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

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