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