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-rw-r--r--src/main.cpp150
1 files changed, 148 insertions, 2 deletions
diff --git a/src/main.cpp b/src/main.cpp
index a0e996ae78..d9bf3bd757 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -667,9 +667,10 @@ bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime)
return true;
if ((int64_t)tx.nLockTime < ((int64_t)tx.nLockTime < LOCKTIME_THRESHOLD ? (int64_t)nBlockHeight : nBlockTime))
return true;
- BOOST_FOREACH(const CTxIn& txin, tx.vin)
- if (!txin.IsFinal())
+ BOOST_FOREACH(const CTxIn& txin, tx.vin) {
+ if (!(txin.nSequence == CTxIn::SEQUENCE_FINAL))
return false;
+ }
return true;
}
@@ -705,6 +706,128 @@ bool CheckFinalTx(const CTransaction &tx, int flags)
return IsFinalTx(tx, nBlockHeight, nBlockTime);
}
+/**
+ * Calculates the block height and previous block's median time past at
+ * which the transaction will be considered final in the context of BIP 68.
+ * Also removes from the vector of input heights any entries which did not
+ * correspond to sequence locked inputs as they do not affect the calculation.
+ */
+static std::pair<int, int64_t> CalculateSequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block)
+{
+ assert(prevHeights->size() == tx.vin.size());
+
+ // Will be set to the equivalent height- and time-based nLockTime
+ // values that would be necessary to satisfy all relative lock-
+ // time constraints given our view of block chain history.
+ // The semantics of nLockTime are the last invalid height/time, so
+ // use -1 to have the effect of any height or time being valid.
+ int nMinHeight = -1;
+ int64_t nMinTime = -1;
+
+ // tx.nVersion is signed integer so requires cast to unsigned otherwise
+ // we would be doing a signed comparison and half the range of nVersion
+ // wouldn't support BIP 68.
+ bool fEnforceBIP68 = static_cast<uint32_t>(tx.nVersion) >= 2
+ && flags & LOCKTIME_VERIFY_SEQUENCE;
+
+ // Do not enforce sequence numbers as a relative lock time
+ // unless we have been instructed to
+ if (!fEnforceBIP68) {
+ return std::make_pair(nMinHeight, nMinTime);
+ }
+
+ for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) {
+ const CTxIn& txin = tx.vin[txinIndex];
+
+ // Sequence numbers with the most significant bit set are not
+ // treated as relative lock-times, nor are they given any
+ // consensus-enforced meaning at this point.
+ if (txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG) {
+ // The height of this input is not relevant for sequence locks
+ (*prevHeights)[txinIndex] = 0;
+ continue;
+ }
+
+ int nCoinHeight = (*prevHeights)[txinIndex];
+
+ if (txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG) {
+ int64_t nCoinTime = block.GetAncestor(std::max(nCoinHeight-1, 0))->GetMedianTimePast();
+ // NOTE: Subtract 1 to maintain nLockTime semantics
+ // BIP 68 relative lock times have the semantics of calculating
+ // the first block or time at which the transaction would be
+ // valid. When calculating the effective block time or height
+ // for the entire transaction, we switch to using the
+ // semantics of nLockTime which is the last invalid block
+ // time or height. Thus we subtract 1 from the calculated
+ // time or height.
+
+ // Time-based relative lock-times are measured from the
+ // smallest allowed timestamp of the block containing the
+ // txout being spent, which is the median time past of the
+ // block prior.
+ nMinTime = std::max(nMinTime, nCoinTime + (int64_t)((txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_MASK) << CTxIn::SEQUENCE_LOCKTIME_GRANULARITY) - 1);
+ } else {
+ nMinHeight = std::max(nMinHeight, nCoinHeight + (int)(txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_MASK) - 1);
+ }
+ }
+
+ return std::make_pair(nMinHeight, nMinTime);
+}
+
+static bool EvaluateSequenceLocks(const CBlockIndex& block, std::pair<int, int64_t> lockPair)
+{
+ assert(block.pprev);
+ int64_t nBlockTime = block.pprev->GetMedianTimePast();
+ if (lockPair.first >= block.nHeight || lockPair.second >= nBlockTime)
+ return false;
+
+ return true;
+}
+
+bool SequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block)
+{
+ return EvaluateSequenceLocks(block, CalculateSequenceLocks(tx, flags, prevHeights, block));
+}
+
+bool CheckSequenceLocks(const CTransaction &tx, int flags)
+{
+ AssertLockHeld(cs_main);
+ AssertLockHeld(mempool.cs);
+
+ CBlockIndex* tip = chainActive.Tip();
+ CBlockIndex index;
+ index.pprev = tip;
+ // CheckSequenceLocks() uses chainActive.Height()+1 to evaluate
+ // height based locks because when SequenceLocks() 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
+ // SequenceLocks() with one more than chainActive.Height().
+ index.nHeight = tip->nHeight + 1;
+
+ // pcoinsTip contains the UTXO set for chainActive.Tip()
+ CCoinsViewMemPool viewMemPool(pcoinsTip, mempool);
+ std::vector<int> prevheights;
+ prevheights.resize(tx.vin.size());
+ for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) {
+ const CTxIn& txin = tx.vin[txinIndex];
+ CCoins coins;
+ if (!viewMemPool.GetCoins(txin.prevout.hash, coins)) {
+ return error("%s: Missing input", __func__);
+ }
+ if (coins.nHeight == MEMPOOL_HEIGHT) {
+ // Assume all mempool transaction confirm in the next block
+ prevheights[txinIndex] = tip->nHeight + 1;
+ } else {
+ prevheights[txinIndex] = coins.nHeight;
+ }
+ }
+
+ std::pair<int, int64_t> lockPair = CalculateSequenceLocks(tx, flags, &prevheights, index);
+ return EvaluateSequenceLocks(index, lockPair);
+}
+
+
unsigned int GetLegacySigOpCount(const CTransaction& tx)
{
unsigned int nSigOps = 0;
@@ -949,6 +1072,14 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C
// we have all inputs cached now, so switch back to dummy, so we don't need to keep lock on mempool
view.SetBackend(dummy);
+
+ // Only accept BIP68 sequence locked 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.
+ // Must keep pool.cs for this unless we change CheckSequenceLocks to take a
+ // CoinsViewCache instead of create its own
+ if (!CheckSequenceLocks(tx, STANDARD_LOCKTIME_VERIFY_FLAGS))
+ return state.DoS(0, false, REJECT_NONSTANDARD, "non-BIP68-final");
}
// Check for non-standard pay-to-script-hash in inputs
@@ -2075,6 +2206,8 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
CCheckQueueControl<CScriptCheck> control(fScriptChecks && nScriptCheckThreads ? &scriptcheckqueue : NULL);
+ std::vector<int> prevheights;
+ int nLockTimeFlags = 0;
CAmount nFees = 0;
int nInputs = 0;
unsigned int nSigOps = 0;
@@ -2098,6 +2231,19 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
return state.DoS(100, error("ConnectBlock(): inputs missing/spent"),
REJECT_INVALID, "bad-txns-inputs-missingorspent");
+ // Check that transaction is BIP68 final
+ // BIP68 lock checks (as opposed to nLockTime checks) must
+ // be in ConnectBlock because they require the UTXO set
+ prevheights.resize(tx.vin.size());
+ for (size_t j = 0; j < tx.vin.size(); j++) {
+ prevheights[j] = view.AccessCoins(tx.vin[j].prevout.hash)->nHeight;
+ }
+
+ if (!SequenceLocks(tx, nLockTimeFlags, &prevheights, *pindex)) {
+ return state.DoS(100, error("ConnectBlock(): contains a non-BIP68-final transaction", __func__),
+ REJECT_INVALID, "bad-txns-nonfinal");
+ }
+
if (fStrictPayToScriptHash)
{
// Add in sigops done by pay-to-script-hash inputs;