private void BeforeSave(CurrencyBlock block)
{
foreach (var transaction in block.Transactions)
{
transaction.Hash = HashProvider.ComputeHashBytes(transaction);
}
block.Hash = block.ToHashBytes(HashProvider);
}
public bool CheckBlock(CurrencyBlock newBlock, CurrencyBlock previousBlock)
{
var blockHash = newBlock.ToHashBytes(_hashProvider);
if (previousBlock.Index + 1 != newBlock.Index)
{ // Check if the block is the last one
var message = $"Invalid index: expected '{previousBlock.Index + 1}' but got '{newBlock.Index}'";
_logger?.LogError(message);
throw new BlockAssertionException(message);
}
if (previousBlock.Hash != newBlock.PreviousHash)
{ // Check if the previous block is correct
var message = $"Invalid previoushash: expected '{previousBlock.Hash}' got '{newBlock.PreviousHash}'";
_logger?.LogError(message);
throw new BlockAssertionException(message);
}
if (blockHash != newBlock.Hash)
{ // Check if the hash is correct
var message = $"Invalid hash: expected '{blockHash}' got '{newBlock.Hash}'";
throw new BlockAssertionException(message);
}
if (newBlock.GetDifficulty() >= GetDifficulty(newBlock.Index ?? 0))
{ // If the difficulty level of the proof-of-work challenge is correct
var message = $"Invalid proof-of-work difficulty: expected '{newBlock.GetDifficulty()}' to be smaller than '{GetDifficulty(newBlock.Index ?? 0)}'";
_logger?.LogError(message);
throw new BlockAssertionException(message);
}
// For each transaction in this block, check if it is valid
foreach (var transaction in newBlock.Transactions)
{
CheckTransaction(transaction);
}
// Check if the sum of output transactions are equal the sum of input transactions + the reward for the block miner
{
var sumOfInputsAmount = newBlock.Transactions.SelectMany(x => x.Data.Inputs).Select(x => x.Amount).Sum();
var sumOfOutputsAmount = newBlock.Transactions.SelectMany(x => x.Data.Outputs).Select(x => x.Amount).Sum();
if (sumOfInputsAmount < sumOfOutputsAmount)
{
var message = $"Invalid block balance: inputs sum '{sumOfInputsAmount}', outputs sum '{sumOfOutputsAmount}'";
_logger?.LogError(message);
throw new BlockAssertionException(message);
}
}
// Check if there is only 1 fee transaction and 1 reward transaction
{
var feeTransactions = newBlock.Transactions.Count(x => x.Type == TransactionType.Fee);
if (feeTransactions > 1)
{
var message = $"Invalid fee transaction count: expected '1' got '${feeTransactions}'";
_logger?.LogError(message);
throw new BlockAssertionException(message);
}
var rewardTransactions = newBlock.Transactions.Count(x => x.Type == TransactionType.Reward);
if (rewardTransactions > 1)
{
var message = $"Invalid reward transaction count: expected '1' got '${rewardTransactions}'";
_logger?.LogError(message);
throw new BlockAssertionException(message);
}
}
return(true);
}