/// <summary>
/// Calculates signature operation cost for single transaction input.
/// </summary>
/// <param name="scriptSig">Signature script.</param>
/// <param name="scriptPubKey">Script public key.</param>
/// <param name="witness">Witness script.</param>
/// <param name="flags">Script verification flags.</param>
/// <returns>Signature operation cost for single transaction input.</returns>
private long CountWitnessSignatureOperation(Script scriptSig, Script scriptPubKey, WitScript witness, DeploymentFlags flags)
{
witness = witness ?? WitScript.Empty;
if (!flags.ScriptFlags.HasFlag(ScriptVerify.Witness))
{
return(0);
}
WitProgramParameters witParams = PayToWitTemplate.Instance.ExtractScriptPubKeyParameters2(scriptPubKey);
if (witParams?.Version == 0)
{
if (witParams.Program.Length == 20)
{
return(1);
}
if (witParams.Program.Length == 32 && witness.PushCount > 0)
{
Script subscript = Script.FromBytesUnsafe(witness.GetUnsafePush(witness.PushCount - 1));
return(subscript.GetSigOpCount(true));
}
}
return(0);
}
private long CountWitnessSigOps(Script scriptSig, Script scriptPubKey, WitScript witness, DeploymentFlags flags)
{
witness = witness ?? WitScript.Empty;
if (!flags.ScriptFlags.HasFlag(ScriptVerify.Witness))
{
return(0);
}
WitProgramParameters witParams = PayToWitTemplate.Instance.ExtractScriptPubKeyParameters2(scriptPubKey);
if (witParams != null)
{
return(this.WitnessSigOps(witParams, witness, flags));
}
if (scriptPubKey.IsPayToScriptHash && scriptSig.IsPushOnly)
{
byte[] data = scriptSig.ToOps().Select(o => o.PushData).LastOrDefault() ?? new byte[0];
Script subScript = Script.FromBytesUnsafe(data);
witParams = PayToWitTemplate.Instance.ExtractScriptPubKeyParameters2(scriptPubKey);
if (witParams != null)
{
return(this.WitnessSigOps(witParams, witness, flags));
}
}
return(0);
}
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);
}
/// <summary>
/// Whether transaction is witness standard.
/// <seealso cref="https://github.com/bitcoin/bitcoin/blob/aa624b61c928295c27ffbb4d27be582f5aa31b56/src/policy/policy.cpp#L196"/>
/// </summary>
/// <param name="tx">Transaction to verify.</param>
/// <param name="mapInputs">Map of previous transactions that have outputs we're spending.</param>
/// <returns>Whether transaction is witness standard.</returns>
private bool IsWitnessStandard(Transaction tx, MempoolCoinView mapInputs)
{
if (tx.IsCoinBase)
{
this.logger.LogTrace("(-)[IS_COINBASE]:true");
return(true); // Coinbases are skipped.
}
foreach (TxIn input in tx.Inputs)
{
// We don't care if witness for this input is empty, since it must not be bloated.
// If the script is invalid without witness, it would be caught sooner or later during validation.
if (input.WitScriptEmpty)
{
continue;
}
TxOut prev = mapInputs.GetOutputFor(input);
// Get the scriptPubKey corresponding to this input.
Script prevScript = prev.ScriptPubKey;
if (prevScript.IsPayToScriptHash(this.network))
{
// If the scriptPubKey is P2SH, we try to extract the redeemScript casually by converting the scriptSig
// into a stack. We do not check IsPushOnly nor compare the hash as these will be done later anyway.
// If the check fails at this stage, we know that this txid must be a bad one.
PayToScriptHashSigParameters sigParams = PayToScriptHashTemplate.Instance.ExtractScriptSigParameters(this.network, input.ScriptSig);
if (sigParams == null || sigParams.RedeemScript == null)
{
this.logger.LogTrace("(-)[BAD_TXID]:false");
return(false);
}
prevScript = sigParams.RedeemScript;
}
// Non-witness program must not be associated with any witness.
if (!prevScript.IsWitness(this.network))
{
this.logger.LogTrace("(-)[WITNESS_MISMATCH]:false");
return(false);
}
// Check P2WSH standard limits.
WitProgramParameters wit = PayToWitTemplate.Instance.ExtractScriptPubKeyParameters2(this.chainIndexer.Network, prevScript);
if (wit == null)
{
this.logger.LogTrace("(-)[BAD_WITNESS_PARAMS]:false");
return(false);
}
// Version 0 segregated witness program validation.
if (wit.Version == 0 && wit.Program.Length == WitnessV0ScriptHashSize)
{
WitScript witness = input.WitScript;
// Get P2WSH script from top of stack.
Script scriptPubKey = Script.FromBytesUnsafe(witness.GetUnsafePush(witness.PushCount - 1));
// Stack items are remainder of stack.
int sizeWitnessStack = witness.PushCount - 1;
// Get the witness stack items.
var stack = new List <byte[]>();
for (int i = 0; i < sizeWitnessStack; i++)
{
stack.Add(witness.GetUnsafePush(i));
}
// Validate P2WSH script isn't larger than max length.
if (scriptPubKey.ToBytes(true).Length > MaxStandardP2wshScriptSize)
{
this.logger.LogTrace("(-)[P2WSH_SCRIPT_SIZE]:false");
return(false);
}
// Validate number items in witness stack isn't larger than max.
if (sizeWitnessStack > MaxStandardP2wshStackItems)
{
this.logger.LogTrace("(-)[P2WSH_STACK_ITEMS]:false");
return(false);
}
// Validate size of each of the witness stack items.
for (int j = 0; j < sizeWitnessStack; j++)
{
if (stack[j].Length > MaxStandardP2wshStackItemSize)
{
this.logger.LogTrace("(-)[P2WSH_STACK_ITEM_SIZE]:false");
return(false);
}
}
}
}
return(true);
}
