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, transactio 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::Sha256dHash;
12 use bitcoin::network::constants::Network;
13 use bitcoin::network::serialize::BitcoinHash;
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 fn block_disconnected(&self, header: &BlockHeader);
84 /// An enum that represents the speed at which we want a transaction to confirm used for feerate
86 pub enum ConfirmationTarget {
87 /// We are happy with this transaction confirming slowly when feerate drops some.
89 /// We'd like this transaction to confirm without major delay, but 12-18 blocks is fine.
91 /// We'd like this transaction to confirm in the next few blocks.
95 /// A trait which should be implemented to provide feerate information on a number of time
98 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
99 /// called from inside the library in response to ChainListener events, P2P events, or timer
101 pub trait FeeEstimator: Sync + Send {
102 /// Gets estimated satoshis of fee required per 1000 Weight-Units.
104 /// Must be no smaller than 253 (ie 1 satoshi-per-byte rounded up to ensure later round-downs
105 /// don't put us below 1 satoshi-per-byte).
107 /// This translates to:
108 /// * satoshis-per-byte * 250
109 /// * ceil(satoshis-per-kbyte / 4)
110 fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u64;
113 /// Utility for tracking registered txn/outpoints and checking for matches
114 pub struct ChainWatchedUtil {
117 // We are more conservative in matching during testing to ensure everything matches *exactly*,
118 // even though during normal runtime we take more optimized match approaches...
120 watched_txn: HashSet<(Sha256dHash, Script)>,
122 watched_txn: HashSet<Script>,
124 watched_outpoints: HashSet<(Sha256dHash, u32)>,
127 impl ChainWatchedUtil {
128 /// Constructs an empty (watches nothing) ChainWatchedUtil
129 pub fn new() -> Self {
132 watched_txn: HashSet::new(),
133 watched_outpoints: HashSet::new(),
137 /// Registers a tx for monitoring, returning true if it was a new tx and false if we'd already
138 /// been watching for it.
139 pub fn register_tx(&mut self, txid: &Sha256dHash, script_pub_key: &Script) -> bool {
140 if self.watch_all { return false; }
143 self.watched_txn.insert((txid.clone(), script_pub_key.clone()))
147 let _tx_unused = txid; // Its used in cfg(test), though
148 self.watched_txn.insert(script_pub_key.clone())
152 /// Registers an outpoint for monitoring, returning true if it was a new outpoint and false if
153 /// we'd already been watching for it
154 pub fn register_outpoint(&mut self, outpoint: (Sha256dHash, u32), _script_pub_key: &Script) -> bool {
155 if self.watch_all { return false; }
156 self.watched_outpoints.insert(outpoint)
159 /// Sets us to match all transactions, returning true if this is a new setting anf false if
160 /// we'd already been set to match everything.
161 pub fn watch_all(&mut self) -> bool {
162 if self.watch_all { return false; }
163 self.watch_all = true;
167 /// Checks if a given transaction matches the current filter.
168 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
172 for out in tx.output.iter() {
174 for &(ref txid, ref script) in self.watched_txn.iter() {
175 if *script == out.script_pubkey {
176 if tx.txid() == *txid {
182 for script in self.watched_txn.iter() {
183 if *script == out.script_pubkey {
188 for input in tx.input.iter() {
189 for outpoint in self.watched_outpoints.iter() {
190 let &(outpoint_hash, outpoint_index) = outpoint;
191 if outpoint_hash == input.previous_output.txid && outpoint_index == input.previous_output.vout {
200 /// Utility to capture some common parts of ChainWatchInterface implementors.
202 /// Keeping a local copy of this in a ChainWatchInterface implementor is likely useful.
203 pub struct ChainWatchInterfaceUtil {
205 watched: Mutex<ChainWatchedUtil>,
206 listeners: Mutex<Vec<Weak<ChainListener>>>,
207 reentered: AtomicUsize,
211 /// Register listener
212 impl ChainWatchInterface for ChainWatchInterfaceUtil {
213 fn install_watch_tx(&self, txid: &Sha256dHash, script_pub_key: &Script) {
214 let mut watched = self.watched.lock().unwrap();
215 if watched.register_tx(txid, script_pub_key) {
216 self.reentered.fetch_add(1, Ordering::Relaxed);
220 fn install_watch_outpoint(&self, outpoint: (Sha256dHash, u32), out_script: &Script) {
221 let mut watched = self.watched.lock().unwrap();
222 if watched.register_outpoint(outpoint, out_script) {
223 self.reentered.fetch_add(1, Ordering::Relaxed);
227 fn watch_all_txn(&self) {
228 let mut watched = self.watched.lock().unwrap();
229 if watched.watch_all() {
230 self.reentered.fetch_add(1, Ordering::Relaxed);
234 fn register_listener(&self, listener: Weak<ChainListener>) {
235 let mut vec = self.listeners.lock().unwrap();
239 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, _unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError> {
240 if genesis_hash != genesis_block(self.network).header.bitcoin_hash() {
241 return Err(ChainError::NotWatched);
243 Err(ChainError::NotSupported)
247 impl ChainWatchInterfaceUtil {
248 /// Creates a new ChainWatchInterfaceUtil for the given network
249 pub fn new(network: Network, logger: Arc<Logger>) -> ChainWatchInterfaceUtil {
250 ChainWatchInterfaceUtil {
252 watched: Mutex::new(ChainWatchedUtil::new()),
253 listeners: Mutex::new(Vec::new()),
254 reentered: AtomicUsize::new(1),
259 /// Notify listeners that a block was connected given a full, unfiltered block.
261 /// Handles re-scanning the block and calling block_connected again if listeners register new
262 /// watch data during the callbacks for you (see ChainListener::block_connected for more info).
263 pub fn block_connected_with_filtering(&self, block: &Block, height: u32) {
264 let mut reentered = true;
266 let mut matched = Vec::new();
267 let mut matched_index = Vec::new();
269 let watched = self.watched.lock().unwrap();
270 for (index, transaction) in block.txdata.iter().enumerate() {
271 if self.does_match_tx_unguarded(transaction, &watched) {
272 matched.push(transaction);
273 matched_index.push(index as u32);
277 reentered = self.block_connected_checked(&block.header, height, matched.as_slice(), matched_index.as_slice());
281 /// Notify listeners that a block was disconnected.
282 pub fn block_disconnected(&self, header: &BlockHeader) {
283 let listeners = self.listeners.lock().unwrap().clone();
284 for listener in listeners.iter() {
285 match listener.upgrade() {
286 Some(arc) => arc.block_disconnected(header),
292 /// Notify listeners that a block was connected, given pre-filtered list of transactions in the
293 /// block which matched the filter (probably using does_match_tx).
295 /// Returns true if notified listeners registered additional watch data (implying that the
296 /// block must be re-scanned and this function called again prior to further block_connected
297 /// calls, see ChainListener::block_connected for more info).
298 pub fn block_connected_checked(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> bool {
299 let last_seen = self.reentered.load(Ordering::Relaxed);
301 let listeners = self.listeners.lock().unwrap().clone();
302 for listener in listeners.iter() {
303 match listener.upgrade() {
304 Some(arc) => arc.block_connected(header, height, txn_matched, indexes_of_txn_matched),
308 return last_seen != self.reentered.load(Ordering::Relaxed);
311 /// Checks if a given transaction matches the current filter.
312 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
313 let watched = self.watched.lock().unwrap();
314 self.does_match_tx_unguarded (tx, &watched)
317 fn does_match_tx_unguarded(&self, tx: &Transaction, watched: &MutexGuard<ChainWatchedUtil>) -> bool {
318 watched.does_match_tx(tx)