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