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 /// Register the given listener to receive events. Only a weak pointer is provided and the
49 /// registration should be freed once that pointer expires.
50 fn register_listener(&self, listener: Weak<ChainListener>);
53 /// Gets the script and value in satoshis for a given unspent transaction output given a
54 /// short_channel_id (aka unspent_tx_output_identier). For BTC/tBTC channels the top three
55 /// bytes are the block height, the next 3 the transaction index within the block, and the
56 /// final two the output within the transaction.
57 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError>;
60 /// An interface to send a transaction to the Bitcoin network.
61 pub trait BroadcasterInterface: Sync + Send {
62 /// Sends a transaction out to (hopefully) be mined.
63 fn broadcast_transaction(&self, tx: &Transaction);
66 /// A trait indicating a desire to listen for events from the chain
67 pub trait ChainListener: Sync + Send {
68 /// Notifies a listener that a block was connected.
69 /// Note that if a new transaction/outpoint is watched during a block_connected call, the block
70 /// *must* be re-scanned with the new transaction/outpoints and block_connected should be
71 /// called again with the same header and (at least) the new transactions.
73 /// Note that if non-new transaction/outpoints may be registered during a call, a second call
74 /// *must not* happen.
76 /// This also means those counting confirmations using block_connected callbacks should watch
77 /// for duplicate headers and not count them towards confirmations!
78 fn block_connected(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]);
79 /// Notifies a listener that a block was disconnected.
80 /// Unlike block_connected, this *must* never be called twice for the same disconnect event.
81 /// Height must be the one of the block which was disconnected (not new height of the best chain)
82 fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32);
85 /// An enum that represents the speed at which we want a transaction to confirm used for feerate
87 pub enum ConfirmationTarget {
88 /// We are happy with this transaction confirming slowly when feerate drops some.
90 /// We'd like this transaction to confirm without major delay, but 12-18 blocks is fine.
92 /// We'd like this transaction to confirm in the next few blocks.
96 /// A trait which should be implemented to provide feerate information on a number of time
99 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
100 /// called from inside the library in response to ChainListener events, P2P events, or timer
102 pub trait FeeEstimator: Sync + Send {
103 /// Gets estimated satoshis of fee required per 1000 Weight-Units.
105 /// Must be no smaller than 253 (ie 1 satoshi-per-byte rounded up to ensure later round-downs
106 /// don't put us below 1 satoshi-per-byte).
108 /// This translates to:
109 /// * satoshis-per-byte * 250
110 /// * ceil(satoshis-per-kbyte / 4)
111 fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u64;
114 /// Utility for tracking registered txn/outpoints and checking for matches
115 pub struct ChainWatchedUtil {
118 // We are more conservative in matching during testing to ensure everything matches *exactly*,
119 // even though during normal runtime we take more optimized match approaches...
121 watched_txn: HashSet<(Sha256dHash, Script)>,
123 watched_txn: HashSet<Script>,
125 watched_outpoints: HashSet<(Sha256dHash, u32)>,
128 impl ChainWatchedUtil {
129 /// Constructs an empty (watches nothing) ChainWatchedUtil
130 pub fn new() -> Self {
133 watched_txn: HashSet::new(),
134 watched_outpoints: HashSet::new(),
138 /// Registers a tx for monitoring, returning true if it was a new tx and false if we'd already
139 /// been watching for it.
140 pub fn register_tx(&mut self, txid: &Sha256dHash, script_pub_key: &Script) -> bool {
141 if self.watch_all { return false; }
144 self.watched_txn.insert((txid.clone(), script_pub_key.clone()))
148 let _tx_unused = txid; // It's used in cfg(test), though
149 self.watched_txn.insert(script_pub_key.clone())
153 /// Registers an outpoint for monitoring, returning true if it was a new outpoint and false if
154 /// we'd already been watching for it
155 pub fn register_outpoint(&mut self, outpoint: (Sha256dHash, u32), _script_pub_key: &Script) -> bool {
156 if self.watch_all { return false; }
157 self.watched_outpoints.insert(outpoint)
160 /// Sets us to match all transactions, returning true if this is a new setting and false if
161 /// we'd already been set to match everything.
162 pub fn watch_all(&mut self) -> bool {
163 if self.watch_all { return false; }
164 self.watch_all = true;
168 /// Checks if a given transaction matches the current filter.
169 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
173 for out in tx.output.iter() {
175 for &(ref txid, ref script) in self.watched_txn.iter() {
176 if *script == out.script_pubkey {
177 if tx.txid() == *txid {
183 for script in self.watched_txn.iter() {
184 if *script == out.script_pubkey {
189 for input in tx.input.iter() {
190 for outpoint in self.watched_outpoints.iter() {
191 let &(outpoint_hash, outpoint_index) = outpoint;
192 if outpoint_hash == input.previous_output.txid && outpoint_index == input.previous_output.vout {
201 /// Utility to capture some common parts of ChainWatchInterface implementors.
203 /// Keeping a local copy of this in a ChainWatchInterface implementor is likely useful.
204 pub struct ChainWatchInterfaceUtil {
206 watched: Mutex<ChainWatchedUtil>,
207 listeners: Mutex<Vec<Weak<ChainListener>>>,
208 reentered: AtomicUsize,
212 /// Register listener
213 impl ChainWatchInterface for ChainWatchInterfaceUtil {
214 fn install_watch_tx(&self, txid: &Sha256dHash, script_pub_key: &Script) {
215 let mut watched = self.watched.lock().unwrap();
216 if watched.register_tx(txid, script_pub_key) {
217 self.reentered.fetch_add(1, Ordering::Relaxed);
221 fn install_watch_outpoint(&self, outpoint: (Sha256dHash, u32), out_script: &Script) {
222 let mut watched = self.watched.lock().unwrap();
223 if watched.register_outpoint(outpoint, out_script) {
224 self.reentered.fetch_add(1, Ordering::Relaxed);
228 fn watch_all_txn(&self) {
229 let mut watched = self.watched.lock().unwrap();
230 if watched.watch_all() {
231 self.reentered.fetch_add(1, Ordering::Relaxed);
235 fn register_listener(&self, listener: Weak<ChainListener>) {
236 let mut vec = self.listeners.lock().unwrap();
240 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, _unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError> {
241 if genesis_hash != genesis_block(self.network).header.bitcoin_hash() {
242 return Err(ChainError::NotWatched);
244 Err(ChainError::NotSupported)
248 impl ChainWatchInterfaceUtil {
249 /// Creates a new ChainWatchInterfaceUtil for the given network
250 pub fn new(network: Network, logger: Arc<Logger>) -> ChainWatchInterfaceUtil {
251 ChainWatchInterfaceUtil {
253 watched: Mutex::new(ChainWatchedUtil::new()),
254 listeners: Mutex::new(Vec::new()),
255 reentered: AtomicUsize::new(1),
260 /// Notify listeners that a block was connected given a full, unfiltered block.
262 /// Handles re-scanning the block and calling block_connected again if listeners register new
263 /// watch data during the callbacks for you (see ChainListener::block_connected for more info).
264 pub fn block_connected_with_filtering(&self, block: &Block, height: u32) {
265 let mut reentered = true;
267 let mut matched = Vec::new();
268 let mut matched_index = Vec::new();
270 let watched = self.watched.lock().unwrap();
271 for (index, transaction) in block.txdata.iter().enumerate() {
272 if self.does_match_tx_unguarded(transaction, &watched) {
273 matched.push(transaction);
274 matched_index.push(index as u32);
278 reentered = self.block_connected_checked(&block.header, height, matched.as_slice(), matched_index.as_slice());
282 /// Notify listeners that a block was disconnected.
283 pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
284 let listeners = self.listeners.lock().unwrap().clone();
285 for listener in listeners.iter() {
286 match listener.upgrade() {
287 Some(arc) => arc.block_disconnected(&header, disconnected_height),
293 /// Notify listeners that a block was connected, given pre-filtered list of transactions in the
294 /// block which matched the filter (probably using does_match_tx).
296 /// Returns true if notified listeners registered additional watch data (implying that the
297 /// block must be re-scanned and this function called again prior to further block_connected
298 /// calls, see ChainListener::block_connected for more info).
299 pub fn block_connected_checked(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> bool {
300 let last_seen = self.reentered.load(Ordering::Relaxed);
302 let listeners = self.listeners.lock().unwrap().clone();
303 for listener in listeners.iter() {
304 match listener.upgrade() {
305 Some(arc) => arc.block_connected(header, height, txn_matched, indexes_of_txn_matched),
309 return last_seen != self.reentered.load(Ordering::Relaxed);
312 /// Checks if a given transaction matches the current filter.
313 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
314 let watched = self.watched.lock().unwrap();
315 self.does_match_tx_unguarded (tx, &watched)
318 fn does_match_tx_unguarded(&self, tx: &Transaction, watched: &MutexGuard<ChainWatchedUtil>) -> bool {
319 watched.does_match_tx(tx)