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

   1 //! A lightweight client for keeping in sync with chain activity.
   2 //!
   3 //! Defines an [`SpvClient`] utility for polling one or more block sources for the best chain tip.
   4 //! It is used to notify listeners of blocks connected or disconnected since the last poll. Useful
   5 //! for keeping a Lightning node in sync with the chain.
   6 //!
   7 //! Defines a [`BlockSource`] trait, which is an asynchronous interface for retrieving block headers
   8 //! and data.
   9 //!
  10 //! Enabling feature `rest-client` or `rpc-client` allows configuring the client to fetch blocks
  11 //! using Bitcoin Core's REST or RPC interface, respectively.
  12 //!
  13 //! Both features support either blocking I/O using `std::net::TcpStream` or, with feature `tokio`,
  14 //! non-blocking I/O using `tokio::net::TcpStream` from inside a Tokio runtime.
  15
  16 #![deny(broken_intra_doc_links)]
  17 #![deny(missing_docs)]
  18 #![deny(unsafe_code)]
  19
  20 #[cfg(any(feature = "rest-client", feature = "rpc-client"))]
  21 pub mod http;
  22
  23 pub mod init;
  24 pub mod poll;
  25
  26 #[cfg(feature = "rest-client")]
  27 pub mod rest;
  28
  29 #[cfg(feature = "rpc-client")]
  30 pub mod rpc;
  31
  32 #[cfg(any(feature = "rest-client", feature = "rpc-client"))]
  33 mod convert;
  34
  35 #[cfg(test)]
  36 mod test_utils;
  37
  38 #[cfg(any(feature = "rest-client", feature = "rpc-client"))]
  39 mod utils;
  40
  41 use crate::poll::{ChainTip, Poll, ValidatedBlockHeader};
  42
  43 use bitcoin::blockdata::block::{Block, BlockHeader};
  44 use bitcoin::hash_types::BlockHash;
  45 use bitcoin::util::uint::Uint256;
  46
  47 use lightning::chain;
  48 use lightning::chain::Listen;
  49
  50 use std::future::Future;
  51 use std::ops::Deref;
  52 use std::pin::Pin;
  53
  54 /// Abstract type for retrieving block headers and data.
  55 pub trait BlockSource : Sync + Send {
  56         /// Returns the header for a given hash. A height hint may be provided in case a block source
  57         /// cannot easily find headers based on a hash. This is merely a hint and thus the returned
  58         /// header must have the same hash as was requested. Otherwise, an error must be returned.
  59         ///
  60         /// Implementations that cannot find headers based on the hash should return a `Transient` error
  61         /// when `height_hint` is `None`.
  62         fn get_header<'a>(&'a mut self, header_hash: &'a BlockHash, height_hint: Option<u32>) -> AsyncBlockSourceResult<'a, BlockHeaderData>;
  63
  64         /// Returns the block for a given hash. A headers-only block source should return a `Transient`
  65         /// error.
  66         fn get_block<'a>(&'a mut self, header_hash: &'a BlockHash) -> AsyncBlockSourceResult<'a, Block>;
  67
  68         /// Returns the hash of the best block and, optionally, its height.
  69         ///
  70         /// When polling a block source, [`Poll`] implementations may pass the height to [`get_header`]
  71         /// to allow for a more efficient lookup.
  72         ///
  73         /// [`get_header`]: Self::get_header
  74         fn get_best_block<'a>(&'a mut self) -> AsyncBlockSourceResult<(BlockHash, Option<u32>)>;
  75 }
  76
  77 /// Result type for `BlockSource` requests.
  78 pub type BlockSourceResult<T> = Result<T, BlockSourceError>;
  79
  80 // TODO: Replace with BlockSourceResult once `async` trait functions are supported. For details,
  81 // see: https://areweasyncyet.rs.
  82 /// Result type for asynchronous `BlockSource` requests.
  83 pub type AsyncBlockSourceResult<'a, T> = Pin<Box<dyn Future<Output = BlockSourceResult<T>> + 'a + Send>>;
  84
  85 /// Error type for `BlockSource` requests.
  86 ///
  87 /// Transient errors may be resolved when re-polling, but no attempt will be made to re-poll on
  88 /// persistent errors.
  89 #[derive(Debug)]
  90 pub struct BlockSourceError {
  91         kind: BlockSourceErrorKind,
  92         error: Box<dyn std::error::Error + Send + Sync>,
  93 }
  94
  95 /// The kind of `BlockSourceError`, either persistent or transient.
  96 #[derive(Clone, Copy, Debug, PartialEq)]
  97 pub enum BlockSourceErrorKind {
  98         /// Indicates an error that won't resolve when retrying a request (e.g., invalid data).
  99         Persistent,
 100
 101         /// Indicates an error that may resolve when retrying a request (e.g., unresponsive).
 102         Transient,
 103 }
 104
 105 impl BlockSourceError {
 106         /// Creates a new persistent error originated from the given error.
 107         pub fn persistent<E>(error: E) -> Self
 108         where E: Into<Box<dyn std::error::Error + Send + Sync>> {
 109                 Self {
 110                         kind: BlockSourceErrorKind::Persistent,
 111                         error: error.into(),
 112                 }
 113         }
 114
 115         /// Creates a new transient error originated from the given error.
 116         pub fn transient<E>(error: E) -> Self
 117         where E: Into<Box<dyn std::error::Error + Send + Sync>> {
 118                 Self {
 119                         kind: BlockSourceErrorKind::Transient,
 120                         error: error.into(),
 121                 }
 122         }
 123
 124         /// Returns the kind of error.
 125         pub fn kind(&self) -> BlockSourceErrorKind {
 126                 self.kind
 127         }
 128
 129         /// Converts the error into the underlying error.
 130         pub fn into_inner(self) -> Box<dyn std::error::Error + Send + Sync> {
 131                 self.error
 132         }
 133 }
 134
 135 /// A block header and some associated data. This information should be available from most block
 136 /// sources (and, notably, is available in Bitcoin Core's RPC and REST interfaces).
 137 #[derive(Clone, Copy, Debug, PartialEq)]
 138 pub struct BlockHeaderData {
 139         /// The block header itself.
 140         pub header: BlockHeader,
 141
 142         /// The block height where the genesis block has height 0.
 143         pub height: u32,
 144
 145         /// The total chain work in expected number of double-SHA256 hashes required to build a chain
 146         /// of equivalent weight.
 147         pub chainwork: Uint256,
 148 }
 149
 150 /// A lightweight client for keeping a listener in sync with the chain, allowing for Simplified
 151 /// Payment Verification (SPV).
 152 ///
 153 /// The client is parameterized by a chain poller which is responsible for polling one or more block
 154 /// sources for the best chain tip. During this process it detects any chain forks, determines which
 155 /// constitutes the best chain, and updates the listener accordingly with any blocks that were
 156 /// connected or disconnected since the last poll.
 157 ///
 158 /// Block headers for the best chain are maintained in the parameterized cache, allowing for a
 159 /// custom cache eviction policy. This offers flexibility to those sensitive to resource usage.
 160 /// Hence, there is a trade-off between a lower memory footprint and potentially increased network
 161 /// I/O as headers are re-fetched during fork detection.
 162 pub struct SpvClient<'a, P: Poll, C: Cache, L: Deref>
 163 where L::Target: chain::Listen {
 164         chain_tip: ValidatedBlockHeader,
 165         chain_poller: P,
 166         chain_notifier: ChainNotifier<'a, C, L>,
 167 }
 168
 169 /// The `Cache` trait defines behavior for managing a block header cache, where block headers are
 170 /// keyed by block hash.
 171 ///
 172 /// Used by [`ChainNotifier`] to store headers along the best chain, which is important for ensuring
 173 /// that blocks can be disconnected if they are no longer accessible from a block source (e.g., if
 174 /// the block source does not store stale forks indefinitely).
 175 ///
 176 /// Implementations may define how long to retain headers such that it's unlikely they will ever be
 177 /// needed to disconnect a block.  In cases where block sources provide access to headers on stale
 178 /// forks reliably, caches may be entirely unnecessary.
 179 pub trait Cache {
 180         /// Retrieves the block header keyed by the given block hash.
 181         fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader>;
 182
 183         /// Called when a block has been connected to the best chain to ensure it is available to be
 184         /// disconnected later if needed.
 185         fn block_connected(&mut self, block_hash: BlockHash, block_header: ValidatedBlockHeader);
 186
 187         /// Called when a block has been disconnected from the best chain. Once disconnected, a block's
 188         /// header is no longer needed and thus can be removed.
 189         fn block_disconnected(&mut self, block_hash: &BlockHash) -> Option<ValidatedBlockHeader>;
 190 }
 191
 192 /// Unbounded cache of block headers keyed by block hash.
 193 pub type UnboundedCache = std::collections::HashMap<BlockHash, ValidatedBlockHeader>;
 194
 195 impl Cache for UnboundedCache {
 196         fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
 197                 self.get(block_hash)
 198         }
 199
 200         fn block_connected(&mut self, block_hash: BlockHash, block_header: ValidatedBlockHeader) {
 201                 self.insert(block_hash, block_header);
 202         }
 203
 204         fn block_disconnected(&mut self, block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
 205                 self.remove(block_hash)
 206         }
 207 }
 208
 209 impl<'a, P: Poll, C: Cache, L: Deref> SpvClient<'a, P, C, L> where L::Target: chain::Listen {
 210         /// Creates a new SPV client using `chain_tip` as the best known chain tip.
 211         ///
 212         /// Subsequent calls to [`poll_best_tip`] will poll for the best chain tip using the given chain
 213         /// poller, which may be configured with one or more block sources to query. At least one block
 214         /// source must provide headers back from the best chain tip to its common ancestor with
 215         /// `chain_tip`.
 216         /// * `header_cache` is used to look up and store headers on the best chain
 217         /// * `chain_listener` is notified of any blocks connected or disconnected
 218         ///
 219         /// [`poll_best_tip`]: SpvClient::poll_best_tip
 220         pub fn new(
 221                 chain_tip: ValidatedBlockHeader,
 222                 chain_poller: P,
 223                 header_cache: &'a mut C,
 224                 chain_listener: L,
 225         ) -> Self {
 226                 let chain_notifier = ChainNotifier { header_cache, chain_listener };
 227                 Self { chain_tip, chain_poller, chain_notifier }
 228         }
 229
 230         /// Polls for the best tip and updates the chain listener with any connected or disconnected
 231         /// blocks accordingly.
 232         ///
 233         /// Returns the best polled chain tip relative to the previous best known tip and whether any
 234         /// blocks were indeed connected or disconnected.
 235         pub async fn poll_best_tip(&mut self) -> BlockSourceResult<(ChainTip, bool)> {
 236                 let chain_tip = self.chain_poller.poll_chain_tip(self.chain_tip).await?;
 237                 let blocks_connected = match chain_tip {
 238                         ChainTip::Common => false,
 239                         ChainTip::Better(chain_tip) => {
 240                                 debug_assert_ne!(chain_tip.block_hash, self.chain_tip.block_hash);
 241                                 debug_assert!(chain_tip.chainwork > self.chain_tip.chainwork);
 242                                 self.update_chain_tip(chain_tip).await
 243                         },
 244                         ChainTip::Worse(chain_tip) => {
 245                                 debug_assert_ne!(chain_tip.block_hash, self.chain_tip.block_hash);
 246                                 debug_assert!(chain_tip.chainwork <= self.chain_tip.chainwork);
 247                                 false
 248                         },
 249                 };
 250                 Ok((chain_tip, blocks_connected))
 251         }
 252
 253         /// Updates the chain tip, syncing the chain listener with any connected or disconnected
 254         /// blocks. Returns whether there were any such blocks.
 255         async fn update_chain_tip(&mut self, best_chain_tip: ValidatedBlockHeader) -> bool {
 256                 match self.chain_notifier.synchronize_listener(
 257                         best_chain_tip, &self.chain_tip, &mut self.chain_poller).await
 258                 {
 259                         Ok(_) => {
 260                                 self.chain_tip = best_chain_tip;
 261                                 true
 262                         },
 263                         Err((_, Some(chain_tip))) if chain_tip.block_hash != self.chain_tip.block_hash => {
 264                                 self.chain_tip = chain_tip;
 265                                 true
 266                         },
 267                         Err(_) => false,
 268                 }
 269         }
 270 }
 271
 272 /// Notifies [listeners] of blocks that have been connected or disconnected from the chain.
 273 ///
 274 /// [listeners]: lightning::chain::Listen
 275 pub struct ChainNotifier<'a, C: Cache, L: Deref> where L::Target: chain::Listen {
 276         /// Cache for looking up headers before fetching from a block source.
 277         header_cache: &'a mut C,
 278
 279         /// Listener that will be notified of connected or disconnected blocks.
 280         chain_listener: L,
 281 }
 282
 283 /// Changes made to the chain between subsequent polls that transformed it from having one chain tip
 284 /// to another.
 285 ///
 286 /// Blocks are given in height-descending order. Therefore, blocks are first disconnected in order
 287 /// before new blocks are connected in reverse order.
 288 struct ChainDifference {
 289         /// The most recent ancestor common between the chain tips.
 290         ///
 291         /// If there are any disconnected blocks, this is where the chain forked.
 292         common_ancestor: ValidatedBlockHeader,
 293
 294         /// Blocks that were disconnected from the chain since the last poll.
 295         disconnected_blocks: Vec<ValidatedBlockHeader>,
 296
 297         /// Blocks that were connected to the chain since the last poll.
 298         connected_blocks: Vec<ValidatedBlockHeader>,
 299 }
 300
 301 impl<'a, C: Cache, L: Deref> ChainNotifier<'a, C, L> where L::Target: chain::Listen {
 302         /// Finds the first common ancestor between `new_header` and `old_header`, disconnecting blocks
 303         /// from `old_header` to get to that point and then connecting blocks until `new_header`.
 304         ///
 305         /// Validates headers along the transition path, but doesn't fetch blocks until the chain is
 306         /// disconnected to the fork point. Thus, this may return an `Err` that includes where the tip
 307         /// ended up which may not be `new_header`. Note that the returned `Err` contains `Some` header
 308         /// if and only if the transition from `old_header` to `new_header` is valid.
 309         async fn synchronize_listener<P: Poll>(
 310                 &mut self,
 311                 new_header: ValidatedBlockHeader,
 312                 old_header: &ValidatedBlockHeader,
 313                 chain_poller: &mut P,
 314         ) -> Result<(), (BlockSourceError, Option<ValidatedBlockHeader>)> {
 315                 let difference = self.find_difference(new_header, old_header, chain_poller).await
 316                         .map_err(|e| (e, None))?;
 317                 self.disconnect_blocks(difference.disconnected_blocks);
 318                 self.connect_blocks(
 319                         difference.common_ancestor,
 320                         difference.connected_blocks,
 321                         chain_poller,
 322                 ).await
 323         }
 324
 325         /// Returns the changes needed to produce the chain with `current_header` as its tip from the
 326         /// chain with `prev_header` as its tip.
 327         ///
 328         /// Walks backwards from `current_header` and `prev_header`, finding the common ancestor.
 329         async fn find_difference<P: Poll>(
 330                 &self,
 331                 current_header: ValidatedBlockHeader,
 332                 prev_header: &ValidatedBlockHeader,
 333                 chain_poller: &mut P,
 334         ) -> BlockSourceResult<ChainDifference> {
 335                 let mut disconnected_blocks = Vec::new();
 336                 let mut connected_blocks = Vec::new();
 337                 let mut current = current_header;
 338                 let mut previous = *prev_header;
 339                 loop {
 340                         // Found the common ancestor.
 341                         if current.block_hash == previous.block_hash {
 342                                 break;
 343                         }
 344
 345                         // Walk back the chain, finding blocks needed to connect and disconnect. Only walk back
 346                         // the header with the greater height, or both if equal heights.
 347                         let current_height = current.height;
 348                         let previous_height = previous.height;
 349                         if current_height <= previous_height {
 350                                 disconnected_blocks.push(previous);
 351                                 previous = self.look_up_previous_header(chain_poller, &previous).await?;
 352                         }
 353                         if current_height >= previous_height {
 354                                 connected_blocks.push(current);
 355                                 current = self.look_up_previous_header(chain_poller, &current).await?;
 356                         }
 357                 }
 358
 359                 let common_ancestor = current;
 360                 Ok(ChainDifference { common_ancestor, disconnected_blocks, connected_blocks })
 361         }
 362
 363         /// Returns the previous header for the given header, either by looking it up in the cache or
 364         /// fetching it if not found.
 365         async fn look_up_previous_header<P: Poll>(
 366                 &self,
 367                 chain_poller: &mut P,
 368                 header: &ValidatedBlockHeader,
 369         ) -> BlockSourceResult<ValidatedBlockHeader> {
 370                 match self.header_cache.look_up(&header.header.prev_blockhash) {
 371                         Some(prev_header) => Ok(*prev_header),
 372                         None => chain_poller.look_up_previous_header(header).await,
 373                 }
 374         }
 375
 376         /// Notifies the chain listeners of disconnected blocks.
 377         fn disconnect_blocks(&mut self, mut disconnected_blocks: Vec<ValidatedBlockHeader>) {
 378                 for header in disconnected_blocks.drain(..) {
 379                         if let Some(cached_header) = self.header_cache.block_disconnected(&header.block_hash) {
 380                                 assert_eq!(cached_header, header);
 381                         }
 382                         self.chain_listener.block_disconnected(&header.header, header.height);
 383                 }
 384         }
 385
 386         /// Notifies the chain listeners of connected blocks.
 387         async fn connect_blocks<P: Poll>(
 388                 &mut self,
 389                 mut new_tip: ValidatedBlockHeader,
 390                 mut connected_blocks: Vec<ValidatedBlockHeader>,
 391                 chain_poller: &mut P,
 392         ) -> Result<(), (BlockSourceError, Option<ValidatedBlockHeader>)> {
 393                 for header in connected_blocks.drain(..).rev() {
 394                         let block = chain_poller
 395                                 .fetch_block(&header).await
 396                                 .or_else(|e| Err((e, Some(new_tip))))?;
 397                         debug_assert_eq!(block.block_hash, header.block_hash);
 398
 399                         self.header_cache.block_connected(header.block_hash, header);
 400                         self.chain_listener.block_connected(&block, header.height);
 401                         new_tip = header;
 402                 }
 403
 404                 Ok(())
 405         }
 406 }
 407
 408 #[cfg(test)]
 409 mod spv_client_tests {
 410         use crate::test_utils::{Blockchain, NullChainListener};
 411         use super::*;
 412
 413         use bitcoin::network::constants::Network;
 414
 415         #[tokio::test]
 416         async fn poll_from_chain_without_headers() {
 417                 let mut chain = Blockchain::default().with_height(3).without_headers();
 418                 let best_tip = chain.at_height(1);
 419
 420                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 421                 let mut cache = UnboundedCache::new();
 422                 let mut listener = NullChainListener {};
 423                 let mut client = SpvClient::new(best_tip, poller, &mut cache, &mut listener);
 424                 match client.poll_best_tip().await {
 425                         Err(e) => {
 426                                 assert_eq!(e.kind(), BlockSourceErrorKind::Persistent);
 427                                 assert_eq!(e.into_inner().as_ref().to_string(), "header not found");
 428                         },
 429                         Ok(_) => panic!("Expected error"),
 430                 }
 431                 assert_eq!(client.chain_tip, best_tip);
 432         }
 433
 434         #[tokio::test]
 435         async fn poll_from_chain_with_common_tip() {
 436                 let mut chain = Blockchain::default().with_height(3);
 437                 let common_tip = chain.tip();
 438
 439                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 440                 let mut cache = UnboundedCache::new();
 441                 let mut listener = NullChainListener {};
 442                 let mut client = SpvClient::new(common_tip, poller, &mut cache, &mut listener);
 443                 match client.poll_best_tip().await {
 444                         Err(e) => panic!("Unexpected error: {:?}", e),
 445                         Ok((chain_tip, blocks_connected)) => {
 446                                 assert_eq!(chain_tip, ChainTip::Common);
 447                                 assert!(!blocks_connected);
 448                         },
 449                 }
 450                 assert_eq!(client.chain_tip, common_tip);
 451         }
 452
 453         #[tokio::test]
 454         async fn poll_from_chain_with_better_tip() {
 455                 let mut chain = Blockchain::default().with_height(3);
 456                 let new_tip = chain.tip();
 457                 let old_tip = chain.at_height(1);
 458
 459                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 460                 let mut cache = UnboundedCache::new();
 461                 let mut listener = NullChainListener {};
 462                 let mut client = SpvClient::new(old_tip, poller, &mut cache, &mut listener);
 463                 match client.poll_best_tip().await {
 464                         Err(e) => panic!("Unexpected error: {:?}", e),
 465                         Ok((chain_tip, blocks_connected)) => {
 466                                 assert_eq!(chain_tip, ChainTip::Better(new_tip));
 467                                 assert!(blocks_connected);
 468                         },
 469                 }
 470                 assert_eq!(client.chain_tip, new_tip);
 471         }
 472
 473         #[tokio::test]
 474         async fn poll_from_chain_with_better_tip_and_without_any_new_blocks() {
 475                 let mut chain = Blockchain::default().with_height(3).without_blocks(2..);
 476                 let new_tip = chain.tip();
 477                 let old_tip = chain.at_height(1);
 478
 479                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 480                 let mut cache = UnboundedCache::new();
 481                 let mut listener = NullChainListener {};
 482                 let mut client = SpvClient::new(old_tip, poller, &mut cache, &mut listener);
 483                 match client.poll_best_tip().await {
 484                         Err(e) => panic!("Unexpected error: {:?}", e),
 485                         Ok((chain_tip, blocks_connected)) => {
 486                                 assert_eq!(chain_tip, ChainTip::Better(new_tip));
 487                                 assert!(!blocks_connected);
 488                         },
 489                 }
 490                 assert_eq!(client.chain_tip, old_tip);
 491         }
 492
 493         #[tokio::test]
 494         async fn poll_from_chain_with_better_tip_and_without_some_new_blocks() {
 495                 let mut chain = Blockchain::default().with_height(3).without_blocks(3..);
 496                 let new_tip = chain.tip();
 497                 let old_tip = chain.at_height(1);
 498
 499                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 500                 let mut cache = UnboundedCache::new();
 501                 let mut listener = NullChainListener {};
 502                 let mut client = SpvClient::new(old_tip, poller, &mut cache, &mut listener);
 503                 match client.poll_best_tip().await {
 504                         Err(e) => panic!("Unexpected error: {:?}", e),
 505                         Ok((chain_tip, blocks_connected)) => {
 506                                 assert_eq!(chain_tip, ChainTip::Better(new_tip));
 507                                 assert!(blocks_connected);
 508                         },
 509                 }
 510                 assert_eq!(client.chain_tip, chain.at_height(2));
 511         }
 512
 513         #[tokio::test]
 514         async fn poll_from_chain_with_worse_tip() {
 515                 let mut chain = Blockchain::default().with_height(3);
 516                 let best_tip = chain.tip();
 517                 chain.disconnect_tip();
 518                 let worse_tip = chain.tip();
 519
 520                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 521                 let mut cache = UnboundedCache::new();
 522                 let mut listener = NullChainListener {};
 523                 let mut client = SpvClient::new(best_tip, poller, &mut cache, &mut listener);
 524                 match client.poll_best_tip().await {
 525                         Err(e) => panic!("Unexpected error: {:?}", e),
 526                         Ok((chain_tip, blocks_connected)) => {
 527                                 assert_eq!(chain_tip, ChainTip::Worse(worse_tip));
 528                                 assert!(!blocks_connected);
 529                         },
 530                 }
 531                 assert_eq!(client.chain_tip, best_tip);
 532         }
 533 }
 534
 535 #[cfg(test)]
 536 mod chain_notifier_tests {
 537         use crate::test_utils::{Blockchain, MockChainListener};
 538         use super::*;
 539
 540         use bitcoin::network::constants::Network;
 541
 542         #[tokio::test]
 543         async fn sync_from_same_chain() {
 544                 let mut chain = Blockchain::default().with_height(3);
 545
 546                 let new_tip = chain.tip();
 547                 let old_tip = chain.at_height(1);
 548                 let chain_listener = &MockChainListener::new()
 549                         .expect_block_connected(*chain.at_height(2))
 550                         .expect_block_connected(*new_tip);
 551                 let mut notifier = ChainNotifier {
 552                         header_cache: &mut chain.header_cache(0..=1),
 553                         chain_listener,
 554                 };
 555                 let mut poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 556                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 557                         Err((e, _)) => panic!("Unexpected error: {:?}", e),
 558                         Ok(_) => {},
 559                 }
 560         }
 561
 562         #[tokio::test]
 563         async fn sync_from_different_chains() {
 564                 let mut test_chain = Blockchain::with_network(Network::Testnet).with_height(1);
 565                 let main_chain = Blockchain::with_network(Network::Bitcoin).with_height(1);
 566
 567                 let new_tip = test_chain.tip();
 568                 let old_tip = main_chain.tip();
 569                 let chain_listener = &MockChainListener::new();
 570                 let mut notifier = ChainNotifier {
 571                         header_cache: &mut main_chain.header_cache(0..=1),
 572                         chain_listener,
 573                 };
 574                 let mut poller = poll::ChainPoller::new(&mut test_chain, Network::Testnet);
 575                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 576                         Err((e, _)) => {
 577                                 assert_eq!(e.kind(), BlockSourceErrorKind::Persistent);
 578                                 assert_eq!(e.into_inner().as_ref().to_string(), "genesis block reached");
 579                         },
 580                         Ok(_) => panic!("Expected error"),
 581                 }
 582         }
 583
 584         #[tokio::test]
 585         async fn sync_from_equal_length_fork() {
 586                 let main_chain = Blockchain::default().with_height(2);
 587                 let mut fork_chain = main_chain.fork_at_height(1);
 588
 589                 let new_tip = fork_chain.tip();
 590                 let old_tip = main_chain.tip();
 591                 let chain_listener = &MockChainListener::new()
 592                         .expect_block_disconnected(*old_tip)
 593                         .expect_block_connected(*new_tip);
 594                 let mut notifier = ChainNotifier {
 595                         header_cache: &mut main_chain.header_cache(0..=2),
 596                         chain_listener,
 597                 };
 598                 let mut poller = poll::ChainPoller::new(&mut fork_chain, Network::Testnet);
 599                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 600                         Err((e, _)) => panic!("Unexpected error: {:?}", e),
 601                         Ok(_) => {},
 602                 }
 603         }
 604
 605         #[tokio::test]
 606         async fn sync_from_shorter_fork() {
 607                 let main_chain = Blockchain::default().with_height(3);
 608                 let mut fork_chain = main_chain.fork_at_height(1);
 609                 fork_chain.disconnect_tip();
 610
 611                 let new_tip = fork_chain.tip();
 612                 let old_tip = main_chain.tip();
 613                 let chain_listener = &MockChainListener::new()
 614                         .expect_block_disconnected(*old_tip)
 615                         .expect_block_disconnected(*main_chain.at_height(2))
 616                         .expect_block_connected(*new_tip);
 617                 let mut notifier = ChainNotifier {
 618                         header_cache: &mut main_chain.header_cache(0..=3),
 619                         chain_listener,
 620                 };
 621                 let mut poller = poll::ChainPoller::new(&mut fork_chain, Network::Testnet);
 622                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 623                         Err((e, _)) => panic!("Unexpected error: {:?}", e),
 624                         Ok(_) => {},
 625                 }
 626         }
 627
 628         #[tokio::test]
 629         async fn sync_from_longer_fork() {
 630                 let mut main_chain = Blockchain::default().with_height(3);
 631                 let mut fork_chain = main_chain.fork_at_height(1);
 632                 main_chain.disconnect_tip();
 633
 634                 let new_tip = fork_chain.tip();
 635                 let old_tip = main_chain.tip();
 636                 let chain_listener = &MockChainListener::new()
 637                         .expect_block_disconnected(*old_tip)
 638                         .expect_block_connected(*fork_chain.at_height(2))
 639                         .expect_block_connected(*new_tip);
 640                 let mut notifier = ChainNotifier {
 641                         header_cache: &mut main_chain.header_cache(0..=2),
 642                         chain_listener,
 643                 };
 644                 let mut poller = poll::ChainPoller::new(&mut fork_chain, Network::Testnet);
 645                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 646                         Err((e, _)) => panic!("Unexpected error: {:?}", e),
 647                         Ok(_) => {},
 648                 }
 649         }
 650
 651         #[tokio::test]
 652         async fn sync_from_chain_without_headers() {
 653                 let mut chain = Blockchain::default().with_height(3).without_headers();
 654
 655                 let new_tip = chain.tip();
 656                 let old_tip = chain.at_height(1);
 657                 let chain_listener = &MockChainListener::new();
 658                 let mut notifier = ChainNotifier {
 659                         header_cache: &mut chain.header_cache(0..=1),
 660                         chain_listener,
 661                 };
 662                 let mut poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 663                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 664                         Err((_, tip)) => assert_eq!(tip, None),
 665                         Ok(_) => panic!("Expected error"),
 666                 }
 667         }
 668
 669         #[tokio::test]
 670         async fn sync_from_chain_without_any_new_blocks() {
 671                 let mut chain = Blockchain::default().with_height(3).without_blocks(2..);
 672
 673                 let new_tip = chain.tip();
 674                 let old_tip = chain.at_height(1);
 675                 let chain_listener = &MockChainListener::new();
 676                 let mut notifier = ChainNotifier {
 677                         header_cache: &mut chain.header_cache(0..=3),
 678                         chain_listener,
 679                 };
 680                 let mut poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 681                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 682                         Err((_, tip)) => assert_eq!(tip, Some(old_tip)),
 683                         Ok(_) => panic!("Expected error"),
 684                 }
 685         }
 686
 687         #[tokio::test]
 688         async fn sync_from_chain_without_some_new_blocks() {
 689                 let mut chain = Blockchain::default().with_height(3).without_blocks(3..);
 690
 691                 let new_tip = chain.tip();
 692                 let old_tip = chain.at_height(1);
 693                 let chain_listener = &MockChainListener::new()
 694                         .expect_block_connected(*chain.at_height(2));
 695                 let mut notifier = ChainNotifier {
 696                         header_cache: &mut chain.header_cache(0..=3),
 697                         chain_listener,
 698                 };
 699                 let mut poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 700                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 701                         Err((_, tip)) => assert_eq!(tip, Some(chain.at_height(2))),
 702                         Ok(_) => panic!("Expected error"),
 703                 }
 704         }
 705 }