git.bitcoin.ninja 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<C: Deref>(&self, confirmables: Vec<C>) -> Result<(), TxSyncError>
  88                 where C::Target: Confirm
  89         {
  90                 // This lock makes sure we're syncing once at a time.
  91                 #[cfg(not(feature = "async-interface"))]
  92                 let mut sync_state = self.sync_state.lock().unwrap();
  93                 #[cfg(feature = "async-interface")]
  94                 let mut sync_state = self.sync_state.lock().await;
  95
  96                 log_trace!(self.logger, "Starting transaction sync.");
  97                 #[cfg(feature = "time")]
  98                 let start_time = std::time::Instant::now();
  99                 let mut num_confirmed = 0;
 100                 let mut num_unconfirmed = 0;
 101
 102                 let mut tip_hash = maybe_await!(self.client.get_tip_hash())?;
 103
 104                 loop {
 105                         let pending_registrations = self.queue.lock().unwrap().process_queues(&mut sync_state);
 106                         let tip_is_new = Some(tip_hash) != sync_state.last_sync_hash;
 107
 108                         // We loop until any registered transactions have been processed at least once, or the
 109                         // tip hasn't been updated during the last iteration.
 110                         if !sync_state.pending_sync && !pending_registrations && !tip_is_new {
 111                                 // Nothing to do.
 112                                 break;
 113                         } else {
 114                                 // Update the known tip to the newest one.
 115                                 if tip_is_new {
 116                                         // First check for any unconfirmed transactions and act on it immediately.
 117                                         match maybe_await!(self.get_unconfirmed_transactions(&confirmables)) {
 118                                                 Ok(unconfirmed_txs) => {
 119                                                         // Double-check the tip hash. If it changed, a reorg happened since
 120                                                         // we started syncing and we need to restart last-minute.
 121                                                         match maybe_await!(self.client.get_tip_hash()) {
 122                                                                 Ok(check_tip_hash) => {
 123                                                                         if check_tip_hash != tip_hash {
 124                                                                                 tip_hash = check_tip_hash;
 125
 126                                                                                 log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 127                                                                                 sync_state.pending_sync = true;
 128                                                                                 continue;
 129                                                                         }
 130                                                                         num_unconfirmed += unconfirmed_txs.len();
 131                                                                         sync_state.sync_unconfirmed_transactions(
 132                                                                                 &confirmables,
 133                                                                                 unconfirmed_txs
 134                                                                         );
 135                                                                 }
 136                                                                 Err(err) => {
 137                                                                         // (Semi-)permanent failure, retry later.
 138                                                                         log_error!(self.logger,
 139                                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 140                                                                                 num_confirmed,
 141                                                                                 num_unconfirmed
 142                                                                                 );
 143                                                                         sync_state.pending_sync = true;
 144                                                                         return Err(TxSyncError::from(err));
 145                                                                 }
 146                                                         }
 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                                         match maybe_await!(self.sync_best_block_updated(&confirmables, &mut sync_state, &tip_hash)) {
 161                                                 Ok(()) => {}
 162                                                 Err(InternalError::Inconsistency) => {
 163                                                         // Immediately restart syncing when we encounter any inconsistencies.
 164                                                         log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 165                                                         sync_state.pending_sync = true;
 166                                                         continue;
 167                                                 }
 168                                                 Err(err) => {
 169                                                         // (Semi-)permanent failure, retry later.
 170                                                         log_error!(self.logger,
 171                                                                 "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 172                                                                 num_confirmed,
 173                                                                 num_unconfirmed
 174                                                         );
 175                                                         sync_state.pending_sync = true;
 176                                                         return Err(TxSyncError::from(err));
 177                                                 }
 178                                         }
 179                                 }
 180
 181                                 match maybe_await!(self.get_confirmed_transactions(&sync_state)) {
 182                                         Ok(confirmed_txs) => {
 183                                                 // Double-check the tip hash. If it changed, a reorg happened since
 184                                                 // we started syncing and we need to restart last-minute.
 185                                                 match maybe_await!(self.client.get_tip_hash()) {
 186                                                         Ok(check_tip_hash) => {
 187                                                                 if check_tip_hash != tip_hash {
 188                                                                         tip_hash = check_tip_hash;
 189
 190                                                                         log_debug!(self.logger,
 191                                                                                 "Encountered inconsistency during transaction sync, restarting.");
 192                                                                         sync_state.pending_sync = true;
 193                                                                         continue;
 194                                                                 }
 195                                                                 num_confirmed += confirmed_txs.len();
 196                                                                 sync_state.sync_confirmed_transactions(
 197                                                                         &confirmables,
 198                                                                         confirmed_txs
 199                                                                 );
 200                                                         }
 201                                                         Err(err) => {
 202                                                                 // (Semi-)permanent failure, retry later.
 203                                                                 log_error!(self.logger,
 204                                                                         "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 205                                                                         num_confirmed,
 206                                                                         num_unconfirmed
 207                                                                 );
 208                                                                 sync_state.pending_sync = true;
 209                                                                 return Err(TxSyncError::from(err));
 210                                                         }
 211                                                 }
 212                                         }
 213                                         Err(InternalError::Inconsistency) => {
 214                                                 // Immediately restart syncing when we encounter any inconsistencies.
 215                                                 log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
 216                                                 sync_state.pending_sync = true;
 217                                                 continue;
 218                                         }
 219                                         Err(err) => {
 220                                                 // (Semi-)permanent failure, retry later.
 221                                                 log_error!(self.logger,
 222                                                         "Failed during transaction sync, aborting. Synced so far: {} confirmed, {} unconfirmed.",
 223                                                         num_confirmed,
 224                                                         num_unconfirmed
 225                                                 );
 226                                                 sync_state.pending_sync = true;
 227                                                 return Err(TxSyncError::from(err));
 228                                         }
 229                                 }
 230                                 sync_state.last_sync_hash = Some(tip_hash);
 231                                 sync_state.pending_sync = false;
 232                         }
 233                 }
 234                 #[cfg(feature = "time")]
 235                 log_debug!(self.logger, "Finished transaction sync at tip {} in {}ms: {} confirmed, {} unconfirmed.",
 236                                 tip_hash, start_time.elapsed().as_millis(), num_confirmed, num_unconfirmed);
 237                 #[cfg(not(feature = "time"))]
 238                 log_debug!(self.logger, "Finished transaction sync at tip {}: {} confirmed, {} unconfirmed.",
 239                                 tip_hash, num_confirmed, num_unconfirmed);
 240                 Ok(())
 241         }
 242
 243         #[maybe_async]
 244         fn sync_best_block_updated<C: Deref>(
 245                 &self, confirmables: &Vec<C>, sync_state: &mut SyncState, tip_hash: &BlockHash,
 246         ) -> Result<(), InternalError>
 247                 where C::Target: Confirm
 248         {
 249                 // Inform the interface of the new block.
 250                 let tip_header = maybe_await!(self.client.get_header_by_hash(tip_hash))?;
 251                 let tip_status = maybe_await!(self.client.get_block_status(&tip_hash))?;
 252                 if tip_status.in_best_chain {
 253                         if let Some(tip_height) = tip_status.height {
 254                                 for c in confirmables {
 255                                         c.best_block_updated(&tip_header, tip_height);
 256                                 }
 257
 258                                 // Prune any sufficiently confirmed output spends
 259                                 sync_state.prune_output_spends(tip_height);
 260                         }
 261                 } else {
 262                         return Err(InternalError::Inconsistency);
 263                 }
 264                 Ok(())
 265         }
 266
 267         #[maybe_async]
 268         fn get_confirmed_transactions(
 269                 &self, sync_state: &SyncState,
 270         ) -> Result<Vec<ConfirmedTx>, InternalError> {
 271
 272                 // First, check the confirmation status of registered transactions as well as the
 273                 // status of dependent transactions of registered outputs.
 274
 275                 let mut confirmed_txs: Vec<ConfirmedTx> = Vec::new();
 276
 277                 for txid in &sync_state.watched_transactions {
 278                         if confirmed_txs.iter().any(|ctx| ctx.txid == *txid) {
 279                                 continue;
 280                         }
 281                         if let Some(confirmed_tx) = maybe_await!(self.get_confirmed_tx(*txid, None, None))? {
 282                                 confirmed_txs.push(confirmed_tx);
 283                         }
 284                 }
 285
 286                 for (_, output) in &sync_state.watched_outputs {
 287                         if let Some(output_status) = maybe_await!(self.client
 288                                 .get_output_status(&output.outpoint.txid, output.outpoint.index as u64))?
 289                         {
 290                                 if let Some(spending_txid) = output_status.txid {
 291                                         if let Some(spending_tx_status) = output_status.status {
 292                                                 if confirmed_txs.iter().any(|ctx| ctx.txid == spending_txid) {
 293                                                         if spending_tx_status.confirmed {
 294                                                                 // Skip inserting duplicate ConfirmedTx entry
 295                                                                 continue;
 296                                                         } else {
 297                                                                 log_trace!(self.logger, "Inconsistency: Detected previously-confirmed Tx {} as unconfirmed", spending_txid);
 298                                                                 return Err(InternalError::Inconsistency);
 299                                                         }
 300                                                 }
 301
 302                                                 if let Some(confirmed_tx) = maybe_await!(self
 303                                                         .get_confirmed_tx(
 304                                                                 spending_txid,
 305                                                                 spending_tx_status.block_hash,
 306                                                                 spending_tx_status.block_height,
 307                                                         ))?
 308                                                 {
 309                                                         confirmed_txs.push(confirmed_tx);
 310                                                 }
 311                                         }
 312                                 }
 313                         }
 314                 }
 315
 316                 // Sort all confirmed transactions first by block height, then by in-block
 317                 // position, and finally feed them to the interface in order.
 318                 confirmed_txs.sort_unstable_by(|tx1, tx2| {
 319                         tx1.block_height.cmp(&tx2.block_height).then_with(|| tx1.pos.cmp(&tx2.pos))
 320                 });
 321
 322                 Ok(confirmed_txs)
 323         }
 324
 325         #[maybe_async]
 326         fn get_confirmed_tx(
 327                 &self, txid: Txid, expected_block_hash: Option<BlockHash>, known_block_height: Option<u32>,
 328         ) -> Result<Option<ConfirmedTx>, InternalError> {
 329                 if let Some(merkle_block) = maybe_await!(self.client.get_merkle_block(&txid))? {
 330                         let block_header = merkle_block.header;
 331                         let block_hash = block_header.block_hash();
 332                         if let Some(expected_block_hash) = expected_block_hash {
 333                                 if expected_block_hash != block_hash {
 334                                         log_trace!(self.logger, "Inconsistency: Tx {} expected in block {}, but is confirmed in {}", txid, expected_block_hash, block_hash);
 335                                         return Err(InternalError::Inconsistency);
 336                                 }
 337                         }
 338
 339                         let mut matches = Vec::new();
 340                         let mut indexes = Vec::new();
 341                         let _ = merkle_block.txn.extract_matches(&mut matches, &mut indexes);
 342                         if indexes.len() != 1 || matches.len() != 1 || matches[0] != txid {
 343                                 log_error!(self.logger, "Retrieved Merkle block for txid {} doesn't match expectations. This should not happen. Please verify server integrity.", txid);
 344                                 return Err(InternalError::Failed);
 345                         }
 346
 347                         // unwrap() safety: len() > 0 is checked above
 348                         let pos = *indexes.first().unwrap() as usize;
 349                         if let Some(tx) = maybe_await!(self.client.get_tx(&txid))? {
 350                                 if tx.txid() != txid {
 351                                         log_error!(self.logger, "Retrieved transaction for txid {} doesn't match expectations. This should not happen. Please verify server integrity.", txid);
 352                                         return Err(InternalError::Failed);
 353                                 }
 354
 355                                 if let Some(block_height) = known_block_height {
 356                                         // We can take a shortcut here if a previous call already gave us the height.
 357                                         return Ok(Some(ConfirmedTx { tx, txid, block_header, pos, block_height }));
 358                                 }
 359
 360                                 let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
 361                                 if let Some(block_height) = block_status.height {
 362                                         return Ok(Some(ConfirmedTx { tx, txid, block_header, pos, block_height }));
 363                                 } else {
 364                                         // If any previously-confirmed block suddenly is no longer confirmed, we found
 365                                         // an inconsistency and should start over.
 366                                         log_trace!(self.logger, "Inconsistency: Tx {} was unconfirmed during syncing.", txid);
 367                                         return Err(InternalError::Inconsistency);
 368                                 }
 369                         }
 370                 }
 371                 Ok(None)
 372         }
 373
 374         #[maybe_async]
 375         fn get_unconfirmed_transactions<C: Deref>(
 376                 &self, confirmables: &Vec<C>,
 377         ) -> Result<Vec<Txid>, InternalError>
 378                 where C::Target: Confirm
 379         {
 380                 // Query the interface for relevant txids and check whether the relevant blocks are still
 381                 // in the best chain, mark them unconfirmed otherwise
 382                 let relevant_txids = confirmables
 383                         .iter()
 384                         .flat_map(|c| c.get_relevant_txids())
 385                         .collect::<HashSet<(Txid, u32, Option<BlockHash>)>>();
 386
 387                 let mut unconfirmed_txs = Vec::new();
 388
 389                 for (txid, _conf_height, block_hash_opt) in relevant_txids {
 390                         if let Some(block_hash) = block_hash_opt {
 391                                 let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
 392                                 if block_status.in_best_chain {
 393                                         // Skip if the block in question is still confirmed.
 394                                         continue;
 395                                 }
 396
 397                                 unconfirmed_txs.push(txid);
 398                         } else {
 399                                 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!");
 400                                 panic!("Untracked confirmation of funding transaction. Please ensure none of your channels had been created with LDK prior to version 0.0.113!");
 401                         }
 402                 }
 403                 Ok(unconfirmed_txs)
 404         }
 405
 406         /// Returns a reference to the underlying esplora client.
 407         ///
 408         /// This is not exported to bindings users as the underlying client from BDK is not exported.
 409         pub fn client(&self) -> &EsploraClientType {
 410                 &self.client
 411         }
 412 }
 413
 414 #[cfg(feature = "async-interface")]
 415 type MutexType<I> = futures::lock::Mutex<I>;
 416 #[cfg(not(feature = "async-interface"))]
 417 type MutexType<I> = std::sync::Mutex<I>;
 418
 419 // The underlying client type.
 420 #[cfg(feature = "async-interface")]
 421 type EsploraClientType = AsyncClient;
 422 #[cfg(not(feature = "async-interface"))]
 423 type EsploraClientType = BlockingClient;
 424
 425
 426 impl<L: Deref> Filter for EsploraSyncClient<L>
 427 where
 428         L::Target: Logger,
 429 {
 430         fn register_tx(&self, txid: &Txid, _script_pubkey: &Script) {
 431                 let mut locked_queue = self.queue.lock().unwrap();
 432                 locked_queue.transactions.insert(*txid);
 433         }
 434
 435         fn register_output(&self, output: WatchedOutput) {
 436                 let mut locked_queue = self.queue.lock().unwrap();
 437                 locked_queue.outputs.insert(output.outpoint.into_bitcoin_outpoint(), output);
 438         }
 439 }