private static TransformBlock<LoadedTx, LoadedTx> InitMerkleValidator(ChainedHeader chainedHeader, MerkleStream merkleStream, CancellationToken cancelToken)
{
return new TransformBlock<LoadedTx, LoadedTx>(
loadedTx =>
{
try
{
merkleStream.AddNode(new MerkleTreeNode(loadedTx.TxIndex, 0, loadedTx.Transaction.Hash, false));
}
//TODO
catch (InvalidOperationException)
{
throw CreateMerkleRootException(chainedHeader);
}
return loadedTx;
},
new ExecutionDataflowBlockOptions { CancellationToken = cancelToken });
}
public static async Task ValidateBlockAsync(ICoreStorage coreStorage, IBlockchainRules rules, ChainedHeader chainedHeader, ISourceBlock<LoadedTx> loadedTxes, CancellationToken cancelToken = default(CancellationToken))
{
// validate merkle root
var merkleStream = new MerkleStream();
var merkleValidator = InitMerkleValidator(chainedHeader, merkleStream, cancelToken);
// begin feeding the merkle validator
loadedTxes.LinkTo(merkleValidator, new DataflowLinkOptions { PropagateCompletion = true });
// validate transactions
var txValidator = InitTxValidator(rules, chainedHeader, cancelToken);
// begin feeding the tx validator
merkleValidator.LinkTo(txValidator, new DataflowLinkOptions { PropagateCompletion = true });
// validate scripts
var scriptValidator = InitScriptValidator(rules, chainedHeader, cancelToken);
// begin feeding the script validator
txValidator.LinkTo(scriptValidator, new DataflowLinkOptions { PropagateCompletion = true });
await merkleValidator.Completion;
await txValidator.Completion;
await scriptValidator.Completion;
if (!rules.BypassPrevTxLoading)
{
try
{
merkleStream.FinishPairing();
}
//TODO
catch (InvalidOperationException)
{
throw CreateMerkleRootException(chainedHeader);
}
if (merkleStream.RootNode.Hash != chainedHeader.MerkleRoot)
throw CreateMerkleRootException(chainedHeader);
}
}
private ISourceBlock <T> InitMerkleValidator <T>(ChainedHeader chainedHeader, ISourceBlock <T> blockTxes, CancellationToken cancelToken)
where T : BlockTx
{
var merkleStream = new MerkleStream <BlockTxNode>();
var txHashes = new HashSet <UInt256>();
var cve_2012_2459 = false;
var merkleValidator = new TransformManyBlock <T, T>(
blockTx =>
{
if (cve_2012_2459)
{
return(new T[0]);
}
if (txHashes.Add(blockTx.Hash))
{
try
{
merkleStream.AddNode(blockTx);
return(new[] { blockTx });
}
//TODO
catch (InvalidOperationException)
{
throw CreateMerkleRootException(chainedHeader);
}
}
else
{
// TODO this needs proper testing, and needs to be made sure this is a safe way to handle the attack
// TODO the block should be unmutated before being shared onto the network
// CVE-2012-2459
// - if a tx has been repeated, this may be a merkle tree malleability attack against the block
// - finish the merkle stream early and verify if the root still matches the block header
//
// - if the root matches, this is a CVE-2012-2459 attack
// - proceed to validate the block normally by ignoring the remaining duplicate transactions
//
// - if the root does not match
// - the block truly did contain duplicate transactions and is invalid
merkleStream.FinishPairing();
if (merkleStream.RootNode.Hash == chainedHeader.MerkleRoot)
{
cve_2012_2459 = true;
}
else
{
throw CreateMerkleRootException(chainedHeader);
}
//TODO throw exception anyway for the sake of the pull tester
//return new DecodedBlockTx[0];
//TODO remove the attacked version of the block
coreStorage.TryRemoveChainedHeader(chainedHeader.Hash);
coreStorage.TryRemoveBlockTransactions(chainedHeader.Hash);
//TODO fail the block as missing, not invalid
throw new MissingDataException(chainedHeader.Hash);
}
},
new ExecutionDataflowBlockOptions {
CancellationToken = cancelToken
});
blockTxes.LinkTo(merkleValidator, new DataflowLinkOptions {
PropagateCompletion = true
});
return(OnCompleteBlock.Create(merkleValidator,
() =>
{
try
{
merkleStream.FinishPairing();
}
//TODO
catch (InvalidOperationException)
{
throw CreateMerkleRootException(chainedHeader);
}
if (merkleStream.RootNode.Hash != chainedHeader.MerkleRoot)
{
throw CreateMerkleRootException(chainedHeader);
}
}, cancelToken));
}
