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-rw-r--r--src/main.cpp76
1 files changed, 65 insertions, 11 deletions
diff --git a/src/main.cpp b/src/main.cpp
index b1f5e3ffd7..52d543c117 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -162,6 +162,29 @@ namespace {
*/
map<uint256, NodeId> mapBlockSource;
+ /**
+ * Filter for transactions that were recently rejected by
+ * AcceptToMemoryPool. These are not rerequested until the chain tip
+ * changes, at which point the entire filter is reset. Protected by
+ * cs_main.
+ *
+ * Without this filter we'd be re-requesting txs from each of our peers,
+ * increasing bandwidth consumption considerably. For instance, with 100
+ * peers, half of which relay a tx we don't accept, that might be a 50x
+ * bandwidth increase. A flooding attacker attempting to roll-over the
+ * filter using minimum-sized, 60byte, transactions might manage to send
+ * 1000/sec if we have fast peers, so we pick 120,000 to give our peers a
+ * two minute window to send invs to us.
+ *
+ * Decreasing the false positive rate is fairly cheap, so we pick one in a
+ * million to make it highly unlikely for users to have issues with this
+ * filter.
+ *
+ * Memory used: 1.7MB
+ */
+ boost::scoped_ptr<CRollingBloomFilter> recentRejects;
+ uint256 hashRecentRejectsChainTip;
+
/** Blocks that are in flight, and that are in the queue to be downloaded. Protected by cs_main. */
struct QueuedBlock {
uint256 hash;
@@ -3248,6 +3271,7 @@ void UnloadBlockIndex()
setDirtyBlockIndex.clear();
setDirtyFileInfo.clear();
mapNodeState.clear();
+ recentRejects.reset(NULL);
BOOST_FOREACH(BlockMap::value_type& entry, mapBlockIndex) {
delete entry.second;
@@ -3268,6 +3292,10 @@ bool LoadBlockIndex()
bool InitBlockIndex() {
const CChainParams& chainparams = Params();
LOCK(cs_main);
+
+ // Initialize global variables that cannot be constructed at startup.
+ recentRejects.reset(new CRollingBloomFilter(120000, 0.000001));
+
// Check whether we're already initialized
if (chainActive.Genesis() != NULL)
return true;
@@ -3398,7 +3426,7 @@ bool LoadExternalBlockFile(FILE* fileIn, CDiskBlockPos *dbp)
}
}
} catch (const std::exception& e) {
- LogPrintf("%s: Deserialize or I/O error - %s", __func__, e.what());
+ LogPrintf("%s: Deserialize or I/O error - %s\n", __func__, e.what());
}
}
} catch (const std::runtime_error& e) {
@@ -3670,10 +3698,21 @@ bool static AlreadyHave(const CInv& inv) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
case MSG_TX:
{
- bool txInMap = false;
- txInMap = mempool.exists(inv.hash);
- return txInMap || mapOrphanTransactions.count(inv.hash) ||
- pcoinsTip->HaveCoins(inv.hash);
+ assert(recentRejects);
+ if (chainActive.Tip()->GetBlockHash() != hashRecentRejectsChainTip)
+ {
+ // If the chain tip has changed previously rejected transactions
+ // might be now valid, e.g. due to a nLockTime'd tx becoming valid,
+ // or a double-spend. Reset the rejects filter and give those
+ // txs a second chance.
+ hashRecentRejectsChainTip = chainActive.Tip()->GetBlockHash();
+ recentRejects->reset();
+ }
+
+ return recentRejects->contains(inv.hash) ||
+ mempool.exists(inv.hash) ||
+ mapOrphanTransactions.count(inv.hash) ||
+ pcoinsTip->HaveCoins(inv.hash);
}
case MSG_BLOCK:
return mapBlockIndex.count(inv.hash);
@@ -4273,6 +4312,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
// Probably non-standard or insufficient fee/priority
LogPrint("mempool", " removed orphan tx %s\n", orphanHash.ToString());
vEraseQueue.push_back(orphanHash);
+ assert(recentRejects);
+ recentRejects->insert(orphanHash);
}
mempool.check(pcoinsTip);
}
@@ -4290,11 +4331,24 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
unsigned int nEvicted = LimitOrphanTxSize(nMaxOrphanTx);
if (nEvicted > 0)
LogPrint("mempool", "mapOrphan overflow, removed %u tx\n", nEvicted);
- } else if (pfrom->fWhitelisted) {
- // Always relay transactions received from whitelisted peers, even
- // if they are already in the mempool (allowing the node to function
- // as a gateway for nodes hidden behind it).
- RelayTransaction(tx);
+ } else {
+ // AcceptToMemoryPool() returned false, possibly because the tx is
+ // already in the mempool; if the tx isn't in the mempool that
+ // means it was rejected and we shouldn't ask for it again.
+ if (!mempool.exists(tx.GetHash())) {
+ assert(recentRejects);
+ recentRejects->insert(tx.GetHash());
+ }
+ if (pfrom->fWhitelisted) {
+ // Always relay transactions received from whitelisted peers, even
+ // if they were rejected from the mempool, allowing the node to
+ // function as a gateway for nodes hidden behind it.
+ //
+ // FIXME: This includes invalid transactions, which means a
+ // whitelisted peer could get us banned! We may want to change
+ // that.
+ RelayTransaction(tx);
+ }
}
int nDoS = 0;
if (state.IsInvalid(nDoS))
@@ -4797,7 +4851,7 @@ bool SendMessages(CNode* pto, bool fSendTrickle)
{
// Periodically clear addrKnown to allow refresh broadcasts
if (nLastRebroadcast)
- pnode->addrKnown.clear();
+ pnode->addrKnown.reset();
// Rebroadcast our address
AdvertizeLocal(pnode);