_ Git - rust-lightning/blob - lightning-block-sync/src/init.rs

   1 //! Utilities to assist in the initial sync required to initialize or reload Rust-Lightning objects
   2 //! from disk.
   3
   4 use crate::{BlockSource, BlockSourceResult, Cache, ChainNotifier};
   5 use crate::poll::{ChainPoller, Validate, ValidatedBlockHeader};
   6
   7 use bitcoin::blockdata::block::BlockHeader;
   8 use bitcoin::hash_types::BlockHash;
   9 use bitcoin::network::constants::Network;
  10
  11 use lightning::chain;
  12
  13 use std::ops::Deref;
  14
  15 /// Returns a validated block header of the source's best chain tip.
  16 ///
  17 /// Upon success, the returned header can be used to initialize [`SpvClient`]. Useful during a fresh
  18 /// start when there are no chain listeners to sync yet.
  19 ///
  20 /// [`SpvClient`]: crate::SpvClient
  21 pub async fn validate_best_block_header<B: Deref>(block_source: B) ->
  22 BlockSourceResult<ValidatedBlockHeader> where B::Target: BlockSource {
  23         let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
  24         block_source
  25                 .get_header(&best_block_hash, best_block_height).await?
  26                 .validate(best_block_hash)
  27 }
  28
  29 /// Performs a one-time sync of chain listeners using a single *trusted* block source, bringing each
  30 /// listener's view of the chain from its paired block hash to `block_source`'s best chain tip.
  31 ///
  32 /// Upon success, the returned header can be used to initialize [`SpvClient`]. In the case of
  33 /// failure, each listener may be left at a different block hash than the one it was originally
  34 /// paired with.
  35 ///
  36 /// Useful during startup to bring the [`ChannelManager`] and each [`ChannelMonitor`] in sync before
  37 /// switching to [`SpvClient`]. For example:
  38 ///
  39 /// ```
  40 /// use bitcoin::hash_types::BlockHash;
  41 /// use bitcoin::network::constants::Network;
  42 ///
  43 /// use lightning::chain;
  44 /// use lightning::chain::Watch;
  45 /// use lightning::chain::chainmonitor;
  46 /// use lightning::chain::chainmonitor::ChainMonitor;
  47 /// use lightning::chain::channelmonitor::ChannelMonitor;
  48 /// use lightning::chain::chaininterface::BroadcasterInterface;
  49 /// use lightning::chain::chaininterface::FeeEstimator;
  50 /// use lightning::chain::keysinterface;
  51 /// use lightning::chain::keysinterface::{EntropySource, NodeSigner, SignerProvider};
  52 /// use lightning::ln::channelmanager::{ChannelManager, ChannelManagerReadArgs};
  53 /// use lightning::routing::router::Router;
  54 /// use lightning::util::config::UserConfig;
  55 /// use lightning::util::logger::Logger;
  56 /// use lightning::util::ser::ReadableArgs;
  57 ///
  58 /// use lightning_block_sync::*;
  59 ///
  60 /// use std::io::Cursor;
  61 ///
  62 /// async fn init_sync<
  63 ///     B: BlockSource,
  64 ///     K: EntropySource + NodeSigner + SignerProvider,
  65 ///     T: BroadcasterInterface,
  66 ///     F: FeeEstimator,
  67 ///     R: Router,
  68 ///     L: Logger,
  69 ///     C: chain::Filter,
  70 ///     P: chainmonitor::Persist<K::Signer>,
  71 /// >(
  72 ///     block_source: &B,
  73 ///     chain_monitor: &ChainMonitor<K::Signer, &C, &T, &F, &L, &P>,
  74 ///     config: UserConfig,
  75 ///     keys_manager: &K,
  76 ///     tx_broadcaster: &T,
  77 ///     fee_estimator: &F,
  78 ///     router: &R,
  79 ///     logger: &L,
  80 ///     persister: &P,
  81 /// ) {
  82 ///     // Read a serialized channel monitor paired with the block hash when it was persisted.
  83 ///     let serialized_monitor = "...";
  84 ///     let (monitor_block_hash, mut monitor) = <(BlockHash, ChannelMonitor<K::Signer>)>::read(
  85 ///             &mut Cursor::new(&serialized_monitor), keys_manager).unwrap();
  86 ///
  87 ///     // Read the channel manager paired with the block hash when it was persisted.
  88 ///     let serialized_manager = "...";
  89 ///     let (manager_block_hash, mut manager) = {
  90 ///             let read_args = ChannelManagerReadArgs::new(
  91 ///                     keys_manager,
  92 ///                     fee_estimator,
  93 ///                     chain_monitor,
  94 ///                     tx_broadcaster,
  95 ///                     router,
  96 ///                     logger,
  97 ///                     config,
  98 ///                     vec![&mut monitor],
  99 ///             );
 100 ///             <(BlockHash, ChannelManager<&ChainMonitor<K::Signer, &C, &T, &F, &L, &P>, &T, &K, &F, &R, &L>)>::read(
 101 ///                     &mut Cursor::new(&serialized_manager), read_args).unwrap()
 102 ///     };
 103 ///
 104 ///     // Synchronize any channel monitors and the channel manager to be on the best block.
 105 ///     let mut cache = UnboundedCache::new();
 106 ///     let mut monitor_listener = (monitor, &*tx_broadcaster, &*fee_estimator, &*logger);
 107 ///     let listeners = vec![
 108 ///             (monitor_block_hash, &monitor_listener as &dyn chain::Listen),
 109 ///             (manager_block_hash, &manager as &dyn chain::Listen),
 110 ///     ];
 111 ///     let chain_tip = init::synchronize_listeners(
 112 ///             block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
 113 ///
 114 ///     // Allow the chain monitor to watch any channels.
 115 ///     let monitor = monitor_listener.0;
 116 ///     chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
 117 ///
 118 ///     // Create an SPV client to notify the chain monitor and channel manager of block events.
 119 ///     let chain_poller = poll::ChainPoller::new(block_source, Network::Bitcoin);
 120 ///     let mut chain_listener = (chain_monitor, &manager);
 121 ///     let spv_client = SpvClient::new(chain_tip, chain_poller, &mut cache, &chain_listener);
 122 /// }
 123 /// ```
 124 ///
 125 /// [`SpvClient`]: crate::SpvClient
 126 /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
 127 /// [`ChannelMonitor`]: lightning::chain::channelmonitor::ChannelMonitor
 128 pub async fn synchronize_listeners<B: Deref + Sized + Send + Sync, C: Cache, L: chain::Listen + ?Sized>(
 129         block_source: B,
 130         network: Network,
 131         header_cache: &mut C,
 132         mut chain_listeners: Vec<(BlockHash, &L)>,
 133 ) -> BlockSourceResult<ValidatedBlockHeader> where B::Target: BlockSource {
 134         let best_header = validate_best_block_header(&*block_source).await?;
 135
 136         // Fetch the header for the block hash paired with each listener.
 137         let mut chain_listeners_with_old_headers = Vec::new();
 138         for (old_block_hash, chain_listener) in chain_listeners.drain(..) {
 139                 let old_header = match header_cache.look_up(&old_block_hash) {
 140                         Some(header) => *header,
 141                         None => block_source
 142                                 .get_header(&old_block_hash, None).await?
 143                                 .validate(old_block_hash)?
 144                 };
 145                 chain_listeners_with_old_headers.push((old_header, chain_listener))
 146         }
 147
 148         // Find differences and disconnect blocks for each listener individually.
 149         let mut chain_poller = ChainPoller::new(block_source, network);
 150         let mut chain_listeners_at_height = Vec::new();
 151         let mut most_common_ancestor = None;
 152         let mut most_connected_blocks = Vec::new();
 153         for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
 154                 // Disconnect any stale blocks, but keep them in the cache for the next iteration.
 155                 let header_cache = &mut ReadOnlyCache(header_cache);
 156                 let (common_ancestor, connected_blocks) = {
 157                         let chain_listener = &DynamicChainListener(chain_listener);
 158                         let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
 159                         let difference =
 160                                 chain_notifier.find_difference(best_header, &old_header, &mut chain_poller).await?;
 161                         chain_notifier.disconnect_blocks(difference.disconnected_blocks);
 162                         (difference.common_ancestor, difference.connected_blocks)
 163                 };
 164
 165                 // Keep track of the most common ancestor and all blocks connected across all listeners.
 166                 chain_listeners_at_height.push((common_ancestor.height, chain_listener));
 167                 if connected_blocks.len() > most_connected_blocks.len() {
 168                         most_common_ancestor = Some(common_ancestor);
 169                         most_connected_blocks = connected_blocks;
 170                 }
 171         }
 172
 173         // Connect new blocks for all listeners at once to avoid re-fetching blocks.
 174         if let Some(common_ancestor) = most_common_ancestor {
 175                 let chain_listener = &ChainListenerSet(chain_listeners_at_height);
 176                 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
 177                 chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
 178                         .await.or_else(|(e, _)| Err(e))?;
 179         }
 180
 181         Ok(best_header)
 182 }
 183
 184 /// A wrapper to make a cache read-only.
 185 ///
 186 /// Used to prevent losing headers that may be needed to disconnect blocks common to more than one
 187 /// listener.
 188 struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
 189
 190 impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
 191         fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
 192                 self.0.look_up(block_hash)
 193         }
 194
 195         fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
 196                 unreachable!()
 197         }
 198
 199         fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
 200                 None
 201         }
 202 }
 203
 204 /// Wrapper for supporting dynamically sized chain listeners.
 205 struct DynamicChainListener<'a, L: chain::Listen + ?Sized>(&'a L);
 206
 207 impl<'a, L: chain::Listen + ?Sized> chain::Listen for DynamicChainListener<'a, L> {
 208         fn filtered_block_connected(&self, _header: &BlockHeader, _txdata: &chain::transaction::TransactionData, _height: u32) {
 209                 unreachable!()
 210         }
 211
 212         fn block_disconnected(&self, header: &BlockHeader, height: u32) {
 213                 self.0.block_disconnected(header, height)
 214         }
 215 }
 216
 217 /// A set of dynamically sized chain listeners, each paired with a starting block height.
 218 struct ChainListenerSet<'a, L: chain::Listen + ?Sized>(Vec<(u32, &'a L)>);
 219
 220 impl<'a, L: chain::Listen + ?Sized> chain::Listen for ChainListenerSet<'a, L> {
 221         // Needed to differentiate test expectations.
 222         #[cfg(test)]
 223         fn block_connected(&self, block: &bitcoin::Block, height: u32) {
 224                 for (starting_height, chain_listener) in self.0.iter() {
 225                         if height > *starting_height {
 226                                 chain_listener.block_connected(block, height);
 227                         }
 228                 }
 229         }
 230
 231         fn filtered_block_connected(&self, header: &BlockHeader, txdata: &chain::transaction::TransactionData, height: u32) {
 232                 for (starting_height, chain_listener) in self.0.iter() {
 233                         if height > *starting_height {
 234                                 chain_listener.filtered_block_connected(header, txdata, height);
 235                         }
 236                 }
 237         }
 238
 239         fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
 240                 unreachable!()
 241         }
 242 }
 243
 244 #[cfg(test)]
 245 mod tests {
 246         use crate::test_utils::{Blockchain, MockChainListener};
 247         use super::*;
 248
 249         use bitcoin::network::constants::Network;
 250
 251         #[tokio::test]
 252         async fn sync_from_same_chain() {
 253                 let chain = Blockchain::default().with_height(4);
 254
 255                 let listener_1 = MockChainListener::new()
 256                         .expect_block_connected(*chain.at_height(2))
 257                         .expect_block_connected(*chain.at_height(3))
 258                         .expect_block_connected(*chain.at_height(4));
 259                 let listener_2 = MockChainListener::new()
 260                         .expect_block_connected(*chain.at_height(3))
 261                         .expect_block_connected(*chain.at_height(4));
 262                 let listener_3 = MockChainListener::new()
 263                         .expect_block_connected(*chain.at_height(4));
 264
 265                 let listeners = vec![
 266                         (chain.at_height(1).block_hash, &listener_1 as &dyn chain::Listen),
 267                         (chain.at_height(2).block_hash, &listener_2 as &dyn chain::Listen),
 268                         (chain.at_height(3).block_hash, &listener_3 as &dyn chain::Listen),
 269                 ];
 270                 let mut cache = chain.header_cache(0..=4);
 271                 match synchronize_listeners(&chain, Network::Bitcoin, &mut cache, listeners).await {
 272                         Ok(header) => assert_eq!(header, chain.tip()),
 273                         Err(e) => panic!("Unexpected error: {:?}", e),
 274                 }
 275         }
 276
 277         #[tokio::test]
 278         async fn sync_from_different_chains() {
 279                 let main_chain = Blockchain::default().with_height(4);
 280                 let fork_chain_1 = main_chain.fork_at_height(1);
 281                 let fork_chain_2 = main_chain.fork_at_height(2);
 282                 let fork_chain_3 = main_chain.fork_at_height(3);
 283
 284                 let listener_1 = MockChainListener::new()
 285                         .expect_block_disconnected(*fork_chain_1.at_height(4))
 286                         .expect_block_disconnected(*fork_chain_1.at_height(3))
 287                         .expect_block_disconnected(*fork_chain_1.at_height(2))
 288                         .expect_block_connected(*main_chain.at_height(2))
 289                         .expect_block_connected(*main_chain.at_height(3))
 290                         .expect_block_connected(*main_chain.at_height(4));
 291                 let listener_2 = MockChainListener::new()
 292                         .expect_block_disconnected(*fork_chain_2.at_height(4))
 293                         .expect_block_disconnected(*fork_chain_2.at_height(3))
 294                         .expect_block_connected(*main_chain.at_height(3))
 295                         .expect_block_connected(*main_chain.at_height(4));
 296                 let listener_3 = MockChainListener::new()
 297                         .expect_block_disconnected(*fork_chain_3.at_height(4))
 298                         .expect_block_connected(*main_chain.at_height(4));
 299
 300                 let listeners = vec![
 301                         (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
 302                         (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
 303                         (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
 304                 ];
 305                 let mut cache = fork_chain_1.header_cache(2..=4);
 306                 cache.extend(fork_chain_2.header_cache(3..=4));
 307                 cache.extend(fork_chain_3.header_cache(4..=4));
 308                 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
 309                         Ok(header) => assert_eq!(header, main_chain.tip()),
 310                         Err(e) => panic!("Unexpected error: {:?}", e),
 311                 }
 312         }
 313
 314         #[tokio::test]
 315         async fn sync_from_overlapping_chains() {
 316                 let main_chain = Blockchain::default().with_height(4);
 317                 let fork_chain_1 = main_chain.fork_at_height(1);
 318                 let fork_chain_2 = fork_chain_1.fork_at_height(2);
 319                 let fork_chain_3 = fork_chain_2.fork_at_height(3);
 320
 321                 let listener_1 = MockChainListener::new()
 322                         .expect_block_disconnected(*fork_chain_1.at_height(4))
 323                         .expect_block_disconnected(*fork_chain_1.at_height(3))
 324                         .expect_block_disconnected(*fork_chain_1.at_height(2))
 325                         .expect_block_connected(*main_chain.at_height(2))
 326                         .expect_block_connected(*main_chain.at_height(3))
 327                         .expect_block_connected(*main_chain.at_height(4));
 328                 let listener_2 = MockChainListener::new()
 329                         .expect_block_disconnected(*fork_chain_2.at_height(4))
 330                         .expect_block_disconnected(*fork_chain_2.at_height(3))
 331                         .expect_block_disconnected(*fork_chain_2.at_height(2))
 332                         .expect_block_connected(*main_chain.at_height(2))
 333                         .expect_block_connected(*main_chain.at_height(3))
 334                         .expect_block_connected(*main_chain.at_height(4));
 335                 let listener_3 = MockChainListener::new()
 336                         .expect_block_disconnected(*fork_chain_3.at_height(4))
 337                         .expect_block_disconnected(*fork_chain_3.at_height(3))
 338                         .expect_block_disconnected(*fork_chain_3.at_height(2))
 339                         .expect_block_connected(*main_chain.at_height(2))
 340                         .expect_block_connected(*main_chain.at_height(3))
 341                         .expect_block_connected(*main_chain.at_height(4));
 342
 343                 let listeners = vec![
 344                         (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
 345                         (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
 346                         (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
 347                 ];
 348                 let mut cache = fork_chain_1.header_cache(2..=4);
 349                 cache.extend(fork_chain_2.header_cache(3..=4));
 350                 cache.extend(fork_chain_3.header_cache(4..=4));
 351                 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
 352                         Ok(header) => assert_eq!(header, main_chain.tip()),
 353                         Err(e) => panic!("Unexpected error: {:?}", e),
 354                 }
 355         }
 356
 357         #[tokio::test]
 358         async fn cache_connected_and_keep_disconnected_blocks() {
 359                 let main_chain = Blockchain::default().with_height(2);
 360                 let fork_chain = main_chain.fork_at_height(1);
 361                 let new_tip = main_chain.tip();
 362                 let old_tip = fork_chain.tip();
 363
 364                 let listener = MockChainListener::new()
 365                         .expect_block_disconnected(*old_tip)
 366                         .expect_block_connected(*new_tip);
 367
 368                 let listeners = vec![(old_tip.block_hash, &listener as &dyn chain::Listen)];
 369                 let mut cache = fork_chain.header_cache(2..=2);
 370                 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
 371                         Ok(_) => {
 372                                 assert!(cache.contains_key(&new_tip.block_hash));
 373                                 assert!(cache.contains_key(&old_tip.block_hash));
 374                         },
 375                         Err(e) => panic!("Unexpected error: {:?}", e),
 376                 }
 377         }
 378 }