--- /dev/null
+use crate::error::{TxSyncError, InternalError};
+use crate::common::{SyncState, FilterQueue, ConfirmedTx};
+
+use lightning::util::logger::Logger;
+use lightning::{log_error, log_given_level, log_info, log_internal, log_debug, log_trace};
+use lightning::chain::WatchedOutput;
+use lightning::chain::{Confirm, Filter};
+
+use bitcoin::{BlockHash, Script, Txid};
+
+use esplora_client::Builder;
+#[cfg(feature = "async-interface")]
+use esplora_client::r#async::AsyncClient;
+#[cfg(not(feature = "async-interface"))]
+use esplora_client::blocking::BlockingClient;
+
+use std::collections::HashSet;
+use core::ops::Deref;
+
+/// Synchronizes LDK with a given [`Esplora`] server.
+///
+/// Needs to be registered with a [`ChainMonitor`] via the [`Filter`] interface to be informed of
+/// transactions and outputs to monitor for on-chain confirmation, unconfirmation, and
+/// reconfirmation.
+///
+/// Note that registration via [`Filter`] needs to happen before any calls to
+/// [`Watch::watch_channel`] to ensure we get notified of the items to monitor.
+///
+/// This uses and exposes either a blocking or async client variant dependent on whether the
+/// `esplora-blocking` or the `esplora-async` feature is enabled.
+///
+/// [`Esplora`]: https://github.com/Blockstream/electrs
+/// [`ChainMonitor`]: lightning::chain::chainmonitor::ChainMonitor
+/// [`Watch::watch_channel`]: lightning::chain::Watch::watch_channel
+/// [`Filter`]: lightning::chain::Filter
+pub struct EsploraSyncClient<L: Deref>
+where
+ L::Target: Logger,
+{
+ sync_state: MutexType<SyncState>,
+ queue: std::sync::Mutex<FilterQueue>,
+ client: EsploraClientType,
+ logger: L,
+}
+
+impl<L: Deref> EsploraSyncClient<L>
+where
+ L::Target: Logger,
+{
+ /// Returns a new [`EsploraSyncClient`] object.
+ pub fn new(server_url: String, logger: L) -> Self {
+ let builder = Builder::new(&server_url);
+ #[cfg(not(feature = "async-interface"))]
+ let client = builder.build_blocking().unwrap();
+ #[cfg(feature = "async-interface")]
+ let client = builder.build_async().unwrap();
+
+ EsploraSyncClient::from_client(client, logger)
+ }
+
+ /// Returns a new [`EsploraSyncClient`] object using the given Esplora client.
+ pub fn from_client(client: EsploraClientType, logger: L) -> Self {
+ let sync_state = MutexType::new(SyncState::new());
+ let queue = std::sync::Mutex::new(FilterQueue::new());
+ Self {
+ sync_state,
+ queue,
+ client,
+ logger,
+ }
+ }
+
+ /// Synchronizes the given `confirmables` via their [`Confirm`] interface implementations. This
+ /// method should be called regularly to keep LDK up-to-date with current chain data.
+ ///
+ /// For example, instances of [`ChannelManager`] and [`ChainMonitor`] can be informed about the
+ /// newest on-chain activity related to the items previously registered via the [`Filter`]
+ /// interface.
+ ///
+ /// [`Confirm`]: lightning::chain::Confirm
+ /// [`ChainMonitor`]: lightning::chain::chainmonitor::ChainMonitor
+ /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
+ /// [`Filter`]: lightning::chain::Filter
+ #[maybe_async]
+ pub fn sync(&self, confirmables: Vec<&(dyn Confirm + Sync + Send)>) -> Result<(), TxSyncError> {
+ // This lock makes sure we're syncing once at a time.
+ #[cfg(not(feature = "async-interface"))]
+ let mut sync_state = self.sync_state.lock().unwrap();
+ #[cfg(feature = "async-interface")]
+ let mut sync_state = self.sync_state.lock().await;
+
+ log_info!(self.logger, "Starting transaction sync.");
+
+ let mut tip_hash = maybe_await!(self.client.get_tip_hash())?;
+
+ loop {
+ let pending_registrations = self.queue.lock().unwrap().process_queues(&mut sync_state);
+ let tip_is_new = Some(tip_hash) != sync_state.last_sync_hash;
+
+ // We loop until any registered transactions have been processed at least once, or the
+ // tip hasn't been updated during the last iteration.
+ if !sync_state.pending_sync && !pending_registrations && !tip_is_new {
+ // Nothing to do.
+ break;
+ } else {
+ // Update the known tip to the newest one.
+ if tip_is_new {
+ // First check for any unconfirmed transactions and act on it immediately.
+ match maybe_await!(self.get_unconfirmed_transactions(&confirmables)) {
+ Ok(unconfirmed_txs) => {
+ // Double-check the tip hash. If it changed, a reorg happened since
+ // we started syncing and we need to restart last-minute.
+ let check_tip_hash = maybe_await!(self.client.get_tip_hash())?;
+ if check_tip_hash != tip_hash {
+ tip_hash = check_tip_hash;
+ continue;
+ }
+
+ self.sync_unconfirmed_transactions(&mut sync_state, &confirmables, unconfirmed_txs);
+ },
+ Err(err) => {
+ // (Semi-)permanent failure, retry later.
+ log_error!(self.logger, "Failed during transaction sync, aborting.");
+ sync_state.pending_sync = true;
+ return Err(TxSyncError::from(err));
+ }
+ }
+
+ match maybe_await!(self.sync_best_block_updated(&confirmables, &tip_hash)) {
+ Ok(()) => {}
+ Err(InternalError::Inconsistency) => {
+ // Immediately restart syncing when we encounter any inconsistencies.
+ log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
+ sync_state.pending_sync = true;
+ continue;
+ }
+ Err(err) => {
+ // (Semi-)permanent failure, retry later.
+ sync_state.pending_sync = true;
+ return Err(TxSyncError::from(err));
+ }
+ }
+ }
+
+ match maybe_await!(self.get_confirmed_transactions(&sync_state)) {
+ Ok(confirmed_txs) => {
+ // Double-check the tip hash. If it changed, a reorg happened since
+ // we started syncing and we need to restart last-minute.
+ let check_tip_hash = maybe_await!(self.client.get_tip_hash())?;
+ if check_tip_hash != tip_hash {
+ tip_hash = check_tip_hash;
+ continue;
+ }
+
+ self.sync_confirmed_transactions(
+ &mut sync_state,
+ &confirmables,
+ confirmed_txs,
+ );
+ }
+ Err(InternalError::Inconsistency) => {
+ // Immediately restart syncing when we encounter any inconsistencies.
+ log_debug!(self.logger, "Encountered inconsistency during transaction sync, restarting.");
+ sync_state.pending_sync = true;
+ continue;
+ }
+ Err(err) => {
+ // (Semi-)permanent failure, retry later.
+ log_error!(self.logger, "Failed during transaction sync, aborting.");
+ sync_state.pending_sync = true;
+ return Err(TxSyncError::from(err));
+ }
+ }
+ sync_state.last_sync_hash = Some(tip_hash);
+ sync_state.pending_sync = false;
+ }
+ }
+ log_info!(self.logger, "Finished transaction sync.");
+ Ok(())
+ }
+
+ #[maybe_async]
+ fn sync_best_block_updated(
+ &self, confirmables: &Vec<&(dyn Confirm + Sync + Send)>, tip_hash: &BlockHash,
+ ) -> Result<(), InternalError> {
+
+ // Inform the interface of the new block.
+ let tip_header = maybe_await!(self.client.get_header_by_hash(tip_hash))?;
+ let tip_status = maybe_await!(self.client.get_block_status(&tip_hash))?;
+ if tip_status.in_best_chain {
+ if let Some(tip_height) = tip_status.height {
+ for c in confirmables {
+ c.best_block_updated(&tip_header, tip_height);
+ }
+ }
+ } else {
+ return Err(InternalError::Inconsistency);
+ }
+ Ok(())
+ }
+
+ fn sync_confirmed_transactions(
+ &self, sync_state: &mut SyncState, confirmables: &Vec<&(dyn Confirm + Sync + Send)>, confirmed_txs: Vec<ConfirmedTx>,
+ ) {
+ for ctx in confirmed_txs {
+ for c in confirmables {
+ c.transactions_confirmed(
+ &ctx.block_header,
+ &[(ctx.pos, &ctx.tx)],
+ ctx.block_height,
+ );
+ }
+
+ sync_state.watched_transactions.remove(&ctx.tx.txid());
+
+ for input in &ctx.tx.input {
+ sync_state.watched_outputs.remove(&input.previous_output);
+ }
+ }
+ }
+
+ #[maybe_async]
+ fn get_confirmed_transactions(
+ &self, sync_state: &SyncState,
+ ) -> Result<Vec<ConfirmedTx>, InternalError> {
+
+ // First, check the confirmation status of registered transactions as well as the
+ // status of dependent transactions of registered outputs.
+
+ let mut confirmed_txs = Vec::new();
+
+ for txid in &sync_state.watched_transactions {
+ if let Some(confirmed_tx) = maybe_await!(self.get_confirmed_tx(&txid, None, None))? {
+ confirmed_txs.push(confirmed_tx);
+ }
+ }
+
+ for (_, output) in &sync_state.watched_outputs {
+ if let Some(output_status) = maybe_await!(self.client
+ .get_output_status(&output.outpoint.txid, output.outpoint.index as u64))?
+ {
+ if let Some(spending_txid) = output_status.txid {
+ if let Some(spending_tx_status) = output_status.status {
+ if let Some(confirmed_tx) = maybe_await!(self
+ .get_confirmed_tx(
+ &spending_txid,
+ spending_tx_status.block_hash,
+ spending_tx_status.block_height,
+ ))?
+ {
+ confirmed_txs.push(confirmed_tx);
+ }
+ }
+ }
+ }
+ }
+
+ // Sort all confirmed transactions first by block height, then by in-block
+ // position, and finally feed them to the interface in order.
+ confirmed_txs.sort_unstable_by(|tx1, tx2| {
+ tx1.block_height.cmp(&tx2.block_height).then_with(|| tx1.pos.cmp(&tx2.pos))
+ });
+
+ Ok(confirmed_txs)
+ }
+
+ #[maybe_async]
+ fn get_confirmed_tx(
+ &self, txid: &Txid, expected_block_hash: Option<BlockHash>, known_block_height: Option<u32>,
+ ) -> Result<Option<ConfirmedTx>, InternalError> {
+ if let Some(merkle_block) = maybe_await!(self.client.get_merkle_block(&txid))? {
+ let block_header = merkle_block.header;
+ let block_hash = block_header.block_hash();
+ if let Some(expected_block_hash) = expected_block_hash {
+ if expected_block_hash != block_hash {
+ log_trace!(self.logger, "Inconsistency: Tx {} expected in block {}, but is confirmed in {}", txid, expected_block_hash, block_hash);
+ return Err(InternalError::Inconsistency);
+ }
+ }
+
+ let mut matches = Vec::new();
+ let mut indexes = Vec::new();
+ let _ = merkle_block.txn.extract_matches(&mut matches, &mut indexes);
+ if indexes.len() != 1 || matches.len() != 1 || matches[0] != *txid {
+ log_error!(self.logger, "Retrieved Merkle block for txid {} doesn't match expectations. This should not happen. Please verify server integrity.", txid);
+ return Err(InternalError::Failed);
+ }
+
+ let pos = *indexes.get(0).ok_or(InternalError::Failed)? as usize;
+ if let Some(tx) = maybe_await!(self.client.get_tx(&txid))? {
+ if let Some(block_height) = known_block_height {
+ // We can take a shortcut here if a previous call already gave us the height.
+ return Ok(Some(ConfirmedTx { tx, block_header, pos, block_height }));
+ }
+
+ let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
+ if let Some(block_height) = block_status.height {
+ return Ok(Some(ConfirmedTx { tx, block_header, pos, block_height }));
+ } else {
+ // If any previously-confirmed block suddenly is no longer confirmed, we found
+ // an inconsistency and should start over.
+ log_trace!(self.logger, "Inconsistency: Tx {} was unconfirmed during syncing.", txid);
+ return Err(InternalError::Inconsistency);
+ }
+ }
+ }
+ Ok(None)
+ }
+
+ #[maybe_async]
+ fn get_unconfirmed_transactions(
+ &self, confirmables: &Vec<&(dyn Confirm + Sync + Send)>,
+ ) -> Result<Vec<Txid>, InternalError> {
+ // Query the interface for relevant txids and check whether the relevant blocks are still
+ // in the best chain, mark them unconfirmed otherwise
+ let relevant_txids = confirmables
+ .iter()
+ .flat_map(|c| c.get_relevant_txids())
+ .collect::<HashSet<(Txid, Option<BlockHash>)>>();
+
+ let mut unconfirmed_txs = Vec::new();
+
+ for (txid, block_hash_opt) in relevant_txids {
+ if let Some(block_hash) = block_hash_opt {
+ let block_status = maybe_await!(self.client.get_block_status(&block_hash))?;
+ if block_status.in_best_chain {
+ // Skip if the block in question is still confirmed.
+ continue;
+ }
+
+ unconfirmed_txs.push(txid);
+ } else {
+ 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!");
+ panic!("Untracked confirmation of funding transaction. Please ensure none of your channels had been created with LDK prior to version 0.0.113!");
+ }
+ }
+ Ok(unconfirmed_txs)
+ }
+
+ fn sync_unconfirmed_transactions(
+ &self, sync_state: &mut SyncState, confirmables: &Vec<&(dyn Confirm + Sync + Send)>, unconfirmed_txs: Vec<Txid>,
+ ) {
+ for txid in unconfirmed_txs {
+ for c in confirmables {
+ c.transaction_unconfirmed(&txid);
+ }
+
+ sync_state.watched_transactions.insert(txid);
+ }
+ }
+
+ /// Returns a reference to the underlying esplora client.
+ pub fn client(&self) -> &EsploraClientType {
+ &self.client
+ }
+}
+
+#[cfg(feature = "async-interface")]
+type MutexType<I> = futures::lock::Mutex<I>;
+#[cfg(not(feature = "async-interface"))]
+type MutexType<I> = std::sync::Mutex<I>;
+
+// The underlying client type.
+#[cfg(feature = "async-interface")]
+type EsploraClientType = AsyncClient;
+#[cfg(not(feature = "async-interface"))]
+type EsploraClientType = BlockingClient;
+
+
+impl<L: Deref> Filter for EsploraSyncClient<L>
+where
+ L::Target: Logger,
+{
+ fn register_tx(&self, txid: &Txid, _script_pubkey: &Script) {
+ let mut locked_queue = self.queue.lock().unwrap();
+ locked_queue.transactions.insert(*txid);
+ }
+
+ fn register_output(&self, output: WatchedOutput) {
+ let mut locked_queue = self.queue.lock().unwrap();
+ locked_queue.outputs.insert(output.outpoint.into_bitcoin_outpoint(), output);
+ }
+}
--- /dev/null
+//! Provides utilities for syncing LDK via the transaction-based [`Confirm`] interface.
+//!
+//! The provided synchronization clients need to be registered with a [`ChainMonitor`] via the
+//! [`Filter`] interface. Then, the respective `fn sync` needs to be called with the [`Confirm`]
+//! implementations to be synchronized, i.e., usually instances of [`ChannelManager`] and
+//! [`ChainMonitor`].
+//!
+//! ## Features and Backend Support
+//!
+//!- `esplora_blocking` enables syncing against an Esplora backend based on a blocking client.
+//!- `esplora_async` enables syncing against an Esplora backend based on an async client.
+//!
+//! ## Version Compatibility
+//!
+//! Currently this crate is compatible with nodes that were created with LDK version 0.0.113 and above.
+//!
+//! ## Usage Example:
+//!
+//! ```ignore
+//! let tx_sync = Arc::new(EsploraSyncClient::new(
+//! esplora_server_url,
+//! Arc::clone(&some_logger),
+//! ));
+//!
+//! let chain_monitor = Arc::new(ChainMonitor::new(
+//! Some(Arc::clone(&tx_sync)),
+//! Arc::clone(&some_broadcaster),
+//! Arc::clone(&some_logger),
+//! Arc::clone(&some_fee_estimator),
+//! Arc::clone(&some_persister),
+//! ));
+//!
+//! let channel_manager = Arc::new(ChannelManager::new(
+//! Arc::clone(&some_fee_estimator),
+//! Arc::clone(&chain_monitor),
+//! Arc::clone(&some_broadcaster),
+//! Arc::clone(&some_router),
+//! Arc::clone(&some_logger),
+//! Arc::clone(&some_entropy_source),
+//! Arc::clone(&some_node_signer),
+//! Arc::clone(&some_signer_provider),
+//! user_config,
+//! chain_params,
+//! ));
+//!
+//! let confirmables = vec![
+//! &*channel_manager as &(dyn Confirm + Sync + Send),
+//! &*chain_monitor as &(dyn Confirm + Sync + Send),
+//! ];
+//!
+//! tx_sync.sync(confirmables).unwrap();
+//! ```
+//!
+//! [`Confirm`]: lightning::chain::Confirm
+//! [`Filter`]: lightning::chain::Filter
+//! [`ChainMonitor`]: lightning::chain::chainmonitor::ChainMonitor
+//! [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
+
+// Prefix these with `rustdoc::` when we update our MSRV to be >= 1.52 to remove warnings.
+#![deny(broken_intra_doc_links)]
+#![deny(private_intra_doc_links)]
+
+#![deny(missing_docs)]
+#![deny(unsafe_code)]
+
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+
+#[cfg(any(feature = "esplora-blocking", feature = "esplora-async"))]
+#[macro_use]
+extern crate bdk_macros;
+
+#[cfg(any(feature = "esplora-blocking", feature = "esplora-async"))]
+mod esplora;
+
+#[cfg(any(feature = "esplora-blocking", feature = "esplora-async"))]
+mod common;
+
+mod error;
+pub use error::TxSyncError;
+
+#[cfg(any(feature = "esplora-blocking", feature = "esplora-async"))]
+pub use esplora::EsploraSyncClient;
projects / rust-lightning / commitdiff