-use crate::{AsyncBlockSourceResult, BlockHeaderData, BlockSourceError, BlockSourceResult};
+use crate::{AsyncBlockSourceResult, BlockHeaderData, BlockSource, BlockSourceError, BlockSourceResult};
use bitcoin::blockdata::block::Block;
use bitcoin::hash_types::BlockHash;
use bitcoin::network::constants::Network;
+use std::ops::DerefMut;
+
/// The `Poll` trait defines behavior for polling block sources for a chain tip and retrieving
/// related chain data. It serves as an adapter for `BlockSource`.
+///
+/// [`ChainPoller`] adapts a single `BlockSource`, while any other implementations of `Poll` are
+/// required to be built in terms of it to ensure chain data validity.
+///
+/// [`ChainPoller`]: ../struct.ChainPoller.html
pub trait Poll {
/// Returns a chain tip in terms of its relationship to the provided chain tip.
fn poll_chain_tip<'a>(&'a mut self, best_known_chain_tip: ValidatedBlockHeader) ->
&self.inner
}
}
+
+/// The canonical `Poll` implementation used for a single `BlockSource`.
+///
+/// Other `Poll` implementations must be built using `ChainPoller` as it provides the only means of
+/// validating chain data.
+pub struct ChainPoller<B: DerefMut<Target=T> + Sized + Sync + Send, T: BlockSource> {
+ block_source: B,
+ network: Network,
+}
+
+impl<B: DerefMut<Target=T> + Sized + Sync + Send, T: BlockSource> ChainPoller<B, T> {
+ /// Creates a new poller for the given block source.
+ ///
+ /// If the `network` parameter is mainnet, then the difficulty between blocks is checked for
+ /// validity.
+ pub fn new(block_source: B, network: Network) -> Self {
+ Self { block_source, network }
+ }
+}
+
+impl<B: DerefMut<Target=T> + Sized + Sync + Send, T: BlockSource> Poll for ChainPoller<B, T> {
+ fn poll_chain_tip<'a>(&'a mut self, best_known_chain_tip: ValidatedBlockHeader) ->
+ AsyncBlockSourceResult<'a, ChainTip>
+ {
+ Box::pin(async move {
+ let (block_hash, height) = self.block_source.get_best_block().await?;
+ if block_hash == best_known_chain_tip.header.block_hash() {
+ return Ok(ChainTip::Common);
+ }
+
+ let chain_tip = self.block_source
+ .get_header(&block_hash, height).await?
+ .validate(block_hash)?;
+ if chain_tip.chainwork > best_known_chain_tip.chainwork {
+ Ok(ChainTip::Better(chain_tip))
+ } else {
+ Ok(ChainTip::Worse(chain_tip))
+ }
+ })
+ }
+
+ fn look_up_previous_header<'a>(&'a mut self, header: &'a ValidatedBlockHeader) ->
+ AsyncBlockSourceResult<'a, ValidatedBlockHeader>
+ {
+ Box::pin(async move {
+ if header.height == 0 {
+ return Err(BlockSourceError::persistent("genesis block reached"));
+ }
+
+ let previous_hash = &header.header.prev_blockhash;
+ let height = header.height - 1;
+ let previous_header = self.block_source
+ .get_header(previous_hash, Some(height)).await?
+ .validate(*previous_hash)?;
+ header.check_builds_on(&previous_header, self.network)?;
+
+ Ok(previous_header)
+ })
+ }
+
+ fn fetch_block<'a>(&'a mut self, header: &'a ValidatedBlockHeader) ->
+ AsyncBlockSourceResult<'a, ValidatedBlock>
+ {
+ Box::pin(async move {
+ self.block_source
+ .get_block(&header.block_hash).await?
+ .validate(header.block_hash)
+ })
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use crate::*;
+ use crate::test_utils::Blockchain;
+ use super::*;
+ use bitcoin::util::uint::Uint256;
+
+ #[tokio::test]
+ async fn poll_empty_chain() {
+ let mut chain = Blockchain::default().with_height(0);
+ let best_known_chain_tip = chain.tip();
+ chain.disconnect_tip();
+
+ let mut poller = ChainPoller::new(&mut chain, Network::Bitcoin);
+ match poller.poll_chain_tip(best_known_chain_tip).await {
+ Err(e) => {
+ assert_eq!(e.kind(), BlockSourceErrorKind::Transient);
+ assert_eq!(e.into_inner().as_ref().to_string(), "empty chain");
+ },
+ Ok(_) => panic!("Expected error"),
+ }
+ }
+
+ #[tokio::test]
+ async fn poll_chain_without_headers() {
+ let mut chain = Blockchain::default().with_height(1).without_headers();
+ let best_known_chain_tip = chain.at_height(0);
+
+ let mut poller = ChainPoller::new(&mut chain, Network::Bitcoin);
+ match poller.poll_chain_tip(best_known_chain_tip).await {
+ Err(e) => {
+ assert_eq!(e.kind(), BlockSourceErrorKind::Persistent);
+ assert_eq!(e.into_inner().as_ref().to_string(), "header not found");
+ },
+ Ok(_) => panic!("Expected error"),
+ }
+ }
+
+ #[tokio::test]
+ async fn poll_chain_with_invalid_pow() {
+ let mut chain = Blockchain::default().with_height(1);
+ let best_known_chain_tip = chain.at_height(0);
+
+ // Invalidate the tip by changing its target.
+ chain.blocks.last_mut().unwrap().header.bits =
+ BlockHeader::compact_target_from_u256(&Uint256::from_be_bytes([0; 32]));
+
+ let mut poller = ChainPoller::new(&mut chain, Network::Bitcoin);
+ match poller.poll_chain_tip(best_known_chain_tip).await {
+ Err(e) => {
+ assert_eq!(e.kind(), BlockSourceErrorKind::Persistent);
+ assert_eq!(e.into_inner().as_ref().to_string(), "block target correct but not attained");
+ },
+ Ok(_) => panic!("Expected error"),
+ }
+ }
+
+ #[tokio::test]
+ async fn poll_chain_with_malformed_headers() {
+ let mut chain = Blockchain::default().with_height(1).malformed_headers();
+ let best_known_chain_tip = chain.at_height(0);
+
+ let mut poller = ChainPoller::new(&mut chain, Network::Bitcoin);
+ match poller.poll_chain_tip(best_known_chain_tip).await {
+ Err(e) => {
+ assert_eq!(e.kind(), BlockSourceErrorKind::Persistent);
+ assert_eq!(e.into_inner().as_ref().to_string(), "invalid block hash");
+ },
+ Ok(_) => panic!("Expected error"),
+ }
+ }
+
+ #[tokio::test]
+ async fn poll_chain_with_common_tip() {
+ let mut chain = Blockchain::default().with_height(0);
+ let best_known_chain_tip = chain.tip();
+
+ let mut poller = ChainPoller::new(&mut chain, Network::Bitcoin);
+ match poller.poll_chain_tip(best_known_chain_tip).await {
+ Err(e) => panic!("Unexpected error: {:?}", e),
+ Ok(tip) => assert_eq!(tip, ChainTip::Common),
+ }
+ }
+
+ #[tokio::test]
+ async fn poll_chain_with_uncommon_tip_but_equal_chainwork() {
+ let mut chain = Blockchain::default().with_height(1);
+ let best_known_chain_tip = chain.tip();
+
+ // Change the nonce to get a different block hash with the same chainwork.
+ chain.blocks.last_mut().unwrap().header.nonce += 1;
+ let worse_chain_tip = chain.tip();
+ assert_eq!(best_known_chain_tip.chainwork, worse_chain_tip.chainwork);
+
+ let mut poller = ChainPoller::new(&mut chain, Network::Bitcoin);
+ match poller.poll_chain_tip(best_known_chain_tip).await {
+ Err(e) => panic!("Unexpected error: {:?}", e),
+ Ok(tip) => assert_eq!(tip, ChainTip::Worse(worse_chain_tip)),
+ }
+ }
+
+ #[tokio::test]
+ async fn poll_chain_with_worse_tip() {
+ let mut chain = Blockchain::default().with_height(1);
+ let best_known_chain_tip = chain.tip();
+
+ chain.disconnect_tip();
+ let worse_chain_tip = chain.tip();
+
+ let mut poller = ChainPoller::new(&mut chain, Network::Bitcoin);
+ match poller.poll_chain_tip(best_known_chain_tip).await {
+ Err(e) => panic!("Unexpected error: {:?}", e),
+ Ok(tip) => assert_eq!(tip, ChainTip::Worse(worse_chain_tip)),
+ }
+ }
+
+ #[tokio::test]
+ async fn poll_chain_with_better_tip() {
+ let mut chain = Blockchain::default().with_height(1);
+ let best_known_chain_tip = chain.at_height(0);
+
+ let better_chain_tip = chain.tip();
+
+ let mut poller = ChainPoller::new(&mut chain, Network::Bitcoin);
+ match poller.poll_chain_tip(best_known_chain_tip).await {
+ Err(e) => panic!("Unexpected error: {:?}", e),
+ Ok(tip) => assert_eq!(tip, ChainTip::Better(better_chain_tip)),
+ }
+ }
+}
projects / rust-lightning / blobdiff