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| author | MarcoFalke <falke.marco@gmail.com> | 2021-06-30 09:43:16 +0200 |
|---|---|---|
| committer | MarcoFalke <falke.marco@gmail.com> | 2021-06-30 09:43:21 +0200 |
| commit | e1a13f12e1ddd93d34a10f5f1a642794063c74f3 (patch) | |
| tree | c2793f6ce00baee1ee64431a51f290ca668dd27e | |
| parent | bfd910cae4e5f8ae9a6ec9dea02a9c28d023b8cb (diff) | |
| parent | f9e37f33ce2d8b463a0bcbe7189c9bc5b36530b7 (diff) | |
| download | bitcoin-e1a13f12e1ddd93d34a10f5f1a642794063c74f3.tar.xz | |
Merge bitcoin/bitcoin#18096: doc: IsFinalTx comment about nSequence & OP_CLTV
f9e37f33ce2d8b463a0bcbe7189c9bc5b36530b7 doc: IsFinalTx comment about nSequence & OP_CLTV (Yuval Kogman)
Pull request description:
It's somewhat surprising that a transaction's `nLockTime` field is ignored
when all `nSequence` fields are final, so this change aims to clarify this
behavior and cross reference relevant details of `OP_CHECKLOCKTIMEVERIFY`.
ACKs for top commit:
MarcoFalke:
ACK f9e37f33ce2d8b463a0bcbe7189c9bc5b36530b7
Tree-SHA512: 88460dacbe4b8115fb1948715f09b21d4f34ba1da9e88d52f0b774a969f845e9eddc5940e7fee66eacdd3062dc40d6d44c3f282b0e5144411fd47eb2320b44f5
| -rw-r--r-- | src/consensus/tx_verify.cpp | 9 | ||||
| -rw-r--r-- | src/script/interpreter.cpp | 6 |
2 files changed, 12 insertions, 3 deletions
diff --git a/src/consensus/tx_verify.cpp b/src/consensus/tx_verify.cpp index f595f16eab..88d8da6ed5 100644 --- a/src/consensus/tx_verify.cpp +++ b/src/consensus/tx_verify.cpp @@ -20,6 +20,15 @@ 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; + + // Even if tx.nLockTime isn't satisfied by nBlockHeight/nBlockTime, a + // transaction is still considered final if all inputs' nSequence == + // SEQUENCE_FINAL (0xffffffff), in which case nLockTime is ignored. + // + // Because of this behavior OP_CHECKLOCKTIMEVERIFY/CheckLockTime() will + // also check that the spending input's nSequence != SEQUENCE_FINAL, + // ensuring that an unsatisfied nLockTime value will actually cause + // IsFinalTx() to return false here: for (const auto& txin : tx.vin) { if (!(txin.nSequence == CTxIn::SEQUENCE_FINAL)) return false; diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp index 8cebbc5d10..ef48f89965 100644 --- a/src/script/interpreter.cpp +++ b/src/script/interpreter.cpp @@ -1740,9 +1740,9 @@ bool GenericTransactionSignatureChecker<T>::CheckLockTime(const CScriptNum& nLoc if (nLockTime > (int64_t)txTo->nLockTime) return false; - // Finally the nLockTime feature can be disabled and thus - // CHECKLOCKTIMEVERIFY bypassed if every txin has been - // finalized by setting nSequence to maxint. The + // Finally the nLockTime feature can be disabled in IsFinalTx() + // and thus CHECKLOCKTIMEVERIFY bypassed if every txin has + // been finalized by setting nSequence to maxint. The // transaction would be allowed into the blockchain, making // the opcode ineffective. // |