diff options
| -rw-r--r-- | src/init.cpp | 2 | ||||
| -rw-r--r-- | src/main.cpp | 103 | ||||
| -rw-r--r-- | src/main.h | 4 |
3 files changed, 50 insertions, 59 deletions
diff --git a/src/init.cpp b/src/init.cpp index da13218a94..6c0898c036 100644 --- a/src/init.cpp +++ b/src/init.cpp @@ -1176,7 +1176,7 @@ bool AppInit2(boost::thread_group& threadGroup) LogPrintf("mapAddressBook.size() = %u\n", pwalletMain ? pwalletMain->mapAddressBook.size() : 0); #endif - RegisterInternalSignals(); + InitRespendFilter(); StartNode(threadGroup); if (fServer) StartRPCThreads(); diff --git a/src/main.cpp b/src/main.cpp index 1294e5b2ed..7baf33c39f 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -125,9 +125,14 @@ 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 bool RelayableRespend(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); +} + ////////////////////////////////////////////////////////////////////////////// // @@ -151,24 +156,10 @@ 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<bool (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(RelayableRespend, _1, _2, _3, doubleSpendFilter)); -} - void RegisterWallet(CWalletInterface* pwalletIn) { g_signals.SyncTransaction.connect(boost::bind(&CWalletInterface::SyncTransaction, pwalletIn, _1, _2)); @@ -908,6 +899,45 @@ 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) { @@ -945,7 +975,7 @@ 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)) { - relayableRespend = g_signals.DetectedDoubleSpend(outpoint, tx, false); + relayableRespend = RelayableRespend(outpoint, tx, false, doubleSpendFilter); if (!relayableRespend) return false; } @@ -1057,45 +1087,6 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa return !relayableRespend; } -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; -} - int CMerkleTx::GetDepthInMainChainINTERNAL(CBlockIndex* &pindexRet) const { diff --git a/src/main.h b/src/main.h index 19f4469008..26450bb721 100644 --- a/src/main.h +++ b/src/main.h @@ -108,8 +108,8 @@ 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); |