Enable ChainMonitor to distribute PeerStorage

To enable ChainMonitor sending peer storage to channel partners whenever a new block is added,
We implement BaseMessageHandler for ChainMonitor.
This allows the `ChainMonitor` to handle the peer storage distribution.

Key changes:
 - Add BaseMessageHandler into the MessageHandler.
 - Implement BaseMessageHandler for ChainMonitor.
 - Process BaseMessageHandler events inside process_events().

Author: Aditya Sharma

fuzz/src/chanmon_consistency.rs

@@ -204,6 +204,7 @@ impl TestChainMonitor {
 				logger.clone(),
 				feeest,
 				Arc::clone(&persister),
+				keys.get_peer_storage_key(),
 			)),
 			logger,
 			keys,

fuzz/src/full_stack.rs

@@ -242,6 +242,7 @@ type PeerMan<'a> = PeerManager<
 	Arc<dyn Logger>,
 	IgnoringMessageHandler,
 	Arc<KeyProvider>,
+	IgnoringMessageHandler,
 >;
 
 struct MoneyLossDetector<'a> {
@@ -626,6 +627,7 @@ pub fn do_test(mut data: &[u8], logger: &Arc<dyn Logger>) {
 		Arc::clone(&logger),
 		fee_est.clone(),
 		Arc::new(TestPersister { update_ret: Mutex::new(ChannelMonitorUpdateStatus::Completed) }),
+		keys_manager.get_peer_storage_key(),
 	));
 
 	let network = Network::Bitcoin;
@@ -659,6 +661,7 @@ pub fn do_test(mut data: &[u8], logger: &Arc<dyn Logger>) {
 		route_handler: gossip_sync.clone(),
 		onion_message_handler: IgnoringMessageHandler {},
 		custom_message_handler: IgnoringMessageHandler {},
+		send_only_message_handler: IgnoringMessageHandler {},
 	};
 	let random_data = [
 		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

lightning-background-processor/src/lib.rs

@@ -1085,7 +1085,7 @@ mod tests {
 	use lightning::routing::gossip::{NetworkGraph, P2PGossipSync};
 	use lightning::routing::router::{CandidateRouteHop, DefaultRouter, Path, RouteHop};
 	use lightning::routing::scoring::{ChannelUsage, LockableScore, ScoreLookUp, ScoreUpdate};
-	use lightning::sign::{ChangeDestinationSource, InMemorySigner, KeysManager};
+	use lightning::sign::{ChangeDestinationSource, InMemorySigner, KeysManager, NodeSigner};
 	use lightning::types::features::{ChannelFeatures, NodeFeatures};
 	use lightning::types::payment::PaymentHash;
 	use lightning::util::config::UserConfig;
@@ -1208,6 +1208,7 @@ mod tests {
 				Arc<test_utils::TestLogger>,
 				IgnoringMessageHandler,
 				Arc<KeysManager>,
+				IgnoringMessageHandler,
 			>,
 		>,
 		chain_monitor: Arc<ChainMonitor>,
@@ -1568,6 +1569,7 @@ mod tests {
 				logger.clone(),
 				fee_estimator.clone(),
 				kv_store.clone(),
+				keys_manager.get_peer_storage_key(),
 			));
 			let best_block = BestBlock::from_network(network);
 			let params = ChainParameters { network, best_block };
@@ -1621,6 +1623,7 @@ mod tests {
 				route_handler: Arc::new(test_utils::TestRoutingMessageHandler::new()),
 				onion_message_handler: messenger.clone(),
 				custom_message_handler: IgnoringMessageHandler {},
+				send_only_message_handler: IgnoringMessageHandler {},
 			};
 			let peer_manager = Arc::new(PeerManager::new(
 				msg_handler,

lightning-liquidity/tests/common/mod.rs

@@ -5,7 +5,7 @@
 #![allow(unused_macros)]
 
 use lightning::chain::Filter;
-use lightning::sign::EntropySource;
+use lightning::sign::{EntropySource, NodeSigner};
 
 use bitcoin::blockdata::constants::{genesis_block, ChainHash};
 use bitcoin::blockdata::transaction::Transaction;
@@ -130,6 +130,7 @@ pub(crate) struct Node {
 				>,
 			>,
 			Arc<KeysManager>,
+			Arc<ChainMonitor>,
 		>,
 	>,
 	pub(crate) liquidity_manager:
@@ -430,6 +431,7 @@ pub(crate) fn create_liquidity_node(
 		logger.clone(),
 		fee_estimator.clone(),
 		kv_store.clone(),
+		keys_manager.get_peer_storage_key(),
 	));
 	let best_block = BestBlock::from_network(network);
 	let chain_params = ChainParameters { network, best_block };
@@ -465,6 +467,7 @@ pub(crate) fn create_liquidity_node(
 		chan_handler: Arc::new(test_utils::TestChannelMessageHandler::new(
 			ChainHash::using_genesis_block(Network::Testnet),
 		)),
+		send_only_message_handler: chain_monitor.clone(),
 		route_handler: Arc::new(test_utils::TestRoutingMessageHandler::new()),
 		onion_message_handler: IgnoringMessageHandler {},
 		custom_message_handler: Arc::clone(&liquidity_manager),

lightning-net-tokio/src/lib.rs

@@ -832,6 +832,7 @@ mod tests {
 			route_handler: Arc::clone(&a_handler),
 			onion_message_handler: Arc::new(IgnoringMessageHandler {}),
 			custom_message_handler: Arc::new(IgnoringMessageHandler {}),
+			send_only_message_handler: Arc::new(IgnoringMessageHandler {}),
 		};
 		let a_manager = Arc::new(PeerManager::new(
 			a_msg_handler,
@@ -855,6 +856,7 @@ mod tests {
 			route_handler: Arc::clone(&b_handler),
 			onion_message_handler: Arc::new(IgnoringMessageHandler {}),
 			custom_message_handler: Arc::new(IgnoringMessageHandler {}),
+			send_only_message_handler: Arc::new(IgnoringMessageHandler {}),
 		};
 		let b_manager = Arc::new(PeerManager::new(
 			b_msg_handler,
@@ -917,6 +919,7 @@ mod tests {
 			onion_message_handler: Arc::new(IgnoringMessageHandler {}),
 			route_handler: Arc::new(lightning::ln::peer_handler::IgnoringMessageHandler {}),
 			custom_message_handler: Arc::new(IgnoringMessageHandler {}),
+			send_only_message_handler: Arc::new(IgnoringMessageHandler {}),
 		};
 		let a_manager = Arc::new(PeerManager::new(
 			a_msg_handler,

lightning/src/chain/chainmonitor.rs

@@ -32,16 +32,17 @@ use crate::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, Balance, MonitorEvent, TransactionOutputs, WithChannelMonitor};
 use crate::chain::transaction::{OutPoint, TransactionData};
 use crate::ln::types::ChannelId;
+use crate::ln::msgs::{self, BaseMessageHandler, Init, MessageSendEvent};
 use crate::sign::ecdsa::EcdsaChannelSigner;
 use crate::events::{self, Event, EventHandler, ReplayEvent};
 use crate::util::logger::{Logger, WithContext};
 use crate::util::errors::APIError;
 use crate::util::persist::MonitorName;
 use crate::util::wakers::{Future, Notifier};
 use crate::ln::channel_state::ChannelDetails;
-
 use crate::prelude::*;
 use crate::sync::{RwLock, RwLockReadGuard, Mutex, MutexGuard};
+use crate::types::features::{InitFeatures, NodeFeatures};
 use core::ops::Deref;
 use core::sync::atomic::{AtomicUsize, Ordering};
 use bitcoin::secp256k1::PublicKey;
@@ -253,6 +254,7 @@ pub struct ChainMonitor<ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F
 	/// A [`Notifier`] used to wake up the background processor in case we have any [`Event`]s for
 	/// it to give to users (or [`MonitorEvent`]s for `ChannelManager` to process).
 	event_notifier: Notifier,
+	pending_send_only_events: Mutex<Vec<MessageSendEvent>>,
 }
 
 impl<ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> ChainMonitor<ChannelSigner, C, T, F, L, P>
@@ -386,7 +388,15 @@ where C::Target: chain::Filter,
 	/// pre-filter blocks or only fetch blocks matching a compact filter. Otherwise, clients may
 	/// always need to fetch full blocks absent another means for determining which blocks contain
 	/// transactions relevant to the watched channels.
-	pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P) -> Self {
+	///
+	/// # Note
+	/// `our_peerstorage_encryption_key` must be obtained from [`crate::sign::NodeSigner::get_peer_storage_key()`].
+	/// This key is used to encrypt peer storage backups.
+	///
+	/// **Important**: This key should not be set arbitrarily or changed after initialization. The same key
+	/// is obtained by the `ChannelManager` through `KeyMananger` to decrypt peer backups.
+	/// Using an inconsistent or incorrect key will result in the inability to decrypt previously encrypted backups.
+	pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P, our_peerstorage_encryption_key: [u8; 32]) -> Self {
 		Self {
 			monitors: RwLock::new(new_hash_map()),
 			chain_source,
@@ -397,6 +407,7 @@ where C::Target: chain::Filter,
 			pending_monitor_events: Mutex::new(Vec::new()),
 			highest_chain_height: AtomicUsize::new(0),
 			event_notifier: Notifier::new(),
+			pending_send_only_events: Mutex::new(Vec::new()),
 		}
 	}
 
@@ -665,6 +676,48 @@ where C::Target: chain::Filter,
 			});
 		}
 	}
+
+	/// Retrieves all node IDs associated with the monitors.
+	///
+	/// This function collects the counterparty node IDs from all monitors into a `HashSet`,
+	/// ensuring unique IDs are returned.
+	fn get_peer_node_ids(&self) -> HashSet<PublicKey> {
+		let mon = self.monitors.read().unwrap();
+		mon
+		.values()
+		.map(|monitor| monitor.monitor.get_counterparty_node_id().clone())
+		.collect()
+	}
+
+	fn send_peer_storage(&self, their_node_id: PublicKey) {
+		// TODO: Serialize `ChannelMonitor`s inside `our_peer_storage` and update [`OurPeerStorage::block_height`] accordingly.
+	}
+}
+
+impl<ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> BaseMessageHandler for ChainMonitor<ChannelSigner, C, T, F, L, P>
+where C::Target: chain::Filter,
+		T::Target: BroadcasterInterface,
+		F::Target: FeeEstimator,
+		L::Target: Logger,
+		P::Target: Persist<ChannelSigner>,
+{
+	fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent> {
+		let mut pending_events = self.pending_send_only_events.lock().unwrap();
+		let mut ret = Vec::new();
+		core::mem::swap(&mut ret, &mut *pending_events);
+		ret	}
+
+	fn peer_disconnected(&self, _their_node_id: PublicKey) {}
+
+	fn provided_node_features(&self) -> NodeFeatures {
+		NodeFeatures::empty()
+	}
+
+	fn provided_init_features(&self, _their_node_id: PublicKey) -> InitFeatures {
+		InitFeatures::empty()
+	}
+
+	fn peer_connected(&self, _their_node_id: PublicKey, _msg: &Init, _inbound: bool) -> Result<(), ()> { Ok(()) }
 }
 
 impl<ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>