Move ChainMonitor to a separate module

Author: jkczyz

fuzz/src/chanmon_consistency.rs

@@ -29,6 +29,7 @@ use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hash_types::{BlockHash, WPubkeyHash};
 
 use lightning::chain;
+use lightning::chain::chainmonitor;
 use lightning::chain::channelmonitor;
 use lightning::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdateErr, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
@@ -83,7 +84,7 @@ impl Writer for VecWriter {
 
 struct TestChainMonitor {
 	pub logger: Arc<dyn Logger>,
-	pub chain_monitor: Arc<channelmonitor::ChainMonitor<EnforcingChannelKeys, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>>>,
+	pub chain_monitor: Arc<chainmonitor::ChainMonitor<EnforcingChannelKeys, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>>>,
 	pub update_ret: Mutex<Result<(), channelmonitor::ChannelMonitorUpdateErr>>,
 	// If we reload a node with an old copy of ChannelMonitors, the ChannelManager deserialization
 	// logic will automatically force-close our channels for us (as we don't have an up-to-date
@@ -96,7 +97,7 @@ struct TestChainMonitor {
 impl TestChainMonitor {
 	pub fn new(broadcaster: Arc<TestBroadcaster>, logger: Arc<dyn Logger>, feeest: Arc<FuzzEstimator>) -> Self {
 		Self {
-			chain_monitor: Arc::new(channelmonitor::ChainMonitor::new(None, broadcaster, logger.clone(), feeest)),
+			chain_monitor: Arc::new(chainmonitor::ChainMonitor::new(None, broadcaster, logger.clone(), feeest)),
 			logger,
 			update_ret: Mutex::new(Ok(())),
 			latest_monitors: Mutex::new(HashMap::new()),

fuzz/src/full_stack.rs

@@ -27,7 +27,7 @@ use bitcoin::hash_types::{Txid, BlockHash, WPubkeyHash};
 
 use lightning::chain;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
-use lightning::chain::channelmonitor;
+use lightning::chain::chainmonitor;
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::keysinterface::{InMemoryChannelKeys, KeysInterface};
 use lightning::ln::channelmanager::{ChannelManager, PaymentHash, PaymentPreimage, PaymentSecret};
@@ -145,13 +145,13 @@ impl<'a> std::hash::Hash for Peer<'a> {
 
 type ChannelMan = ChannelManager<
 	EnforcingChannelKeys,
-	Arc<channelmonitor::ChainMonitor<EnforcingChannelKeys, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>>>,
+	Arc<chainmonitor::ChainMonitor<EnforcingChannelKeys, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>>>,
 	Arc<TestBroadcaster>, Arc<KeyProvider>, Arc<FuzzEstimator>, Arc<dyn Logger>>;
 type PeerMan<'a> = PeerManager<Peer<'a>, Arc<ChannelMan>, Arc<NetGraphMsgHandler<Arc<dyn chain::Access>, Arc<dyn Logger>>>, Arc<dyn Logger>>;
 
 struct MoneyLossDetector<'a> {
 	manager: Arc<ChannelMan>,
-	monitor: Arc<channelmonitor::ChainMonitor<EnforcingChannelKeys, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>>>,
+	monitor: Arc<chainmonitor::ChainMonitor<EnforcingChannelKeys, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>>>,
 	handler: PeerMan<'a>,
 
 	peers: &'a RefCell<[bool; 256]>,
@@ -165,7 +165,7 @@ struct MoneyLossDetector<'a> {
 impl<'a> MoneyLossDetector<'a> {
 	pub fn new(peers: &'a RefCell<[bool; 256]>,
 	           manager: Arc<ChannelMan>,
-	           monitor: Arc<channelmonitor::ChainMonitor<EnforcingChannelKeys, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>>>,
+	           monitor: Arc<chainmonitor::ChainMonitor<EnforcingChannelKeys, Arc<dyn chain::Filter>, Arc<TestBroadcaster>, Arc<FuzzEstimator>, Arc<dyn Logger>>>,
 	           handler: PeerMan<'a>) -> Self {
 		MoneyLossDetector {
 			manager,
@@ -333,7 +333,7 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
 	};
 
 	let broadcast = Arc::new(TestBroadcaster{});
-	let monitor = Arc::new(channelmonitor::ChainMonitor::new(None, broadcast.clone(), Arc::clone(&logger), fee_est.clone()));
+	let monitor = Arc::new(chainmonitor::ChainMonitor::new(None, broadcast.clone(), Arc::clone(&logger), fee_est.clone()));
 
 	let keys_manager = Arc::new(KeyProvider { node_secret: our_network_key.clone(), counter: AtomicU64::new(0) });
 	let mut config = UserConfig::default();

lightning-net-tokio/src/lib.rs

@@ -36,7 +36,7 @@
 //! type Logger = dyn lightning::util::logger::Logger;
 //! type ChainAccess = dyn lightning::chain::Access;
 //! type ChainFilter = dyn lightning::chain::Filter;
-//! type ChainMonitor = lightning::chain::channelmonitor::ChainMonitor<lightning::chain::keysinterface::InMemoryChannelKeys, Arc<ChainFilter>, Arc<TxBroadcaster>, Arc<FeeEstimator>, Arc<Logger>>;
+//! type ChainMonitor = lightning::chain::chainmonitor::ChainMonitor<lightning::chain::keysinterface::InMemoryChannelKeys, Arc<ChainFilter>, Arc<TxBroadcaster>, Arc<FeeEstimator>, Arc<Logger>>;
 //! type ChannelManager = lightning::ln::channelmanager::SimpleArcChannelManager<ChainMonitor, TxBroadcaster, FeeEstimator, Logger>;
 //! type PeerManager = lightning::ln::peer_handler::SimpleArcPeerManager<lightning_net_tokio::SocketDescriptor, ChainMonitor, TxBroadcaster, FeeEstimator, ChainAccess, Logger>;
 //!

lightning/src/chain/chainmonitor.rs

@@ -0,0 +1,219 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Logic to connect off-chain channel management with on-chain transaction monitoring.
+//!
+//! [`ChainMonitor`] is a simple implementation of [`chain::Watch`] used both to process blocks and
+//! to update on-chain [`ChannelMonitor`]s accordingly. If any on-chain events need further
+//! processing, it will make those available as [`MonitorEvent`]s to be consumed.
+//!
+//! `ChainMonitor` may be used directly to monitor channels locally or as a part of a distributed
+//! setup to monitor channels remotely. In the latter case, a custom `chain::Watch` implementation
+//! would be responsible for routing each update to a remote server and for retrieving monitor
+//! events. The remote server would make use of `ChainMonitor` for block processing and for
+//! servicing `ChannelMonitor` updates from the client.
+//!
+//! [`ChainMonitor`]: struct.ChainMonitor.html
+//! [`chain::Watch`]: ../trait.Watch.html
+//! [`ChannelMonitor`]: ../channelmonitor/struct.ChannelMonitor.html
+//! [`MonitorEvent`]: ../channelmonitor/enum.MonitorEvent.html
+
+use bitcoin::blockdata::block::BlockHeader;
+
+use chain;
+use chain::Filter;
+use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
+use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent, MonitorUpdateError};
+use chain::transaction::{OutPoint, TransactionData};
+use chain::keysinterface::ChannelKeys;
+use util::logger::Logger;
+use util::events;
+use util::events::Event;
+
+use std::collections::{HashMap, hash_map};
+use std::sync::Mutex;
+use std::ops::Deref;
+
+/// An implementation of [`chain::Watch`] for monitoring channels.
+///
+/// Connected and disconnected blocks must be provided to `ChainMonitor` as documented by
+/// [`chain::Watch`]. May be used in conjunction with [`ChannelManager`] to monitor channels locally
+/// or used independently to monitor channels remotely.
+///
+/// [`chain::Watch`]: ../trait.Watch.html
+/// [`ChannelManager`]: ../../ln/channelmanager/struct.ChannelManager.html
+pub struct ChainMonitor<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref>
+	where C::Target: chain::Filter,
+        T::Target: BroadcasterInterface,
+        F::Target: FeeEstimator,
+        L::Target: Logger,
+{
+	/// The monitors
+	pub monitors: Mutex<HashMap<OutPoint, ChannelMonitor<ChanSigner>>>,
+	chain_source: Option<C>,
+	broadcaster: T,
+	logger: L,
+	fee_estimator: F
+}
+
+impl<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref> ChainMonitor<ChanSigner, C, T, F, L>
+	where C::Target: chain::Filter,
+	      T::Target: BroadcasterInterface,
+	      F::Target: FeeEstimator,
+	      L::Target: Logger,
+{
+	/// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
+	/// of a channel and reacting accordingly based on transactions in the connected block. See
+	/// [`ChannelMonitor::block_connected`] for details. Any HTLCs that were resolved on chain will
+	/// be returned by [`chain::Watch::release_pending_monitor_events`].
+	///
+	/// Calls back to [`chain::Filter`] if any monitor indicated new outputs to watch, returning
+	/// `true` if so. In this case, if providing pre-filtered blocks, the caller should re-fetch the
+	/// block to obtain updated `txdata` and recall `block_connected`.
+	///
+	/// [`ChannelMonitor::block_connected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_connected
+	/// [`chain::Watch::release_pending_monitor_events`]: ../trait.Watch.html#tymethod.release_pending_monitor_events
+	/// [`chain::Filter`]: ../trait.Filter.html
+	pub fn block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) -> bool {
+		let mut has_new_outputs_to_watch = false;
+		{
+			let mut monitors = self.monitors.lock().unwrap();
+			for monitor in monitors.values_mut() {
+				let mut txn_outputs = monitor.block_connected(header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
+				has_new_outputs_to_watch |= !txn_outputs.is_empty();
+
+				if let Some(ref chain_source) = self.chain_source {
+					for (txid, outputs) in txn_outputs.drain(..) {
+						for (idx, output) in outputs.iter().enumerate() {
+							chain_source.register_output(&OutPoint { txid, index: idx as u16 }, &output.script_pubkey);
+						}
+					}
+				}
+			}
+		}
+		has_new_outputs_to_watch
+	}
+
+	/// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
+	/// of a channel based on the disconnected block. See [`ChannelMonitor::block_disconnected`] for
+	/// details.
+	///
+	/// [`ChannelMonitor::block_disconnected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_disconnected
+	pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
+		let mut monitors = self.monitors.lock().unwrap();
+		for monitor in monitors.values_mut() {
+			monitor.block_disconnected(header, disconnected_height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
+		}
+	}
+
+	/// Creates a new `ChainMonitor` used to watch on-chain activity pertaining to channels.
+	///
+	/// When an optional chain source implementing [`chain::Filter`] is provided, the chain monitor
+	/// will call back to it indicating transactions and outputs of interest. This allows clients to
+	/// 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.
+	///
+	/// [`chain::Filter`]: ../trait.Filter.html
+	pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F) -> Self {
+		Self {
+			monitors: Mutex::new(HashMap::new()),
+			chain_source,
+			broadcaster,
+			logger,
+			fee_estimator: feeest,
+		}
+	}
+
+	/// Adds or updates the monitor which monitors the channel referred to by the given outpoint.
+	///
+	/// Calls back to [`chain::Filter`] with the funding transaction and outputs to watch.
+	///
+	/// [`chain::Filter`]: ../trait.Filter.html
+	fn add_monitor(&self, outpoint: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), MonitorUpdateError> {
+		let mut monitors = self.monitors.lock().unwrap();
+		let entry = match monitors.entry(outpoint) {
+			hash_map::Entry::Occupied(_) => return Err(MonitorUpdateError("Channel monitor for given outpoint is already present")),
+			hash_map::Entry::Vacant(e) => e,
+		};
+		{
+			let funding_txo = monitor.get_funding_txo();
+			log_trace!(self.logger, "Got new Channel Monitor for channel {}", log_bytes!(funding_txo.0.to_channel_id()[..]));
+
+			if let Some(ref chain_source) = self.chain_source {
+				chain_source.register_tx(&funding_txo.0.txid, &funding_txo.1);
+				for (txid, outputs) in monitor.get_outputs_to_watch().iter() {
+					for (idx, script_pubkey) in outputs.iter().enumerate() {
+						chain_source.register_output(&OutPoint { txid: *txid, index: idx as u16 }, &script_pubkey);
+					}
+				}
+			}
+		}
+		entry.insert(monitor);
+		Ok(())
+	}
+
+	/// Updates the monitor which monitors the channel referred to by the given outpoint.
+	fn update_monitor(&self, outpoint: OutPoint, update: ChannelMonitorUpdate) -> Result<(), MonitorUpdateError> {
+		let mut monitors = self.monitors.lock().unwrap();
+		match monitors.get_mut(&outpoint) {
+			Some(orig_monitor) => {
+				log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(orig_monitor));
+				orig_monitor.update_monitor(update, &self.broadcaster, &self.logger)
+			},
+			None => Err(MonitorUpdateError("No such monitor registered"))
+		}
+	}
+}
+
+impl<ChanSigner: ChannelKeys, C: Deref + Sync + Send, T: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send> chain::Watch for ChainMonitor<ChanSigner, C, T, F, L>
+	where C::Target: chain::Filter,
+	      T::Target: BroadcasterInterface,
+	      F::Target: FeeEstimator,
+	      L::Target: Logger,
+{
+	type Keys = ChanSigner;
+
+	fn watch_channel(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), ChannelMonitorUpdateErr> {
+		match self.add_monitor(funding_txo, monitor) {
+			Ok(_) => Ok(()),
+			Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
+		}
+	}
+
+	fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
+		match self.update_monitor(funding_txo, update) {
+			Ok(_) => Ok(()),
+			Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
+		}
+	}
+
+	fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
+		let mut pending_monitor_events = Vec::new();
+		for chan in self.monitors.lock().unwrap().values_mut() {
+			pending_monitor_events.append(&mut chan.get_and_clear_pending_monitor_events());
+		}
+		pending_monitor_events
+	}
+}
+
+impl<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref> events::EventsProvider for ChainMonitor<ChanSigner, C, T, F, L>
+	where C::Target: chain::Filter,
+	      T::Target: BroadcasterInterface,
+	      F::Target: FeeEstimator,
+	      L::Target: Logger,
+{
+	fn get_and_clear_pending_events(&self) -> Vec<Event> {
+		let mut pending_events = Vec::new();
+		for chan in self.monitors.lock().unwrap().values_mut() {
+			pending_events.append(&mut chan.get_and_clear_pending_events());
+		}
+		pending_events
+	}
+}