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,Weak,MutexGuard,Arc};
18 use std::sync::atomic::{AtomicUsize, Ordering};
19 use std::collections::HashSet;
21 /// Used to give chain error details upstream
23 /// Client doesn't support UTXO lookup (but the chain hash matches our genesis block hash)
25 /// Chain isn't the one watched
27 /// Tx doesn't exist or is unconfirmed
31 /// An interface to request notification of certain scripts as they appear the
34 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
35 /// called from inside the library in response to ChainListener events, P2P events, or timer
37 pub trait ChainWatchInterface: Sync + Send {
38 /// Provides a txid/random-scriptPubKey-in-the-tx which much be watched for.
39 fn install_watch_tx(&self, txid: &Sha256dHash, script_pub_key: &Script);
41 /// Provides an outpoint which must be watched for, providing any transactions which spend the
43 fn install_watch_outpoint(&self, outpoint: (Sha256dHash, u32), out_script: &Script);
45 /// Indicates that a listener needs to see all transactions.
46 fn watch_all_txn(&self);
48 /// Gets the script and value in satoshis for a given unspent transaction output given a
49 /// short_channel_id (aka unspent_tx_output_identier). For BTC/tBTC channels the top three
50 /// bytes are the block height, the next 3 the transaction index within the block, and the
51 /// final two the output within the transaction.
52 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError>;
54 /// Gets the list of transactions and transaction indices that the ChainWatchInterface is
56 fn filter_block<'a>(&self, block: &'a Block) -> (Vec<&'a Transaction>, Vec<u32>);
58 /// Returns a usize that changes when the ChainWatchInterface's watched data is modified.
59 /// Users of `filter_block` should pre-save a copy of `reentered`'s return value and use it to
60 /// determine whether they need to re-filter a given block.
61 fn reentered(&self) -> usize;
64 /// An interface to send a transaction to the Bitcoin network.
65 pub trait BroadcasterInterface: Sync + Send {
66 /// Sends a transaction out to (hopefully) be mined.
67 fn broadcast_transaction(&self, tx: &Transaction);
70 /// A trait indicating a desire to listen for events from the chain
71 pub trait ChainListener: Sync + Send {
72 /// Notifies a listener that a block was connected.
73 /// Note that if a new transaction/outpoint is watched during a block_connected call, the block
74 /// *must* be re-scanned with the new transaction/outpoints and block_connected should be
75 /// called again with the same header and (at least) the new transactions.
77 /// Note that if non-new transaction/outpoints may be registered during a call, a second call
78 /// *must not* happen.
80 /// This also means those counting confirmations using block_connected callbacks should watch
81 /// for duplicate headers and not count them towards confirmations!
82 fn block_connected(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]);
83 /// Notifies a listener that a block was disconnected.
84 /// Unlike block_connected, this *must* never be called twice for the same disconnect event.
85 /// Height must be the one of the block which was disconnected (not new height of the best chain)
86 fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32);
89 /// An enum that represents the speed at which we want a transaction to confirm used for feerate
91 pub enum ConfirmationTarget {
92 /// We are happy with this transaction confirming slowly when feerate drops some.
94 /// We'd like this transaction to confirm without major delay, but 12-18 blocks is fine.
96 /// We'd like this transaction to confirm in the next few blocks.
100 /// A trait which should be implemented to provide feerate information on a number of time
103 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
104 /// called from inside the library in response to ChainListener events, P2P events, or timer
106 pub trait FeeEstimator: Sync + Send {
107 /// Gets estimated satoshis of fee required per 1000 Weight-Units.
109 /// Must be no smaller than 253 (ie 1 satoshi-per-byte rounded up to ensure later round-downs
110 /// don't put us below 1 satoshi-per-byte).
112 /// This translates to:
113 /// * satoshis-per-byte * 250
114 /// * ceil(satoshis-per-kbyte / 4)
115 fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u64;
118 /// Utility for tracking registered txn/outpoints and checking for matches
119 pub struct ChainWatchedUtil {
122 // We are more conservative in matching during testing to ensure everything matches *exactly*,
123 // even though during normal runtime we take more optimized match approaches...
125 watched_txn: HashSet<(Sha256dHash, Script)>,
127 watched_txn: HashSet<Script>,
129 watched_outpoints: HashSet<(Sha256dHash, u32)>,
132 impl ChainWatchedUtil {
133 /// Constructs an empty (watches nothing) ChainWatchedUtil
134 pub fn new() -> Self {
137 watched_txn: HashSet::new(),
138 watched_outpoints: HashSet::new(),
142 /// Registers a tx for monitoring, returning true if it was a new tx and false if we'd already
143 /// been watching for it.
144 pub fn register_tx(&mut self, txid: &Sha256dHash, script_pub_key: &Script) -> bool {
145 if self.watch_all { return false; }
148 self.watched_txn.insert((txid.clone(), script_pub_key.clone()))
152 let _tx_unused = txid; // It's used in cfg(test), though
153 self.watched_txn.insert(script_pub_key.clone())
157 /// Registers an outpoint for monitoring, returning true if it was a new outpoint and false if
158 /// we'd already been watching for it
159 pub fn register_outpoint(&mut self, outpoint: (Sha256dHash, u32), _script_pub_key: &Script) -> bool {
160 if self.watch_all { return false; }
161 self.watched_outpoints.insert(outpoint)
164 /// Sets us to match all transactions, returning true if this is a new setting and false if
165 /// we'd already been set to match everything.
166 pub fn watch_all(&mut self) -> bool {
167 if self.watch_all { return false; }
168 self.watch_all = true;
172 /// Checks if a given transaction matches the current filter.
173 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
177 for out in tx.output.iter() {
179 for &(ref txid, ref script) in self.watched_txn.iter() {
180 if *script == out.script_pubkey {
181 if tx.txid() == *txid {
187 for script in self.watched_txn.iter() {
188 if *script == out.script_pubkey {
193 for input in tx.input.iter() {
194 for outpoint in self.watched_outpoints.iter() {
195 let &(outpoint_hash, outpoint_index) = outpoint;
196 if outpoint_hash == input.previous_output.txid && outpoint_index == input.previous_output.vout {
205 /// Utility for notifying listeners about new blocks, and handling block rescans if new watch
206 /// data is registered.
207 pub struct BlockNotifier<'a> {
208 listeners: Mutex<Vec<Weak<ChainListener + 'a>>>, //TODO(vmw): try removing Weak
209 chain_monitor: Arc<ChainWatchInterface>,
212 impl<'a> BlockNotifier<'a> {
213 /// Constructs a new BlockNotifier without any listeners.
214 pub fn new(chain_monitor: Arc<ChainWatchInterface>) -> BlockNotifier<'a> {
216 listeners: Mutex::new(Vec::new()),
221 /// Register the given listener to receive events. Only a weak pointer is provided and
222 /// the registration should be freed once that pointer expires.
224 pub fn register_listener(&self, listener: Weak<ChainListener + 'a>) {
225 let mut vec = self.listeners.lock().unwrap();
229 /// Notify listeners that a block was connected given a full, unfiltered block.
231 /// Handles re-scanning the block and calling block_connected again if listeners register new
232 /// watch data during the callbacks for you (see ChainListener::block_connected for more info).
233 pub fn block_connected<'b>(&self, block: &'b Block, height: u32) {
234 let mut reentered = true;
236 let (matched, matched_index) = self.chain_monitor.filter_block(block);
237 reentered = self.block_connected_checked(&block.header, height, matched.as_slice(), matched_index.as_slice());
241 /// Notify listeners that a block was connected, given pre-filtered list of transactions in the
242 /// block which matched the filter (probably using does_match_tx).
244 /// Returns true if notified listeners registered additional watch data (implying that the
245 /// block must be re-scanned and this function called again prior to further block_connected
246 /// calls, see ChainListener::block_connected for more info).
247 pub fn block_connected_checked(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> bool {
248 let last_seen = self.chain_monitor.reentered();
250 let listeners = self.listeners.lock().unwrap().clone();
251 for listener in listeners.iter() {
252 match listener.upgrade() {
253 Some(arc) => arc.block_connected(header, height, txn_matched, indexes_of_txn_matched),
257 return last_seen != self.chain_monitor.reentered();
261 /// Notify listeners that a block was disconnected.
262 pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
263 let listeners = self.listeners.lock().unwrap().clone();
264 for listener in listeners.iter() {
265 match listener.upgrade() {
266 Some(arc) => arc.block_disconnected(&header, disconnected_height),
274 /// Utility to capture some common parts of ChainWatchInterface implementors.
276 /// Keeping a local copy of this in a ChainWatchInterface implementor is likely useful.
277 pub struct ChainWatchInterfaceUtil {
279 watched: Mutex<ChainWatchedUtil>,
280 reentered: AtomicUsize,
284 /// Register listener
285 impl ChainWatchInterface for ChainWatchInterfaceUtil {
286 fn install_watch_tx(&self, txid: &Sha256dHash, script_pub_key: &Script) {
287 let mut watched = self.watched.lock().unwrap();
288 if watched.register_tx(txid, script_pub_key) {
289 self.reentered.fetch_add(1, Ordering::Relaxed);
293 fn install_watch_outpoint(&self, outpoint: (Sha256dHash, u32), out_script: &Script) {
294 let mut watched = self.watched.lock().unwrap();
295 if watched.register_outpoint(outpoint, out_script) {
296 self.reentered.fetch_add(1, Ordering::Relaxed);
300 fn watch_all_txn(&self) {
301 let mut watched = self.watched.lock().unwrap();
302 if watched.watch_all() {
303 self.reentered.fetch_add(1, Ordering::Relaxed);
307 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, _unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError> {
308 if genesis_hash != genesis_block(self.network).header.bitcoin_hash() {
309 return Err(ChainError::NotWatched);
311 Err(ChainError::NotSupported)
314 fn filter_block<'a>(&self, block: &'a Block) -> (Vec<&'a Transaction>, Vec<u32>) {
315 let mut matched = Vec::new();
316 let mut matched_index = Vec::new();
318 let watched = self.watched.lock().unwrap();
319 for (index, transaction) in block.txdata.iter().enumerate() {
320 if self.does_match_tx_unguarded(transaction, &watched) {
321 matched.push(transaction);
322 matched_index.push(index as u32);
326 (matched, matched_index)
329 fn reentered(&self) -> usize {
330 self.reentered.load(Ordering::Relaxed)
334 impl ChainWatchInterfaceUtil {
335 /// Creates a new ChainWatchInterfaceUtil for the given network
336 pub fn new(network: Network, logger: Arc<Logger>) -> ChainWatchInterfaceUtil {
337 ChainWatchInterfaceUtil {
339 watched: Mutex::new(ChainWatchedUtil::new()),
340 reentered: AtomicUsize::new(1),
346 /// Checks if a given transaction matches the current filter.
347 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
348 let watched = self.watched.lock().unwrap();
349 self.does_match_tx_unguarded (tx, &watched)
352 fn does_match_tx_unguarded(&self, tx: &Transaction, watched: &MutexGuard<ChainWatchedUtil>) -> bool {
353 watched.does_match_tx(tx)