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