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