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