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Exclude peers if we don't have a complete set of their block summaries.

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This tightens up the decision making by adding two requirements:

1. The peer must return the same number of summaries to the ones requested.
2. The peer must return a summary that matches its latest reported signature.

This ensures we are always making sync decisions based on accurate data, and removes peers that are currently mid re-org. This is probably more validation than is actually necessary, but it's best to be really thorough here so it is as optimized as possible.
This commit is contained in:
CalDescent 2021-05-16 09:15:37 +01:00
parent 66711c2e9d
commit 28d50bccf9
1 changed files with 21 additions and 5 deletions
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26
src/main/java/org/qortal/controller/Synchronizer.java
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@ -282,7 +282,9 @@ public class Synchronizer {
return peers;
// Count the number of blocks this peer has beyond our common block
final int peerHeight = peer.getChainTipData().getLastHeight();
final PeerChainTipData peerChainTipData = peer.getChainTipData();
final int peerHeight = peerChainTipData.getLastHeight();
final byte[] peerLastBlockSignature = peerChainTipData.getLastBlockSignature();
final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
// Limit the number of blocks we are comparing. FUTURE: we could request more in batches, but there may not be a case when this is needed
int summariesRequired = Math.min(peerAdditionalBlocksAfterCommonBlock, MAXIMUM_REQUEST_SIZE);
@ -302,15 +304,23 @@ public class Synchronizer {
if (summariesRequired > 0) {
LOGGER.trace(String.format("Requesting %d block summar%s from peer %s after common block %.8s. Peer height: %d", summariesRequired, (summariesRequired != 1 ? "ies" : "y"), peer, Base58.encode(commonBlockSummary.getSignature()), peerHeight));
List<BlockSummaryData> blockSummaries = this.getBlockSummaries(peer, commonBlockSummary.getSignature(), summariesRequired);
peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(blockSummaries);
// Forget any cached summaries
peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(null);
// Request new block summaries
List<BlockSummaryData> blockSummaries = this.getBlockSummaries(peer, commonBlockSummary.getSignature(), summariesRequired);
if (blockSummaries != null) {
LOGGER.trace(String.format("Peer %s returned %d block summar%s", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y")));
if (blockSummaries.size() < summariesRequired)
// This could mean that the peer has re-orged. But we still have the same common block, so it's safe to proceed with this set of signatures instead.
LOGGER.debug(String.format("Peer %s returned %d block summar%s instead of expected %d", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y"), summariesRequired));
// This could mean that the peer has re-orged. Exclude this peer until they return the summaries we expect.
LOGGER.debug(String.format("Peer %s returned %d block summar%s instead of expected %d - excluding them from this round", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y"), summariesRequired));
else if (blockSummaryWithSignature(peerLastBlockSignature, blockSummaries) == null)
// We don't have a block summary for the peer's reported chain tip, so should exclude it
LOGGER.debug(String.format("Peer %s didn't return a block summary with signature %.8s - excluding them from this round", peer, Base58.encode(peerLastBlockSignature)));
else
// All looks good, so store the retrieved block summaries in the peer's cache
peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(blockSummaries);
}
} else {
// There are no block summaries after this common block
@ -451,6 +461,12 @@ public class Synchronizer {
return minChainLength;
}
private BlockSummaryData blockSummaryWithSignature(byte[] signature, List<BlockSummaryData> blockSummaries) {
if (blockSummaries != null)
return blockSummaries.stream().filter(blockSummary -> Arrays.equals(blockSummary.getSignature(), signature)).findAny().orElse(null);
return null;
}
/**
* Attempt to synchronize blockchain with peer.