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-rw-r--r--src/main.cpp43
1 files changed, 20 insertions, 23 deletions
diff --git a/src/main.cpp b/src/main.cpp
index ca2734b766..e1a0973352 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -625,34 +625,11 @@ unsigned int LimitOrphanTxSize(unsigned int nMaxOrphans)
bool IsStandardTx(const CTransaction& tx, string& reason)
{
- AssertLockHeld(cs_main);
if (tx.nVersion > CTransaction::CURRENT_VERSION || tx.nVersion < 1) {
reason = "version";
return false;
}
- // Treat non-final transactions as non-standard to prevent a specific type
- // of double-spend attack, as well as DoS attacks. (if the transaction
- // can't be mined, the attacker isn't expending resources broadcasting it)
- // Basically we don't want to propagate transactions that can't be included in
- // the next block.
- //
- // However, IsFinalTx() is confusing... Without arguments, it uses
- // chainActive.Height() to evaluate nLockTime; when a block is accepted, chainActive.Height()
- // is set to the value of nHeight in the block. However, when IsFinalTx()
- // is called within CBlock::AcceptBlock(), the height of the block *being*
- // evaluated is what is used. Thus if we want to know if a transaction can
- // be part of the *next* block, we need to call IsFinalTx() with one more
- // than chainActive.Height().
- //
- // Timestamps on the other hand don't get any special treatment, because we
- // can't know what timestamp the next block will have, and there aren't
- // timestamp applications where it matters.
- if (!IsFinalTx(tx, chainActive.Height() + 1)) {
- reason = "non-final";
- 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
@@ -941,6 +918,26 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
error("AcceptToMemoryPool : nonstandard transaction: %s", reason),
REJECT_NONSTANDARD, reason);
+ // Only accept nLockTime-using transactions that can be mined in the next
+ // block; we don't want our mempool filled up with transactions that can't
+ // be mined yet.
+ //
+ // However, IsFinalTx() is confusing... Without arguments, it uses
+ // chainActive.Height() to evaluate nLockTime; when a block is accepted,
+ // chainActive.Height() is set to the value of nHeight in the block.
+ // However, when IsFinalTx() is called within CBlock::AcceptBlock(), the
+ // height of the block *being* evaluated is what is used. Thus if we want
+ // to know if a transaction can be part of the *next* block, we need to
+ // call IsFinalTx() with one more than chainActive.Height().
+ //
+ // Timestamps on the other hand don't get any special treatment, because we
+ // can't know what timestamp the next block will have, and there aren't
+ // timestamp applications where it matters.
+ if (!IsFinalTx(tx, chainActive.Height() + 1))
+ return state.DoS(0,
+ error("AcceptToMemoryPool : non-final"),
+ REJECT_NONSTANDARD, "non-final");
+
// is it already in the memory pool?
uint256 hash = tx.GetHash();
if (pool.exists(hash))