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-rw-r--r--src/main.cpp8
-rw-r--r--src/main.h2
-rw-r--r--src/wallet.cpp2
3 files changed, 11 insertions, 1 deletions
diff --git a/src/main.cpp b/src/main.cpp
index 2b102e5b9d..df8f7efa22 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -362,6 +362,14 @@ bool CTransaction::IsStandard() const
if (!IsFinal())
return false;
+ // Extremely large transactions with lots of inputs can cost the network
+ // almost as much to process as they cost the sender in fees, because
+ // computing signature hashes is O(ninputs*txsize). Limiting transactions
+ // to MAX_STANDARD_TX_SIZE mitigates CPU exhaustion attacks.
+ unsigned int sz = this->GetSerializeSize(SER_NETWORK, CTransaction::CURRENT_VERSION);
+ if (sz >= MAX_STANDARD_TX_SIZE)
+ return false;
+
BOOST_FOREACH(const CTxIn& txin, vin)
{
// Biggest 'standard' txin is a 3-signature 3-of-3 CHECKMULTISIG
diff --git a/src/main.h b/src/main.h
index 23a4d3ba31..d8e6a1bd33 100644
--- a/src/main.h
+++ b/src/main.h
@@ -28,6 +28,8 @@ struct CBlockIndexWorkComparator;
static const unsigned int MAX_BLOCK_SIZE = 1000000;
/** The maximum size for mined blocks */
static const unsigned int MAX_BLOCK_SIZE_GEN = MAX_BLOCK_SIZE/2;
+/** The maximum size for transactions we're willing to relay/mine **/
+static const unsigned int MAX_STANDARD_TX_SIZE = MAX_BLOCK_SIZE_GEN/5;
/** The maximum allowed number of signature check operations in a block (network rule) */
static const unsigned int MAX_BLOCK_SIGOPS = MAX_BLOCK_SIZE/50;
/** The maximum number of orphan transactions kept in memory */
diff --git a/src/wallet.cpp b/src/wallet.cpp
index b8ef2a20bf..2317ac31ac 100644
--- a/src/wallet.cpp
+++ b/src/wallet.cpp
@@ -1208,7 +1208,7 @@ bool CWallet::CreateTransaction(const vector<pair<CScript, int64> >& vecSend, CW
// Limit size
unsigned int nBytes = ::GetSerializeSize(*(CTransaction*)&wtxNew, SER_NETWORK, PROTOCOL_VERSION);
- if (nBytes >= MAX_BLOCK_SIZE_GEN/5)
+ if (nBytes >= MAX_STANDARD_TX_SIZE)
return false;
dPriority /= nBytes;