Policy to reject extremely small transactions

A transaction with 1 segwit input and 1 P2WPHK output has non-witness size of 82 bytes. Anything smaller than this have unnecessary malloc overhead and are not relayed/mined.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index 1b9e982753..571e764043 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.