_ 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();
  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         ///
  63         /// This is not exported to bindings users as the underlying client from BDK is not exported.
  64         pub fn from_client(client: EsploraClientType, logger: L) -> Self {
  65                 let sync_state = MutexType::new(SyncState::new());
  66                 let queue = std::sync::Mutex::new(FilterQueue::new());
  67                 Self {
  68                         sync_state,
  69                         queue,
  70                         client,
  71                         logger,
  72                 }
  73         }
  74
  75         /// Synchronizes the given `confirmables` via their [`Confirm`] interface implementations. This
  76         /// method should be called regularly to keep LDK up-to-date with current chain data.
  77         ///
  78         /// For example, instances of [`ChannelManager`] and [`ChainMonitor`] can be informed about the
  79         /// newest on-chain activity related to the items previously registered via the [`Filter`]
  80         /// interface.
  81         ///
  82         /// [`Confirm`]: lightning::chain::Confirm
  83         /// [`ChainMonitor`]: lightning::chain::chainmonitor::ChainMonitor
  84         /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
  85         /// [`Filter`]: lightning::chain::Filter
  86         #[maybe_async]
  87         pub fn sync(&self, confirmables: Vec<&(dyn Confirm + Sync + Send)>) -> Result<(), TxSyncError> {
  88                 // This lock makes sure we're syncing once at a time.
  89                 #[cfg(not(feature = "async-interface"))]
  90                 let mut sync_state = self.sync_state.lock().unwrap();
  91                 #[cfg(feature = "async-interface")]
  92                 let mut sync_state = self.sync_state.lock().await;
  93
  94                 log_trace!(self.logger, "Starting transaction sync.");
  95                 #[cfg(feature = "time")]
  96                 let start_time = std::time::Instant::now();
  97                 let mut num_confirmed = 0;
  98                 let mut num_unconfirmed = 0;
  99
 100                 let mut tip_hash = maybe_await!(self.client.get_tip_hash())?;
 101
 102                 loop {
 103                         let pending_registrations = self.queue.lock().unwrap().process_queues(&mut sync_state);
 104                         let tip_is_new = Some(tip_hash) != sync_state.last_sync_hash;
 105
 106                         // We loop until any registered transactions have been processed at least once, or the
 107                         // tip hasn't been updated during the last iteration.
 108                         if !sync_state.pending_sync && !pending_registrations && !tip_is_new {
 109                                 // Nothing to do.
 110                                 break;
 111                         } else {
 112                                 // Update the known tip to the newest one.
 113                                 if tip_is_new {
 114                                         // First check for any unconfirmed transactions and act on it immediately.
 115                                         match maybe_await!(self.get_unconfirmed_transactions(&confirmables)) {
 116                                                 Ok(unconfirmed_txs) => {
 117                                                         // Double-check the tip hash. If it changed, a reorg happened since
 118                                                         // we started syncing and we need to restart last-minute.
 119                                                         match maybe_await!(self.client.get_tip_hash()) {
 120                                                                 Ok(check_tip_hash) => {
 121                                                                         if check_tip_hash != tip_hash {
 122                                                                                 tip_hash = check_tip_hash;
 123
 124                                                                                 log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 125                                                                                 sync_state.pending_sync = true;
 126                                                                                 continue;
 127                                                                         }
 128                                                                         num_unconfirmed += unconfirmed_txs.len();
 129                                                                         sync_state.sync_unconfirmed_transactions(
 130                                                                                 &confirmables,
 131                                                                                 unconfirmed_txs
 132                                                                         );
 133                                                                 }
 134                                                                 Err(err) => {
 135                                                                         // (Semi-)permanent failure, retry later.
 136                                                                         log_error!(self.logger,
 137                                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 138                                                                                 num_confirmed,
 139                                                                                 num_unconfirmed
 140                                                                                 );
 141                                                                         sync_state.pending_sync = true;
 142                                                                         return Err(TxSyncError::from(err));
 143                                                                 }
 144                                                         }
 145                                                 },
 146                                                 Err(err) => {
 147                                                         // (Semi-)permanent failure, retry later.
 148                                                         log_error!(self.logger,
 149                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 150                                                                 num_confirmed,
 151                                                                 num_unconfirmed
 152                                                         );
 153                                                         sync_state.pending_sync = true;
 154                                                         return Err(TxSyncError::from(err));
 155                                                 }
 156                                         }
 157
 158                                         match maybe_await!(self.sync_best_block_updated(&confirmables, &mut sync_state, &tip_hash)) {
 159                                                 Ok(()) => {}
 160                                                 Err(InternalError::Inconsistency) => {
 161                                                         // Immediately restart syncing when we encounter any inconsistencies.
 162                                                         log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 163                                                         sync_state.pending_sync = true;
 164                                                         continue;
 165                                                 }
 166                                                 Err(err) => {
 167                                                         // (Semi-)permanent failure, retry later.
 168                                                         log_error!(self.logger,
 169                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 170                                                                 num_confirmed,
 171                                                                 num_unconfirmed
 172                                                         );
 173                                                         sync_state.pending_sync = true;
 174                                                         return Err(TxSyncError::from(err));
 175                                                 }
 176                                         }
 177                                 }
 178
 179                                 match maybe_await!(self.get_confirmed_transactions(&sync_state)) {
 180                                         Ok(confirmed_txs) => {
 181                                                 // Double-check the tip hash. If it changed, a reorg happened since
 182                                                 // we started syncing and we need to restart last-minute.
 183                                                 match maybe_await!(self.client.get_tip_hash()) {
 184                                                         Ok(check_tip_hash) => {
 185                                                                 if check_tip_hash != tip_hash {
 186                                                                         tip_hash = check_tip_hash;
 187
 188                                                                         log_debug!(self.logger,
 189                                                                                 "Encountered inconsistency during transaction sync, restarting.");
 190                                                                         sync_state.pending_sync = true;
 191                                                                         continue;
 192                                                                 }
 193                                                                 num_confirmed += confirmed_txs.len();
 194                                                                 sync_state.sync_confirmed_transactions(
 195                                                                         &confirmables,
 196                                                                         confirmed_txs
 197                                                                 );
 198                                                         }
 199                                                         Err(err) => {
 200                                                                 // (Semi-)permanent failure, retry later.
 201                                                                 log_error!(self.logger,
 202                                                                         "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 203                                                                         num_confirmed,
 204                                                                         num_unconfirmed
 205                                                                 );
 206                                                                 sync_state.pending_sync = true;
 207                                                                 return Err(TxSyncError::from(err));
 208                                                         }
 209                                                 }
 210                                         }
 211                                         Err(InternalError::Inconsistency) => {
 212                                                 // Immediately restart syncing when we encounter any inconsistencies.
 213                                                 log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 214                                                 sync_state.pending_sync = true;
 215                                                 continue;
 216                                         }
 217                                         Err(err) => {
 218                                                 // (Semi-)permanent failure, retry later.
 219                                                 log_error!(self.logger,
 220                                                         "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 221                                                         num_confirmed,
 222                                                         num_unconfirmed
 223                                                 );
 224                                                 sync_state.pending_sync = true;
 225                                                 return Err(TxSyncError::from(err));
 226                                         }
 227                                 }
 228                                 sync_state.last_sync_hash = Some(tip_hash);
 229                                 sync_state.pending_sync = false;
 230                         }
 231                 }
 232                 #[cfg(feature = "time")]
 233                 log_debug!(self.logger, "Finished transaction sync at tip {} in {}ms: {} confirmed, {} unconfirmed.",
 234                                 tip_hash, start_time.elapsed().as_millis(), num_confirmed, num_unconfirmed);
 235                 #[cfg(not(feature = "time"))]
 236                 log_debug!(self.logger, "Finished transaction sync at tip {}: {} confirmed, {} unconfirmed.",
 237                                 tip_hash, num_confirmed, num_unconfirmed);
 238                 Ok(())
 239         }
 240
 241         #[maybe_async]
 242         fn sync_best_block_updated(
 243                 &self, confirmables: &Vec<&(dyn Confirm + Sync + Send)>, sync_state: &mut SyncState, tip_hash: &BlockHash,
 244         ) -> Result<(), InternalError> {
 245
 246                 // Inform the interface of the new block.
 247                 let tip_header = maybe_await!(self.client.get_header_by_hash(tip_hash))?;
 248                 let tip_status = maybe_await!(self.client.get_block_status(&tip_hash))?;
 249                 if tip_status.in_best_chain {
 250                         if let Some(tip_height) = tip_status.height {
 251                                 for c in confirmables {
 252                                         c.best_block_updated(&tip_header, tip_height);
 253                                 }
 254
 255                                 // Prune any sufficiently confirmed output spends
 256                                 sync_state.prune_output_spends(tip_height);
 257                         }
 258                 } else {
 259                         return Err(InternalError::Inconsistency);
 260                 }
 261                 Ok(())
 262         }
 263
 264         #[maybe_async]
 265         fn get_confirmed_transactions(
 266                 &self, sync_state: &SyncState,
 267         ) -> Result<Vec<ConfirmedTx>, InternalError> {
 268
 269                 // First, check the confirmation status of registered transactions as well as the
 270                 // status of dependent transactions of registered outputs.
 271
 272                 let mut confirmed_txs: Vec<ConfirmedTx> = Vec::new();
 273
 274                 for txid in &sync_state.watched_transactions {
 275                         if confirmed_txs.iter().any(|ctx| ctx.txid == *txid) {
 276                                 continue;
 277                         }
 278                         if let Some(confirmed_tx) = maybe_await!(self.get_confirmed_tx(*txid, None, None))? {
 279                                 confirmed_txs.push(confirmed_tx);
 280                         }
 281                 }
 282
 283                 for (_, output) in &sync_state.watched_outputs {
 284                         if let Some(output_status) = maybe_await!(self.client
 285                                 .get_output_status(&output.outpoint.txid, output.outpoint.index as u64))?
 286                         {
 287                                 if let Some(spending_txid) = output_status.txid {
 288                                         if let Some(spending_tx_status) = output_status.status {
 289                                                 if confirmed_txs.iter().any(|ctx| ctx.txid == spending_txid) {
 290                                                         if spending_tx_status.confirmed {
 291                                                                 // Skip inserting duplicate ConfirmedTx entry
 292                                                                 continue;
 293                                                         } else {
 294                                                                 log_trace!(self.logger, "Inconsistency: Detected previously-confirmed Tx {} as unconfirmed", spending_txid);
 295                                                                 return Err(InternalError::Inconsistency);
 296                                                         }
 297                                                 }
 298
 299                                                 if let Some(confirmed_tx) = maybe_await!(self
 300                                                         .get_confirmed_tx(
 301                                                                 spending_txid,
 302                                                                 spending_tx_status.block_hash,
 303                                                                 spending_tx_status.block_height,
 304                                                         ))?
 305                                                 {
 306                                                         confirmed_txs.push(confirmed_tx);
 307                                                 }
 308                                         }
 309                                 }
 310                         }
 311                 }
 312
 313                 // Sort all confirmed transactions first by block height, then by in-block
 314                 // position, and finally feed them to the interface in order.
 315                 confirmed_txs.sort_unstable_by(|tx1, tx2| {
 316                         tx1.block_height.cmp(&tx2.block_height).then_with(|| tx1.pos.cmp(&tx2.pos))
 317                 });
 318
 319                 Ok(confirmed_txs)
 320         }
 321
 322         #[maybe_async]
 323         fn get_confirmed_tx(
 324                 &self, txid: Txid, expected_block_hash: Option<BlockHash>, known_block_height: Option<u32>,
 325         ) -> Result<Option<ConfirmedTx>, InternalError> {
 326                 if let Some(merkle_block) = maybe_await!(self.client.get_merkle_block(&txid))? {
 327                         let block_header = merkle_block.header;
 328                         let block_hash = block_header.block_hash();
 329                         if let Some(expected_block_hash) = expected_block_hash {
 330                                 if expected_block_hash != block_hash {
 331                                         log_trace!(self.logger, "Inconsistency: Tx {} expected in block {}, but is confirmed in {}", txid, expected_block_hash, block_hash);
 332                                         return Err(InternalError::Inconsistency);
 333                                 }
 334                         }
 335
 336                         let mut matches = Vec::new();
 337                         let mut indexes = Vec::new();
 338                         let _ = merkle_block.txn.extract_matches(&mut matches, &mut indexes);
 339                         if indexes.len() != 1 || matches.len() != 1 || matches[0] != txid {
 340                                 log_error!(self.logger, "Retrieved Merkle block for txid {} doesn't match expectations. This should not happen. Please verify server integrity.", txid);
 341                                 return Err(InternalError::Failed);
 342                         }
 343
 344                         // unwrap() safety: len() > 0 is checked above
 345                         let pos = *indexes.first().unwrap() as usize;
 346                         if let Some(tx) = maybe_await!(self.client.get_tx(&txid))? {
 347                                 if tx.txid() != txid {
 348                                         log_error!(self.logger, "Retrieved transaction for txid {} doesn't match expectations. This should not happen. Please verify server integrity.", txid);
 349                                         return Err(InternalError::Failed);
 350                                 }
 351
 352                                 if let Some(block_height) = known_block_height {
 353                                         // We can take a shortcut here if a previous call already gave us the height.
 354                                         return Ok(Some(ConfirmedTx { tx, txid, block_header, pos, block_height }));
 355                                 }
 356
 357                                 let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
 358                                 if let Some(block_height) = block_status.height {
 359                                         return Ok(Some(ConfirmedTx { tx, txid, block_header, pos, block_height }));
 360                                 } else {
 361                                         // If any previously-confirmed block suddenly is no longer confirmed, we found
 362                                         // an inconsistency and should start over.
 363                                         log_trace!(self.logger, "Inconsistency: Tx {} was unconfirmed during syncing.", txid);
 364                                         return Err(InternalError::Inconsistency);
 365                                 }
 366                         }
 367                 }
 368                 Ok(None)
 369         }
 370
 371         #[maybe_async]
 372         fn get_unconfirmed_transactions(
 373                 &self, confirmables: &Vec<&(dyn Confirm + Sync + Send)>,
 374         ) -> Result<Vec<Txid>, InternalError> {
 375                 // Query the interface for relevant txids and check whether the relevant blocks are still
 376                 // in the best chain, mark them unconfirmed otherwise
 377                 let relevant_txids = confirmables
 378                         .iter()
 379                         .flat_map(|c| c.get_relevant_txids())
 380                         .collect::<HashSet<(Txid, u32, Option<BlockHash>)>>();
 381
 382                 let mut unconfirmed_txs = Vec::new();
 383
 384                 for (txid, _conf_height, block_hash_opt) in relevant_txids {
 385                         if let Some(block_hash) = block_hash_opt {
 386                                 let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
 387                                 if block_status.in_best_chain {
 388                                         // Skip if the block in question is still confirmed.
 389                                         continue;
 390                                 }
 391
 392                                 unconfirmed_txs.push(txid);
 393                         } else {
 394                                 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!");
 395                                 panic!("Untracked confirmation of funding transaction. Please ensure none of your channels had been created with LDK prior to version 0.0.113!");
 396                         }
 397                 }
 398                 Ok(unconfirmed_txs)
 399         }
 400
 401         /// Returns a reference to the underlying esplora client.
 402         ///
 403         /// This is not exported to bindings users as the underlying client from BDK is not exported.
 404         pub fn client(&self) -> &EsploraClientType {
 405                 &self.client
 406         }
 407 }
 408
 409 #[cfg(feature = "async-interface")]
 410 type MutexType<I> = futures::lock::Mutex<I>;
 411 #[cfg(not(feature = "async-interface"))]
 412 type MutexType<I> = std::sync::Mutex<I>;
 413
 414 // The underlying client type.
 415 #[cfg(feature = "async-interface")]
 416 type EsploraClientType = AsyncClient;
 417 #[cfg(not(feature = "async-interface"))]
 418 type EsploraClientType = BlockingClient;
 419
 420
 421 impl<L: Deref> Filter for EsploraSyncClient<L>
 422 where
 423         L::Target: Logger,
 424 {
 425         fn register_tx(&self, txid: &Txid, _script_pubkey: &Script) {
 426                 let mut locked_queue = self.queue.lock().unwrap();
 427                 locked_queue.transactions.insert(*txid);
 428         }
 429
 430         fn register_output(&self, output: WatchedOutput) {
 431                 let mut locked_queue = self.queue.lock().unwrap();
 432                 locked_queue.outputs.insert(output.outpoint.into_bitcoin_outpoint(), output);
 433         }
 434 }