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-rw-r--r--src/init.cpp2
-rw-r--r--src/main.cpp103
-rw-r--r--src/main.h4
3 files changed, 59 insertions, 50 deletions
diff --git a/src/init.cpp b/src/init.cpp
index 031b9db480..323192ab79 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1229,7 +1229,7 @@ bool AppInit2(boost::thread_group& threadGroup)
LogPrintf("mapAddressBook.size() = %u\n", pwalletMain ? pwalletMain->mapAddressBook.size() : 0);
#endif
- InitRespendFilter();
+ RegisterInternalSignals();
StartNode(threadGroup);
if (fServer)
StartRPCThreads();
diff --git a/src/main.cpp b/src/main.cpp
index dd9e76378e..7ff1bdb2e7 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -126,14 +126,9 @@ namespace {
} // anon namespace
-// Bloom filter to limit respend relays to one
+// Forward reference functions defined here:
static const unsigned int MAX_DOUBLESPEND_BLOOM = 1000;
-static CBloomFilter doubleSpendFilter;
-void InitRespendFilter() {
- seed_insecure_rand();
- doubleSpendFilter = CBloomFilter(MAX_DOUBLESPEND_BLOOM, 0.01, insecure_rand(), BLOOM_UPDATE_NONE);
-}
-
+static bool RelayableRespend(const COutPoint& outPoint, const CTransaction& doubleSpend, bool fInBlock, CBloomFilter& filter);
//////////////////////////////////////////////////////////////////////////////
//
@@ -157,10 +152,24 @@ 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));
@@ -897,45 +906,6 @@ 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)
{
@@ -973,7 +943,7 @@ 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 = RelayableRespend(outpoint, tx, false, doubleSpendFilter);
+ relayableRespend = g_signals.DetectedDoubleSpend(outpoint, tx, false);
if (!relayableRespend)
return false;
}
@@ -1085,6 +1055,45 @@ 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 20a83db605..33afa06fa8 100644
--- a/src/main.h
+++ b/src/main.h
@@ -112,8 +112,8 @@ struct CNodeStateStats;
struct CBlockTemplate;
-/** Initialize respend bloom filter **/
-void InitRespendFilter();
+/** Set up internal signal handlers **/
+void RegisterInternalSignals();
/** Register a wallet to receive updates from core */
void RegisterWallet(CWalletInterface* pwalletIn);