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};
35 use chain::ChainListener;
37 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
38 use chain::channelmonitor;
39 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent, Persist};
40 use chain::transaction::{OutPoint, TransactionData};
41 use chain::keysinterface::Sign;
42 use util::logger::Logger;
44 use util::events::Event;
46 use std::collections::{HashMap, hash_map};
50 /// An implementation of [`chain::Watch`] for monitoring channels.
52 /// Connected and disconnected blocks must be provided to `ChainMonitor` as documented by
53 /// [`chain::Watch`]. May be used in conjunction with [`ChannelManager`] to monitor channels locally
54 /// or used independently to monitor channels remotely. See the [module-level documentation] for
57 /// [`chain::Watch`]: ../trait.Watch.html
58 /// [`ChannelManager`]: ../../ln/channelmanager/struct.ChannelManager.html
59 /// [module-level documentation]: index.html
60 pub struct ChainMonitor<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
61 where C::Target: chain::Filter,
62 T::Target: BroadcasterInterface,
63 F::Target: FeeEstimator,
65 P::Target: channelmonitor::Persist<ChannelSigner>,
68 pub monitors: Mutex<HashMap<OutPoint, ChannelMonitor<ChannelSigner>>>,
69 chain_source: Option<C>,
76 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> ChainMonitor<ChannelSigner, C, T, F, L, P>
77 where C::Target: chain::Filter,
78 T::Target: BroadcasterInterface,
79 F::Target: FeeEstimator,
81 P::Target: channelmonitor::Persist<ChannelSigner>,
83 /// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
84 /// of a channel and reacting accordingly based on transactions in the connected block. See
85 /// [`ChannelMonitor::block_connected`] for details. Any HTLCs that were resolved on chain will
86 /// be returned by [`chain::Watch::release_pending_monitor_events`].
88 /// Calls back to [`chain::Filter`] if any monitor indicated new outputs to watch. Subsequent
89 /// calls must not exclude any transactions matching the new outputs nor any in-block
90 /// descendants of such transactions. It is not necessary to re-fetch the block to obtain
93 /// [`ChannelMonitor::block_connected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_connected
94 /// [`chain::Watch::release_pending_monitor_events`]: ../trait.Watch.html#tymethod.release_pending_monitor_events
95 /// [`chain::Filter`]: ../trait.Filter.html
96 pub fn block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) {
97 let mut monitors = self.monitors.lock().unwrap();
98 for monitor in monitors.values_mut() {
99 let mut txn_outputs = monitor.block_connected(header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
101 if let Some(ref chain_source) = self.chain_source {
102 for (txid, outputs) in txn_outputs.drain(..) {
103 for (idx, output) in outputs.iter() {
104 chain_source.register_output(&OutPoint { txid, index: *idx as u16 }, &output.script_pubkey);
111 /// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
112 /// of a channel based on the disconnected block. See [`ChannelMonitor::block_disconnected`] for
115 /// [`ChannelMonitor::block_disconnected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_disconnected
116 pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
117 let mut monitors = self.monitors.lock().unwrap();
118 for monitor in monitors.values_mut() {
119 monitor.block_disconnected(header, disconnected_height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
123 /// Creates a new `ChainMonitor` used to watch on-chain activity pertaining to channels.
125 /// When an optional chain source implementing [`chain::Filter`] is provided, the chain monitor
126 /// will call back to it indicating transactions and outputs of interest. This allows clients to
127 /// pre-filter blocks or only fetch blocks matching a compact filter. Otherwise, clients may
128 /// always need to fetch full blocks absent another means for determining which blocks contain
129 /// transactions relevant to the watched channels.
131 /// [`chain::Filter`]: ../trait.Filter.html
132 pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P) -> Self {
134 monitors: Mutex::new(HashMap::new()),
138 fee_estimator: feeest,
144 impl<ChannelSigner: Sign, C: Deref + Send + Sync, T: Deref + Send + Sync, F: Deref + Send + Sync, L: Deref + Send + Sync, P: Deref + Send + Sync>
145 ChainListener for ChainMonitor<ChannelSigner, C, T, F, L, P>
148 C::Target: chain::Filter,
149 T::Target: BroadcasterInterface,
150 F::Target: FeeEstimator,
152 P::Target: channelmonitor::Persist<ChannelSigner>,
154 fn block_connected(&self, block: &Block, height: u32) {
155 let txdata: Vec<_> = block.txdata.iter().enumerate().collect();
156 ChainMonitor::block_connected(self, &block.header, &txdata, height);
159 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
160 ChainMonitor::block_disconnected(self, header, height);
164 impl<ChannelSigner: Sign, C: Deref + Sync + Send, T: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send, P: Deref + Sync + Send>
165 chain::Watch<ChannelSigner> for ChainMonitor<ChannelSigner, C, T, F, L, P>
166 where C::Target: chain::Filter,
167 T::Target: BroadcasterInterface,
168 F::Target: FeeEstimator,
170 P::Target: channelmonitor::Persist<ChannelSigner>,
172 /// Adds the monitor that watches the channel referred to by the given outpoint.
174 /// Calls back to [`chain::Filter`] with the funding transaction and outputs to watch.
176 /// Note that we persist the given `ChannelMonitor` while holding the `ChainMonitor`
179 /// [`chain::Filter`]: ../trait.Filter.html
180 fn watch_channel(&self, funding_outpoint: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr> {
181 let mut monitors = self.monitors.lock().unwrap();
182 let entry = match monitors.entry(funding_outpoint) {
183 hash_map::Entry::Occupied(_) => {
184 log_error!(self.logger, "Failed to add new channel data: channel monitor for given outpoint is already present");
185 return Err(ChannelMonitorUpdateErr::PermanentFailure)},
186 hash_map::Entry::Vacant(e) => e,
188 if let Err(e) = self.persister.persist_new_channel(funding_outpoint, &monitor) {
189 log_error!(self.logger, "Failed to persist new channel data");
193 let funding_txo = monitor.get_funding_txo();
194 log_trace!(self.logger, "Got new Channel Monitor for channel {}", log_bytes!(funding_txo.0.to_channel_id()[..]));
196 if let Some(ref chain_source) = self.chain_source {
197 chain_source.register_tx(&funding_txo.0.txid, &funding_txo.1);
198 for (txid, outputs) in monitor.get_outputs_to_watch().iter() {
199 for (idx, script_pubkey) in outputs.iter() {
200 chain_source.register_output(&OutPoint { txid: *txid, index: *idx as u16 }, script_pubkey);
205 entry.insert(monitor);
209 /// Note that we persist the given `ChannelMonitor` update while holding the
210 /// `ChainMonitor` monitors lock.
211 fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
212 // Update the monitor that watches the channel referred to by the given outpoint.
213 let mut monitors = self.monitors.lock().unwrap();
214 match monitors.get_mut(&funding_txo) {
216 log_error!(self.logger, "Failed to update channel monitor: no such monitor registered");
218 // We should never ever trigger this from within ChannelManager. Technically a
219 // user could use this object with some proxying in between which makes this
220 // possible, but in tests and fuzzing, this should be a panic.
221 #[cfg(any(test, feature = "fuzztarget"))]
222 panic!("ChannelManager generated a channel update for a channel that was not yet registered!");
223 #[cfg(not(any(test, feature = "fuzztarget")))]
224 Err(ChannelMonitorUpdateErr::PermanentFailure)
226 Some(orig_monitor) => {
227 log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(orig_monitor));
228 let update_res = orig_monitor.update_monitor(&update, &self.broadcaster, &self.fee_estimator, &self.logger);
229 if let Err(e) = &update_res {
230 log_error!(self.logger, "Failed to update channel monitor: {:?}", e);
232 // Even if updating the monitor returns an error, the monitor's state will
233 // still be changed. So, persist the updated monitor despite the error.
234 let persist_res = self.persister.update_persisted_channel(funding_txo, &update, orig_monitor);
235 if let Err(ref e) = persist_res {
236 log_error!(self.logger, "Failed to persist channel monitor update: {:?}", e);
238 if update_res.is_err() {
239 Err(ChannelMonitorUpdateErr::PermanentFailure)
247 fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
248 let mut pending_monitor_events = Vec::new();
249 for chan in self.monitors.lock().unwrap().values_mut() {
250 pending_monitor_events.append(&mut chan.get_and_clear_pending_monitor_events());
252 pending_monitor_events
256 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> events::EventsProvider for ChainMonitor<ChannelSigner, C, T, F, L, P>
257 where C::Target: chain::Filter,
258 T::Target: BroadcasterInterface,
259 F::Target: FeeEstimator,
261 P::Target: channelmonitor::Persist<ChannelSigner>,
263 fn get_and_clear_pending_events(&self) -> Vec<Event> {
264 let mut pending_events = Vec::new();
265 for chan in self.monitors.lock().unwrap().values_mut() {
266 pending_events.append(&mut chan.get_and_clear_pending_events());