1 //! Traits and utility impls which allow other parts of rust-lightning to interact with the
2 //! blockchain - receiving notifications of new blocks and block disconnections and allowing
3 //! rust-lightning to request that you monitor the chain for certain outpoints/transactions.
5 use bitcoin::blockdata::block::{Block, BlockHeader};
6 use bitcoin::blockdata::transaction::Transaction;
7 use bitcoin::blockdata::script::Script;
8 use bitcoin::blockdata::constants::genesis_block;
9 use bitcoin::util::hash::Sha256dHash;
10 use bitcoin::network::constants::Network;
11 use bitcoin::network::serialize::BitcoinHash;
13 use util::logger::Logger;
15 use std::sync::{Mutex,Weak,MutexGuard,Arc};
16 use std::sync::atomic::{AtomicUsize, Ordering};
17 use std::collections::HashSet;
19 /// Used to give chain error details upstream
21 /// Client doesn't support UTXO lookup (but the chain hash matches our genesis block hash)
23 /// Chain isn't the one watched
25 /// Tx doesn't exist or is unconfirmed
29 /// An interface to request notification of certain scripts as they appear the
31 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
32 /// called from inside the library in response to ChainListener events, P2P events, or timer
34 pub trait ChainWatchInterface: Sync + Send {
35 /// Provides a txid/random-scriptPubKey-in-the-tx which much be watched for.
36 fn install_watch_tx(&self, txid: &Sha256dHash, script_pub_key: &Script);
38 /// Provides an outpoint which must be watched for, providing any transactions which spend the
40 fn install_watch_outpoint(&self, outpoint: (Sha256dHash, u32), out_script: &Script);
42 /// Indicates that a listener needs to see all transactions.
43 fn watch_all_txn(&self);
45 /// Register the given listener to receive events. Only a weak pointer is provided and the
46 /// registration should be freed once that pointer expires.
47 fn register_listener(&self, listener: Weak<ChainListener>);
50 /// Gets the script and value in satoshis for a given unspent transaction output given a
51 /// short_channel_id (aka unspent_tx_output_identier). For BTC/tBTC channels the top three
52 /// bytes are the block height, the next 3 the transaction index within the block, and the
53 /// final two the output within the transaction.
54 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError>;
57 /// An interface to send a transaction to the Bitcoin network.
58 pub trait BroadcasterInterface: Sync + Send {
59 /// Sends a transaction out to (hopefully) be mined.
60 fn broadcast_transaction(&self, tx: &Transaction);
63 /// A trait indicating a desire to listen for events from the chain
64 pub trait ChainListener: Sync + Send {
65 /// Notifies a listener that a block was connected.
66 /// Note that if a new transaction/outpoint is watched during a block_connected call, the block
67 /// *must* be re-scanned with the new transaction/outpoints and block_connected should be
68 /// called again with the same header and (at least) the new transactions.
69 /// Note that if non-new transaction/outpoints may be registered during a call, a second call
70 /// *must not* happen.
71 /// This also means those counting confirmations using block_connected callbacks should watch
72 /// for duplicate headers and not count them towards confirmations!
73 fn block_connected(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]);
74 /// Notifies a listener that a block was disconnected.
75 /// Unlike block_connected, this *must* never be called twice for the same disconnect event.
76 fn block_disconnected(&self, header: &BlockHeader);
79 /// An enum that represents the speed at which we want a transaction to confirm used for feerate
81 pub enum ConfirmationTarget {
82 /// We are happy with this transaction confirming slowly when feerate drops some.
84 /// We'd like this transaction to confirm without major delay, but 12-18 blocks is fine.
86 /// We'd like this transaction to confirm in the next few blocks.
90 /// A trait which should be implemented to provide feerate information on a number of time
92 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
93 /// called from inside the library in response to ChainListener events, P2P events, or timer
95 pub trait FeeEstimator: Sync + Send {
96 /// Gets estimated satoshis of fee required per 1000 Weight-Units. This translates to:
97 /// * satoshis-per-byte * 250
98 /// * ceil(satoshis-per-kbyte / 4)
99 /// Must be no smaller than 253 (ie 1 satoshi-per-byte rounded up to ensure later round-downs
100 /// don't put us below 1 satoshi-per-byte).
101 fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u64;
104 /// Utility for tracking registered txn/outpoints and checking for matches
105 pub struct ChainWatchedUtil {
108 // We are more conservative in matching during testing to ensure everything matches *exactly*,
109 // even though during normal runtime we take more optimized match approaches...
111 watched_txn: HashSet<(Sha256dHash, Script)>,
113 watched_txn: HashSet<Script>,
115 watched_outpoints: HashSet<(Sha256dHash, u32)>,
118 impl ChainWatchedUtil {
119 /// Constructs an empty (watches nothing) ChainWatchedUtil
120 pub fn new() -> Self {
123 watched_txn: HashSet::new(),
124 watched_outpoints: HashSet::new(),
128 /// Registers a tx for monitoring, returning true if it was a new tx and false if we'd already
129 /// been watching for it.
130 pub fn register_tx(&mut self, txid: &Sha256dHash, script_pub_key: &Script) -> bool {
131 if self.watch_all { return false; }
134 self.watched_txn.insert((txid.clone(), script_pub_key.clone()))
138 let _tx_unused = txid; // Its used in cfg(test), though
139 self.watched_txn.insert(script_pub_key.clone())
143 /// Registers an outpoint for monitoring, returning true if it was a new outpoint and false if
144 /// we'd already been watching for it
145 pub fn register_outpoint(&mut self, outpoint: (Sha256dHash, u32), _script_pub_key: &Script) -> bool {
146 if self.watch_all { return false; }
147 self.watched_outpoints.insert(outpoint)
150 /// Sets us to match all transactions, returning true if this is a new setting anf false if
151 /// we'd already been set to match everything.
152 pub fn watch_all(&mut self) -> bool {
153 if self.watch_all { return false; }
154 self.watch_all = true;
158 /// Checks if a given transaction matches the current filter.
159 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
163 for out in tx.output.iter() {
165 for &(ref txid, ref script) in self.watched_txn.iter() {
166 if *script == out.script_pubkey {
167 if tx.txid() == *txid {
173 for script in self.watched_txn.iter() {
174 if *script == out.script_pubkey {
179 for input in tx.input.iter() {
180 for outpoint in self.watched_outpoints.iter() {
181 let &(outpoint_hash, outpoint_index) = outpoint;
182 if outpoint_hash == input.previous_output.txid && outpoint_index == input.previous_output.vout {
191 /// Utility to capture some common parts of ChainWatchInterface implementors.
192 /// Keeping a local copy of this in a ChainWatchInterface implementor is likely useful.
193 pub struct ChainWatchInterfaceUtil {
195 watched: Mutex<ChainWatchedUtil>,
196 listeners: Mutex<Vec<Weak<ChainListener>>>,
197 reentered: AtomicUsize,
201 /// Register listener
202 impl ChainWatchInterface for ChainWatchInterfaceUtil {
203 fn install_watch_tx(&self, txid: &Sha256dHash, script_pub_key: &Script) {
204 let mut watched = self.watched.lock().unwrap();
205 if watched.register_tx(txid, script_pub_key) {
206 self.reentered.fetch_add(1, Ordering::Relaxed);
210 fn install_watch_outpoint(&self, outpoint: (Sha256dHash, u32), out_script: &Script) {
211 let mut watched = self.watched.lock().unwrap();
212 if watched.register_outpoint(outpoint, out_script) {
213 self.reentered.fetch_add(1, Ordering::Relaxed);
217 fn watch_all_txn(&self) {
218 let mut watched = self.watched.lock().unwrap();
219 if watched.watch_all() {
220 self.reentered.fetch_add(1, Ordering::Relaxed);
224 fn register_listener(&self, listener: Weak<ChainListener>) {
225 let mut vec = self.listeners.lock().unwrap();
229 fn get_chain_utxo(&self, genesis_hash: Sha256dHash, _unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError> {
230 if genesis_hash != genesis_block(self.network).header.bitcoin_hash() {
231 return Err(ChainError::NotWatched);
233 Err(ChainError::NotSupported)
237 impl ChainWatchInterfaceUtil {
238 /// Creates a new ChainWatchInterfaceUtil for the given network
239 pub fn new(network: Network, logger: Arc<Logger>) -> ChainWatchInterfaceUtil {
240 ChainWatchInterfaceUtil {
242 watched: Mutex::new(ChainWatchedUtil::new()),
243 listeners: Mutex::new(Vec::new()),
244 reentered: AtomicUsize::new(1),
249 /// Notify listeners that a block was connected given a full, unfiltered block.
250 /// Handles re-scanning the block and calling block_connected again if listeners register new
251 /// watch data during the callbacks for you (see ChainListener::block_connected for more info).
252 pub fn block_connected_with_filtering(&self, block: &Block, height: u32) {
253 let mut reentered = true;
255 let mut matched = Vec::new();
256 let mut matched_index = Vec::new();
258 let watched = self.watched.lock().unwrap();
259 for (index, transaction) in block.txdata.iter().enumerate() {
260 if self.does_match_tx_unguarded(transaction, &watched) {
261 matched.push(transaction);
262 matched_index.push(index as u32);
266 reentered = self.block_connected_checked(&block.header, height, matched.as_slice(), matched_index.as_slice());
270 /// Notify listeners that a block was disconnected.
271 pub fn block_disconnected(&self, header: &BlockHeader) {
272 let listeners = self.listeners.lock().unwrap().clone();
273 for listener in listeners.iter() {
274 match listener.upgrade() {
275 Some(arc) => arc.block_disconnected(header),
281 /// Notify listeners that a block was connected, given pre-filtered list of transactions in the
282 /// block which matched the filter (probably using does_match_tx).
283 /// Returns true if notified listeners registered additional watch data (implying that the
284 /// block must be re-scanned and this function called again prior to further block_connected
285 /// calls, see ChainListener::block_connected for more info).
286 pub fn block_connected_checked(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> bool {
287 let last_seen = self.reentered.load(Ordering::Relaxed);
289 let listeners = self.listeners.lock().unwrap().clone();
290 for listener in listeners.iter() {
291 match listener.upgrade() {
292 Some(arc) => arc.block_connected(header, height, txn_matched, indexes_of_txn_matched),
296 return last_seen != self.reentered.load(Ordering::Relaxed);
299 /// Checks if a given transaction matches the current filter.
300 pub fn does_match_tx(&self, tx: &Transaction) -> bool {
301 let watched = self.watched.lock().unwrap();
302 self.does_match_tx_unguarded (tx, &watched)
305 fn does_match_tx_unguarded(&self, tx: &Transaction, watched: &MutexGuard<ChainWatchedUtil>) -> bool {
306 watched.does_match_tx(tx)