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Relay double-spends, subject to anti-DOS

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cef3711500 (diff-7ec3c68a81efff79b6ca22ac1f1eabbaL929)
This commit is contained in:
lateminer
2018-01-10 21:52:38 +03:00
parent 48feed03ef
commit 72875a2116
12 changed files with 150 additions and 56 deletions
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98
src/main.cpp
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@@ -561,6 +561,14 @@ void FindNextBlocksToDownload(NodeId nodeid, unsigned int count, std::vector<CBl
} // anon namespace
// Bloom filter to limit respend relays to one
static const unsigned int MAX_DOUBLESPEND_BLOOM = 100000;
static CBloomFilter doubleSpendFilter;
void InitRespendFilter() {
seed_insecure_rand();
doubleSpendFilter = CBloomFilter(MAX_DOUBLESPEND_BLOOM, 0.01, insecure_rand(), BLOOM_UPDATE_NONE);
}
bool GetNodeStateStats(NodeId nodeid, CNodeStateStats &stats) {
LOCK(cs_main);
CNodeState *state = State(nodeid);
@@ -1017,6 +1025,41 @@ std::string FormatStateMessage(const CValidationState &state)
state.GetRejectCode());
}
// Exponentially limit the rate of nSize flow to nLimit. nLimit unit is thousands-per-minute.
bool RateLimitExceeded(double& dCount, int64_t& nLastTime, int64_t nLimit, unsigned int nSize)
{
static CCriticalSection csLimiter;
int64_t nNow = GetTime();
LOCK(csLimiter);
dCount *= pow(1.0 - 1.0/600.0, (double)(nNow - nLastTime));
nLastTime = nNow;
if (dCount >= nLimit*10*1000)
return true;
dCount += nSize;
return false;
}
static bool RespendRelayExceeded(const CTransaction& doubleSpend)
{
// Apply an independent rate limit to double-spend relays
static double dRespendCount;
static int64_t nLastRespendTime;
static int64_t nRespendLimit = GetArg("-limitrespendrelay", 100);
unsigned int nSize = ::GetSerializeSize(doubleSpend, SER_NETWORK, PROTOCOL_VERSION);
if (RateLimitExceeded(dRespendCount, nLastRespendTime, nRespendLimit, nSize))
{
LogPrint("mempool", "Double-spend relay rejected by rate limiter\n");
return true;
}
LogPrint("mempool", "Rate limit dRespendCount: %g => %g\n", dRespendCount, dRespendCount+nSize);
return false;
}
bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
bool* pfMissingInputs, bool fOverrideMempoolLimit, bool fRejectAbsurdFee,
std::vector<uint256>& vHashTxnToUncache)
@@ -1066,13 +1109,26 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C
return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-in-mempool");
// Check for conflicts with in-memory transactions
bool fRespend = false;
COutPoint relayForOutpoint;
set<uint256> setConflicts;
{
LOCK(pool.cs); // protect pool.mapNextTx
BOOST_FOREACH(const CTxIn &txin, tx.vin)
{
COutPoint outpoint = txin.prevout;
// A respend is a tx that conflicts with a member of the pool
if (pool.mapNextTx.count(txin.prevout))
{
fRespend = true;
// Relay only one tx per respent outpoint, but not if tx is equivalent to pool member
if (!doubleSpendFilter.contains(outpoint) && !tx.IsEquivalentTo(*pool.mapNextTx[outpoint].ptx))
{
relayForOutpoint = outpoint;
break;
}
/*
const CTransaction *ptxConflicting = pool.mapNextTx[txin.prevout].ptx;
if (!setConflicts.count(ptxConflicting->GetHash()))
{
@@ -1105,8 +1161,12 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C
setConflicts.insert(ptxConflicting->GetHash());
}
*/
}
}
if (fRespend && (relayForOutpoint.IsNull() || RespendRelayExceeded(tx)))
return false;
}
{
@@ -1215,22 +1275,15 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C
// be annoying or make others' transactions take longer to confirm.
if (fLimitFree && nModifiedFees < ::minRelayTxFee.GetFee(nSize))
{
static CCriticalSection csFreeLimiter;
static double dFreeCount;
static int64_t nLastTime;
int64_t nNow = GetTime();
static int64_t nLastFreeTime;
static int64_t nFreeLimit = GetArg("-limitfreerelay", DEFAULT_LIMITFREERELAY);
LOCK(csFreeLimiter);
// Use an exponentially decaying ~10-minute window:
dFreeCount *= pow(1.0 - 1.0/600.0, (double)(nNow - nLastTime));
nLastTime = nNow;
// -limitfreerelay unit is thousand-bytes-per-minute
// At default rate it would take over a month to fill 1GB
if (dFreeCount >= GetArg("-limitfreerelay", DEFAULT_LIMITFREERELAY) * 10 * 1000)
if (RateLimitExceeded(dFreeCount, nLastFreeTime, nFreeLimit, nSize))
return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "rate limited free transaction");
LogPrint("mempool", "Rate limit dFreeCount: %g => %g\n", dFreeCount, dFreeCount+nSize);
dFreeCount += nSize;
}
if (fRejectAbsurdFee && nFees > ::minRelayTxFee.GetFee(nSize) * 10000)
@@ -1434,8 +1487,19 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C
}
pool.RemoveStaged(allConflicting);
// Store transaction in memory
pool.addUnchecked(hash, entry, setAncestors, !IsInitialBlockDownload());
if (fRespend)
{
// Clear the filter on average every MAX_DOUBLE_SPEND_BLOOM insertions
if (insecure_rand()%MAX_DOUBLESPEND_BLOOM == 0)
doubleSpendFilter.clear();
doubleSpendFilter.insert(relayForOutpoint);
RelayTransaction(tx);
}
else
{
// Store transaction in memory
pool.addUnchecked(hash, entry, !IsInitialBlockDownload());
}
// Add memory address index
if (fAddressIndex) {
@@ -1455,9 +1519,9 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C
}
}
SyncWithWallets(tx, NULL);
SyncWithWallets(tx, NULL, fRespend);
return true;
return !fRespend;
}
bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
@@ -3149,7 +3213,7 @@ bool static DisconnectTip(CValidationState& state, const Consensus::Params& cons
// Let wallets know transactions went from 1-confirmed to
// 0-confirmed or conflicted:
BOOST_FOREACH(const CTransaction &tx, block.vtx) {
SyncWithWallets(tx, NULL);
SyncWithWallets(tx, NULL, false);
}
return true;
}
@@ -3208,11 +3272,11 @@ bool static ConnectTip(CValidationState& state, const CChainParams& chainparams,
// Tell wallet about transactions that went from mempool
// to conflicted:
BOOST_FOREACH(const CTransaction &tx, txConflicted) {
SyncWithWallets(tx, NULL);
SyncWithWallets(tx, NULL, false);
}
// ... and about transactions that got confirmed:
BOOST_FOREACH(const CTransaction &tx, pblock->vtx) {
SyncWithWallets(tx, pblock);
SyncWithWallets(tx, pblock, false);
}
int64_t nTime6 = GetTimeMicros(); nTimePostConnect += nTime6 - nTime5; nTimeTotal += nTime6 - nTime1;