_ 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_option, 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 ///             <(Option<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 mut listeners = vec![
  87 ///             (monitor_block_hash, &mut monitor_listener as &mut dyn chain::Listen),
  88 ///     ];
  89 ///     if let Some(manager_block_hash) = manager_block_hash_option {
  90 ///             listeners.push((manager_block_hash, &mut manager as &mut dyn chain::Listen))
  91 ///     }
  92 ///     let chain_tip = init::synchronize_listeners(
  93 ///             block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
  94 ///
  95 ///     // Allow the chain monitor to watch any channels.
  96 ///     let monitor = monitor_listener.0;
  97 ///     chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
  98 ///
  99 ///     // Create an SPV client to notify the chain monitor and channel manager of block events.
 100 ///     let chain_poller = poll::ChainPoller::new(block_source, Network::Bitcoin);
 101 ///     let mut chain_listener = (chain_monitor, &manager);
 102 ///     let spv_client = SpvClient::new(chain_tip, chain_poller, &mut cache, &chain_listener);
 103 /// }
 104 /// ```
 105 ///
 106 /// [`SpvClient`]: ../struct.SpvClient.html
 107 /// [`ChannelManager`]: ../../lightning/ln/channelmanager/struct.ChannelManager.html
 108 /// [`ChannelMonitor`]: ../../lightning/chain/channelmonitor/struct.ChannelMonitor.html
 109 pub async fn synchronize_listeners<B: BlockSource, C: Cache>(
 110         block_source: &mut B,
 111         network: Network,
 112         header_cache: &mut C,
 113         mut chain_listeners: Vec<(BlockHash, &mut dyn chain::Listen)>,
 114 ) -> BlockSourceResult<ValidatedBlockHeader> {
 115         let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
 116         let best_header = block_source
 117                 .get_header(&best_block_hash, best_block_height).await?
 118                 .validate(best_block_hash)?;
 119
 120         // Fetch the header for the block hash paired with each listener.
 121         let mut chain_listeners_with_old_headers = Vec::new();
 122         for (old_block_hash, chain_listener) in chain_listeners.drain(..) {
 123                 let old_header = match header_cache.look_up(&old_block_hash) {
 124                         Some(header) => *header,
 125                         None => block_source
 126                                 .get_header(&old_block_hash, None).await?
 127                                 .validate(old_block_hash)?
 128                 };
 129                 chain_listeners_with_old_headers.push((old_header, chain_listener))
 130         }
 131
 132         // Find differences and disconnect blocks for each listener individually.
 133         let mut chain_poller = ChainPoller::new(block_source, network);
 134         let mut chain_listeners_at_height = Vec::new();
 135         let mut most_common_ancestor = None;
 136         let mut most_connected_blocks = Vec::new();
 137         for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
 138                 // Disconnect any stale blocks, but keep them in the cache for the next iteration.
 139                 let header_cache = &mut ReadOnlyCache(header_cache);
 140                 let (common_ancestor, connected_blocks) = {
 141                         let chain_listener = &DynamicChainListener(chain_listener);
 142                         let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
 143                         let difference =
 144                                 chain_notifier.find_difference(best_header, &old_header, &mut chain_poller).await?;
 145                         chain_notifier.disconnect_blocks(difference.disconnected_blocks);
 146                         (difference.common_ancestor, difference.connected_blocks)
 147                 };
 148
 149                 // Keep track of the most common ancestor and all blocks connected across all listeners.
 150                 chain_listeners_at_height.push((common_ancestor.height, chain_listener));
 151                 if connected_blocks.len() > most_connected_blocks.len() {
 152                         most_common_ancestor = Some(common_ancestor);
 153                         most_connected_blocks = connected_blocks;
 154                 }
 155         }
 156
 157         // Connect new blocks for all listeners at once to avoid re-fetching blocks.
 158         if let Some(common_ancestor) = most_common_ancestor {
 159                 let chain_listener = &ChainListenerSet(chain_listeners_at_height);
 160                 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
 161                 chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
 162                         .await.or_else(|(e, _)| Err(e))?;
 163         }
 164
 165         Ok(best_header)
 166 }
 167
 168 /// A wrapper to make a cache read-only.
 169 ///
 170 /// Used to prevent losing headers that may be needed to disconnect blocks common to more than one
 171 /// listener.
 172 struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
 173
 174 impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
 175         fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
 176                 self.0.look_up(block_hash)
 177         }
 178
 179         fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
 180                 unreachable!()
 181         }
 182
 183         fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
 184                 None
 185         }
 186 }
 187
 188 /// Wrapper for supporting dynamically sized chain listeners.
 189 struct DynamicChainListener<'a>(&'a mut dyn chain::Listen);
 190
 191 impl<'a> chain::Listen for DynamicChainListener<'a> {
 192         fn block_connected(&self, _block: &Block, _height: u32) {
 193                 unreachable!()
 194         }
 195
 196         fn block_disconnected(&self, header: &BlockHeader, height: u32) {
 197                 self.0.block_disconnected(header, height)
 198         }
 199 }
 200
 201 /// A set of dynamically sized chain listeners, each paired with a starting block height.
 202 struct ChainListenerSet<'a>(Vec<(u32, &'a mut dyn chain::Listen)>);
 203
 204 impl<'a> chain::Listen for ChainListenerSet<'a> {
 205         fn block_connected(&self, block: &Block, height: u32) {
 206                 for (starting_height, chain_listener) in self.0.iter() {
 207                         if height > *starting_height {
 208                                 chain_listener.block_connected(block, height);
 209                         }
 210                 }
 211         }
 212
 213         fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
 214                 unreachable!()
 215         }
 216 }
 217
 218 #[cfg(test)]
 219 mod tests {
 220         use crate::test_utils::{Blockchain, MockChainListener};
 221         use super::*;
 222
 223         use bitcoin::network::constants::Network;
 224
 225         #[tokio::test]
 226         async fn sync_from_same_chain() {
 227                 let mut chain = Blockchain::default().with_height(4);
 228
 229                 let mut listener_1 = MockChainListener::new()
 230                         .expect_block_connected(*chain.at_height(2))
 231                         .expect_block_connected(*chain.at_height(3))
 232                         .expect_block_connected(*chain.at_height(4));
 233                 let mut listener_2 = MockChainListener::new()
 234                         .expect_block_connected(*chain.at_height(3))
 235                         .expect_block_connected(*chain.at_height(4));
 236                 let mut listener_3 = MockChainListener::new()
 237                         .expect_block_connected(*chain.at_height(4));
 238
 239                 let listeners = vec![
 240                         (chain.at_height(1).block_hash, &mut listener_1 as &mut dyn chain::Listen),
 241                         (chain.at_height(2).block_hash, &mut listener_2 as &mut dyn chain::Listen),
 242                         (chain.at_height(3).block_hash, &mut listener_3 as &mut dyn chain::Listen),
 243                 ];
 244                 let mut cache = chain.header_cache(0..=4);
 245                 match synchronize_listeners(&mut chain, Network::Bitcoin, &mut cache, listeners).await {
 246                         Ok(header) => assert_eq!(header, chain.tip()),
 247                         Err(e) => panic!("Unexpected error: {:?}", e),
 248                 }
 249         }
 250
 251         #[tokio::test]
 252         async fn sync_from_different_chains() {
 253                 let mut main_chain = Blockchain::default().with_height(4);
 254                 let fork_chain_1 = main_chain.fork_at_height(1);
 255                 let fork_chain_2 = main_chain.fork_at_height(2);
 256                 let fork_chain_3 = main_chain.fork_at_height(3);
 257
 258                 let mut listener_1 = MockChainListener::new()
 259                         .expect_block_disconnected(*fork_chain_1.at_height(4))
 260                         .expect_block_disconnected(*fork_chain_1.at_height(3))
 261                         .expect_block_disconnected(*fork_chain_1.at_height(2))
 262                         .expect_block_connected(*main_chain.at_height(2))
 263                         .expect_block_connected(*main_chain.at_height(3))
 264                         .expect_block_connected(*main_chain.at_height(4));
 265                 let mut listener_2 = MockChainListener::new()
 266                         .expect_block_disconnected(*fork_chain_2.at_height(4))
 267                         .expect_block_disconnected(*fork_chain_2.at_height(3))
 268                         .expect_block_connected(*main_chain.at_height(3))
 269                         .expect_block_connected(*main_chain.at_height(4));
 270                 let mut listener_3 = MockChainListener::new()
 271                         .expect_block_disconnected(*fork_chain_3.at_height(4))
 272                         .expect_block_connected(*main_chain.at_height(4));
 273
 274                 let listeners = vec![
 275                         (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
 276                         (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
 277                         (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
 278                 ];
 279                 let mut cache = fork_chain_1.header_cache(2..=4);
 280                 cache.extend(fork_chain_2.header_cache(3..=4));
 281                 cache.extend(fork_chain_3.header_cache(4..=4));
 282                 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
 283                         Ok(header) => assert_eq!(header, main_chain.tip()),
 284                         Err(e) => panic!("Unexpected error: {:?}", e),
 285                 }
 286         }
 287
 288         #[tokio::test]
 289         async fn sync_from_overlapping_chains() {
 290                 let mut main_chain = Blockchain::default().with_height(4);
 291                 let fork_chain_1 = main_chain.fork_at_height(1);
 292                 let fork_chain_2 = fork_chain_1.fork_at_height(2);
 293                 let fork_chain_3 = fork_chain_2.fork_at_height(3);
 294
 295                 let mut listener_1 = MockChainListener::new()
 296                         .expect_block_disconnected(*fork_chain_1.at_height(4))
 297                         .expect_block_disconnected(*fork_chain_1.at_height(3))
 298                         .expect_block_disconnected(*fork_chain_1.at_height(2))
 299                         .expect_block_connected(*main_chain.at_height(2))
 300                         .expect_block_connected(*main_chain.at_height(3))
 301                         .expect_block_connected(*main_chain.at_height(4));
 302                 let mut listener_2 = MockChainListener::new()
 303                         .expect_block_disconnected(*fork_chain_2.at_height(4))
 304                         .expect_block_disconnected(*fork_chain_2.at_height(3))
 305                         .expect_block_disconnected(*fork_chain_2.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_3 = MockChainListener::new()
 310                         .expect_block_disconnected(*fork_chain_3.at_height(4))
 311                         .expect_block_disconnected(*fork_chain_3.at_height(3))
 312                         .expect_block_disconnected(*fork_chain_3.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
 317                 let listeners = vec![
 318                         (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
 319                         (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
 320                         (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
 321                 ];
 322                 let mut cache = fork_chain_1.header_cache(2..=4);
 323                 cache.extend(fork_chain_2.header_cache(3..=4));
 324                 cache.extend(fork_chain_3.header_cache(4..=4));
 325                 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
 326                         Ok(header) => assert_eq!(header, main_chain.tip()),
 327                         Err(e) => panic!("Unexpected error: {:?}", e),
 328                 }
 329         }
 330
 331         #[tokio::test]
 332         async fn cache_connected_and_keep_disconnected_blocks() {
 333                 let mut main_chain = Blockchain::default().with_height(2);
 334                 let fork_chain = main_chain.fork_at_height(1);
 335                 let new_tip = main_chain.tip();
 336                 let old_tip = fork_chain.tip();
 337
 338                 let mut listener = MockChainListener::new()
 339                         .expect_block_disconnected(*old_tip)
 340                         .expect_block_connected(*new_tip);
 341
 342                 let listeners = vec![(old_tip.block_hash, &mut listener as &mut dyn chain::Listen)];
 343                 let mut cache = fork_chain.header_cache(2..=2);
 344                 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
 345                         Ok(_) => {
 346                                 assert!(cache.contains_key(&new_tip.block_hash));
 347                                 assert!(cache.contains_key(&old_tip.block_hash));
 348                         },
 349                         Err(e) => panic!("Unexpected error: {:?}", e),
 350                 }
 351         }
 352 }