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[rust-lightning] / lightning / src / chain / chainmonitor.rs
1 // This file is Copyright its original authors, visible in version control
2 // history.
3 //
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
8 // licenses.
9
10 //! Logic to connect off-chain channel management with on-chain transaction monitoring.
11 //!
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.
15 //!
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.
19 //!
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.
25 //!
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
31
32 use bitcoin::blockdata::block::BlockHeader;
33
34 use chain;
35 use chain::Filter;
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;
42 use util::events;
43 use util::events::Event;
44
45 use std::collections::{HashMap, hash_map};
46 use std::sync::Mutex;
47 use std::ops::Deref;
48
49 /// An implementation of [`chain::Watch`] for monitoring channels.
50 ///
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
54 /// details.
55 ///
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,
63         L::Target: Logger,
64         P::Target: channelmonitor::Persist<ChannelSigner>,
65 {
66         /// The monitors
67         pub monitors: Mutex<HashMap<OutPoint, ChannelMonitor<ChannelSigner>>>,
68         chain_source: Option<C>,
69         broadcaster: T,
70         logger: L,
71         fee_estimator: F,
72         persister: P,
73 }
74
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,
79             L::Target: Logger,
80             P::Target: channelmonitor::Persist<ChannelSigner>,
81 {
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`].
86         ///
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
90         /// updated `txdata`.
91         ///
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 mut monitors = self.monitors.lock().unwrap();
97                 for monitor in monitors.values_mut() {
98                         let mut txn_outputs = monitor.block_connected(header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
99
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);
104                                         }
105                                 }
106                         }
107                 }
108         }
109
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
112         /// details.
113         ///
114         /// [`ChannelMonitor::block_disconnected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_disconnected
115         pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
116                 let mut monitors = self.monitors.lock().unwrap();
117                 for monitor in monitors.values_mut() {
118                         monitor.block_disconnected(header, disconnected_height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
119                 }
120         }
121
122         /// Creates a new `ChainMonitor` used to watch on-chain activity pertaining to channels.
123         ///
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.
129         ///
130         /// [`chain::Filter`]: ../trait.Filter.html
131         pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P) -> Self {
132                 Self {
133                         monitors: Mutex::new(HashMap::new()),
134                         chain_source,
135                         broadcaster,
136                         logger,
137                         fee_estimator: feeest,
138                         persister,
139                 }
140         }
141 }
142
143 impl<ChannelSigner: Sign, C: Deref + Sync + Send, T: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send, P: Deref + Sync + Send>
144 chain::Watch<ChannelSigner> for ChainMonitor<ChannelSigner, C, T, F, L, P>
145 where C::Target: chain::Filter,
146             T::Target: BroadcasterInterface,
147             F::Target: FeeEstimator,
148             L::Target: Logger,
149             P::Target: channelmonitor::Persist<ChannelSigner>,
150 {
151         /// Adds the monitor that watches the channel referred to by the given outpoint.
152         ///
153         /// Calls back to [`chain::Filter`] with the funding transaction and outputs to watch.
154         ///
155         /// Note that we persist the given `ChannelMonitor` while holding the `ChainMonitor`
156         /// monitors lock.
157         ///
158         /// [`chain::Filter`]: ../trait.Filter.html
159         fn watch_channel(&self, funding_outpoint: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr> {
160                 let mut monitors = self.monitors.lock().unwrap();
161                 let entry = match monitors.entry(funding_outpoint) {
162                         hash_map::Entry::Occupied(_) => {
163                                 log_error!(self.logger, "Failed to add new channel data: channel monitor for given outpoint is already present");
164                                 return Err(ChannelMonitorUpdateErr::PermanentFailure)},
165                         hash_map::Entry::Vacant(e) => e,
166                 };
167                 if let Err(e) = self.persister.persist_new_channel(funding_outpoint, &monitor) {
168                         log_error!(self.logger, "Failed to persist new channel data");
169                         return Err(e);
170                 }
171                 {
172                         let funding_txo = monitor.get_funding_txo();
173                         log_trace!(self.logger, "Got new Channel Monitor for channel {}", log_bytes!(funding_txo.0.to_channel_id()[..]));
174
175                         if let Some(ref chain_source) = self.chain_source {
176                                 chain_source.register_tx(&funding_txo.0.txid, &funding_txo.1);
177                                 for (txid, outputs) in monitor.get_outputs_to_watch().iter() {
178                                         for (idx, script_pubkey) in outputs.iter() {
179                                                 chain_source.register_output(&OutPoint { txid: *txid, index: *idx as u16 }, script_pubkey);
180                                         }
181                                 }
182                         }
183                 }
184                 entry.insert(monitor);
185                 Ok(())
186         }
187
188         /// Note that we persist the given `ChannelMonitor` update while holding the
189         /// `ChainMonitor` monitors lock.
190         fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
191                 // Update the monitor that watches the channel referred to by the given outpoint.
192                 let mut monitors = self.monitors.lock().unwrap();
193                 match monitors.get_mut(&funding_txo) {
194                         None => {
195                                 log_error!(self.logger, "Failed to update channel monitor: no such monitor registered");
196
197                                 // We should never ever trigger this from within ChannelManager. Technically a
198                                 // user could use this object with some proxying in between which makes this
199                                 // possible, but in tests and fuzzing, this should be a panic.
200                                 #[cfg(any(test, feature = "fuzztarget"))]
201                                 panic!("ChannelManager generated a channel update for a channel that was not yet registered!");
202                                 #[cfg(not(any(test, feature = "fuzztarget")))]
203                                 Err(ChannelMonitorUpdateErr::PermanentFailure)
204                         },
205                         Some(orig_monitor) => {
206                                 log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(orig_monitor));
207                                 let update_res = orig_monitor.update_monitor(&update, &self.broadcaster, &self.fee_estimator, &self.logger);
208                                 if let Err(e) = &update_res {
209                                         log_error!(self.logger, "Failed to update channel monitor: {:?}", e);
210                                 }
211                                 // Even if updating the monitor returns an error, the monitor's state will
212                                 // still be changed. So, persist the updated monitor despite the error.
213                                 let persist_res = self.persister.update_persisted_channel(funding_txo, &update, orig_monitor);
214                                 if let Err(ref e) = persist_res {
215                                         log_error!(self.logger, "Failed to persist channel monitor update: {:?}", e);
216                                 }
217                                 if update_res.is_err() {
218                                         Err(ChannelMonitorUpdateErr::PermanentFailure)
219                                 } else {
220                                         persist_res
221                                 }
222                         }
223                 }
224         }
225
226         fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
227                 let mut pending_monitor_events = Vec::new();
228                 for chan in self.monitors.lock().unwrap().values_mut() {
229                         pending_monitor_events.append(&mut chan.get_and_clear_pending_monitor_events());
230                 }
231                 pending_monitor_events
232         }
233 }
234
235 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> events::EventsProvider for ChainMonitor<ChannelSigner, C, T, F, L, P>
236         where C::Target: chain::Filter,
237               T::Target: BroadcasterInterface,
238               F::Target: FeeEstimator,
239               L::Target: Logger,
240               P::Target: channelmonitor::Persist<ChannelSigner>,
241 {
242         fn get_and_clear_pending_events(&self) -> Vec<Event> {
243                 let mut pending_events = Vec::new();
244                 for chan in self.monitors.lock().unwrap().values_mut() {
245                         pending_events.append(&mut chan.get_and_clear_pending_events());
246                 }
247                 pending_events
248         }
249 }