1 //! Traits and utility impls which allow other parts of rust-lightning to interact with the
4 //! Includes traits for monitoring and receiving notifications of new blocks and block
5 //! disconnections, transaction broadcasting, and feerate information requests.
7 use bitcoin::blockdata::block::{Block, BlockHeader};
8 use bitcoin::blockdata::transaction::Transaction;
9 use bitcoin::blockdata::script::Script;
10 use bitcoin::blockdata::constants::genesis_block;
11 use bitcoin::util::hash::BitcoinHash;
12 use bitcoin_hashes::sha256d::Hash as Sha256dHash;
13 use bitcoin::network::constants::Network;
15 use util::logger::Logger;
17 use std::sync::{Mutex, MutexGuard, Arc};
18 use std::sync::atomic::{AtomicUsize, Ordering};
19 use std::collections::HashSet;
21 use std::marker::PhantomData;
24 /// Used to give chain error details upstream
26 /// Client doesn't support UTXO lookup (but the chain hash matches our genesis block hash)
28 /// Chain isn't the one watched
30 /// Tx doesn't exist or is unconfirmed
34 /// An interface to request notification of certain scripts as they appear the
37 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
38 /// called from inside the library in response to ChainListener events, P2P events, or timer
40 pub trait ChainWatchInterface: Sync + Send {
41 /// Provides a txid/random-scriptPubKey-in-the-tx which much be watched for.
42 fn install_watch_tx(&self, txid: &Sha256dHash, script_pub_key: &Script);
44 /// Provides an outpoint which must be watched for, providing any transactions which spend the
46 fn install_watch_outpoint(&self, outpoint: (Sha256dHash, u32), out_script: &Script);
48 /// Indicates that a listener needs to see all transactions.
49 fn watch_all_txn(&self);
51 /// Gets the script and value in satoshis for a given unspent transaction output given a
52 /// short_channel_id (aka unspent_tx_output_identier). For BTC/tBTC channels the top three
53 /// bytes are the block height, the next 3 the transaction index within the block, and the
54 /// final two the output within the transaction.
55 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError>;
57 /// Gets the list of transactions and transaction indices that the ChainWatchInterface is
59 fn filter_block<'a>(&self, block: &'a Block) -> (Vec<&'a Transaction>, Vec<u32>);
61 /// Returns a usize that changes when the ChainWatchInterface's watched data is modified.
62 /// Users of `filter_block` should pre-save a copy of `reentered`'s return value and use it to
63 /// determine whether they need to re-filter a given block.
64 fn reentered(&self) -> usize;
67 /// An interface to send a transaction to the Bitcoin network.
68 pub trait BroadcasterInterface: Sync + Send {
69 /// Sends a transaction out to (hopefully) be mined.
70 fn broadcast_transaction(&self, tx: &Transaction);
73 /// A trait indicating a desire to listen for events from the chain
74 pub trait ChainListener: Sync + Send {
75 /// Notifies a listener that a block was connected.
77 /// The txn_matched array should be set to references to transactions which matched the
78 /// relevant installed watch outpoints/txn, or the full set of transactions in the block.
80 /// Note that if txn_matched includes only matched transactions, and a new
81 /// transaction/outpoint is watched during a block_connected call, the block *must* be
82 /// re-scanned with the new transaction/outpoints and block_connected should be called
83 /// again with the same header and (at least) the new transactions.
85 /// Note that if non-new transaction/outpoints are be registered during a call, a second call
86 /// *must not* happen.
88 /// This also means those counting confirmations using block_connected callbacks should watch
89 /// for duplicate headers and not count them towards confirmations!
90 fn block_connected(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]);
91 /// Notifies a listener that a block was disconnected.
92 /// Unlike block_connected, this *must* never be called twice for the same disconnect event.
93 /// Height must be the one of the block which was disconnected (not new height of the best chain)
94 fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32);
97 /// An enum that represents the speed at which we want a transaction to confirm used for feerate
99 pub enum ConfirmationTarget {
100 /// We are happy with this transaction confirming slowly when feerate drops some.
102 /// We'd like this transaction to confirm without major delay, but 12-18 blocks is fine.
104 /// We'd like this transaction to confirm in the next few blocks.
108 /// A trait which should be implemented to provide feerate information on a number of time
111 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
112 /// called from inside the library in response to ChainListener events, P2P events, or timer
114 pub trait FeeEstimator: Sync + Send {
115 /// Gets estimated satoshis of fee required per 1000 Weight-Units.
117 /// Must be no smaller than 253 (ie 1 satoshi-per-byte rounded up to ensure later round-downs
118 /// don't put us below 1 satoshi-per-byte).
120 /// This translates to:
121 /// * satoshis-per-byte * 250
122 /// * ceil(satoshis-per-kbyte / 4)
123 fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u64;
126 /// Minimum relay fee as required by bitcoin network mempool policy.
127 pub const MIN_RELAY_FEE_SAT_PER_1000_WEIGHT: u64 = 4000;
129 /// Utility for tracking registered txn/outpoints and checking for matches
130 #[cfg_attr(test, derive(PartialEq))]
131 pub struct ChainWatchedUtil {
134 // We are more conservative in matching during testing to ensure everything matches *exactly*,
135 // even though during normal runtime we take more optimized match approaches...
137 watched_txn: HashSet<(Sha256dHash, Script)>,
139 watched_txn: HashSet<Script>,
141 watched_outpoints: HashSet<(Sha256dHash, u32)>,
144 impl ChainWatchedUtil {
145 /// Constructs an empty (watches nothing) ChainWatchedUtil
146 pub fn new() -> Self {
149 watched_txn: HashSet::new(),
150 watched_outpoints: HashSet::new(),
154 /// Registers a tx for monitoring, returning true if it was a new tx and false if we'd already
155 /// been watching for it.
156 pub fn register_tx(&mut self, txid: &Sha256dHash, script_pub_key: &Script) -> bool {
157 if self.watch_all { return false; }
160 self.watched_txn.insert((txid.clone(), script_pub_key.clone()))
164 let _tx_unused = txid; // It's used in cfg(test), though
165 self.watched_txn.insert(script_pub_key.clone())
169 /// Registers an outpoint for monitoring, returning true if it was a new outpoint and false if
170 /// we'd already been watching for it
171 pub fn register_outpoint(&mut self, outpoint: (Sha256dHash, u32), _script_pub_key: &Script) -> bool {
172 if self.watch_all { return false; }
173 self.watched_outpoints.insert(outpoint)
176 /// Sets us to match all transactions, returning true if this is a new setting and false if
177 /// we'd already been set to match everything.
178 pub fn watch_all(&mut self) -> bool {
179 if self.watch_all { return false; }
180 self.watch_all = true;
184 /// Checks if a given transaction matches the current filter.
185 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
189 for out in tx.output.iter() {
191 for &(ref txid, ref script) in self.watched_txn.iter() {
192 if *script == out.script_pubkey {
193 if tx.txid() == *txid {
199 for script in self.watched_txn.iter() {
200 if *script == out.script_pubkey {
205 for input in tx.input.iter() {
206 for outpoint in self.watched_outpoints.iter() {
207 let &(outpoint_hash, outpoint_index) = outpoint;
208 if outpoint_hash == input.previous_output.txid && outpoint_index == input.previous_output.vout {
217 /// BlockNotifierArc is useful when you need a BlockNotifier that points to ChainListeners with
218 /// static lifetimes, e.g. when you're using lightning-net-tokio (since tokio::spawn requires
219 /// parameters with static lifetimes). Other times you can afford a reference, which is more
220 /// efficient, in which case BlockNotifierRef is a more appropriate type. Defining these type
221 /// aliases prevents issues such as overly long function definitions.
222 pub type BlockNotifierArc = Arc<BlockNotifier<'static, Arc<ChainListener>>>;
224 /// BlockNotifierRef is useful when you want a BlockNotifier that points to ChainListeners
225 /// with nonstatic lifetimes. This is useful for when static lifetimes are not needed. Nonstatic
226 /// lifetimes are more efficient but less flexible, and should be used by default unless static
227 /// lifetimes are required, e.g. when you're using lightning-net-tokio (since tokio::spawn
228 /// requires parameters with static lifetimes), in which case BlockNotifierArc is a more
229 /// appropriate type. Defining these type aliases for common usages prevents issues such as
230 /// overly long function definitions.
231 pub type BlockNotifierRef<'a> = BlockNotifier<'a, &'a ChainListener>;
233 /// Utility for notifying listeners about new blocks, and handling block rescans if new watch
234 /// data is registered.
236 /// Rather than using a plain BlockNotifier, it is preferable to use either a BlockNotifierArc
237 /// or a BlockNotifierRef for conciseness. See their documentation for more details, but essentially
238 /// you should default to using a BlockNotifierRef, and use a BlockNotifierArc instead when you
239 /// require ChainListeners with static lifetimes, such as when you're using lightning-net-tokio.
240 pub struct BlockNotifier<'a, CL: Deref<Target = ChainListener + 'a> + 'a> {
241 listeners: Mutex<Vec<CL>>,
242 chain_monitor: Arc<ChainWatchInterface>,
243 phantom: PhantomData<&'a ()>,
246 impl<'a, CL: Deref<Target = ChainListener + 'a> + 'a> BlockNotifier<'a, CL> {
247 /// Constructs a new BlockNotifier without any listeners.
248 pub fn new(chain_monitor: Arc<ChainWatchInterface>) -> BlockNotifier<'a, CL> {
250 listeners: Mutex::new(Vec::new()),
252 phantom: PhantomData,
256 /// Register the given listener to receive events.
257 pub fn register_listener(&self, listener: CL) {
258 let mut vec = self.listeners.lock().unwrap();
261 /// Unregister the given listener to no longer
264 /// If the same listener is registered multiple times, unregistering
265 /// will remove ALL occurrences of that listener. Comparison is done using
266 /// the pointer returned by the Deref trait implementation.
267 pub fn unregister_listener(&self, listener: CL) {
268 let mut vec = self.listeners.lock().unwrap();
269 // item is a ref to an abstract thing that dereferences to a ChainListener,
270 // so dereference it twice to get the ChainListener itself
271 vec.retain(|item | !ptr::eq(&(**item), &(*listener)));
274 /// Notify listeners that a block was connected given a full, unfiltered block.
276 /// Handles re-scanning the block and calling block_connected again if listeners register new
277 /// watch data during the callbacks for you (see ChainListener::block_connected for more info).
278 pub fn block_connected<'b>(&self, block: &'b Block, height: u32) {
279 let mut reentered = true;
281 let (matched, matched_index) = self.chain_monitor.filter_block(block);
282 reentered = self.block_connected_checked(&block.header, height, matched.as_slice(), matched_index.as_slice());
286 /// Notify listeners that a block was connected, given pre-filtered list of transactions in the
287 /// block which matched the filter (probably using does_match_tx).
289 /// Returns true if notified listeners registered additional watch data (implying that the
290 /// block must be re-scanned and this function called again prior to further block_connected
291 /// calls, see ChainListener::block_connected for more info).
292 pub fn block_connected_checked(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> bool {
293 let last_seen = self.chain_monitor.reentered();
295 let listeners = self.listeners.lock().unwrap();
296 for listener in listeners.iter() {
297 listener.block_connected(header, height, txn_matched, indexes_of_txn_matched);
299 return last_seen != self.chain_monitor.reentered();
302 /// Notify listeners that a block was disconnected.
303 pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
304 let listeners = self.listeners.lock().unwrap();
305 for listener in listeners.iter() {
306 listener.block_disconnected(&header, disconnected_height);
311 /// Utility to capture some common parts of ChainWatchInterface implementors.
313 /// Keeping a local copy of this in a ChainWatchInterface implementor is likely useful.
314 pub struct ChainWatchInterfaceUtil {
316 watched: Mutex<ChainWatchedUtil>,
317 reentered: AtomicUsize,
321 // We only expose PartialEq in test since its somewhat unclear exactly what it should do and we're
322 // only comparing a subset of fields (essentially just checking that the set of things we're
323 // watching is the same).
325 impl PartialEq for ChainWatchInterfaceUtil {
326 fn eq(&self, o: &Self) -> bool {
327 self.network == o.network &&
328 *self.watched.lock().unwrap() == *o.watched.lock().unwrap()
332 /// Register listener
333 impl ChainWatchInterface for ChainWatchInterfaceUtil {
334 fn install_watch_tx(&self, txid: &Sha256dHash, script_pub_key: &Script) {
335 let mut watched = self.watched.lock().unwrap();
336 if watched.register_tx(txid, script_pub_key) {
337 self.reentered.fetch_add(1, Ordering::Relaxed);
341 fn install_watch_outpoint(&self, outpoint: (Sha256dHash, u32), out_script: &Script) {
342 let mut watched = self.watched.lock().unwrap();
343 if watched.register_outpoint(outpoint, out_script) {
344 self.reentered.fetch_add(1, Ordering::Relaxed);
348 fn watch_all_txn(&self) {
349 let mut watched = self.watched.lock().unwrap();
350 if watched.watch_all() {
351 self.reentered.fetch_add(1, Ordering::Relaxed);
355 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, _unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError> {
356 if genesis_hash != genesis_block(self.network).header.bitcoin_hash() {
357 return Err(ChainError::NotWatched);
359 Err(ChainError::NotSupported)
362 fn filter_block<'a>(&self, block: &'a Block) -> (Vec<&'a Transaction>, Vec<u32>) {
363 let mut matched = Vec::new();
364 let mut matched_index = Vec::new();
366 let watched = self.watched.lock().unwrap();
367 for (index, transaction) in block.txdata.iter().enumerate() {
368 if self.does_match_tx_unguarded(transaction, &watched) {
369 matched.push(transaction);
370 matched_index.push(index as u32);
374 (matched, matched_index)
377 fn reentered(&self) -> usize {
378 self.reentered.load(Ordering::Relaxed)
382 impl ChainWatchInterfaceUtil {
383 /// Creates a new ChainWatchInterfaceUtil for the given network
384 pub fn new(network: Network, logger: Arc<Logger>) -> ChainWatchInterfaceUtil {
385 ChainWatchInterfaceUtil {
387 watched: Mutex::new(ChainWatchedUtil::new()),
388 reentered: AtomicUsize::new(1),
393 /// Checks if a given transaction matches the current filter.
394 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
395 let watched = self.watched.lock().unwrap();
396 self.does_match_tx_unguarded (tx, &watched)
399 fn does_match_tx_unguarded(&self, tx: &Transaction, watched: &MutexGuard<ChainWatchedUtil>) -> bool {
400 watched.does_match_tx(tx)
406 use ln::functional_test_utils::{create_chanmon_cfgs, create_node_cfgs};
407 use super::{BlockNotifier, ChainListener};
411 fn register_listener_test() {
412 let chanmon_cfgs = create_chanmon_cfgs(1);
413 let node_cfgs = create_node_cfgs(1, &chanmon_cfgs);
414 let block_notifier = BlockNotifier::new(node_cfgs[0].chain_monitor.clone());
415 assert_eq!(block_notifier.listeners.lock().unwrap().len(), 0);
416 let listener = &node_cfgs[0].chan_monitor.simple_monitor as &ChainListener;
417 block_notifier.register_listener(listener);
418 let vec = block_notifier.listeners.lock().unwrap();
419 assert_eq!(vec.len(), 1);
420 let item = vec.first().clone().unwrap();
421 assert!(ptr::eq(&(**item), &(*listener)));
425 fn unregister_single_listener_test() {
426 let chanmon_cfgs = create_chanmon_cfgs(2);
427 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
428 let block_notifier = BlockNotifier::new(node_cfgs[0].chain_monitor.clone());
429 let listener1 = &node_cfgs[0].chan_monitor.simple_monitor as &ChainListener;
430 let listener2 = &node_cfgs[1].chan_monitor.simple_monitor as &ChainListener;
431 block_notifier.register_listener(listener1);
432 block_notifier.register_listener(listener2);
433 let vec = block_notifier.listeners.lock().unwrap();
434 assert_eq!(vec.len(), 2);
436 block_notifier.unregister_listener(listener1);
437 let vec = block_notifier.listeners.lock().unwrap();
438 assert_eq!(vec.len(), 1);
439 let item = vec.first().clone().unwrap();
440 assert!(ptr::eq(&(**item), &(*listener2)));
444 fn unregister_single_listener_ref_test() {
445 let chanmon_cfgs = create_chanmon_cfgs(2);
446 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
447 let block_notifier = BlockNotifier::new(node_cfgs[0].chain_monitor.clone());
448 block_notifier.register_listener(&node_cfgs[0].chan_monitor.simple_monitor as &ChainListener);
449 block_notifier.register_listener(&node_cfgs[1].chan_monitor.simple_monitor as &ChainListener);
450 let vec = block_notifier.listeners.lock().unwrap();
451 assert_eq!(vec.len(), 2);
453 block_notifier.unregister_listener(&node_cfgs[0].chan_monitor.simple_monitor);
454 let vec = block_notifier.listeners.lock().unwrap();
455 assert_eq!(vec.len(), 1);
456 let item = vec.first().clone().unwrap();
457 assert!(ptr::eq(&(**item), &(*&node_cfgs[1].chan_monitor.simple_monitor)));
461 fn unregister_multiple_of_the_same_listeners_test() {
462 let chanmon_cfgs = create_chanmon_cfgs(2);
463 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
464 let block_notifier = BlockNotifier::new(node_cfgs[0].chain_monitor.clone());
465 let listener1 = &node_cfgs[0].chan_monitor.simple_monitor as &ChainListener;
466 let listener2 = &node_cfgs[1].chan_monitor.simple_monitor as &ChainListener;
467 block_notifier.register_listener(listener1);
468 block_notifier.register_listener(listener1);
469 block_notifier.register_listener(listener2);
470 let vec = block_notifier.listeners.lock().unwrap();
471 assert_eq!(vec.len(), 3);
473 block_notifier.unregister_listener(listener1);
474 let vec = block_notifier.listeners.lock().unwrap();
475 assert_eq!(vec.len(), 1);
476 let item = vec.first().clone().unwrap();
477 assert!(ptr::eq(&(**item), &(*listener2)));