_ 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 #![deny(broken_intra_doc_links)]
  20 #![deny(unsafe_code)]
  21
  22 #[cfg(any(feature = "rest-client", feature = "rpc-client"))]
  23 pub mod http;
  24
  25 pub mod init;
  26 pub mod poll;
  27
  28 #[cfg(feature = "rest-client")]
  29 pub mod rest;
  30
  31 #[cfg(feature = "rpc-client")]
  32 pub mod rpc;
  33
  34 #[cfg(any(feature = "rest-client", feature = "rpc-client"))]
  35 mod convert;
  36
  37 #[cfg(test)]
  38 mod test_utils;
  39
  40 #[cfg(any(feature = "rest-client", feature = "rpc-client"))]
  41 mod utils;
  42
  43 use crate::poll::{ChainTip, Poll, ValidatedBlockHeader};
  44
  45 use bitcoin::blockdata::block::{Block, BlockHeader};
  46 use bitcoin::hash_types::BlockHash;
  47 use bitcoin::util::uint::Uint256;
  48
  49 use lightning::chain;
  50 use lightning::chain::Listen;
  51
  52 use std::future::Future;
  53 use std::ops::Deref;
  54 use std::pin::Pin;
  55
  56 /// Abstract type for retrieving block headers and data.
  57 pub trait BlockSource : Sync + Send {
  58         /// Returns the header for a given hash. A height hint may be provided in case a block source
  59         /// cannot easily find headers based on a hash. This is merely a hint and thus the returned
  60         /// header must have the same hash as was requested. Otherwise, an error must be returned.
  61         ///
  62         /// Implementations that cannot find headers based on the hash should return a `Transient` error
  63         /// when `height_hint` is `None`.
  64         fn get_header<'a>(&'a mut self, header_hash: &'a BlockHash, height_hint: Option<u32>) -> AsyncBlockSourceResult<'a, BlockHeaderData>;
  65
  66         /// Returns the block for a given hash. A headers-only block source should return a `Transient`
  67         /// error.
  68         fn get_block<'a>(&'a mut self, header_hash: &'a BlockHash) -> AsyncBlockSourceResult<'a, Block>;
  69
  70         /// Returns the hash of the best block and, optionally, its height.
  71         ///
  72         /// When polling a block source, [`Poll`] implementations may pass the height to [`get_header`]
  73         /// to allow for a more efficient lookup.
  74         ///
  75         /// [`Poll`]: poll/trait.Poll.html
  76         /// [`get_header`]: #tymethod.get_header
  77         fn get_best_block<'a>(&'a mut self) -> AsyncBlockSourceResult<(BlockHash, Option<u32>)>;
  78 }
  79
  80 /// Result type for `BlockSource` requests.
  81 type BlockSourceResult<T> = Result<T, BlockSourceError>;
  82
  83 // TODO: Replace with BlockSourceResult once `async` trait functions are supported. For details,
  84 // see: https://areweasyncyet.rs.
  85 /// Result type for asynchronous `BlockSource` requests.
  86 type AsyncBlockSourceResult<'a, T> = Pin<Box<dyn Future<Output = BlockSourceResult<T>> + 'a + Send>>;
  87
  88 /// Error type for `BlockSource` requests.
  89 ///
  90 /// Transient errors may be resolved when re-polling, but no attempt will be made to re-poll on
  91 /// persistent errors.
  92 #[derive(Debug)]
  93 pub struct BlockSourceError {
  94         kind: BlockSourceErrorKind,
  95         error: Box<dyn std::error::Error + Send + Sync>,
  96 }
  97
  98 /// The kind of `BlockSourceError`, either persistent or transient.
  99 #[derive(Clone, Copy, Debug, PartialEq)]
 100 pub enum BlockSourceErrorKind {
 101         /// Indicates an error that won't resolve when retrying a request (e.g., invalid data).
 102         Persistent,
 103
 104         /// Indicates an error that may resolve when retrying a request (e.g., unresponsive).
 105         Transient,
 106 }
 107
 108 impl BlockSourceError {
 109         /// Creates a new persistent error originated from the given error.
 110         pub fn persistent<E>(error: E) -> Self
 111         where E: Into<Box<dyn std::error::Error + Send + Sync>> {
 112                 Self {
 113                         kind: BlockSourceErrorKind::Persistent,
 114                         error: error.into(),
 115                 }
 116         }
 117
 118         /// Creates a new transient error originated from the given error.
 119         pub fn transient<E>(error: E) -> Self
 120         where E: Into<Box<dyn std::error::Error + Send + Sync>> {
 121                 Self {
 122                         kind: BlockSourceErrorKind::Transient,
 123                         error: error.into(),
 124                 }
 125         }
 126
 127         /// Returns the kind of error.
 128         pub fn kind(&self) -> BlockSourceErrorKind {
 129                 self.kind
 130         }
 131
 132         /// Converts the error into the underlying error.
 133         pub fn into_inner(self) -> Box<dyn std::error::Error + Send + Sync> {
 134                 self.error
 135         }
 136 }
 137
 138 /// A block header and some associated data. This information should be available from most block
 139 /// sources (and, notably, is available in Bitcoin Core's RPC and REST interfaces).
 140 #[derive(Clone, Copy, Debug, PartialEq)]
 141 pub struct BlockHeaderData {
 142         /// The block header itself.
 143         pub header: BlockHeader,
 144
 145         /// The block height where the genesis block has height 0.
 146         pub height: u32,
 147
 148         /// The total chain work in expected number of double-SHA256 hashes required to build a chain
 149         /// of equivalent weight.
 150         pub chainwork: Uint256,
 151 }
 152
 153 /// A lightweight client for keeping a listener in sync with the chain, allowing for Simplified
 154 /// Payment Verification (SPV).
 155 ///
 156 /// The client is parameterized by a chain poller which is responsible for polling one or more block
 157 /// sources for the best chain tip. During this process it detects any chain forks, determines which
 158 /// constitutes the best chain, and updates the listener accordingly with any blocks that were
 159 /// connected or disconnected since the last poll.
 160 ///
 161 /// Block headers for the best chain are maintained in the parameterized cache, allowing for a
 162 /// custom cache eviction policy. This offers flexibility to those sensitive to resource usage.
 163 /// Hence, there is a trade-off between a lower memory footprint and potentially increased network
 164 /// I/O as headers are re-fetched during fork detection.
 165 pub struct SpvClient<'a, P: Poll, C: Cache, L: Deref>
 166 where L::Target: chain::Listen {
 167         chain_tip: ValidatedBlockHeader,
 168         chain_poller: P,
 169         chain_notifier: ChainNotifier<'a, C, L>,
 170 }
 171
 172 /// The `Cache` trait defines behavior for managing a block header cache, where block headers are
 173 /// keyed by block hash.
 174 ///
 175 /// Used by [`ChainNotifier`] to store headers along the best chain, which is important for ensuring
 176 /// that blocks can be disconnected if they are no longer accessible from a block source (e.g., if
 177 /// the block source does not store stale forks indefinitely).
 178 ///
 179 /// Implementations may define how long to retain headers such that it's unlikely they will ever be
 180 /// needed to disconnect a block.  In cases where block sources provide access to headers on stale
 181 /// forks reliably, caches may be entirely unnecessary.
 182 ///
 183 /// [`ChainNotifier`]: struct.ChainNotifier.html
 184 pub trait Cache {
 185         /// Retrieves the block header keyed by the given block hash.
 186         fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader>;
 187
 188         /// Called when a block has been connected to the best chain to ensure it is available to be
 189         /// disconnected later if needed.
 190         fn block_connected(&mut self, block_hash: BlockHash, block_header: ValidatedBlockHeader);
 191
 192         /// Called when a block has been disconnected from the best chain. Once disconnected, a block's
 193         /// header is no longer needed and thus can be removed.
 194         fn block_disconnected(&mut self, block_hash: &BlockHash) -> Option<ValidatedBlockHeader>;
 195 }
 196
 197 /// Unbounded cache of block headers keyed by block hash.
 198 pub type UnboundedCache = std::collections::HashMap<BlockHash, ValidatedBlockHeader>;
 199
 200 impl Cache for UnboundedCache {
 201         fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
 202                 self.get(block_hash)
 203         }
 204
 205         fn block_connected(&mut self, block_hash: BlockHash, block_header: ValidatedBlockHeader) {
 206                 self.insert(block_hash, block_header);
 207         }
 208
 209         fn block_disconnected(&mut self, block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
 210                 self.remove(block_hash)
 211         }
 212 }
 213
 214 impl<'a, P: Poll, C: Cache, L: Deref> SpvClient<'a, P, C, L> where L::Target: chain::Listen {
 215         /// Creates a new SPV client using `chain_tip` as the best known chain tip.
 216         ///
 217         /// Subsequent calls to [`poll_best_tip`] will poll for the best chain tip using the given chain
 218         /// poller, which may be configured with one or more block sources to query. At least one block
 219         /// source must provide headers back from the best chain tip to its common ancestor with
 220         /// `chain_tip`.
 221         /// * `header_cache` is used to look up and store headers on the best chain
 222         /// * `chain_listener` is notified of any blocks connected or disconnected
 223         ///
 224         /// [`poll_best_tip`]: struct.SpvClient.html#method.poll_best_tip
 225         pub fn new(
 226                 chain_tip: ValidatedBlockHeader,
 227                 chain_poller: P,
 228                 header_cache: &'a mut C,
 229                 chain_listener: L,
 230         ) -> Self {
 231                 let chain_notifier = ChainNotifier { header_cache, chain_listener };
 232                 Self { chain_tip, chain_poller, chain_notifier }
 233         }
 234
 235         /// Polls for the best tip and updates the chain listener with any connected or disconnected
 236         /// blocks accordingly.
 237         ///
 238         /// Returns the best polled chain tip relative to the previous best known tip and whether any
 239         /// blocks were indeed connected or disconnected.
 240         pub async fn poll_best_tip(&mut self) -> BlockSourceResult<(ChainTip, bool)> {
 241                 let chain_tip = self.chain_poller.poll_chain_tip(self.chain_tip).await?;
 242                 let blocks_connected = match chain_tip {
 243                         ChainTip::Common => false,
 244                         ChainTip::Better(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                                 self.update_chain_tip(chain_tip).await
 248                         },
 249                         ChainTip::Worse(chain_tip) => {
 250                                 debug_assert_ne!(chain_tip.block_hash, self.chain_tip.block_hash);
 251                                 debug_assert!(chain_tip.chainwork <= self.chain_tip.chainwork);
 252                                 false
 253                         },
 254                 };
 255                 Ok((chain_tip, blocks_connected))
 256         }
 257
 258         /// Updates the chain tip, syncing the chain listener with any connected or disconnected
 259         /// blocks. Returns whether there were any such blocks.
 260         async fn update_chain_tip(&mut self, best_chain_tip: ValidatedBlockHeader) -> bool {
 261                 match self.chain_notifier.synchronize_listener(
 262                         best_chain_tip, &self.chain_tip, &mut self.chain_poller).await
 263                 {
 264                         Ok(_) => {
 265                                 self.chain_tip = best_chain_tip;
 266                                 true
 267                         },
 268                         Err((_, Some(chain_tip))) if chain_tip.block_hash != self.chain_tip.block_hash => {
 269                                 self.chain_tip = chain_tip;
 270                                 true
 271                         },
 272                         Err(_) => false,
 273                 }
 274         }
 275 }
 276
 277 /// Notifies [listeners] of blocks that have been connected or disconnected from the chain.
 278 ///
 279 /// [listeners]: ../../lightning/chain/trait.Listen.html
 280 pub struct ChainNotifier<'a, C: Cache, L: Deref> where L::Target: chain::Listen {
 281         /// Cache for looking up headers before fetching from a block source.
 282         header_cache: &'a mut C,
 283
 284         /// Listener that will be notified of connected or disconnected blocks.
 285         chain_listener: L,
 286 }
 287
 288 /// Changes made to the chain between subsequent polls that transformed it from having one chain tip
 289 /// to another.
 290 ///
 291 /// Blocks are given in height-descending order. Therefore, blocks are first disconnected in order
 292 /// before new blocks are connected in reverse order.
 293 struct ChainDifference {
 294         /// The most recent ancestor common between the chain tips.
 295         ///
 296         /// If there are any disconnected blocks, this is where the chain forked.
 297         common_ancestor: ValidatedBlockHeader,
 298
 299         /// Blocks that were disconnected from the chain since the last poll.
 300         disconnected_blocks: Vec<ValidatedBlockHeader>,
 301
 302         /// Blocks that were connected to the chain since the last poll.
 303         connected_blocks: Vec<ValidatedBlockHeader>,
 304 }
 305
 306 impl<'a, C: Cache, L: Deref> ChainNotifier<'a, C, L> where L::Target: chain::Listen {
 307         /// Finds the first common ancestor between `new_header` and `old_header`, disconnecting blocks
 308         /// from `old_header` to get to that point and then connecting blocks until `new_header`.
 309         ///
 310         /// Validates headers along the transition path, but doesn't fetch blocks until the chain is
 311         /// disconnected to the fork point. Thus, this may return an `Err` that includes where the tip
 312         /// ended up which may not be `new_header`. Note that the returned `Err` contains `Some` header
 313         /// if and only if the transition from `old_header` to `new_header` is valid.
 314         async fn synchronize_listener<P: Poll>(
 315                 &mut self,
 316                 new_header: ValidatedBlockHeader,
 317                 old_header: &ValidatedBlockHeader,
 318                 chain_poller: &mut P,
 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);
 323                 self.connect_blocks(
 324                         difference.common_ancestor,
 325                         difference.connected_blocks,
 326                         chain_poller,
 327                 ).await
 328         }
 329
 330         /// Returns the changes needed to produce the chain with `current_header` as its tip from the
 331         /// chain with `prev_header` as its tip.
 332         ///
 333         /// Walks backwards from `current_header` and `prev_header`, finding the common ancestor.
 334         async fn find_difference<P: Poll>(
 335                 &self,
 336                 current_header: ValidatedBlockHeader,
 337                 prev_header: &ValidatedBlockHeader,
 338                 chain_poller: &mut P,
 339         ) -> BlockSourceResult<ChainDifference> {
 340                 let mut disconnected_blocks = Vec::new();
 341                 let mut connected_blocks = Vec::new();
 342                 let mut current = current_header;
 343                 let mut previous = *prev_header;
 344                 loop {
 345                         // Found the common ancestor.
 346                         if current.block_hash == previous.block_hash {
 347                                 break;
 348                         }
 349
 350                         // Walk back the chain, finding blocks needed to connect and disconnect. Only walk back
 351                         // the header with the greater height, or both if equal heights.
 352                         let current_height = current.height;
 353                         let previous_height = previous.height;
 354                         if current_height <= previous_height {
 355                                 disconnected_blocks.push(previous);
 356                                 previous = self.look_up_previous_header(chain_poller, &previous).await?;
 357                         }
 358                         if current_height >= previous_height {
 359                                 connected_blocks.push(current);
 360                                 current = self.look_up_previous_header(chain_poller, &current).await?;
 361                         }
 362                 }
 363
 364                 let common_ancestor = current;
 365                 Ok(ChainDifference { common_ancestor, disconnected_blocks, connected_blocks })
 366         }
 367
 368         /// Returns the previous header for the given header, either by looking it up in the cache or
 369         /// fetching it if not found.
 370         async fn look_up_previous_header<P: Poll>(
 371                 &self,
 372                 chain_poller: &mut P,
 373                 header: &ValidatedBlockHeader,
 374         ) -> BlockSourceResult<ValidatedBlockHeader> {
 375                 match self.header_cache.look_up(&header.header.prev_blockhash) {
 376                         Some(prev_header) => Ok(*prev_header),
 377                         None => chain_poller.look_up_previous_header(header).await,
 378                 }
 379         }
 380
 381         /// Notifies the chain listeners of disconnected blocks.
 382         fn disconnect_blocks(&mut self, mut disconnected_blocks: Vec<ValidatedBlockHeader>) {
 383                 for header in disconnected_blocks.drain(..) {
 384                         if let Some(cached_header) = self.header_cache.block_disconnected(&header.block_hash) {
 385                                 assert_eq!(cached_header, header);
 386                         }
 387                         self.chain_listener.block_disconnected(&header.header, header.height);
 388                 }
 389         }
 390
 391         /// Notifies the chain listeners of connected blocks.
 392         async fn connect_blocks<P: Poll>(
 393                 &mut self,
 394                 mut new_tip: ValidatedBlockHeader,
 395                 mut connected_blocks: Vec<ValidatedBlockHeader>,
 396                 chain_poller: &mut P,
 397         ) -> Result<(), (BlockSourceError, Option<ValidatedBlockHeader>)> {
 398                 for header in connected_blocks.drain(..).rev() {
 399                         let block = chain_poller
 400                                 .fetch_block(&header).await
 401                                 .or_else(|e| Err((e, Some(new_tip))))?;
 402                         debug_assert_eq!(block.block_hash, header.block_hash);
 403
 404                         self.header_cache.block_connected(header.block_hash, header);
 405                         self.chain_listener.block_connected(&block, header.height);
 406                         new_tip = header;
 407                 }
 408
 409                 Ok(())
 410         }
 411 }
 412
 413 #[cfg(test)]
 414 mod spv_client_tests {
 415         use crate::test_utils::{Blockchain, NullChainListener};
 416         use super::*;
 417
 418         use bitcoin::network::constants::Network;
 419
 420         #[tokio::test]
 421         async fn poll_from_chain_without_headers() {
 422                 let mut chain = Blockchain::default().with_height(3).without_headers();
 423                 let best_tip = chain.at_height(1);
 424
 425                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 426                 let mut cache = UnboundedCache::new();
 427                 let mut listener = NullChainListener {};
 428                 let mut client = SpvClient::new(best_tip, poller, &mut cache, &mut listener);
 429                 match client.poll_best_tip().await {
 430                         Err(e) => {
 431                                 assert_eq!(e.kind(), BlockSourceErrorKind::Persistent);
 432                                 assert_eq!(e.into_inner().as_ref().to_string(), "header not found");
 433                         },
 434                         Ok(_) => panic!("Expected error"),
 435                 }
 436                 assert_eq!(client.chain_tip, best_tip);
 437         }
 438
 439         #[tokio::test]
 440         async fn poll_from_chain_with_common_tip() {
 441                 let mut chain = Blockchain::default().with_height(3);
 442                 let common_tip = chain.tip();
 443
 444                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 445                 let mut cache = UnboundedCache::new();
 446                 let mut listener = NullChainListener {};
 447                 let mut client = SpvClient::new(common_tip, poller, &mut cache, &mut listener);
 448                 match client.poll_best_tip().await {
 449                         Err(e) => panic!("Unexpected error: {:?}", e),
 450                         Ok((chain_tip, blocks_connected)) => {
 451                                 assert_eq!(chain_tip, ChainTip::Common);
 452                                 assert!(!blocks_connected);
 453                         },
 454                 }
 455                 assert_eq!(client.chain_tip, common_tip);
 456         }
 457
 458         #[tokio::test]
 459         async fn poll_from_chain_with_better_tip() {
 460                 let mut chain = Blockchain::default().with_height(3);
 461                 let new_tip = chain.tip();
 462                 let old_tip = chain.at_height(1);
 463
 464                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 465                 let mut cache = UnboundedCache::new();
 466                 let mut listener = NullChainListener {};
 467                 let mut client = SpvClient::new(old_tip, poller, &mut cache, &mut listener);
 468                 match client.poll_best_tip().await {
 469                         Err(e) => panic!("Unexpected error: {:?}", e),
 470                         Ok((chain_tip, blocks_connected)) => {
 471                                 assert_eq!(chain_tip, ChainTip::Better(new_tip));
 472                                 assert!(blocks_connected);
 473                         },
 474                 }
 475                 assert_eq!(client.chain_tip, new_tip);
 476         }
 477
 478         #[tokio::test]
 479         async fn poll_from_chain_with_better_tip_and_without_any_new_blocks() {
 480                 let mut chain = Blockchain::default().with_height(3).without_blocks(2..);
 481                 let new_tip = chain.tip();
 482                 let old_tip = chain.at_height(1);
 483
 484                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 485                 let mut cache = UnboundedCache::new();
 486                 let mut listener = NullChainListener {};
 487                 let mut client = SpvClient::new(old_tip, poller, &mut cache, &mut listener);
 488                 match client.poll_best_tip().await {
 489                         Err(e) => panic!("Unexpected error: {:?}", e),
 490                         Ok((chain_tip, blocks_connected)) => {
 491                                 assert_eq!(chain_tip, ChainTip::Better(new_tip));
 492                                 assert!(!blocks_connected);
 493                         },
 494                 }
 495                 assert_eq!(client.chain_tip, old_tip);
 496         }
 497
 498         #[tokio::test]
 499         async fn poll_from_chain_with_better_tip_and_without_some_new_blocks() {
 500                 let mut chain = Blockchain::default().with_height(3).without_blocks(3..);
 501                 let new_tip = chain.tip();
 502                 let old_tip = chain.at_height(1);
 503
 504                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 505                 let mut cache = UnboundedCache::new();
 506                 let mut listener = NullChainListener {};
 507                 let mut client = SpvClient::new(old_tip, poller, &mut cache, &mut listener);
 508                 match client.poll_best_tip().await {
 509                         Err(e) => panic!("Unexpected error: {:?}", e),
 510                         Ok((chain_tip, blocks_connected)) => {
 511                                 assert_eq!(chain_tip, ChainTip::Better(new_tip));
 512                                 assert!(blocks_connected);
 513                         },
 514                 }
 515                 assert_eq!(client.chain_tip, chain.at_height(2));
 516         }
 517
 518         #[tokio::test]
 519         async fn poll_from_chain_with_worse_tip() {
 520                 let mut chain = Blockchain::default().with_height(3);
 521                 let best_tip = chain.tip();
 522                 chain.disconnect_tip();
 523                 let worse_tip = chain.tip();
 524
 525                 let poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 526                 let mut cache = UnboundedCache::new();
 527                 let mut listener = NullChainListener {};
 528                 let mut client = SpvClient::new(best_tip, poller, &mut cache, &mut listener);
 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 chain_listener = &MockChainListener::new()
 554                         .expect_block_connected(*chain.at_height(2))
 555                         .expect_block_connected(*new_tip);
 556                 let mut notifier = ChainNotifier {
 557                         header_cache: &mut chain.header_cache(0..=1),
 558                         chain_listener,
 559                 };
 560                 let mut poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 561                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 562                         Err((e, _)) => panic!("Unexpected error: {:?}", e),
 563                         Ok(_) => {},
 564                 }
 565         }
 566
 567         #[tokio::test]
 568         async fn sync_from_different_chains() {
 569                 let mut test_chain = Blockchain::with_network(Network::Testnet).with_height(1);
 570                 let main_chain = Blockchain::with_network(Network::Bitcoin).with_height(1);
 571
 572                 let new_tip = test_chain.tip();
 573                 let old_tip = main_chain.tip();
 574                 let chain_listener = &MockChainListener::new();
 575                 let mut notifier = ChainNotifier {
 576                         header_cache: &mut main_chain.header_cache(0..=1),
 577                         chain_listener,
 578                 };
 579                 let mut poller = poll::ChainPoller::new(&mut test_chain, Network::Testnet);
 580                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 581                         Err((e, _)) => {
 582                                 assert_eq!(e.kind(), BlockSourceErrorKind::Persistent);
 583                                 assert_eq!(e.into_inner().as_ref().to_string(), "genesis block reached");
 584                         },
 585                         Ok(_) => panic!("Expected error"),
 586                 }
 587         }
 588
 589         #[tokio::test]
 590         async fn sync_from_equal_length_fork() {
 591                 let main_chain = Blockchain::default().with_height(2);
 592                 let mut fork_chain = main_chain.fork_at_height(1);
 593
 594                 let new_tip = fork_chain.tip();
 595                 let old_tip = main_chain.tip();
 596                 let chain_listener = &MockChainListener::new()
 597                         .expect_block_disconnected(*old_tip)
 598                         .expect_block_connected(*new_tip);
 599                 let mut notifier = ChainNotifier {
 600                         header_cache: &mut main_chain.header_cache(0..=2),
 601                         chain_listener,
 602                 };
 603                 let mut poller = poll::ChainPoller::new(&mut fork_chain, Network::Testnet);
 604                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 605                         Err((e, _)) => panic!("Unexpected error: {:?}", e),
 606                         Ok(_) => {},
 607                 }
 608         }
 609
 610         #[tokio::test]
 611         async fn sync_from_shorter_fork() {
 612                 let main_chain = Blockchain::default().with_height(3);
 613                 let mut fork_chain = main_chain.fork_at_height(1);
 614                 fork_chain.disconnect_tip();
 615
 616                 let new_tip = fork_chain.tip();
 617                 let old_tip = main_chain.tip();
 618                 let chain_listener = &MockChainListener::new()
 619                         .expect_block_disconnected(*old_tip)
 620                         .expect_block_disconnected(*main_chain.at_height(2))
 621                         .expect_block_connected(*new_tip);
 622                 let mut notifier = ChainNotifier {
 623                         header_cache: &mut main_chain.header_cache(0..=3),
 624                         chain_listener,
 625                 };
 626                 let mut poller = poll::ChainPoller::new(&mut fork_chain, Network::Testnet);
 627                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 628                         Err((e, _)) => panic!("Unexpected error: {:?}", e),
 629                         Ok(_) => {},
 630                 }
 631         }
 632
 633         #[tokio::test]
 634         async fn sync_from_longer_fork() {
 635                 let mut main_chain = Blockchain::default().with_height(3);
 636                 let mut fork_chain = main_chain.fork_at_height(1);
 637                 main_chain.disconnect_tip();
 638
 639                 let new_tip = fork_chain.tip();
 640                 let old_tip = main_chain.tip();
 641                 let chain_listener = &MockChainListener::new()
 642                         .expect_block_disconnected(*old_tip)
 643                         .expect_block_connected(*fork_chain.at_height(2))
 644                         .expect_block_connected(*new_tip);
 645                 let mut notifier = ChainNotifier {
 646                         header_cache: &mut main_chain.header_cache(0..=2),
 647                         chain_listener,
 648                 };
 649                 let mut poller = poll::ChainPoller::new(&mut fork_chain, Network::Testnet);
 650                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 651                         Err((e, _)) => panic!("Unexpected error: {:?}", e),
 652                         Ok(_) => {},
 653                 }
 654         }
 655
 656         #[tokio::test]
 657         async fn sync_from_chain_without_headers() {
 658                 let mut chain = Blockchain::default().with_height(3).without_headers();
 659
 660                 let new_tip = chain.tip();
 661                 let old_tip = chain.at_height(1);
 662                 let chain_listener = &MockChainListener::new();
 663                 let mut notifier = ChainNotifier {
 664                         header_cache: &mut chain.header_cache(0..=1),
 665                         chain_listener,
 666                 };
 667                 let mut poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 668                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 669                         Err((_, tip)) => assert_eq!(tip, None),
 670                         Ok(_) => panic!("Expected error"),
 671                 }
 672         }
 673
 674         #[tokio::test]
 675         async fn sync_from_chain_without_any_new_blocks() {
 676                 let mut chain = Blockchain::default().with_height(3).without_blocks(2..);
 677
 678                 let new_tip = chain.tip();
 679                 let old_tip = chain.at_height(1);
 680                 let chain_listener = &MockChainListener::new();
 681                 let mut notifier = ChainNotifier {
 682                         header_cache: &mut chain.header_cache(0..=3),
 683                         chain_listener,
 684                 };
 685                 let mut poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 686                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 687                         Err((_, tip)) => assert_eq!(tip, Some(old_tip)),
 688                         Ok(_) => panic!("Expected error"),
 689                 }
 690         }
 691
 692         #[tokio::test]
 693         async fn sync_from_chain_without_some_new_blocks() {
 694                 let mut chain = Blockchain::default().with_height(3).without_blocks(3..);
 695
 696                 let new_tip = chain.tip();
 697                 let old_tip = chain.at_height(1);
 698                 let chain_listener = &MockChainListener::new()
 699                         .expect_block_connected(*chain.at_height(2));
 700                 let mut notifier = ChainNotifier {
 701                         header_cache: &mut chain.header_cache(0..=3),
 702                         chain_listener,
 703                 };
 704                 let mut poller = poll::ChainPoller::new(&mut chain, Network::Testnet);
 705                 match notifier.synchronize_listener(new_tip, &old_tip, &mut poller).await {
 706                         Err((_, tip)) => assert_eq!(tip, Some(chain.at_height(2))),
 707                         Ok(_) => panic!("Expected error"),
 708                 }
 709         }
 710 }