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Revert "Relay double-spends, subject to anti-DOS"

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This reverts commit d640a3ceab.
This commit is contained in:
Wladimir J. van der Laan
2014-07-17 14:09:55 +02:00
parent 3015e0bca6
commit 98e84aae7a
6 changed files with 15 additions and 109 deletions
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16
src/core.cpp
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@@ -124,22 +124,6 @@ CTransaction& CTransaction::operator=(const CTransaction &tx) {
return *this;
}
bool CTransaction::IsEquivalentTo(const CTransaction& tx) const
{
if (nVersion != tx.nVersion ||
nLockTime != tx.nLockTime ||
vin.size() != tx.vin.size() ||
vout != tx.vout)
return false;
for (unsigned int i = 0; i < vin.size(); i++)
{
if (vin[i].nSequence != tx.vin[i].nSequence ||
vin[i].prevout != tx.vin[i].prevout)
return false;
}
return true;
}
int64_t CTransaction::GetValueOut() const
{
int64_t nValueOut = 0;

3
src/core.h
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@@ -255,9 +255,6 @@ public:
return hash;
}
// True if only scriptSigs are different
bool IsEquivalentTo(const CTransaction& tx) const;
// Return sum of txouts.
int64_t GetValueOut() const;
// GetValueIn() is a method on CCoinsViewCache, because

1
src/init.cpp
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@@ -1229,7 +1229,6 @@ bool AppInit2(boost::thread_group& threadGroup)
LogPrintf("mapAddressBook.size() = %u\n", pwalletMain ? pwalletMain->mapAddressBook.size() : 0);
#endif
RegisterInternalSignals();
StartNode(threadGroup);
if (fServer)
StartRPCThreads();

100
src/main.cpp
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@@ -7,7 +7,6 @@
#include "addrman.h"
#include "alert.h"
#include "bloom.h"
#include "chainparams.h"
#include "checkpoints.h"
#include "checkqueue.h"
@@ -126,10 +125,6 @@ namespace {
} // anon namespace
// Forward reference functions defined here:
static const unsigned int MAX_DOUBLESPEND_BLOOM = 1000;
static void RelayDoubleSpend(const COutPoint& outPoint, const CTransaction& doubleSpend, bool fInBlock, CBloomFilter& filter);
//////////////////////////////////////////////////////////////////////////////
//
// dispatching functions
@@ -152,25 +147,10 @@ struct CMainSignals {
boost::signals2::signal<void (const uint256 &)> Inventory;
// Tells listeners to broadcast their data.
boost::signals2::signal<void ()> Broadcast;
// Notifies listeners of detection of a double-spent transaction. Arguments are outpoint that is
// double-spent, first transaction seen, double-spend transaction, and whether the second double-spend
// transaction was first seen in a block.
// Note: only notifies if the previous transaction is in the memory pool; if previous transction was in a block,
// then the double-spend simply fails when we try to lookup the inputs in the current UTXO set.
boost::signals2::signal<void (const COutPoint&, const CTransaction&, bool)> DetectedDoubleSpend;
} g_signals;
} // anon namespace
void RegisterInternalSignals() {
static CBloomFilter doubleSpendFilter;
seed_insecure_rand();
doubleSpendFilter = CBloomFilter(MAX_DOUBLESPEND_BLOOM, 0.01, insecure_rand(), BLOOM_UPDATE_NONE);
g_signals.DetectedDoubleSpend.connect(boost::bind(RelayDoubleSpend, _1, _2, _3, doubleSpendFilter));
}
void RegisterWallet(CWalletInterface* pwalletIn) {
g_signals.SyncTransaction.connect(boost::bind(&CWalletInterface::SyncTransaction, pwalletIn, _1, _2));
g_signals.EraseTransaction.connect(boost::bind(&CWalletInterface::EraseFromWallet, pwalletIn, _1));
@@ -890,22 +870,6 @@ int64_t GetMinRelayFee(const CTransaction& tx, unsigned int nBytes, bool fAllowF
return nMinFee;
}
// 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);
// Use an exponentially decaying ~10-minute window:
dCount *= pow(1.0 - 1.0/600.0, (double)(nNow - nLastTime));
nLastTime = nNow;
if (dCount >= nLimit*10*1000)
return true;
dCount += nSize;
return false;
}
bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
bool* pfMissingInputs, bool fRejectInsaneFee)
@@ -940,10 +904,9 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
for (unsigned int i = 0; i < tx.vin.size(); i++)
{
COutPoint outpoint = tx.vin[i].prevout;
// Does tx conflict with a member of the pool, and is it not equivalent to that member?
if (pool.mapNextTx.count(outpoint) && !tx.IsEquivalentTo(*pool.mapNextTx[outpoint].ptx))
if (pool.mapNextTx.count(outpoint))
{
g_signals.DetectedDoubleSpend(outpoint, tx, false);
// Disable replacement feature for now
return false;
}
}
@@ -1015,15 +978,23 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
// be annoying or make others' transactions take longer to confirm.
if (fLimitFree && nFees < ::minRelayTxFee.GetFee(nSize))
{
static CCriticalSection csFreeLimiter;
static double dFreeCount;
static int64_t nLastFreeTime;
static int64_t nFreeLimit = GetArg("-limitfreerelay", 15);
static int64_t nLastTime;
int64_t nNow = GetTime();
if (RateLimitExceeded(dFreeCount, nLastFreeTime, nFreeLimit, nSize))
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", 15)*10*1000)
return state.DoS(0, error("AcceptToMemoryPool : free transaction rejected by rate limiter"),
REJECT_INSUFFICIENTFEE, "insufficient priority");
LogPrint("mempool", "Rate limit dFreeCount: %g => %g\n", dFreeCount, dFreeCount+nSize);
dFreeCount += nSize;
}
if (fRejectInsaneFee && nFees > ::minRelayTxFee.GetFee(nSize) * 10000)
@@ -1046,49 +1017,6 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
return true;
}
static void
RelayDoubleSpend(const COutPoint& outPoint, const CTransaction& doubleSpend, bool fInBlock, CBloomFilter& filter)
{
// Relaying double-spend attempts to our peers lets them detect when
// somebody might be trying to cheat them. However, blindly relaying
// every double-spend across the entire network gives attackers
// a denial-of-service attack: just generate a stream of double-spends
// re-spending the same (limited) set of outpoints owned by the attacker.
// So, we use a bloom filter and only relay (at most) the first double
// spend for each outpoint. False-positives ("we have already relayed")
// are OK, because if the peer doesn't hear about the double-spend
// from us they are very likely to hear about it from another peer, since
// each peer uses a different, randomized bloom filter.
if (fInBlock || filter.contains(outPoint)) return;
// 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;
}
LogPrint("mempool", "Rate limit dRespendCount: %g => %g\n", dRespendCount, dRespendCount+nSize);
// Clear the filter on average every MAX_DOUBLE_SPEND_BLOOM
// insertions
if (insecure_rand()%MAX_DOUBLESPEND_BLOOM == 0)
filter.clear();
filter.insert(outPoint);
RelayTransaction(doubleSpend);
// Share conflict with wallet
g_signals.SyncTransaction(doubleSpend, NULL);
}
int CMerkleTx::GetDepthInMainChainINTERNAL(CBlockIndex* &pindexRet) const
{

3
src/main.h
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@@ -112,9 +112,6 @@ struct CNodeStateStats;
struct CBlockTemplate;
/** Set up internal signal handlers **/
void RegisterInternalSignals();
/** Register a wallet to receive updates from core */
void RegisterWallet(CWalletInterface* pwalletIn);
/** Unregister a wallet from core */

1
src/txmempool.cpp
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@@ -420,6 +420,7 @@ void CTxMemPool::remove(const CTransaction &tx, std::list<CTransaction>& removed
void CTxMemPool::removeConflicts(const CTransaction &tx, std::list<CTransaction>& removed)
{
// Remove transactions which depend on inputs of tx, recursively
list<CTransaction> result;
LOCK(cs);
BOOST_FOREACH(const CTxIn &txin, tx.vin) {
std::map<COutPoint, CInPoint>::iterator it = mapNextTx.find(txin.prevout);