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