_ Git - rust-lightning/blob - lightning-transaction-sync/src/esplora.rs

   1 use crate::error::{TxSyncError, InternalError};
   2 use crate::common::{SyncState, FilterQueue, ConfirmedTx};
   3
   4 use lightning::util::logger::Logger;
   5 use lightning::{log_error, log_debug, log_trace};
   6 use lightning::chain::WatchedOutput;
   7 use lightning::chain::{Confirm, Filter};
   8
   9 use bitcoin::{BlockHash, Script, Txid};
  10
  11 use esplora_client::Builder;
  12 #[cfg(feature = "async-interface")]
  13 use esplora_client::r#async::AsyncClient;
  14 #[cfg(not(feature = "async-interface"))]
  15 use esplora_client::blocking::BlockingClient;
  16
  17 use std::time::Instant;
  18 use std::collections::HashSet;
  19 use core::ops::Deref;
  20
  21 /// Synchronizes LDK with a given [`Esplora`] server.
  22 ///
  23 /// Needs to be registered with a [`ChainMonitor`] via the [`Filter`] interface to be informed of
  24 /// transactions and outputs to monitor for on-chain confirmation, unconfirmation, and
  25 /// reconfirmation.
  26 ///
  27 /// Note that registration via [`Filter`] needs to happen before any calls to
  28 /// [`Watch::watch_channel`] to ensure we get notified of the items to monitor.
  29 ///
  30 /// This uses and exposes either a blocking or async client variant dependent on whether the
  31 /// `esplora-blocking` or the `esplora-async` feature is enabled.
  32 ///
  33 /// [`Esplora`]: https://github.com/Blockstream/electrs
  34 /// [`ChainMonitor`]: lightning::chain::chainmonitor::ChainMonitor
  35 /// [`Watch::watch_channel`]: lightning::chain::Watch::watch_channel
  36 /// [`Filter`]: lightning::chain::Filter
  37 pub struct EsploraSyncClient<L: Deref>
  38 where
  39         L::Target: Logger,
  40 {
  41         sync_state: MutexType<SyncState>,
  42         queue: std::sync::Mutex<FilterQueue>,
  43         client: EsploraClientType,
  44         logger: L,
  45 }
  46
  47 impl<L: Deref> EsploraSyncClient<L>
  48 where
  49         L::Target: Logger,
  50 {
  51         /// Returns a new [`EsploraSyncClient`] object.
  52         pub fn new(server_url: String, logger: L) -> Self {
  53                 let builder = Builder::new(&server_url);
  54                 #[cfg(not(feature = "async-interface"))]
  55                 let client = builder.build_blocking().unwrap();
  56                 #[cfg(feature = "async-interface")]
  57                 let client = builder.build_async().unwrap();
  58
  59                 EsploraSyncClient::from_client(client, logger)
  60         }
  61
  62         /// Returns a new [`EsploraSyncClient`] object using the given Esplora client.
  63         pub fn from_client(client: EsploraClientType, logger: L) -> Self {
  64                 let sync_state = MutexType::new(SyncState::new());
  65                 let queue = std::sync::Mutex::new(FilterQueue::new());
  66                 Self {
  67                         sync_state,
  68                         queue,
  69                         client,
  70                         logger,
  71                 }
  72         }
  73
  74         /// Synchronizes the given `confirmables` via their [`Confirm`] interface implementations. This
  75         /// method should be called regularly to keep LDK up-to-date with current chain data.
  76         ///
  77         /// For example, instances of [`ChannelManager`] and [`ChainMonitor`] can be informed about the
  78         /// newest on-chain activity related to the items previously registered via the [`Filter`]
  79         /// interface.
  80         ///
  81         /// [`Confirm`]: lightning::chain::Confirm
  82         /// [`ChainMonitor`]: lightning::chain::chainmonitor::ChainMonitor
  83         /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
  84         /// [`Filter`]: lightning::chain::Filter
  85         #[maybe_async]
  86         pub fn sync(&self, confirmables: Vec<&(dyn Confirm + Sync + Send)>) -> Result<(), TxSyncError> {
  87                 // This lock makes sure we're syncing once at a time.
  88                 #[cfg(not(feature = "async-interface"))]
  89                 let mut sync_state = self.sync_state.lock().unwrap();
  90                 #[cfg(feature = "async-interface")]
  91                 let mut sync_state = self.sync_state.lock().await;
  92
  93                 log_trace!(self.logger, "Starting transaction sync.");
  94                 let start_time = Instant::now();
  95                 let mut num_confirmed = 0;
  96                 let mut num_unconfirmed = 0;
  97
  98                 let mut tip_hash = maybe_await!(self.client.get_tip_hash())?;
  99
 100                 loop {
 101                         let pending_registrations = self.queue.lock().unwrap().process_queues(&mut sync_state);
 102                         let tip_is_new = Some(tip_hash) != sync_state.last_sync_hash;
 103
 104                         // We loop until any registered transactions have been processed at least once, or the
 105                         // tip hasn't been updated during the last iteration.
 106                         if !sync_state.pending_sync && !pending_registrations && !tip_is_new {
 107                                 // Nothing to do.
 108                                 break;
 109                         } else {
 110                                 // Update the known tip to the newest one.
 111                                 if tip_is_new {
 112                                         // First check for any unconfirmed transactions and act on it immediately.
 113                                         match maybe_await!(self.get_unconfirmed_transactions(&confirmables)) {
 114                                                 Ok(unconfirmed_txs) => {
 115                                                         // Double-check the tip hash. If it changed, a reorg happened since
 116                                                         // we started syncing and we need to restart last-minute.
 117                                                         let check_tip_hash = maybe_await!(self.client.get_tip_hash())?;
 118                                                         if check_tip_hash != tip_hash {
 119                                                                 tip_hash = check_tip_hash;
 120
 121                                                                 log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 122                                                                 sync_state.pending_sync = true;
 123                                                                 continue;
 124                                                         }
 125                                                         num_unconfirmed += unconfirmed_txs.len();
 126                                                         sync_state.sync_unconfirmed_transactions(&confirmables, unconfirmed_txs);
 127                                                 },
 128                                                 Err(err) => {
 129                                                         // (Semi-)permanent failure, retry later.
 130                                                         log_error!(self.logger,
 131                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 132                                                                 num_confirmed,
 133                                                                 num_unconfirmed
 134                                                         );
 135                                                         sync_state.pending_sync = true;
 136                                                         return Err(TxSyncError::from(err));
 137                                                 }
 138                                         }
 139
 140                                         match maybe_await!(self.sync_best_block_updated(&confirmables, &tip_hash)) {
 141                                                 Ok(()) => {}
 142                                                 Err(InternalError::Inconsistency) => {
 143                                                         // Immediately restart syncing when we encounter any inconsistencies.
 144                                                         log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 145                                                         sync_state.pending_sync = true;
 146                                                         continue;
 147                                                 }
 148                                                 Err(err) => {
 149                                                         // (Semi-)permanent failure, retry later.
 150                                                         log_error!(self.logger,
 151                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 152                                                                 num_confirmed,
 153                                                                 num_unconfirmed
 154                                                         );
 155                                                         sync_state.pending_sync = true;
 156                                                         return Err(TxSyncError::from(err));
 157                                                 }
 158                                         }
 159                                 }
 160
 161                                 match maybe_await!(self.get_confirmed_transactions(&sync_state)) {
 162                                         Ok(confirmed_txs) => {
 163                                                 // Double-check the tip hash. If it changed, a reorg happened since
 164                                                 // we started syncing and we need to restart last-minute.
 165                                                 let check_tip_hash = maybe_await!(self.client.get_tip_hash())?;
 166                                                 if check_tip_hash != tip_hash {
 167                                                         tip_hash = check_tip_hash;
 168                                                         continue;
 169                                                 }
 170
 171                                                 num_confirmed += confirmed_txs.len();
 172                                                 sync_state.sync_confirmed_transactions(
 173                                                         &confirmables,
 174                                                         confirmed_txs,
 175                                                 );
 176                                         }
 177                                         Err(InternalError::Inconsistency) => {
 178                                                 // Immediately restart syncing when we encounter any inconsistencies.
 179                                                 log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 180                                                 sync_state.pending_sync = true;
 181                                                 continue;
 182                                         }
 183                                         Err(err) => {
 184                                                 // (Semi-)permanent failure, retry later.
 185                                                 log_error!(self.logger,
 186                                                         "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 187                                                         num_confirmed,
 188                                                         num_unconfirmed
 189                                                 );
 190                                                 sync_state.pending_sync = true;
 191                                                 return Err(TxSyncError::from(err));
 192                                         }
 193                                 }
 194                                 sync_state.last_sync_hash = Some(tip_hash);
 195                                 sync_state.pending_sync = false;
 196                         }
 197                 }
 198                 log_debug!(self.logger, "Finished transaction sync at tip {} in {}ms: {} confirmed, {} unconfirmed.",
 199                                 tip_hash, start_time.elapsed().as_millis(), num_confirmed, num_unconfirmed);
 200                 Ok(())
 201         }
 202
 203         #[maybe_async]
 204         fn sync_best_block_updated(
 205                 &self, confirmables: &Vec<&(dyn Confirm + Sync + Send)>, tip_hash: &BlockHash,
 206         ) -> Result<(), InternalError> {
 207
 208                 // Inform the interface of the new block.
 209                 let tip_header = maybe_await!(self.client.get_header_by_hash(tip_hash))?;
 210                 let tip_status = maybe_await!(self.client.get_block_status(&tip_hash))?;
 211                 if tip_status.in_best_chain {
 212                         if let Some(tip_height) = tip_status.height {
 213                                 for c in confirmables {
 214                                         c.best_block_updated(&tip_header, tip_height);
 215                                 }
 216                         }
 217                 } else {
 218                         return Err(InternalError::Inconsistency);
 219                 }
 220                 Ok(())
 221         }
 222
 223         #[maybe_async]
 224         fn get_confirmed_transactions(
 225                 &self, sync_state: &SyncState,
 226         ) -> Result<Vec<ConfirmedTx>, InternalError> {
 227
 228                 // First, check the confirmation status of registered transactions as well as the
 229                 // status of dependent transactions of registered outputs.
 230
 231                 let mut confirmed_txs = Vec::new();
 232
 233                 for txid in &sync_state.watched_transactions {
 234                         if let Some(confirmed_tx) = maybe_await!(self.get_confirmed_tx(&txid, None, None))? {
 235                                 confirmed_txs.push(confirmed_tx);
 236                         }
 237                 }
 238
 239                 for (_, output) in &sync_state.watched_outputs {
 240                         if let Some(output_status) = maybe_await!(self.client
 241                                 .get_output_status(&output.outpoint.txid, output.outpoint.index as u64))?
 242                         {
 243                                 if let Some(spending_txid) = output_status.txid {
 244                                         if let Some(spending_tx_status) = output_status.status {
 245                                                 if let Some(confirmed_tx) = maybe_await!(self
 246                                                         .get_confirmed_tx(
 247                                                                 &spending_txid,
 248                                                                 spending_tx_status.block_hash,
 249                                                                 spending_tx_status.block_height,
 250                                                         ))?
 251                                                 {
 252                                                         confirmed_txs.push(confirmed_tx);
 253                                                 }
 254                                         }
 255                                 }
 256                         }
 257                 }
 258
 259                 // Sort all confirmed transactions first by block height, then by in-block
 260                 // position, and finally feed them to the interface in order.
 261                 confirmed_txs.sort_unstable_by(|tx1, tx2| {
 262                         tx1.block_height.cmp(&tx2.block_height).then_with(|| tx1.pos.cmp(&tx2.pos))
 263                 });
 264
 265                 Ok(confirmed_txs)
 266         }
 267
 268         #[maybe_async]
 269         fn get_confirmed_tx(
 270                 &self, txid: &Txid, expected_block_hash: Option<BlockHash>, known_block_height: Option<u32>,
 271         ) -> Result<Option<ConfirmedTx>, InternalError> {
 272                 if let Some(merkle_block) = maybe_await!(self.client.get_merkle_block(&txid))? {
 273                         let block_header = merkle_block.header;
 274                         let block_hash = block_header.block_hash();
 275                         if let Some(expected_block_hash) = expected_block_hash {
 276                                 if expected_block_hash != block_hash {
 277                                         log_trace!(self.logger, "Inconsistency: Tx {} expected in block {}, but is confirmed in {}", txid, expected_block_hash, block_hash);
 278                                         return Err(InternalError::Inconsistency);
 279                                 }
 280                         }
 281
 282                         let mut matches = Vec::new();
 283                         let mut indexes = Vec::new();
 284                         let _ = merkle_block.txn.extract_matches(&mut matches, &mut indexes);
 285                         if indexes.len() != 1 || matches.len() != 1 || matches[0] != *txid {
 286                                 log_error!(self.logger, "Retrieved Merkle block for txid {} doesn't match expectations. This should not happen. Please verify server integrity.", txid);
 287                                 return Err(InternalError::Failed);
 288                         }
 289
 290                         // unwrap() safety: len() > 0 is checked above
 291                         let pos = *indexes.first().unwrap() as usize;
 292                         if let Some(tx) = maybe_await!(self.client.get_tx(&txid))? {
 293                                 if let Some(block_height) = known_block_height {
 294                                         // We can take a shortcut here if a previous call already gave us the height.
 295                                         return Ok(Some(ConfirmedTx { tx, block_header, pos, block_height }));
 296                                 }
 297
 298                                 let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
 299                                 if let Some(block_height) = block_status.height {
 300                                         return Ok(Some(ConfirmedTx { tx, block_header, pos, block_height }));
 301                                 } else {
 302                                         // If any previously-confirmed block suddenly is no longer confirmed, we found
 303                                         // an inconsistency and should start over.
 304                                         log_trace!(self.logger, "Inconsistency: Tx {} was unconfirmed during syncing.", txid);
 305                                         return Err(InternalError::Inconsistency);
 306                                 }
 307                         }
 308                 }
 309                 Ok(None)
 310         }
 311
 312         #[maybe_async]
 313         fn get_unconfirmed_transactions(
 314                 &self, confirmables: &Vec<&(dyn Confirm + Sync + Send)>,
 315         ) -> Result<Vec<Txid>, InternalError> {
 316                 // Query the interface for relevant txids and check whether the relevant blocks are still
 317                 // in the best chain, mark them unconfirmed otherwise
 318                 let relevant_txids = confirmables
 319                         .iter()
 320                         .flat_map(|c| c.get_relevant_txids())
 321                         .collect::<HashSet<(Txid, u32, Option<BlockHash>)>>();
 322
 323                 let mut unconfirmed_txs = Vec::new();
 324
 325                 for (txid, _conf_height, block_hash_opt) in relevant_txids {
 326                         if let Some(block_hash) = block_hash_opt {
 327                                 let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
 328                                 if block_status.in_best_chain {
 329                                         // Skip if the block in question is still confirmed.
 330                                         continue;
 331                                 }
 332
 333                                 unconfirmed_txs.push(txid);
 334                         } else {
 335                                 log_error!(self.logger, "Untracked confirmation of funding transaction. Please ensure none of your channels had been created with LDK prior to version 0.0.113!");
 336                                 panic!("Untracked confirmation of funding transaction. Please ensure none of your channels had been created with LDK prior to version 0.0.113!");
 337                         }
 338                 }
 339                 Ok(unconfirmed_txs)
 340         }
 341
 342         /// Returns a reference to the underlying esplora client.
 343         pub fn client(&self) -> &EsploraClientType {
 344                 &self.client
 345         }
 346 }
 347
 348 #[cfg(feature = "async-interface")]
 349 type MutexType<I> = futures::lock::Mutex<I>;
 350 #[cfg(not(feature = "async-interface"))]
 351 type MutexType<I> = std::sync::Mutex<I>;
 352
 353 // The underlying client type.
 354 #[cfg(feature = "async-interface")]
 355 type EsploraClientType = AsyncClient;
 356 #[cfg(not(feature = "async-interface"))]
 357 type EsploraClientType = BlockingClient;
 358
 359
 360 impl<L: Deref> Filter for EsploraSyncClient<L>
 361 where
 362         L::Target: Logger,
 363 {
 364         fn register_tx(&self, txid: &Txid, _script_pubkey: &Script) {
 365                 let mut locked_queue = self.queue.lock().unwrap();
 366                 locked_queue.transactions.insert(*txid);
 367         }
 368
 369         fn register_output(&self, output: WatchedOutput) {
 370                 let mut locked_queue = self.queue.lock().unwrap();
 371                 locked_queue.outputs.insert(output.outpoint.into_bitcoin_outpoint(), output);
 372         }
 373 }