1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 //! Logic to connect off-chain channel management with on-chain transaction monitoring.
12 //! [`ChainMonitor`] is an implementation of [`chain::Watch`] used both to process blocks and to
13 //! update [`ChannelMonitor`]s accordingly. If any on-chain events need further processing, it will
14 //! make those available as [`MonitorEvent`]s to be consumed.
16 //! `ChainMonitor` is parameterized by an optional chain source, which must implement the
17 //! [`chain::Filter`] trait. This provides a mechanism to signal new relevant outputs back to light
18 //! clients, such that transactions spending those outputs are included in block data.
20 //! `ChainMonitor` may be used directly to monitor channels locally or as a part of a distributed
21 //! setup to monitor channels remotely. In the latter case, a custom `chain::Watch` implementation
22 //! would be responsible for routing each update to a remote server and for retrieving monitor
23 //! events. The remote server would make use of `ChainMonitor` for block processing and for
24 //! servicing `ChannelMonitor` updates from the client.
26 //! [`ChainMonitor`]: struct.ChainMonitor.html
27 //! [`chain::Filter`]: ../trait.Filter.html
28 //! [`chain::Watch`]: ../trait.Watch.html
29 //! [`ChannelMonitor`]: ../channelmonitor/struct.ChannelMonitor.html
30 //! [`MonitorEvent`]: ../channelmonitor/enum.MonitorEvent.html
32 use bitcoin::blockdata::block::{Block, BlockHeader};
36 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
37 use chain::channelmonitor;
38 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent, Persist};
39 use chain::transaction::{OutPoint, TransactionData};
40 use chain::keysinterface::Sign;
41 use util::logger::Logger;
43 use util::events::Event;
45 use std::collections::{HashMap, hash_map};
46 use std::sync::RwLock;
49 /// An implementation of [`chain::Watch`] for monitoring channels.
51 /// Connected and disconnected blocks must be provided to `ChainMonitor` as documented by
52 /// [`chain::Watch`]. May be used in conjunction with [`ChannelManager`] to monitor channels locally
53 /// or used independently to monitor channels remotely. See the [module-level documentation] for
56 /// [`chain::Watch`]: ../trait.Watch.html
57 /// [`ChannelManager`]: ../../ln/channelmanager/struct.ChannelManager.html
58 /// [module-level documentation]: index.html
59 pub struct ChainMonitor<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
60 where C::Target: chain::Filter,
61 T::Target: BroadcasterInterface,
62 F::Target: FeeEstimator,
64 P::Target: channelmonitor::Persist<ChannelSigner>,
67 pub monitors: RwLock<HashMap<OutPoint, ChannelMonitor<ChannelSigner>>>,
68 chain_source: Option<C>,
75 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> ChainMonitor<ChannelSigner, C, T, F, L, P>
76 where C::Target: chain::Filter,
77 T::Target: BroadcasterInterface,
78 F::Target: FeeEstimator,
80 P::Target: channelmonitor::Persist<ChannelSigner>,
82 /// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
83 /// of a channel and reacting accordingly based on transactions in the connected block. See
84 /// [`ChannelMonitor::block_connected`] for details. Any HTLCs that were resolved on chain will
85 /// be returned by [`chain::Watch::release_pending_monitor_events`].
87 /// Calls back to [`chain::Filter`] if any monitor indicated new outputs to watch. Subsequent
88 /// calls must not exclude any transactions matching the new outputs nor any in-block
89 /// descendants of such transactions. It is not necessary to re-fetch the block to obtain
92 /// [`ChannelMonitor::block_connected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_connected
93 /// [`chain::Watch::release_pending_monitor_events`]: ../trait.Watch.html#tymethod.release_pending_monitor_events
94 /// [`chain::Filter`]: ../trait.Filter.html
95 pub fn block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) {
96 let monitors = self.monitors.read().unwrap();
97 for monitor in monitors.values() {
98 let mut txn_outputs = monitor.block_connected(header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
100 if let Some(ref chain_source) = self.chain_source {
101 for (txid, outputs) in txn_outputs.drain(..) {
102 for (idx, output) in outputs.iter() {
103 chain_source.register_output(&OutPoint { txid, index: *idx as u16 }, &output.script_pubkey);
110 /// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
111 /// of a channel based on the disconnected block. See [`ChannelMonitor::block_disconnected`] for
114 /// [`ChannelMonitor::block_disconnected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_disconnected
115 pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
116 let monitors = self.monitors.read().unwrap();
117 for monitor in monitors.values() {
118 monitor.block_disconnected(header, disconnected_height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
122 /// Creates a new `ChainMonitor` used to watch on-chain activity pertaining to channels.
124 /// When an optional chain source implementing [`chain::Filter`] is provided, the chain monitor
125 /// will call back to it indicating transactions and outputs of interest. This allows clients to
126 /// pre-filter blocks or only fetch blocks matching a compact filter. Otherwise, clients may
127 /// always need to fetch full blocks absent another means for determining which blocks contain
128 /// transactions relevant to the watched channels.
130 /// [`chain::Filter`]: ../trait.Filter.html
131 pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P) -> Self {
133 monitors: RwLock::new(HashMap::new()),
137 fee_estimator: feeest,
143 impl<ChannelSigner: Sign, C: Deref + Send + Sync, T: Deref + Send + Sync, F: Deref + Send + Sync, L: Deref + Send + Sync, P: Deref + Send + Sync>
144 chain::Listen for ChainMonitor<ChannelSigner, C, T, F, L, P>
147 C::Target: chain::Filter,
148 T::Target: BroadcasterInterface,
149 F::Target: FeeEstimator,
151 P::Target: channelmonitor::Persist<ChannelSigner>,
153 fn block_connected(&self, block: &Block, height: u32) {
154 let txdata: Vec<_> = block.txdata.iter().enumerate().collect();
155 ChainMonitor::block_connected(self, &block.header, &txdata, height);
158 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
159 ChainMonitor::block_disconnected(self, header, height);
163 impl<ChannelSigner: Sign, C: Deref + Sync + Send, T: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send, P: Deref + Sync + Send>
164 chain::Watch<ChannelSigner> for ChainMonitor<ChannelSigner, C, T, F, L, P>
165 where C::Target: chain::Filter,
166 T::Target: BroadcasterInterface,
167 F::Target: FeeEstimator,
169 P::Target: channelmonitor::Persist<ChannelSigner>,
171 /// Adds the monitor that watches the channel referred to by the given outpoint.
173 /// Calls back to [`chain::Filter`] with the funding transaction and outputs to watch.
175 /// Note that we persist the given `ChannelMonitor` while holding the `ChainMonitor`
178 /// [`chain::Filter`]: ../trait.Filter.html
179 fn watch_channel(&self, funding_outpoint: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr> {
180 let mut monitors = self.monitors.write().unwrap();
181 let entry = match monitors.entry(funding_outpoint) {
182 hash_map::Entry::Occupied(_) => {
183 log_error!(self.logger, "Failed to add new channel data: channel monitor for given outpoint is already present");
184 return Err(ChannelMonitorUpdateErr::PermanentFailure)},
185 hash_map::Entry::Vacant(e) => e,
187 if let Err(e) = self.persister.persist_new_channel(funding_outpoint, &monitor) {
188 log_error!(self.logger, "Failed to persist new channel data");
192 let funding_txo = monitor.get_funding_txo();
193 log_trace!(self.logger, "Got new Channel Monitor for channel {}", log_bytes!(funding_txo.0.to_channel_id()[..]));
195 if let Some(ref chain_source) = self.chain_source {
196 chain_source.register_tx(&funding_txo.0.txid, &funding_txo.1);
197 for (txid, outputs) in monitor.get_outputs_to_watch().iter() {
198 for (idx, script_pubkey) in outputs.iter() {
199 chain_source.register_output(&OutPoint { txid: *txid, index: *idx as u16 }, script_pubkey);
204 entry.insert(monitor);
208 /// Note that we persist the given `ChannelMonitor` update while holding the
209 /// `ChainMonitor` monitors lock.
210 fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
211 // Update the monitor that watches the channel referred to by the given outpoint.
212 let monitors = self.monitors.read().unwrap();
213 match monitors.get(&funding_txo) {
215 log_error!(self.logger, "Failed to update channel monitor: no such monitor registered");
217 // We should never ever trigger this from within ChannelManager. Technically a
218 // user could use this object with some proxying in between which makes this
219 // possible, but in tests and fuzzing, this should be a panic.
220 #[cfg(any(test, feature = "fuzztarget"))]
221 panic!("ChannelManager generated a channel update for a channel that was not yet registered!");
222 #[cfg(not(any(test, feature = "fuzztarget")))]
223 Err(ChannelMonitorUpdateErr::PermanentFailure)
226 log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(monitor));
227 let update_res = monitor.update_monitor(&update, &self.broadcaster, &self.fee_estimator, &self.logger);
228 if let Err(e) = &update_res {
229 log_error!(self.logger, "Failed to update channel monitor: {:?}", e);
231 // Even if updating the monitor returns an error, the monitor's state will
232 // still be changed. So, persist the updated monitor despite the error.
233 let persist_res = self.persister.update_persisted_channel(funding_txo, &update, monitor);
234 if let Err(ref e) = persist_res {
235 log_error!(self.logger, "Failed to persist channel monitor update: {:?}", e);
237 if update_res.is_err() {
238 Err(ChannelMonitorUpdateErr::PermanentFailure)
246 fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
247 let mut pending_monitor_events = Vec::new();
248 for monitor in self.monitors.read().unwrap().values() {
249 pending_monitor_events.append(&mut monitor.get_and_clear_pending_monitor_events());
251 pending_monitor_events
255 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> events::EventsProvider for ChainMonitor<ChannelSigner, C, T, F, L, P>
256 where C::Target: chain::Filter,
257 T::Target: BroadcasterInterface,
258 F::Target: FeeEstimator,
260 P::Target: channelmonitor::Persist<ChannelSigner>,
262 fn get_and_clear_pending_events(&self) -> Vec<Event> {
263 let mut pending_events = Vec::new();
264 for monitor in self.monitors.read().unwrap().values() {
265 pending_events.append(&mut monitor.get_and_clear_pending_events());