public override Task <FetchCoinsResponse> FetchCoinsAsync(uint256[] txIds)
{
return(_Session.Do(() =>
{
using (StopWatch.Instance.Start(o => PerformanceCounter.AddQueryTime(o)))
{
var blockHash = GetCurrentHash();
UnspentOutputs[] result = new UnspentOutputs[txIds.Length];
int i = 0;
PerformanceCounter.AddQueriedEntities(txIds.Length);
foreach (var input in txIds)
{
var coin = _Session.Transaction.Select <byte[], Coins>("Coins", input.ToBytes(false))?.Value;
result[i++] = coin == null ? null : new UnspentOutputs(input, coin);
}
return new FetchCoinsResponse(result, blockHash);
}
}));
}
private bool VerifySignature(UnspentOutputs txFrom, Transaction txTo, int txToInN, ScriptVerify flagScriptVerify)
{
var input = txTo.Inputs[txToInN];
if (input.PrevOut.N >= txFrom._Outputs.Length)
{
return(false);
}
if (input.PrevOut.Hash != txFrom.TransactionId)
{
return(false);
}
var output = txFrom._Outputs[input.PrevOut.N];
var txData = new PrecomputedTransactionData(txTo);
var checker = new TransactionChecker(txTo, txToInN, output.Value, txData);
var ctx = new ScriptEvaluationContext {
ScriptVerify = flagScriptVerify
};
return(ctx.VerifyScript(input.ScriptSig, output.ScriptPubKey, checker));
}
// Stratis kernel protocol
// coinstake must meet hash target according to the protocol:
// kernel (input 0) must meet the formula
// hash(nStakeModifier + txPrev.block.nTime + txPrev.nTime + txPrev.vout.hash + txPrev.vout.n + nTime) < bnTarget * nWeight
// this ensures that the chance of getting a coinstake is proportional to the
// amount of coins one owns.
// The reason this hash is chosen is the following:
// nStakeModifier: scrambles computation to make it very difficult to precompute
// future proof-of-stake
// txPrev.block.nTime: prevent nodes from guessing a good timestamp to
// generate transaction for future advantage,
// obsolete since v3
// txPrev.nTime: slightly scrambles computation
// txPrev.vout.hash: hash of txPrev, to reduce the chance of nodes
// generating coinstake at the same time
// txPrev.vout.n: output number of txPrev, to reduce the chance of nodes
// generating coinstake at the same time
// nTime: current timestamp
// block/tx hash should not be used here as they can be generated in vast
// quantities so as to generate blocks faster, degrading the system back into
// a proof-of-work situation.
//
private void CheckStakeKernelHashV2(ContextInformation context, ChainedBlock pindexPrev, uint nBits,
uint nTimeBlockFrom,
BlockStake prevBlockStake, UnspentOutputs txPrev, OutPoint prevout, uint nTimeTx)
{
if (nTimeTx < txPrev.Time)
{
ConsensusErrors.StakeTimeViolation.Throw();
}
// Base target
var bnTarget = new Target(nBits).ToBigInteger();
// TODO: Investigate:
// The POS protocol should probably put a limit on the max amount that can be staked
// not a hard limit but a limit that allow any amount to be staked with a max weight value.
// the max weight should not exceed the max uint256 array size (array siez = 32)
// Weighted target
var nValueIn = txPrev._Outputs[prevout.N].Value.Satoshi;
var bnWeight = BigInteger.ValueOf(nValueIn);
bnTarget = bnTarget.Multiply(bnWeight);
context.Stake.TargetProofOfStake = ToUInt256(bnTarget);
var nStakeModifier = prevBlockStake.StakeModifier; //pindexPrev.Header.BlockStake.StakeModifier;
uint256 bnStakeModifierV2 = prevBlockStake.StakeModifierV2; //pindexPrev.Header.BlockStake.StakeModifierV2;
int nStakeModifierHeight = pindexPrev.Height;
var nStakeModifierTime = pindexPrev.Header.Time;
// Calculate hash
using (var ms = new MemoryStream())
{
var serializer = new BitcoinStream(ms, true);
if (IsProtocolV3((int)nTimeTx))
{
serializer.ReadWrite(bnStakeModifierV2);
}
else
{
serializer.ReadWrite(nStakeModifier);
serializer.ReadWrite(nTimeBlockFrom);
}
serializer.ReadWrite(txPrev.Time);
serializer.ReadWrite(prevout.Hash);
serializer.ReadWrite(prevout.N);
serializer.ReadWrite(nTimeTx);
context.Stake.HashProofOfStake = Hashes.Hash256(ms.ToArray());
}
//LogPrintf("CheckStakeKernelHash() : using modifier 0x%016x at height=%d timestamp=%s for block from timestamp=%s\n",
// nStakeModifier, nStakeModifierHeight,
// DateTimeStrFormat(nStakeModifierTime),
// DateTimeStrFormat(nTimeBlockFrom));
//LogPrintf("CheckStakeKernelHash() : check modifier=0x%016x nTimeBlockFrom=%u nTimeTxPrev=%u nPrevout=%u nTimeTx=%u hashProof=%s\n",
// nStakeModifier,
// nTimeBlockFrom, txPrev.nTime, prevout.n, nTimeTx,
// hashProofOfStake.ToString());
// Now check if proof-of-stake hash meets target protocol
var hashProofOfStakeTarget = new BigInteger(1, context.Stake.HashProofOfStake.ToBytes(false));
if (hashProofOfStakeTarget.CompareTo(bnTarget) > 0)
{
ConsensusErrors.StakeHashInvalidTarget.Throw();
}
// if (fDebug && !fPrintProofOfStake)
// {
// LogPrintf("CheckStakeKernelHash() : using modifier 0x%016x at height=%d timestamp=%s for block from timestamp=%s\n",
// nStakeModifier, nStakeModifierHeight,
// DateTimeStrFormat(nStakeModifierTime),
// DateTimeStrFormat(nTimeBlockFrom));
// LogPrintf("CheckStakeKernelHash() : pass modifier=0x%016x nTimeBlockFrom=%u nTimeTxPrev=%u nPrevout=%u nTimeTx=%u hashProof=%s\n",
// nStakeModifier,
// nTimeBlockFrom, txPrev.nTime, prevout.n, nTimeTx,
// hashProofOfStake.ToString());
// }
}
public override async Task <FetchCoinsResponse> FetchCoinsAsync(uint256[] txIds)
{
Guard.NotNull(txIds, nameof(txIds));
FetchCoinsResponse result = null;
uint256 innerBlockHash = null;
UnspentOutputs[] outputs = new UnspentOutputs[txIds.Length];
List <int> miss = new List <int>();
List <uint256> missedTxIds = new List <uint256>();
using (_Lock.LockRead())
{
WaitOngoingTasks();
for (int i = 0; i < txIds.Length; i++)
{
CacheItem cache;
if (!_Unspents.TryGetValue(txIds[i], out cache))
{
miss.Add(i);
missedTxIds.Add(txIds[i]);
}
else
{
outputs[i] = cache.UnspentOutputs == null ? null :
cache.UnspentOutputs.IsPrunable ? null :
cache.UnspentOutputs.Clone();
}
}
PerformanceCounter.AddMissCount(miss.Count);
PerformanceCounter.AddHitCount(txIds.Length - miss.Count);
}
var fetchedCoins = await Inner.FetchCoinsAsync(missedTxIds.ToArray()).ConfigureAwait(false);
using (_Lock.LockWrite())
{
_Flushing.Wait();
innerBlockHash = fetchedCoins.BlockHash;
if (_BlockHash == null)
{
Debug.Assert(_Unspents.Count == 0);
_InnerBlockHash = innerBlockHash;
_BlockHash = innerBlockHash;
}
for (int i = 0; i < miss.Count; i++)
{
var index = miss[i];
var unspent = fetchedCoins.UnspentOutputs[i];
outputs[index] = unspent;
CacheItem cache = new CacheItem();
cache.ExistInInner = unspent != null;
cache.IsDirty = false;
cache.UnspentOutputs = unspent;
cache.OriginalOutputs = unspent?._Outputs.ToArray();
_Unspents.TryAdd(txIds[index], cache);
}
result = new FetchCoinsResponse(outputs, _BlockHash);
}
if (CacheEntryCount > MaxItems)
{
Evict();
if (CacheEntryCount > MaxItems)
{
await FlushAsync().ConfigureAwait(false);
Evict();
}
}
return(result);
}
// Stratis kernel protocol
// coinstake must meet hash target according to the protocol:
// kernel (input 0) must meet the formula
// hash(nStakeModifier + txPrev.block.nTime + txPrev.nTime + txPrev.vout.hash + txPrev.vout.n + nTime) < bnTarget * nWeight
// this ensures that the chance of getting a coinstake is proportional to the
// amount of coins one owns.
// The reason this hash is chosen is the following:
// nStakeModifier: scrambles computation to make it very difficult to precompute
// future proof-of-stake
// txPrev.block.nTime: prevent nodes from guessing a good timestamp to
// generate transaction for future advantage,
// obsolete since v3
// txPrev.nTime: slightly scrambles computation
// txPrev.vout.hash: hash of txPrev, to reduce the chance of nodes
// generating coinstake at the same time
// txPrev.vout.n: output number of txPrev, to reduce the chance of nodes
// generating coinstake at the same time
// nTime: current timestamp
// block/tx hash should not be used here as they can be generated in vast
// quantities so as to generate blocks faster, degrading the system back into
// a proof-of-work situation.
//
private void CheckStakeKernelHashV2(ContextInformation context, ChainedBlock pindexPrev, uint nBits, uint nTimeBlockFrom,
BlockStake prevBlockStake, UnspentOutputs txPrev, OutPoint prevout, uint nTimeTx)
{
if (nTimeTx < txPrev.Time)
{
ConsensusErrors.StakeTimeViolation.Throw();
}
// Base target
var bnTarget = new Target(nBits).ToBigInteger();
// Weighted target
var nValueIn = txPrev._Outputs[prevout.N].Value.Satoshi;
var bnWeight = BigInteger.ValueOf(nValueIn);
bnTarget = bnTarget.Multiply(bnWeight);
// todo: investigate this issue, is the convertion to uint256 similar to the c++ implementation
//context.Stake.TargetProofOfStake = Target.ToUInt256(bnTarget,);
var nStakeModifier = prevBlockStake.StakeModifier; //pindexPrev.Header.BlockStake.StakeModifier;
uint256 bnStakeModifierV2 = prevBlockStake.StakeModifierV2; //pindexPrev.Header.BlockStake.StakeModifierV2;
int nStakeModifierHeight = pindexPrev.Height;
var nStakeModifierTime = pindexPrev.Header.Time;
// Calculate hash
using (var ms = new MemoryStream())
{
var serializer = new BitcoinStream(ms, true);
if (IsProtocolV3((int)nTimeTx))
{
serializer.ReadWrite(bnStakeModifierV2);
}
else
{
serializer.ReadWrite(nStakeModifier);
serializer.ReadWrite(nTimeBlockFrom);
}
serializer.ReadWrite(txPrev.Time);
serializer.ReadWrite(prevout.Hash);
serializer.ReadWrite(prevout.N);
serializer.ReadWrite(nTimeTx);
context.Stake.HashProofOfStake = Hashes.Hash256(ms.ToArray());
}
//LogPrintf("CheckStakeKernelHash() : using modifier 0x%016x at height=%d timestamp=%s for block from timestamp=%s\n",
// nStakeModifier, nStakeModifierHeight,
// DateTimeStrFormat(nStakeModifierTime),
// DateTimeStrFormat(nTimeBlockFrom));
//LogPrintf("CheckStakeKernelHash() : check modifier=0x%016x nTimeBlockFrom=%u nTimeTxPrev=%u nPrevout=%u nTimeTx=%u hashProof=%s\n",
// nStakeModifier,
// nTimeBlockFrom, txPrev.nTime, prevout.n, nTimeTx,
// hashProofOfStake.ToString());
// Now check if proof-of-stake hash meets target protocol
var hashProofOfStakeTarget = new BigInteger(context.Stake.HashProofOfStake.ToBytes(false));
if (hashProofOfStakeTarget.CompareTo(bnTarget) > 0)
{
ConsensusErrors.StakeHashInvalidTarget.Throw();
}
// if (fDebug && !fPrintProofOfStake)
// {
// LogPrintf("CheckStakeKernelHash() : using modifier 0x%016x at height=%d timestamp=%s for block from timestamp=%s\n",
// nStakeModifier, nStakeModifierHeight,
// DateTimeStrFormat(nStakeModifierTime),
// DateTimeStrFormat(nTimeBlockFrom));
// LogPrintf("CheckStakeKernelHash() : pass modifier=0x%016x nTimeBlockFrom=%u nTimeTxPrev=%u nPrevout=%u nTimeTx=%u hashProof=%s\n",
// nStakeModifier,
// nTimeBlockFrom, txPrev.nTime, prevout.n, nTimeTx,
// hashProofOfStake.ToString());
// }
}