubkey = false;
+	config.own_channel_config.commit_upfront_shutdown_pubkey = false;
 	let user_cfgs = [None, Some(config), None];
 	let chanmon_cfgs = create_chanmon_cfgs(3);
 	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
@@ -576,7 +576,7 @@ fn test_segwit_v0_shutdown_script() {
 	let mut config = UserConfig::default();
 	config.own_channel_config.announced_channel = true;
 	config.peer_channel_config_limits.force_announced_channel_preference = false;
-	config.channel_options.commit_upfront_shutdown_pubkey = false;
+	config.own_channel_config.commit_upfront_shutdown_pubkey = false;
 	let user_cfgs = [None, Some(config), None];
 	let chanmon_cfgs = create_chanmon_cfgs(3);
 	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
@@ -611,7 +611,7 @@ fn test_anysegwit_shutdown_script() {
 	let mut config = UserConfig::default();
 	config.own_channel_config.announced_channel = true;
 	config.peer_channel_config_limits.force_announced_channel_preference = false;
-	config.channel_options.commit_upfront_shutdown_pubkey = false;
+	config.own_channel_config.commit_upfront_shutdown_pubkey = false;
 	let user_cfgs = [None, Some(config), None];
 	let chanmon_cfgs = create_chanmon_cfgs(3);
 	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
@@ -646,7 +646,7 @@ fn test_unsupported_anysegwit_shutdown_script() {
 	let mut config = UserConfig::default();
 	config.own_channel_config.announced_channel = true;
 	config.peer_channel_config_limits.force_announced_channel_preference = false;
-	config.channel_options.commit_upfront_shutdown_pubkey = false;
+	config.own_channel_config.commit_upfront_shutdown_pubkey = false;
 	let user_cfgs = [None, Some(config), None];
 	let chanmon_cfgs = create_chanmon_cfgs(3);
 	let mut node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
@@ -688,7 +688,7 @@ fn test_invalid_shutdown_script() {
 	let mut config = UserConfig::default();
 	config.own_channel_config.announced_channel = true;
 	config.peer_channel_config_limits.force_announced_channel_preference = false;
-	config.channel_options.commit_upfront_shutdown_pubkey = false;
+	config.own_channel_config.commit_upfront_shutdown_pubkey = false;
 	let user_cfgs = [None, Some(config), None];
 	let chanmon_cfgs = create_chanmon_cfgs(3);
 	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);

lightning/src/util/config.rs

@@ -87,7 +87,7 @@ pub struct ChannelHandshakeConfig {
 	///
 	/// If this option is set, channels may be created that will not be readable by LDK versions
 	/// prior to 0.0.106, causing [`ChannelManager`]'s read method to return a
-	/// [`DecodeError:InvalidValue`].
+	/// [`DecodeError::InvalidValue`].
 	///
 	/// Note that setting this to true does *not* prevent us from opening channels with
 	/// counterparties that do not support the `scid_alias` option; we will simply fall back to a
@@ -100,7 +100,7 @@ pub struct ChannelHandshakeConfig {
 	/// Default value: false. This value is likely to change to true in the future.
 	///
 	/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
-	/// [`DecodeError:InvalidValue`]: crate::ln::msgs::DecodeError::InvalidValue
+	/// [`DecodeError::InvalidValue`]: crate::ln::msgs::DecodeError::InvalidValue
 	pub negotiate_scid_privacy: bool,
 	/// Set to announce the channel publicly and notify all nodes that they can route via this
 	/// channel.
@@ -112,6 +112,20 @@ pub struct ChannelHandshakeConfig {
 	///
 	/// Default value: false.
 	pub announced_channel: bool,
+	/// When set, we commit to an upfront shutdown_pubkey at channel open. If our counterparty
+	/// supports it, they will then enforce the mutual-close output to us matches what we provided
+	/// at intialization, preventing us from closing to an alternate pubkey.
+	///
+	/// This is set to true by default to provide a slight increase in security, though ultimately
+	/// any attacker who is able to take control of a channel can just as easily send the funds via
+	/// lightning payments, so we never require that our counterparties support this option.
+	///
+	/// The upfront key committed is provided from [`KeysInterface::get_shutdown_scriptpubkey`].
+	///
+	/// Default value: true.
+	///
+	/// [`KeysInterface::get_shutdown_scriptpubkey`]: crate::chain::keysinterface::KeysInterface::get_shutdown_scriptpubkey
+	pub commit_upfront_shutdown_pubkey: bool,
 }
 
 impl Default for ChannelHandshakeConfig {
@@ -123,6 +137,7 @@ impl Default for ChannelHandshakeConfig {
 			max_inbound_htlc_value_in_flight_percent_of_channel: 10,
 			negotiate_scid_privacy: false,
 			announced_channel: false,
+			commit_upfront_shutdown_pubkey: true,
 		}
 	}
 }