Add a method to update the current UserConfig in ChannelManager

The `UserConfig` is used to set the default configuration on new
channels and also controls some global behavior in
`ChannelManager`, so should probably be updatable without
restarting the node. Here we add such a method.

We also take this opportunity to rename the `UserConfig` related
methods and update their docs since `UserConfig` has been more than
just the default configuration for new channels for some time.

Fixes #2420

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -3801,11 +3801,18 @@ where
 		}
 	}
 
-	/// Gets the current configuration applied to all new channels.
-	pub fn get_current_default_configuration(&self) -> UserConfig {
+	/// Gets the current [`UserConfig`] which controls some global behavior and includes the
+	/// default configuration applied to all new channels.
+	pub fn get_current_config(&self) -> UserConfig {
 		self.config.read().unwrap().clone()
 	}
 
+	/// Updates the current [`UserConfig`] which controls some global behavior and includes the
+	/// default configuration applied to all new channels.
+	pub fn set_current_config(&self, new_config: UserConfig) {
+		*self.config.write().unwrap() = new_config;
+	}
+
 	#[cfg(test)]
 	pub fn create_and_insert_outbound_scid_alias_for_test(&self) -> u64 {
 		self.create_and_insert_outbound_scid_alias()

lightning/src/ln/dual_funding_tests.rs

@@ -62,7 +62,7 @@ fn do_test_v2_channel_establishment(session: V2ChannelEstablishmentTestSession)
 		funding_satoshis,
 		initiator_funding_inputs.clone(),
 		42, /* user_channel_id */
-		&nodes[0].node.get_current_default_configuration(),
+		&nodes[0].node.get_current_config(),
 		nodes[0].best_block_info().1,
 		nodes[0].node.create_and_insert_outbound_scid_alias_for_test(),
 		ConfirmationTarget::NonAnchorChannelFee,

lightning/src/ln/functional_test_utils.rs

@@ -866,7 +866,7 @@ impl<'a, 'b, 'c> Drop for Node<'a, 'b, 'c> {
 				)>::read(
 					&mut io::Cursor::new(w.0),
 					ChannelManagerReadArgs {
-						config: self.node.get_current_default_configuration(),
+						config: self.node.get_current_config(),
 						entropy_source: self.keys_manager,
 						node_signer: self.keys_manager,
 						signer_provider: self.keys_manager,
@@ -1651,7 +1651,7 @@ pub fn exchange_open_accept_chan<'a, 'b, 'c>(
 		42
 	);
 	node_b.node.handle_open_channel(node_a_id, &open_channel_msg);
-	if node_b.node.get_current_default_configuration().manually_accept_inbound_channels {
+	if node_b.node.get_current_config().manually_accept_inbound_channels {
 		let events = node_b.node.get_and_clear_pending_events();
 		assert_eq!(events.len(), 1);
 		match &events[0] {
@@ -1830,7 +1830,7 @@ pub fn create_unannounced_chan_between_nodes_with_value<'a, 'b, 'c, 'd>(
 	let node_a_id = nodes[a].node.get_our_node_id();
 	let node_b_id = nodes[b].node.get_our_node_id();
 
-	let mut no_announce_cfg = nodes[a].node.get_current_default_configuration();
+	let mut no_announce_cfg = nodes[a].node.get_current_config();
 	no_announce_cfg.channel_handshake_config.announce_for_forwarding = false;
 	nodes[a]
 		.node

lightning/src/ln/onion_route_tests.rs

@@ -1776,7 +1776,7 @@ fn do_test_onion_failure_stale_channel_update(announce_for_forwarding: bool) {
 		let chan_2_monitor_serialized = get_monitor!(nodes[1], channel_to_update.0).encode();
 		reload_node!(
 			nodes[1],
-			nodes[1].node.get_current_default_configuration().clone(),
+			nodes[1].node.get_current_config(),
 			&nodes[1].node.encode(),
 			&[&chan_1_monitor_serialized, &chan_2_monitor_serialized],
 			persister,

lightning/src/ln/reorg_tests.rs

@@ -323,7 +323,7 @@ fn do_test_unconf_chan(reload_node: bool, reorg_after_reload: bool, use_funding_
 		let nodes_0_serialized = nodes[0].node.encode();
 		let chan_0_monitor_serialized = get_monitor!(nodes[0], chan.2).encode();
 
-		reload_node!(nodes[0], nodes[0].node.get_current_default_configuration().clone(), &nodes_0_serialized, &[&chan_0_monitor_serialized], persister, new_chain_monitor, nodes_0_deserialized);
+		reload_node!(nodes[0], nodes[0].node.get_current_config(), &nodes_0_serialized, &[&chan_0_monitor_serialized], persister, new_chain_monitor, nodes_0_deserialized);
 	}
 
 	if reorg_after_reload {