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Optimize orphan transaction handling

Changes suggested by Sergio Demian Lerner to
help prevent potential DoS attacks.
tags/v0.15.1
Gavin Andresen 9 years ago
parent
commit
77b99cf7ad
2 changed files with 58 additions and 18 deletions
  1. 30
    16
      src/main.cpp
  2. 28
    2
      src/test/DoS_tests.cpp

+ 30
- 16
src/main.cpp View File

@@ -43,7 +43,7 @@ map<uint256, CBlock*> mapOrphanBlocks;
multimap<uint256, CBlock*> mapOrphanBlocksByPrev;

map<uint256, CDataStream*> mapOrphanTransactions;
multimap<uint256, CDataStream*> mapOrphanTransactionsByPrev;
map<uint256, map<uint256, CDataStream*> > mapOrphanTransactionsByPrev;

// Constant stuff for coinbase transactions we create:
CScript COINBASE_FLAGS;
@@ -160,17 +160,37 @@ void static ResendWalletTransactions()
// mapOrphanTransactions
//

void AddOrphanTx(const CDataStream& vMsg)
bool AddOrphanTx(const CDataStream& vMsg)
{
CTransaction tx;
CDataStream(vMsg) >> tx;
uint256 hash = tx.GetHash();
if (mapOrphanTransactions.count(hash))
return;
return false;

CDataStream* pvMsg = new CDataStream(vMsg);

// Ignore big transactions, to avoid a
// send-big-orphans memory exhaustion attack. If a peer has a legitimate
// large transaction with a missing parent then we assume
// it will rebroadcast it later, after the parent transaction(s)
// have been mined or received.
// 10,000 orphans, each of which is at most 5,000 bytes big is
// at most 500 megabytes of orphans:
if (pvMsg->size() > 5000)
{
delete pvMsg;
printf("ignoring large orphan tx (size: %u, hash: %s)\n", pvMsg->size(), hash.ToString().substr(0,10).c_str());
return false;
}

CDataStream* pvMsg = mapOrphanTransactions[hash] = new CDataStream(vMsg);
mapOrphanTransactions[hash] = pvMsg;
BOOST_FOREACH(const CTxIn& txin, tx.vin)
mapOrphanTransactionsByPrev.insert(make_pair(txin.prevout.hash, pvMsg));
mapOrphanTransactionsByPrev[txin.prevout.hash].insert(make_pair(hash, pvMsg));

printf("stored orphan tx %s (mapsz %u)\n", hash.ToString().substr(0,10).c_str(),
mapOrphanTransactions.size());
return true;
}

void static EraseOrphanTx(uint256 hash)
@@ -182,14 +202,9 @@ void static EraseOrphanTx(uint256 hash)
CDataStream(*pvMsg) >> tx;
BOOST_FOREACH(const CTxIn& txin, tx.vin)
{
for (multimap<uint256, CDataStream*>::iterator mi = mapOrphanTransactionsByPrev.lower_bound(txin.prevout.hash);
mi != mapOrphanTransactionsByPrev.upper_bound(txin.prevout.hash);)
{
if ((*mi).second == pvMsg)
mapOrphanTransactionsByPrev.erase(mi++);
else
mi++;
}
mapOrphanTransactionsByPrev[txin.prevout.hash].erase(hash);
if (mapOrphanTransactionsByPrev[txin.prevout.hash].empty())
mapOrphanTransactionsByPrev.erase(txin.prevout.hash);
}
delete pvMsg;
mapOrphanTransactions.erase(hash);
@@ -2569,8 +2584,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
for (unsigned int i = 0; i < vWorkQueue.size(); i++)
{
uint256 hashPrev = vWorkQueue[i];
for (multimap<uint256, CDataStream*>::iterator mi = mapOrphanTransactionsByPrev.lower_bound(hashPrev);
mi != mapOrphanTransactionsByPrev.upper_bound(hashPrev);
for (map<uint256, CDataStream*>::iterator mi = mapOrphanTransactionsByPrev[hashPrev].begin();
mi != mapOrphanTransactionsByPrev[hashPrev].end();
++mi)
{
const CDataStream& vMsg = *((*mi).second);
@@ -2594,7 +2609,6 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
}
else if (fMissingInputs)
{
printf("storing orphan tx %s\n", inv.hash.ToString().substr(0,10).c_str());
AddOrphanTx(vMsg);

// DoS prevention: do not allow mapOrphanTransactions to grow unbounded

+ 28
- 2
src/test/DoS_tests.cpp View File

@@ -13,10 +13,10 @@
#include <stdint.h>

// Tests this internal-to-main.cpp method:
extern void AddOrphanTx(const CDataStream& vMsg);
extern bool AddOrphanTx(const CDataStream& vMsg);
extern unsigned int LimitOrphanTxSize(unsigned int nMaxOrphans);
extern std::map<uint256, CDataStream*> mapOrphanTransactions;
extern std::multimap<uint256, CDataStream*> mapOrphanTransactionsByPrev;
extern std::map<uint256, std::map<uint256, CDataStream*> > mapOrphanTransactionsByPrev;

CService ip(uint32_t i)
{
@@ -184,6 +184,32 @@ BOOST_AUTO_TEST_CASE(DoS_mapOrphans)
AddOrphanTx(ds);
}

// This really-big orphan should be ignored:
for (int i = 0; i < 10; i++)
{
CTransaction txPrev = RandomOrphan();

CTransaction tx;
tx.vout.resize(1);
tx.vout[0].nValue = 1*CENT;
tx.vout[0].scriptPubKey.SetBitcoinAddress(key.GetPubKey());
tx.vin.resize(500);
for (int j = 0; j < tx.vin.size(); j++)
{
tx.vin[j].prevout.n = j;
tx.vin[j].prevout.hash = txPrev.GetHash();
}
SignSignature(keystore, txPrev, tx, 0);
// Re-use same signature for other inputs
// (they don't have to be valid for this test)
for (int j = 1; j < tx.vin.size(); j++)
tx.vin[j].scriptSig = tx.vin[0].scriptSig;

CDataStream ds(SER_DISK, CLIENT_VERSION);
ds << tx;
BOOST_CHECK(!AddOrphanTx(ds));
}

// Test LimitOrphanTxSize() function:
LimitOrphanTxSize(40);
BOOST_CHECK(mapOrphanTransactions.size() <= 40);

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