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bitcoin
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Merge pull request #4450

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0da6b3f Remove signal DoubleSpendDetected, use function (Tom Harding)
88dd359 Check signatures before respend relay (Tom Harding)
pull/4452/merge
Wladimir J. van der Laan 11 years ago
parent 21876d3831 0da6b3fd18
commit e61c6d69ad
No known key found for this signature in database
GPG Key ID: 74810B012346C9A6
3 changed files with 64 additions and 66 deletions
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2
src/init.cpp
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@ -1183,7 +1183,7 @@ bool AppInit2(boost::thread_group& threadGroup)
LogPrintf("mapAddressBook.size() = %u\n", pwalletMain ? pwalletMain->mapAddressBook.size() : 0);
#endif
RegisterInternalSignals();
InitRespendFilter();
StartNode(threadGroup);
if (fServer)
StartRPCThreads();

118
src/main.cpp
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@ -123,9 +123,14 @@ namespace {
} // anon namespace
// Forward reference functions defined here:
// Bloom filter to limit respend relays to one
static const unsigned int MAX_DOUBLESPEND_BLOOM = 1000;
static void RelayDoubleSpend(const COutPoint& outPoint, const CTransaction& doubleSpend, bool fInBlock, CBloomFilter& filter);
static CBloomFilter doubleSpendFilter;
void InitRespendFilter() {
seed_insecure_rand();
doubleSpendFilter = CBloomFilter(MAX_DOUBLESPEND_BLOOM, 0.01, insecure_rand(), BLOOM_UPDATE_NONE);
}
//////////////////////////////////////////////////////////////////////////////
//
@ -149,24 +154,10 @@ 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));
@ -901,6 +892,45 @@ bool RateLimitExceeded(double& dCount, int64_t& nLastTime, int64_t nLimit, unsig
return false;
}
static bool RelayableRespend(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 false;
// 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 false;
}
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);
return true;
}
bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
bool* pfMissingInputs, bool fRejectInsaneFee)
{
@ -929,6 +959,7 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
return false;
// Check for conflicts with in-memory transactions
bool relayableRespend = false;
{
LOCK(pool.cs); // protect pool.mapNextTx
for (unsigned int i = 0; i < tx.vin.size(); i++)
@ -937,7 +968,8 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
// 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))
{
g_signals.DetectedDoubleSpend(outpoint, tx, false);
relayableRespend = RelayableRespend(outpoint, tx, false, doubleSpendFilter);
if (!relayableRespend)
return false;
}
}
@ -1031,55 +1063,21 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
{
return error("AcceptToMemoryPool: : ConnectInputs failed %s", hash.ToString());
}
if (relayableRespend)
{
RelayTransaction(tx);
}
else
{
// Store transaction in memory
pool.addUnchecked(hash, entry);
}
g_signals.SyncTransaction(tx, NULL);
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);
g_signals.SyncTransaction(tx, NULL);
// Share conflict with wallet
g_signals.SyncTransaction(doubleSpend, NULL);
return !relayableRespend;
}

4
src/main.h
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@ -109,8 +109,8 @@ struct CNodeStateStats;
struct CBlockTemplate;
/** Set up internal signal handlers **/
void RegisterInternalSignals();
/** Initialize respend bloom filter **/
void InitRespendFilter();
/** Register a wallet to receive updates from core */
void RegisterWallet(CWalletInterface* pwalletIn);

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