Merge #11423: [Policy] Several transaction standardness rules

364bae5 qa: Pad scriptPubKeys to get minimum sized txs (MarcoFalke)
7485488 Policy to reject extremely small transactions (Johnson Lau)
0f8719b Add transaction tests for constant scriptCode (Johnson Lau)
9dabfe4 Add constant scriptCode policy in non-segwit scripts (Johnson Lau)

Pull request description:

  This disables `OP_CODESEPARATOR` in non-segwit scripts (even in an unexecuted branch), and makes a positive `FindAndDelete` result invalid. This ensures that the `scriptCode` serialized in `SignatureHash` is always the same as the script passing to the `EvalScript`.

Tree-SHA512: a0552cb920294d130251c48053fa2ff1fbdd26332e62b52147d918837852750f0ce35ce2cd1cbdb86588943312f8154ccb4925e850dbb7c2254bc353070cd5f8

1 files changed, 6 insertions, 0 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index 8a941561bb..cd5f9d8ec0 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -582,6 +582,12 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
     if (fRequireStandard && !IsStandardTx(tx, reason, witnessEnabled))
         return state.DoS(0, false, REJECT_NONSTANDARD, reason);
 
+    // Do not work on transactions that are too small.
+    // A transaction with 1 segwit input and 1 P2WPHK output has non-witness size of 82 bytes.
+    // Transactions smaller than this are not relayed to reduce unnecessary malloc overhead.
+    if (::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) < MIN_STANDARD_TX_NONWITNESS_SIZE)
+        return state.DoS(0, false, REJECT_NONSTANDARD, "tx-size-small");
+
     // 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.