_ 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::collections::HashSet;
  18 use core::ops::Deref;
  19
  20 /// Synchronizes LDK with a given [`Esplora`] server.
  21 ///
  22 /// Needs to be registered with a [`ChainMonitor`] via the [`Filter`] interface to be informed of
  23 /// transactions and outputs to monitor for on-chain confirmation, unconfirmation, and
  24 /// reconfirmation.
  25 ///
  26 /// Note that registration via [`Filter`] needs to happen before any calls to
  27 /// [`Watch::watch_channel`] to ensure we get notified of the items to monitor.
  28 ///
  29 /// This uses and exposes either a blocking or async client variant dependent on whether the
  30 /// `esplora-blocking` or the `esplora-async` feature is enabled.
  31 ///
  32 /// [`Esplora`]: https://github.com/Blockstream/electrs
  33 /// [`ChainMonitor`]: lightning::chain::chainmonitor::ChainMonitor
  34 /// [`Watch::watch_channel`]: lightning::chain::Watch::watch_channel
  35 /// [`Filter`]: lightning::chain::Filter
  36 pub struct EsploraSyncClient<L: Deref>
  37 where
  38         L::Target: Logger,
  39 {
  40         sync_state: MutexType<SyncState>,
  41         queue: std::sync::Mutex<FilterQueue>,
  42         client: EsploraClientType,
  43         logger: L,
  44 }
  45
  46 impl<L: Deref> EsploraSyncClient<L>
  47 where
  48         L::Target: Logger,
  49 {
  50         /// Returns a new [`EsploraSyncClient`] object.
  51         pub fn new(server_url: String, logger: L) -> Self {
  52                 let builder = Builder::new(&server_url);
  53                 #[cfg(not(feature = "async-interface"))]
  54                 let client = builder.build_blocking().unwrap();
  55                 #[cfg(feature = "async-interface")]
  56                 let client = builder.build_async().unwrap();
  57
  58                 EsploraSyncClient::from_client(client, logger)
  59         }
  60
  61         /// Returns a new [`EsploraSyncClient`] object using the given Esplora client.
  62         pub fn from_client(client: EsploraClientType, logger: L) -> Self {
  63                 let sync_state = MutexType::new(SyncState::new());
  64                 let queue = std::sync::Mutex::new(FilterQueue::new());
  65                 Self {
  66                         sync_state,
  67                         queue,
  68                         client,
  69                         logger,
  70                 }
  71         }
  72
  73         /// Synchronizes the given `confirmables` via their [`Confirm`] interface implementations. This
  74         /// method should be called regularly to keep LDK up-to-date with current chain data.
  75         ///
  76         /// For example, instances of [`ChannelManager`] and [`ChainMonitor`] can be informed about the
  77         /// newest on-chain activity related to the items previously registered via the [`Filter`]
  78         /// interface.
  79         ///
  80         /// [`Confirm`]: lightning::chain::Confirm
  81         /// [`ChainMonitor`]: lightning::chain::chainmonitor::ChainMonitor
  82         /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
  83         /// [`Filter`]: lightning::chain::Filter
  84         #[maybe_async]
  85         pub fn sync(&self, confirmables: Vec<&(dyn Confirm + Sync + Send)>) -> Result<(), TxSyncError> {
  86                 // This lock makes sure we're syncing once at a time.
  87                 #[cfg(not(feature = "async-interface"))]
  88                 let mut sync_state = self.sync_state.lock().unwrap();
  89                 #[cfg(feature = "async-interface")]
  90                 let mut sync_state = self.sync_state.lock().await;
  91
  92                 log_trace!(self.logger, "Starting transaction sync.");
  93                 #[cfg(feature = "time")]
  94                 let start_time = std::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                                                         match maybe_await!(self.client.get_tip_hash()) {
 118                                                                 Ok(check_tip_hash) => {
 119                                                                         if check_tip_hash != tip_hash {
 120                                                                                 tip_hash = check_tip_hash;
 121
 122                                                                                 log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 123                                                                                 sync_state.pending_sync = true;
 124                                                                                 continue;
 125                                                                         }
 126                                                                         num_unconfirmed += unconfirmed_txs.len();
 127                                                                         sync_state.sync_unconfirmed_transactions(
 128                                                                                 &confirmables,
 129                                                                                 unconfirmed_txs
 130                                                                         );
 131                                                                 }
 132                                                                 Err(err) => {
 133                                                                         // (Semi-)permanent failure, retry later.
 134                                                                         log_error!(self.logger,
 135                                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 136                                                                                 num_confirmed,
 137                                                                                 num_unconfirmed
 138                                                                                 );
 139                                                                         sync_state.pending_sync = true;
 140                                                                         return Err(TxSyncError::from(err));
 141                                                                 }
 142                                                         }
 143                                                 },
 144                                                 Err(err) => {
 145                                                         // (Semi-)permanent failure, retry later.
 146                                                         log_error!(self.logger,
 147                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 148                                                                 num_confirmed,
 149                                                                 num_unconfirmed
 150                                                         );
 151                                                         sync_state.pending_sync = true;
 152                                                         return Err(TxSyncError::from(err));
 153                                                 }
 154                                         }
 155
 156                                         match maybe_await!(self.sync_best_block_updated(&confirmables, &mut sync_state, &tip_hash)) {
 157                                                 Ok(()) => {}
 158                                                 Err(InternalError::Inconsistency) => {
 159                                                         // Immediately restart syncing when we encounter any inconsistencies.
 160                                                         log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 161                                                         sync_state.pending_sync = true;
 162                                                         continue;
 163                                                 }
 164                                                 Err(err) => {
 165                                                         // (Semi-)permanent failure, retry later.
 166                                                         log_error!(self.logger,
 167                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 168                                                                 num_confirmed,
 169                                                                 num_unconfirmed
 170                                                         );
 171                                                         sync_state.pending_sync = true;
 172                                                         return Err(TxSyncError::from(err));
 173                                                 }
 174                                         }
 175                                 }
 176
 177                                 match maybe_await!(self.get_confirmed_transactions(&sync_state)) {
 178                                         Ok(confirmed_txs) => {
 179                                                 // Double-check the tip hash. If it changed, a reorg happened since
 180                                                 // we started syncing and we need to restart last-minute.
 181                                                 match maybe_await!(self.client.get_tip_hash()) {
 182                                                         Ok(check_tip_hash) => {
 183                                                                 if check_tip_hash != tip_hash {
 184                                                                         tip_hash = check_tip_hash;
 185
 186                                                                         log_debug!(self.logger,
 187                                                                                 "Encountered inconsistency during transaction sync, restarting.");
 188                                                                         sync_state.pending_sync = true;
 189                                                                         continue;
 190                                                                 }
 191                                                                 num_confirmed += confirmed_txs.len();
 192                                                                 sync_state.sync_confirmed_transactions(
 193                                                                         &confirmables,
 194                                                                         confirmed_txs
 195                                                                 );
 196                                                         }
 197                                                         Err(err) => {
 198                                                                 // (Semi-)permanent failure, retry later.
 199                                                                 log_error!(self.logger,
 200                                                                         "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 201                                                                         num_confirmed,
 202                                                                         num_unconfirmed
 203                                                                 );
 204                                                                 sync_state.pending_sync = true;
 205                                                                 return Err(TxSyncError::from(err));
 206                                                         }
 207                                                 }
 208                                         }
 209                                         Err(InternalError::Inconsistency) => {
 210                                                 // Immediately restart syncing when we encounter any inconsistencies.
 211                                                 log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 212                                                 sync_state.pending_sync = true;
 213                                                 continue;
 214                                         }
 215                                         Err(err) => {
 216                                                 // (Semi-)permanent failure, retry later.
 217                                                 log_error!(self.logger,
 218                                                         "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 219                                                         num_confirmed,
 220                                                         num_unconfirmed
 221                                                 );
 222                                                 sync_state.pending_sync = true;
 223                                                 return Err(TxSyncError::from(err));
 224                                         }
 225                                 }
 226                                 sync_state.last_sync_hash = Some(tip_hash);
 227                                 sync_state.pending_sync = false;
 228                         }
 229                 }
 230                 #[cfg(feature = "time")]
 231                 log_debug!(self.logger, "Finished transaction sync at tip {} in {}ms: {} confirmed, {} unconfirmed.",
 232                                 tip_hash, start_time.elapsed().as_millis(), num_confirmed, num_unconfirmed);
 233                 #[cfg(not(feature = "time"))]
 234                 log_debug!(self.logger, "Finished transaction sync at tip {}: {} confirmed, {} unconfirmed.",
 235                                 tip_hash, num_confirmed, num_unconfirmed);
 236                 Ok(())
 237         }
 238
 239         #[maybe_async]
 240         fn sync_best_block_updated(
 241                 &self, confirmables: &Vec<&(dyn Confirm + Sync + Send)>, sync_state: &mut SyncState, tip_hash: &BlockHash,
 242         ) -> Result<(), InternalError> {
 243
 244                 // Inform the interface of the new block.
 245                 let tip_header = maybe_await!(self.client.get_header_by_hash(tip_hash))?;
 246                 let tip_status = maybe_await!(self.client.get_block_status(&tip_hash))?;
 247                 if tip_status.in_best_chain {
 248                         if let Some(tip_height) = tip_status.height {
 249                                 for c in confirmables {
 250                                         c.best_block_updated(&tip_header, tip_height);
 251                                 }
 252
 253                                 // Prune any sufficiently confirmed output spends
 254                                 sync_state.prune_output_spends(tip_height);
 255                         }
 256                 } else {
 257                         return Err(InternalError::Inconsistency);
 258                 }
 259                 Ok(())
 260         }
 261
 262         #[maybe_async]
 263         fn get_confirmed_transactions(
 264                 &self, sync_state: &SyncState,
 265         ) -> Result<Vec<ConfirmedTx>, InternalError> {
 266
 267                 // First, check the confirmation status of registered transactions as well as the
 268                 // status of dependent transactions of registered outputs.
 269
 270                 let mut confirmed_txs: Vec<ConfirmedTx> = Vec::new();
 271
 272                 for txid in &sync_state.watched_transactions {
 273                         if confirmed_txs.iter().any(|ctx| ctx.txid == *txid) {
 274                                 continue;
 275                         }
 276                         if let Some(confirmed_tx) = maybe_await!(self.get_confirmed_tx(*txid, None, None))? {
 277                                 confirmed_txs.push(confirmed_tx);
 278                         }
 279                 }
 280
 281                 for (_, output) in &sync_state.watched_outputs {
 282                         if let Some(output_status) = maybe_await!(self.client
 283                                 .get_output_status(&output.outpoint.txid, output.outpoint.index as u64))?
 284                         {
 285                                 if let Some(spending_txid) = output_status.txid {
 286                                         if let Some(spending_tx_status) = output_status.status {
 287                                                 if confirmed_txs.iter().any(|ctx| ctx.txid == spending_txid) {
 288                                                         if spending_tx_status.confirmed {
 289                                                                 // Skip inserting duplicate ConfirmedTx entry
 290                                                                 continue;
 291                                                         } else {
 292                                                                 log_trace!(self.logger, "Inconsistency: Detected previously-confirmed Tx {} as unconfirmed", spending_txid);
 293                                                                 return Err(InternalError::Inconsistency);
 294                                                         }
 295                                                 }
 296
 297                                                 if let Some(confirmed_tx) = maybe_await!(self
 298                                                         .get_confirmed_tx(
 299                                                                 spending_txid,
 300                                                                 spending_tx_status.block_hash,
 301                                                                 spending_tx_status.block_height,
 302                                                         ))?
 303                                                 {
 304                                                         confirmed_txs.push(confirmed_tx);
 305                                                 }
 306                                         }
 307                                 }
 308                         }
 309                 }
 310
 311                 // Sort all confirmed transactions first by block height, then by in-block
 312                 // position, and finally feed them to the interface in order.
 313                 confirmed_txs.sort_unstable_by(|tx1, tx2| {
 314                         tx1.block_height.cmp(&tx2.block_height).then_with(|| tx1.pos.cmp(&tx2.pos))
 315                 });
 316
 317                 Ok(confirmed_txs)
 318         }
 319
 320         #[maybe_async]
 321         fn get_confirmed_tx(
 322                 &self, txid: Txid, expected_block_hash: Option<BlockHash>, known_block_height: Option<u32>,
 323         ) -> Result<Option<ConfirmedTx>, InternalError> {
 324                 if let Some(merkle_block) = maybe_await!(self.client.get_merkle_block(&txid))? {
 325                         let block_header = merkle_block.header;
 326                         let block_hash = block_header.block_hash();
 327                         if let Some(expected_block_hash) = expected_block_hash {
 328                                 if expected_block_hash != block_hash {
 329                                         log_trace!(self.logger, "Inconsistency: Tx {} expected in block {}, but is confirmed in {}", txid, expected_block_hash, block_hash);
 330                                         return Err(InternalError::Inconsistency);
 331                                 }
 332                         }
 333
 334                         let mut matches = Vec::new();
 335                         let mut indexes = Vec::new();
 336                         let _ = merkle_block.txn.extract_matches(&mut matches, &mut indexes);
 337                         if indexes.len() != 1 || matches.len() != 1 || matches[0] != txid {
 338                                 log_error!(self.logger, "Retrieved Merkle block for txid {} doesn't match expectations. This should not happen. Please verify server integrity.", txid);
 339                                 return Err(InternalError::Failed);
 340                         }
 341
 342                         // unwrap() safety: len() > 0 is checked above
 343                         let pos = *indexes.first().unwrap() as usize;
 344                         if let Some(tx) = maybe_await!(self.client.get_tx(&txid))? {
 345                                 if tx.txid() != txid {
 346                                         log_error!(self.logger, "Retrieved transaction for txid {} doesn't match expectations. This should not happen. Please verify server integrity.", txid);
 347                                         return Err(InternalError::Failed);
 348                                 }
 349
 350                                 if let Some(block_height) = known_block_height {
 351                                         // We can take a shortcut here if a previous call already gave us the height.
 352                                         return Ok(Some(ConfirmedTx { tx, txid, block_header, pos, block_height }));
 353                                 }
 354
 355                                 let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
 356                                 if let Some(block_height) = block_status.height {
 357                                         return Ok(Some(ConfirmedTx { tx, txid, block_header, pos, block_height }));
 358                                 } else {
 359                                         // If any previously-confirmed block suddenly is no longer confirmed, we found
 360                                         // an inconsistency and should start over.
 361                                         log_trace!(self.logger, "Inconsistency: Tx {} was unconfirmed during syncing.", txid);
 362                                         return Err(InternalError::Inconsistency);
 363                                 }
 364                         }
 365                 }
 366                 Ok(None)
 367         }
 368
 369         #[maybe_async]
 370         fn get_unconfirmed_transactions(
 371                 &self, confirmables: &Vec<&(dyn Confirm + Sync + Send)>,
 372         ) -> Result<Vec<Txid>, InternalError> {
 373                 // Query the interface for relevant txids and check whether the relevant blocks are still
 374                 // in the best chain, mark them unconfirmed otherwise
 375                 let relevant_txids = confirmables
 376                         .iter()
 377                         .flat_map(|c| c.get_relevant_txids())
 378                         .collect::<HashSet<(Txid, u32, Option<BlockHash>)>>();
 379
 380                 let mut unconfirmed_txs = Vec::new();
 381
 382                 for (txid, _conf_height, block_hash_opt) in relevant_txids {
 383                         if let Some(block_hash) = block_hash_opt {
 384                                 let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
 385                                 if block_status.in_best_chain {
 386                                         // Skip if the block in question is still confirmed.
 387                                         continue;
 388                                 }
 389
 390                                 unconfirmed_txs.push(txid);
 391                         } else {
 392                                 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!");
 393                                 panic!("Untracked confirmation of funding transaction. Please ensure none of your channels had been created with LDK prior to version 0.0.113!");
 394                         }
 395                 }
 396                 Ok(unconfirmed_txs)
 397         }
 398
 399         /// Returns a reference to the underlying esplora client.
 400         pub fn client(&self) -> &EsploraClientType {
 401                 &self.client
 402         }
 403 }
 404
 405 #[cfg(feature = "async-interface")]
 406 type MutexType<I> = futures::lock::Mutex<I>;
 407 #[cfg(not(feature = "async-interface"))]
 408 type MutexType<I> = std::sync::Mutex<I>;
 409
 410 // The underlying client type.
 411 #[cfg(feature = "async-interface")]
 412 type EsploraClientType = AsyncClient;
 413 #[cfg(not(feature = "async-interface"))]
 414 type EsploraClientType = BlockingClient;
 415
 416
 417 impl<L: Deref> Filter for EsploraSyncClient<L>
 418 where
 419         L::Target: Logger,
 420 {
 421         fn register_tx(&self, txid: &Txid, _script_pubkey: &Script) {
 422                 let mut locked_queue = self.queue.lock().unwrap();
 423                 locked_queue.transactions.insert(*txid);
 424         }
 425
 426         fn register_output(&self, output: WatchedOutput) {
 427                 let mut locked_queue = self.queue.lock().unwrap();
 428                 locked_queue.outputs.insert(output.outpoint.into_bitcoin_outpoint(), output);
 429         }
 430 }