Fix off-by-one errors in use of IsFinalTx()

Previously CreateNewBlock() didn't take into account the fact that
IsFinalTx() without any arguments tests if the transaction is considered
final in the *current* block, when both those functions really needed to
know if the transaction would be final in the *next* block.

Additionally the UI had a similar misunderstanding.

Also adds some basic tests to check that CreateNewBlock() is in fact
mining nLockTime-using transactions correctly.

Thanks to Wladimir J. van der Laan for rebase.
This commit is contained in:
Peter Todd 2014-01-26 21:50:15 -05:00
parent d0a94f2c2f
commit 665bdd3bc9
No known key found for this signature in database
GPG Key ID: 2481403DA5F091FB
5 changed files with 73 additions and 7 deletions

View File

@ -365,7 +365,24 @@ bool IsStandardTx(const CTransaction& tx, string& reason)
return false;
}
if (!IsFinalTx(tx)) {
// 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 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;
}

View File

@ -158,7 +158,7 @@ CBlockTemplate* CreateNewBlock(const CScript& scriptPubKeyIn)
mi != mempool.mapTx.end(); ++mi)
{
const CTransaction& tx = mi->second.GetTx();
if (tx.IsCoinBase() || !IsFinalTx(tx))
if (tx.IsCoinBase() || !IsFinalTx(tx, pindexPrev->nHeight + 1))
continue;
COrphan* porphan = NULL;

View File

@ -20,10 +20,10 @@
QString TransactionDesc::FormatTxStatus(const CWalletTx& wtx)
{
if (!IsFinalTx(wtx))
if (!IsFinalTx(wtx, chainActive.Height() + 1))
{
if (wtx.nLockTime < LOCKTIME_THRESHOLD)
return tr("Open for %n more block(s)", "", wtx.nLockTime - chainActive.Height() + 1);
return tr("Open for %n more block(s)", "", wtx.nLockTime - chainActive.Height());
else
return tr("Open until %1").arg(GUIUtil::dateTimeStr(wtx.nLockTime));
}

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@ -168,12 +168,12 @@ void TransactionRecord::updateStatus(const CWalletTx &wtx)
status.depth = wtx.GetDepthInMainChain();
status.cur_num_blocks = chainActive.Height();
if (!IsFinalTx(wtx))
if (!IsFinalTx(wtx, chainActive.Height() + 1))
{
if (wtx.nLockTime < LOCKTIME_THRESHOLD)
{
status.status = TransactionStatus::OpenUntilBlock;
status.open_for = wtx.nLockTime - chainActive.Height() + 1;
status.open_for = wtx.nLockTime - chainActive.Height();
}
else
{

View File

@ -51,7 +51,7 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
{
CScript scriptPubKey = CScript() << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f") << OP_CHECKSIG;
CBlockTemplate *pblocktemplate;
CTransaction tx;
CTransaction tx,tx2;
CScript script;
uint256 hash;
@ -204,8 +204,57 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
delete pblocktemplate;
chainActive.Tip()->nHeight = nHeight;
// non-final txs in mempool
SetMockTime(chainActive.Tip()->GetMedianTimePast()+1);
// height locked
tx.vin[0].prevout.hash = txFirst[0]->GetHash();
tx.vin[0].scriptSig = CScript() << OP_1;
tx.vin[0].nSequence = 0;
tx.vout[0].nValue = 4900000000LL;
tx.vout[0].scriptPubKey = CScript() << OP_1;
tx.nLockTime = chainActive.Tip()->nHeight+1;
hash = tx.GetHash();
mempool.addUnchecked(hash, CTxMemPoolEntry(tx, 11, GetTime(), 111.0, 11));
BOOST_CHECK(!IsFinalTx(tx, chainActive.Tip()->nHeight + 1));
// time locked
tx2.vin.resize(1);
tx2.vin[0].prevout.hash = txFirst[1]->GetHash();
tx2.vin[0].prevout.n = 0;
tx2.vin[0].scriptSig = CScript() << OP_1;
tx2.vin[0].nSequence = 0;
tx2.vout.resize(1);
tx2.vout[0].nValue = 4900000000LL;
tx2.vout[0].scriptPubKey = CScript() << OP_1;
tx2.nLockTime = chainActive.Tip()->GetMedianTimePast()+1;
hash = tx2.GetHash();
mempool.addUnchecked(hash, CTxMemPoolEntry(tx2, 11, GetTime(), 111.0, 11));
BOOST_CHECK(!IsFinalTx(tx2));
BOOST_CHECK(pblocktemplate = CreateNewBlock(scriptPubKey));
// Neither tx should have make it into the template.
BOOST_CHECK_EQUAL(pblocktemplate->block.vtx.size(), 1);
delete pblocktemplate;
// However if we advance height and time by one, both will.
chainActive.Tip()->nHeight++;
SetMockTime(chainActive.Tip()->GetMedianTimePast()+2);
BOOST_CHECK(IsFinalTx(tx, chainActive.Tip()->nHeight + 1));
BOOST_CHECK(IsFinalTx(tx2));
BOOST_CHECK(pblocktemplate = CreateNewBlock(scriptPubKey));
BOOST_CHECK_EQUAL(pblocktemplate->block.vtx.size(), 3);
delete pblocktemplate;
chainActive.Tip()->nHeight--;
SetMockTime(0);
BOOST_FOREACH(CTransaction *tx, txFirst)
delete tx;
}
BOOST_AUTO_TEST_CASE(sha256transform_equality)