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Merge pull request #5521

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0ea28ba Reject non-final txs even in testnet/regtest (Peter Todd)
This commit is contained in:
Wladimir J. van der Laan 2015-01-07 16:24:40 +01:00
commit 8e4578af0f
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GPG key ID: 74810B012346C9A6
1 changed files with 20 additions and 23 deletions
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43
src/main.cpp
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@ -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))