private long GetTransactionSigOpCost(Transaction tx, CoinView inputs, ConsensusFlags flags)
{
long nSigOps = GetLegacySigOpCount(tx) * WITNESS_SCALE_FACTOR;
if (tx.IsCoinBase)
{
return(nSigOps);
}
if (flags.ScriptFlags.HasFlag(ScriptVerify.P2SH))
{
nSigOps += GetP2SHSigOpCount(tx, inputs) * WITNESS_SCALE_FACTOR;
}
for (var i = 0; i < tx.Inputs.Count; i++)
{
var prevout = inputs.GetOutputFor(tx.Inputs[i]);
nSigOps += CountWitnessSigOps(tx.Inputs[i].ScriptSig, prevout.ScriptPubKey, tx.Inputs[i].WitScript, flags);
}
return(nSigOps);
}
private long WitnessSigOps(WitProgramParameters witParams, WitScript witScript, ConsensusFlags flags)
{
if (witParams.Version == 0)
{
if (witParams.Program.Length == 20)
{
return(1);
}
if (witParams.Program.Length == 32 && witScript.PushCount > 0)
{
Script subscript = Script.FromBytesUnsafe(witScript.GetUnsafePush(witScript.PushCount - 1));
return(subscript.GetSigOpCount(true));
}
}
// Future flags may be implemented here.
return(0);
}
private long CountWitnessSigOps(Script scriptSig, Script scriptPubKey, WitScript witness, ConsensusFlags flags)
{
witness = witness ?? WitScript.Empty;
if (!flags.ScriptFlags.HasFlag(ScriptVerify.Witness))
{
return(0);
}
var witParams = PayToWitTemplate.Instance.ExtractScriptPubKeyParameters2(scriptPubKey);
if (witParams != null)
{
return(WitnessSigOps(witParams, witness, flags));
}
if (scriptPubKey.IsPayToScriptHash && scriptSig.IsPushOnly)
{
var data = scriptSig.ToOps().Select(o => o.PushData).LastOrDefault() ?? new byte[0];
var subScript = Script.FromBytesUnsafe(data);
witParams = PayToWitTemplate.Instance.ExtractScriptPubKeyParameters2(scriptPubKey);
if (witParams != null)
{
return(WitnessSigOps(witParams, witness, flags));
}
}
return(0);
}
/// <summary>
/// Pull blocks, validate them and update the UTXO Set
/// </summary>
/// <param name="utxo">UTXO Set</param>
/// <param name="puller">Block source</param>
/// <returns>Stream of validated blocks</returns>
public IEnumerable <Block> Run(CoinViewStack utxoStack, BlockPuller puller)
{
var utxo = utxoStack.Top;
var cache = utxoStack.Find <CacheCoinView>();
var lookaheadPuller = puller as ILookaheadBlockPuller;
puller.SetLocation(utxo.Tip);
ThresholdConditionCache bip9 = new ThresholdConditionCache(_ConsensusParams);
StopWatch watch = new StopWatch();
bool rejected = false;
while (true)
{
Block block = null;
while (true)
{
rejected = false;
try
{
using (watch.Start(o => PerformanceCounter.AddBlockFetchingTime(o)))
{
block = puller.NextBlock();
}
ChainedBlock next;
ContextInformation context;
ConsensusFlags flags;
using (watch.Start(o => PerformanceCounter.AddBlockProcessingTime(o)))
{
CheckBlockHeader(block.Header);
next = new ChainedBlock(block.Header, block.Header.GetHash(), utxo.Tip);
context = new ContextInformation(next, this._ConsensusParams);
ContextualCheckBlockHeader(block.Header, context);
var states = bip9.GetStates(utxo.Tip);
flags = new ConsensusFlags(next, states, _ConsensusParams);
ContextualCheckBlock(block, flags, context);
CheckBlock(block);
}
var commitable = new CommitableCoinView(next, utxo);
using (watch.Start(o => PerformanceCounter.AddUTXOFetchingTime(o)))
{
commitable.FetchCoins(GetIdsToFetch(block, flags.EnforceBIP30));
}
commitable.SetInner(NullCoinView.Instance);
Task prefetching = GetPrefetchingTask(cache, lookaheadPuller, flags);
using (watch.Start(o => PerformanceCounter.AddBlockProcessingTime(o)))
{
ExecuteBlock(block, next, flags, commitable, null);
}
using (watch.Start(o => PerformanceCounter.AddUTXOFetchingTime(o)))
{
prefetching.Wait();
commitable.Commit(utxo);
}
}
catch (ConsensusErrorException ex)
{
rejected = true;
if (ex.ConsensusError == ConsensusErrors.TimeTooNew)
{
puller.Reject(block, RejectionMode.Temporary);
}
else
{
puller.Reject(block, RejectionMode.Permanent);
}
}
if (!rejected)
{
yield return(block);
}
}
}
}
public void ExecuteBlock(Block block, ChainedBlock index, ConsensusFlags flags, CommitableCoinView view, TaskScheduler taskScheduler)
{
PerformanceCounter.AddProcessedBlocks(1);
taskScheduler = taskScheduler ?? TaskScheduler.Default;
if (flags.EnforceBIP30)
{
foreach (var tx in block.Transactions)
{
var coins = view.AccessCoins(tx.GetHash());
if (coins != null && !coins.IsPrunable)
{
ConsensusErrors.BadTransactionBIP30.Throw();
}
}
}
long nSigOpsCost = 0;
Money nFees = Money.Zero;
List <Task <bool> > checkInputs = new List <Task <bool> >();
for (int i = 0; i < block.Transactions.Count; i++)
{
PerformanceCounter.AddProcessedTransactions(1);
var tx = block.Transactions[i];
if (!tx.IsCoinBase)
{
int[] prevheights;
if (!view.HaveInputs(tx))
{
ConsensusErrors.BadTransactionMissingInput.Throw();
}
prevheights = new int[tx.Inputs.Count];
// Check that transaction is BIP68 final
// BIP68 lock checks (as opposed to nLockTime checks) must
// be in ConnectBlock because they require the UTXO set
for (var j = 0; j < tx.Inputs.Count; j++)
{
prevheights[j] = (int)view.AccessCoins(tx.Inputs[j].PrevOut.Hash).Height;
}
if (!tx.CheckSequenceLocks(prevheights, index, flags.LockTimeFlags))
{
ConsensusErrors.BadTransactionNonFinal.Throw();
}
}
// GetTransactionSigOpCost counts 3 types of sigops:
// * legacy (always)
// * p2sh (when P2SH enabled in flags and excludes coinbase)
// * witness (when witness enabled in flags and excludes coinbase)
nSigOpsCost += GetTransactionSigOpCost(tx, view, flags);
if (nSigOpsCost > MAX_BLOCK_SIGOPS_COST)
{
ConsensusErrors.BadBlockSigOps.Throw();
}
if (!tx.IsCoinBase)
{
CheckIntputs(tx, view, index.Height);
nFees += view.GetValueIn(tx) - tx.TotalOut;
int ii = i;
var localTx = tx;
PrecomputedTransactionData txData = new PrecomputedTransactionData(tx);
for (int iInput = 0; iInput < tx.Inputs.Count; iInput++)
{
PerformanceCounter.AddProcessedInputs(1);
var input = tx.Inputs[iInput];
int iiIntput = iInput;
var txout = view.GetOutputFor(input);
var checkInput = new Task <bool>(() =>
{
if (UseConsensusLib)
{
Script.BitcoinConsensusError error;
return(Script.VerifyScriptConsensus(txout.ScriptPubKey, tx, (uint)iiIntput, flags.ScriptFlags, out error));
}
else
{
var checker = new TransactionChecker(tx, iiIntput, txout.Value, txData);
var ctx = new ScriptEvaluationContext();
ctx.ScriptVerify = flags.ScriptFlags;
return(ctx.VerifyScript(input.ScriptSig, txout.ScriptPubKey, checker));
}
});
checkInput.Start(taskScheduler);
checkInputs.Add(checkInput);
}
}
view.Update(tx, index.Height);
}
Money blockReward = nFees + GetBlockSubsidy(index.Height);
if (block.Transactions[0].TotalOut > blockReward)
{
ConsensusErrors.BadCoinbaseAmount.Throw();
}
var passed = checkInputs.All(c => c.GetAwaiter().GetResult());
if (!passed)
{
ConsensusErrors.BadTransactionScriptError.Throw();
}
}
public void ContextualCheckBlock(Block block, ConsensusFlags consensusFlags, ContextInformation context)
{
int nHeight = context.BestBlock == null ? 0 : context.BestBlock.Height + 1;
// Start enforcing BIP113 (Median Time Past) using versionbits logic.
var nLockTimeCutoff = consensusFlags.LockTimeFlags.HasFlag(LockTimeFlags.MedianTimePast) ?
context.BestBlock.MedianTimePast :
block.Header.BlockTime;
// Check that all transactions are finalized
foreach (var transaction in block.Transactions)
{
if (!transaction.IsFinal(nLockTimeCutoff, nHeight))
{
ConsensusErrors.BadTransactionNonFinal.Throw();
}
}
// Enforce rule that the coinbase starts with serialized block height
if (consensusFlags.EnforceBIP34)
{
Script expect = new Script(Op.GetPushOp(nHeight));
Script actual = block.Transactions[0].Inputs[0].ScriptSig;
if (!StartWith(actual.ToBytes(true), expect.ToBytes(true)))
{
ConsensusErrors.BadCoinbaseHeight.Throw();
}
}
// Validation for witness commitments.
// * We compute the witness hash (which is the hash including witnesses) of all the block's transactions, except the
// coinbase (where 0x0000....0000 is used instead).
// * The coinbase scriptWitness is a stack of a single 32-byte vector, containing a witness nonce (unconstrained).
// * We build a merkle tree with all those witness hashes as leaves (similar to the hashMerkleRoot in the block header).
// * There must be at least one output whose scriptPubKey is a single 36-byte push, the first 4 bytes of which are
// {0xaa, 0x21, 0xa9, 0xed}, and the following 32 bytes are SHA256^2(witness root, witness nonce). In case there are
// multiple, the last one is used.
bool fHaveWitness = false;
if (consensusFlags.ScriptFlags.HasFlag(ScriptVerify.Witness))
{
int commitpos = GetWitnessCommitmentIndex(block);
if (commitpos != -1)
{
bool malleated = false;
uint256 hashWitness = BlockWitnessMerkleRoot(block, ref malleated);
// The malleation check is ignored; as the transaction tree itself
// already does not permit it, it is impossible to trigger in the
// witness tree.
var witness = block.Transactions[0].Inputs[0].WitScript;
if (witness.PushCount != 1 || witness.Pushes.First().Length != 32)
{
ConsensusErrors.BadWitnessNonceSize.Throw();
}
byte[] hashed = new byte[64];
Buffer.BlockCopy(hashWitness.ToBytes(), 0, hashed, 0, 32);
Buffer.BlockCopy(witness.Pushes.First(), 0, hashed, 32, 32);
hashWitness = Hashes.Hash256(hashed);
if (!EqualsArray(hashWitness.ToBytes(), block.Transactions[0].Outputs[commitpos].ScriptPubKey.ToBytes(true).Skip(6).ToArray(), 32))
{
ConsensusErrors.BadWitnessMerkleMatch.Throw();
}
fHaveWitness = true;
}
}
if (!fHaveWitness)
{
for (var i = 0; i < block.Transactions.Count; i++)
{
if (block.Transactions[i].HasWitness)
{
ConsensusErrors.UnexpectedWitness.Throw();
}
}
}
// After the coinbase witness nonce and commitment are verified,
// we can check if the block weight passes (before we've checked the
// coinbase witness, it would be possible for the weight to be too
// large by filling up the coinbase witness, which doesn't change
// the block hash, so we couldn't mark the block as permanently
// failed).
if (GetBlockWeight(block) > MAX_BLOCK_WEIGHT)
{
ConsensusErrors.BadCoinbaseHeight.Throw();
}
}
private static Task GetPrefetchingTask(CacheCoinView cache, ILookaheadBlockPuller lookaheadPuller, ConsensusFlags flags)
{
Task prefetching = Task.FromResult <bool>(true);
if (cache != null && lookaheadPuller != null)
{
var nextBlock = lookaheadPuller.TryGetLookahead(0);
if (nextBlock != null)
{
prefetching = Task.Run(() => cache.FetchCoins(GetIdsToFetch(nextBlock, flags.EnforceBIP30)));
}
}
return(prefetching);
}
