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