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