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::BlockHeader;
36 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
37 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent, MonitorUpdateError};
38 use chain::transaction::{OutPoint, TransactionData};
39 use chain::keysinterface::ChannelKeys;
40 use util::logger::Logger;
42 use util::events::Event;
44 use std::collections::{HashMap, hash_map};
48 /// An implementation of [`chain::Watch`] for monitoring channels.
50 /// Connected and disconnected blocks must be provided to `ChainMonitor` as documented by
51 /// [`chain::Watch`]. May be used in conjunction with [`ChannelManager`] to monitor channels locally
52 /// or used independently to monitor channels remotely. See the [module-level documentation] for
55 /// [`chain::Watch`]: ../trait.Watch.html
56 /// [`ChannelManager`]: ../../ln/channelmanager/struct.ChannelManager.html
57 /// [module-level documentation]: index.html
58 pub struct ChainMonitor<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref>
59 where C::Target: chain::Filter,
60 T::Target: BroadcasterInterface,
61 F::Target: FeeEstimator,
65 pub monitors: Mutex<HashMap<OutPoint, ChannelMonitor<ChanSigner>>>,
66 chain_source: Option<C>,
72 impl<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref> ChainMonitor<ChanSigner, C, T, F, L>
73 where C::Target: chain::Filter,
74 T::Target: BroadcasterInterface,
75 F::Target: FeeEstimator,
78 /// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
79 /// of a channel and reacting accordingly based on transactions in the connected block. See
80 /// [`ChannelMonitor::block_connected`] for details. Any HTLCs that were resolved on chain will
81 /// be returned by [`chain::Watch::release_pending_monitor_events`].
83 /// Calls back to [`chain::Filter`] if any monitor indicated new outputs to watch, returning
84 /// `true` if so. Subsequent calls must not exclude any transactions matching the new outputs
85 /// nor any in-block descendants of such transactions. It is not necessary to re-fetch the block
86 /// to obtain updated `txdata`.
88 /// [`ChannelMonitor::block_connected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_connected
89 /// [`chain::Watch::release_pending_monitor_events`]: ../trait.Watch.html#tymethod.release_pending_monitor_events
90 /// [`chain::Filter`]: ../trait.Filter.html
91 pub fn block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) -> bool {
92 let mut has_new_outputs_to_watch = false;
94 let mut monitors = self.monitors.lock().unwrap();
95 for monitor in monitors.values_mut() {
96 let mut txn_outputs = monitor.block_connected(header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
97 has_new_outputs_to_watch |= !txn_outputs.is_empty();
99 if let Some(ref chain_source) = self.chain_source {
100 for (txid, outputs) in txn_outputs.drain(..) {
101 for (idx, output) in outputs.iter().enumerate() {
102 chain_source.register_output(&OutPoint { txid, index: idx as u16 }, &output.script_pubkey);
108 has_new_outputs_to_watch
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) -> Self {
134 monitors: Mutex::new(HashMap::new()),
138 fee_estimator: feeest,
142 /// Adds the monitor that watches the channel referred to by the given outpoint.
144 /// Calls back to [`chain::Filter`] with the funding transaction and outputs to watch.
146 /// [`chain::Filter`]: ../trait.Filter.html
147 fn add_monitor(&self, outpoint: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), MonitorUpdateError> {
148 let mut monitors = self.monitors.lock().unwrap();
149 let entry = match monitors.entry(outpoint) {
150 hash_map::Entry::Occupied(_) => return Err(MonitorUpdateError("Channel monitor for given outpoint is already present")),
151 hash_map::Entry::Vacant(e) => e,
154 let funding_txo = monitor.get_funding_txo();
155 log_trace!(self.logger, "Got new Channel Monitor for channel {}", log_bytes!(funding_txo.0.to_channel_id()[..]));
157 if let Some(ref chain_source) = self.chain_source {
158 chain_source.register_tx(&funding_txo.0.txid, &funding_txo.1);
159 for (txid, outputs) in monitor.get_outputs_to_watch().iter() {
160 for (idx, script_pubkey) in outputs.iter().enumerate() {
161 chain_source.register_output(&OutPoint { txid: *txid, index: idx as u16 }, &script_pubkey);
166 entry.insert(monitor);
170 /// Updates the monitor that watches the channel referred to by the given outpoint.
171 fn update_monitor(&self, outpoint: OutPoint, update: ChannelMonitorUpdate) -> Result<(), MonitorUpdateError> {
172 let mut monitors = self.monitors.lock().unwrap();
173 match monitors.get_mut(&outpoint) {
174 Some(orig_monitor) => {
175 log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(orig_monitor));
176 orig_monitor.update_monitor(update, &self.broadcaster, &self.logger)
178 None => Err(MonitorUpdateError("No such monitor registered"))
183 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>
184 where C::Target: chain::Filter,
185 T::Target: BroadcasterInterface,
186 F::Target: FeeEstimator,
189 type Keys = ChanSigner;
191 fn watch_channel(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), ChannelMonitorUpdateErr> {
192 match self.add_monitor(funding_txo, monitor) {
194 Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
198 fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
199 match self.update_monitor(funding_txo, update) {
201 Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
205 fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
206 let mut pending_monitor_events = Vec::new();
207 for chan in self.monitors.lock().unwrap().values_mut() {
208 pending_monitor_events.append(&mut chan.get_and_clear_pending_monitor_events());
210 pending_monitor_events
214 impl<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref> events::EventsProvider for ChainMonitor<ChanSigner, C, T, F, L>
215 where C::Target: chain::Filter,
216 T::Target: BroadcasterInterface,
217 F::Target: FeeEstimator,
220 fn get_and_clear_pending_events(&self) -> Vec<Event> {
221 let mut pending_events = Vec::new();
222 for chan in self.monitors.lock().unwrap().values_mut() {
223 pending_events.append(&mut chan.get_and_clear_pending_events());