public void TestDuplicateTransaction()
{
BlockMessage validBlock1 = BlockMessage.Read(new BitcoinStreamReader(new MemoryStream(KnownBlocks.Block100001)));
BlockMessage validBlock2 = BlockMessage.Read(new BitcoinStreamReader(new MemoryStream(KnownBlocks.Block100002)));
Assert.True(BlockContentValidator.IsMerkleTreeValid(validBlock1));
Assert.True(BlockContentValidator.IsMerkleTreeValid(validBlock2));
Assert.That(validBlock1.Transactions.Length, Is.EqualTo(12));
Assert.That(validBlock2.Transactions.Length, Is.EqualTo(9));
List<Tx> transactions1 = new List<Tx>(validBlock1.Transactions);
transactions1.Add(validBlock1.Transactions[8]);
transactions1.Add(validBlock1.Transactions[9]);
transactions1.Add(validBlock1.Transactions[10]);
transactions1.Add(validBlock1.Transactions[11]);
BlockMessage invalidBlock1 = new BlockMessage(validBlock1.BlockHeader, transactions1.ToArray());
List<Tx> transactions2 = new List<Tx>(validBlock2.Transactions);
transactions2.Add(validBlock2.Transactions[8]);
BlockMessage invalidBlock2 = new BlockMessage(validBlock2.BlockHeader, transactions2.ToArray());
Assert.That(MerkleTreeUtils.GetTreeRoot(invalidBlock1.Transactions), Is.EqualTo(invalidBlock1.BlockHeader.MerkleRoot));
Assert.That(MerkleTreeUtils.GetTreeRoot(invalidBlock2.Transactions), Is.EqualTo(invalidBlock2.BlockHeader.MerkleRoot));
Assert.False(BlockContentValidator.IsMerkleTreeValid(invalidBlock1));
Assert.False(BlockContentValidator.IsMerkleTreeValid(invalidBlock2));
}
internal static bool IsValidCoinbaseTransaction(BlockMessage block)
{
if (block.Transactions == null || block.Transactions.Length == 0)
{
return false;
}
if (!IsValidCoinbaseTransaction(block.Transactions[0]))
{
return false;
}
// also checking that there is only one coinbase transaction
for (int i = 1; i < block.Transactions.Length; i++)
{
Tx transaction = block.Transactions[i];
foreach (TxIn input in transaction.Inputs)
{
if (input.PreviousOutput.Hash.All(b => b == 0) || input.PreviousOutput.Index < 0)
{
return false;
}
}
}
return true;
}
public void AddBlockContent(BlockMessage block)
{
transactionalResource.Enlist();
byte[] blockHash = CryptoUtils.DoubleSha256(BitcoinStreamWriter.GetBytes(block.BlockHeader.Write));
StoredBlock storedBlock = storage.FindBlockByHash(blockHash);
if (storedBlock == null || storedBlock.HasContent)
{
return;
}
if (!BlockContentValidator.IsMerkleTreeValid(block))
{
// If merkle tree is invalid than we cannot rely on its header hash to mark block in storage as invalid.
throw new BitcoinProtocolViolationException($"Merkle tree did not pass validation (block: {BitConverter.ToString(blockHash)}).");
}
// since block is already stored in storage we assume that its header is valid
if (!BlockContentValidator.IsValid(storedBlock, block))
{
//todo: mark chain as broken
throw new BitcoinProtocolViolationException($"Block content was invalid (block: {BitConverter.ToString(blockHash)}).");
}
StoredBlock updatedBlock = storage.AddBlockContent(storedBlock.Hash, BitcoinStreamWriter.GetBytes(block.Write));
//todo: test state updates
currentState = currentState.Update(storedBlock, updatedBlock);
}
//todo: add XMLDOC here and to other validators
public static bool IsMerkleTreeValid(BlockMessage block)
{
if (block.Transactions == null || block.Transactions.Length == 0)
{
return false;
}
List<byte[]> transactionHashes = new List<byte[]>(block.Transactions.Length);
HashSet<byte[]> transactionHashSet = new HashSet<byte[]>(ByteArrayComparer.Instance);
foreach (Tx transaction in block.Transactions)
{
byte[] hash = CryptoUtils.DoubleSha256(BitcoinStreamWriter.GetBytes(transaction.Write));
if (!transactionHashSet.Add(hash))
{
// Duplicate transactions can be used to construct invalid block that has same merkle tree root as valid block.
// Such blocks should not prevent acceptance of valid blocks.
// See: https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2012-2459
return false;
}
transactionHashes.Add(hash);
}
byte[] merkleTreeRoot = MerkleTreeUtils.GetTreeRoot(transactionHashes);
return merkleTreeRoot.SequenceEqual(block.BlockHeader.MerkleRoot);
}
public void TestInvalidCoinbase()
{
BlockMessage validBlock = BitcoinStreamReader.FromBytes(KnownBlocks.Block100000, BlockMessage.Read);
Assert.True(BlockContentValidator.IsValidCoinbaseTransaction(validBlock));
Tx validCoinbaseTransaction = validBlock.Transactions[0];
TxIn validCoinbaseInput = validCoinbaseTransaction.Inputs[0];
// first checking that we reconstruct block correctly
{
List<Tx> transactions = new List<Tx>();
transactions.Add(new Tx(
validCoinbaseTransaction.Version,
new TxIn[] {new TxIn(new TxOutPoint(new byte[32], -1), validCoinbaseInput.SignatureScript, validCoinbaseInput.Sequence)},
validCoinbaseTransaction.Outputs,
validCoinbaseTransaction.LockTime));
transactions.AddRange(validBlock.Transactions.Skip(1));
BlockMessage invalidBlock = new BlockMessage(validBlock.BlockHeader, transactions.ToArray());
Assert.True(BlockContentValidator.IsValidCoinbaseTransaction(invalidBlock));
}
// cheking invalid signature
{
List<Tx> transactions = new List<Tx>();
transactions.Add(new Tx(
validCoinbaseTransaction.Version,
new TxIn[] {new TxIn(new TxOutPoint(new byte[32], -1), new byte[101], validCoinbaseInput.Sequence)},
validCoinbaseTransaction.Outputs,
validCoinbaseTransaction.LockTime));
transactions.AddRange(validBlock.Transactions.Skip(1));
BlockMessage invalidBlock = new BlockMessage(validBlock.BlockHeader, transactions.ToArray());
Assert.False(BlockContentValidator.IsValidCoinbaseTransaction(invalidBlock));
}
// cheking invalid output index
{
List<Tx> transactions = new List<Tx>();
transactions.Add(new Tx(
validCoinbaseTransaction.Version,
new TxIn[] {new TxIn(new TxOutPoint(new byte[32], 0), validCoinbaseInput.SignatureScript, validCoinbaseInput.Sequence)},
validCoinbaseTransaction.Outputs,
validCoinbaseTransaction.LockTime));
transactions.AddRange(validBlock.Transactions.Skip(1));
BlockMessage invalidBlock = new BlockMessage(validBlock.BlockHeader, transactions.ToArray());
Assert.False(BlockContentValidator.IsValidCoinbaseTransaction(invalidBlock));
}
// cheking duplicate coinbase
{
List<Tx> transactions = new List<Tx>();
transactions.Add(new Tx(
validCoinbaseTransaction.Version,
new TxIn[] {new TxIn(new TxOutPoint(new byte[32], -1), new byte[10], validCoinbaseInput.Sequence)},
validCoinbaseTransaction.Outputs,
validCoinbaseTransaction.LockTime));
transactions.Add(new Tx(
validCoinbaseTransaction.Version,
new TxIn[] {new TxIn(new TxOutPoint(new byte[32], -1), new byte[20], validCoinbaseInput.Sequence)},
validCoinbaseTransaction.Outputs,
validCoinbaseTransaction.LockTime));
transactions.AddRange(validBlock.Transactions.Skip(1));
BlockMessage invalidBlock = new BlockMessage(validBlock.BlockHeader, transactions.ToArray());
Assert.False(BlockContentValidator.IsValidCoinbaseTransaction(invalidBlock));
}
}
public void TestWrongMerkleTreeRoot()
{
BlockMessage validBlock1 = BlockMessage.Read(new BitcoinStreamReader(new MemoryStream(KnownBlocks.Block100001)));
BlockMessage validBlock2 = BlockMessage.Read(new BitcoinStreamReader(new MemoryStream(KnownBlocks.Block100002)));
Assert.That(BlockContentValidator.IsMerkleTreeValid(validBlock1));
Assert.That(BlockContentValidator.IsMerkleTreeValid(validBlock2));
BlockMessage invalidBlock1 = new BlockMessage(validBlock1.BlockHeader, validBlock2.Transactions);
BlockMessage invalidBlock2 = new BlockMessage(validBlock2.BlockHeader, validBlock1.Transactions);
Assert.False(BlockContentValidator.IsMerkleTreeValid(invalidBlock1));
Assert.False(BlockContentValidator.IsMerkleTreeValid(invalidBlock2));
}
public void TestNoTransactions()
{
BlockMessage block = new BlockMessage(GenesisBlock.GetHeader(), new Tx[0]);
Assert.False(BlockContentValidator.IsMerkleTreeValid(block));
}
private UnspentOutputsUpdate PrepareUnspentOutputsUpdate(StoredBlock block, BlockMessage blockMessage)
{
ScriptParser parser = new ScriptParser();
ulong inputsSum = GetBlockReward(block);
ulong outputsSum = 0;
UnspentOutputsUpdate update = new UnspentOutputsUpdate(storage);
for (int transactionNumber = 0; transactionNumber < blockMessage.Transactions.Length; transactionNumber++)
{
Tx transaction = blockMessage.Transactions[transactionNumber];
ulong transactionInputsSum = 0;
ulong transactionOutputsSum = 0;
byte[] transactionHash = CryptoUtils.DoubleSha256(BitcoinStreamWriter.GetBytes(transaction.Write));
List<UnspentOutput> unspentOutputs = update.FindUnspentOutputs(transactionHash);
if (unspentOutputs.Any())
{
//todo: use network settings
if (block.Height == 91842 || block.Height == 91880)
{
// this blocks are exceptions from BIP-30
foreach (UnspentOutput unspentOutput in unspentOutputs)
{
update.Spend(unspentOutput.TransactionHash, unspentOutput.OutputNumber, block);
}
}
else
{
throw new BitcoinProtocolViolationException(
$"The transaction '{BitConverter.ToString(transactionHash)}'" +
$" in block '{BitConverter.ToString(block.Hash)}'" +
$" has same hash as an existing unspent transaction (see BIP-30).");
}
}
//todo: check transaction hash against genesis block transaction hash
if (transactionNumber != 0)
{
foreach (TxIn input in transaction.Inputs)
{
UnspentOutput output = update.FindUnspentOutput(input.PreviousOutput.Hash, input.PreviousOutput.Index);
if (output == null)
{
throw new BitcoinProtocolViolationException(
$"The input of the transaction '{BitConverter.ToString(transactionHash)}'" +
$" in block '{BitConverter.ToString(block.Hash)}'" +
$" has been already spent or did not exist.");
}
//todo: check for overflow
transactionInputsSum += output.Sum;
List<ScriptCommand> inputCommands;
if (!parser.TryParse(input.SignatureScript, out inputCommands))
{
throw new BitcoinProtocolViolationException(
$"The transaction '{BitConverter.ToString(transactionHash)}'" +
$" in block '{BitConverter.ToString(block.Hash)}'" +
$" has an invalid signature script.");
}
if (inputCommands.Any(c => !IsValidSignatureCommand(c.Code)))
{
throw new BitcoinProtocolViolationException(
$"The transaction '{BitConverter.ToString(transactionHash)}'" +
$" in block '{BitConverter.ToString(block.Hash)}'" +
$" has forbidden commands in the signature script.");
}
//todo: check signature for the output
update.Spend(output.TransactionHash, output.OutputNumber, block);
}
}
for (int outputNumber = 0; outputNumber < transaction.Outputs.Length; outputNumber++)
{
TxOut output = transaction.Outputs[outputNumber];
//todo: check for overflow
transactionOutputsSum += output.Value;
List<ScriptCommand> commands;
if (!parser.TryParse(output.PubkeyScript, out commands))
{
//todo: how Bitcoin Core works in this scenario?
throw new BitcoinProtocolViolationException(
$"The output of transaction '{BitConverter.ToString(transactionHash)}'" +
$" in block '{BitConverter.ToString(block.Hash)}'" +
$" has an invalid pubkey script script.");
}
UnspentOutput unspentOutput = UnspentOutput.Create(block, transaction, outputNumber);
update.Add(unspentOutput);
}
if (transactionNumber != 0 && transactionInputsSum < transactionOutputsSum)
{
// for coinbase transaction output sum is checked later as part of total block inputs, outputs and reward sums equation
throw new BitcoinProtocolViolationException(
$"The sum of the inputs in the transaction '{BitConverter.ToString(transactionHash)}'" +
$" in block '{BitConverter.ToString(block.Hash)}'" +
$" is less than the sum of the outputs.");
}
//todo: check for overflow
inputsSum += transactionInputsSum;
//todo: check for overflow
outputsSum += transactionOutputsSum;
}
if (inputsSum != outputsSum)
{
throw new BitcoinProtocolViolationException(
$"The sum of the inputs and the reward" +
$" in the block '{BitConverter.ToString(block.Hash)}'" +
$" does not match the sum of the outputs.");
}
return update;
}
private void ProcessBlockMessage(BlockMessage blockMessage)
{
byte[] blockHash = CryptoUtils.DoubleSha256(BitcoinStreamWriter.GetBytes(blockMessage.BlockHeader.Write));
lock (lockObject)
{
if (!requiredBlocks.ContainsKey(blockHash))
{
return;
}
//todo: here there is a lock within lock
//todo: if block is invalid don't ask for it again
//todo: if block is invalid truncate headers chain and select other chain if necessary
node.Blockchain.AddBlockContent(blockMessage);
RemoveRequiredBlock(blockHash);
}
}
public void AddBlockContent(BlockMessage block)
{
//todo: add XMLDOC
ExecuteInTransaction(() => blockchain.AddBlockContent(block));
}
public static bool IsValid(StoredBlock storedBlock, BlockMessage block)
{
//todo: add other validations, recheck each field constraints
return IsValidCoinbaseTransaction(block);
}