Add txids with non-standard inputs to reject filter

Our policy checks for non-standard inputs depend only on the non-witness
portion of a transaction: we look up the scriptPubKey of the input being
spent from our UTXO set (which is covered by the input txid), and the p2sh
checks only rely on the scriptSig portion of the input.

Consequently it's safe to add txids of transactions that fail these checks to
the reject filter, as the witness is irrelevant to the failure. This is helpful
for any situation where we might request the transaction again via txid (either
from txid-relay peers, or if we might fetch the transaction via txid due to
parent-fetching of orphans).

Further, in preparation for future witness versions being deployed on the
network, ensure that WITNESS_UNKNOWN transactions are rejected in
AreInputsStandard(), so that transactions spending v1 (or greater) witness
outputs will fall into this category of having their txid added to the reject
filter.

Github-Pull: #19620
Rebased-From: 7989901c7eb62ca28b3d1e5d5831041a7267e495

1 files changed, 13 insertions, 2 deletions

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 3d0efa041d..4a183f0c9a 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1055,6 +1055,7 @@ static bool MaybePunishNode(NodeId nodeid, const CValidationState& state, bool v
         return true;
     case ValidationInvalidReason::RECENT_CONSENSUS_CHANGE:
     case ValidationInvalidReason::BLOCK_TIME_FUTURE:
+    case ValidationInvalidReason::TX_INPUTS_NOT_STANDARD:
     case ValidationInvalidReason::TX_NOT_STANDARD:
     case ValidationInvalidReason::TX_MISSING_INPUTS:
     case ValidationInvalidReason::TX_PREMATURE_SPEND:
@@ -1846,10 +1847,15 @@ void static ProcessOrphanTx(CConnman* connman, std::set<uint256>& orphan_work_se
             // Probably non-standard or insufficient fee
             LogPrint(BCLog::MEMPOOL, "   removed orphan tx %s\n", orphanHash.ToString());
             assert(IsTransactionReason(orphan_state.GetReason()));
-            if (!orphanTx.HasWitness() && orphan_state.GetReason() != ValidationInvalidReason::TX_WITNESS_MUTATED) {
+            if ((!orphanTx.HasWitness() && orphan_state.GetReason() != ValidationInvalidReason::TX_WITNESS_MUTATED) ||
+                orphan_state.GetReason() == ValidationInvalidReason::TX_INPUTS_NOT_STANDARD) {
                 // Do not use rejection cache for witness transactions or
                 // witness-stripped transactions, as they can have been malleated.
                 // See https://github.com/bitcoin/bitcoin/issues/8279 for details.
+                // However, if the transaction failed for TX_INPUTS_NOT_STANDARD,
+                // then we know that the witness was irrelevant to the policy
+                // failure, since this check depends only on the txid
+                // (the scriptPubKey being spent is covered by the txid).
                 assert(recentRejects);
                 recentRejects->insert(orphanHash);
             }
@@ -2574,10 +2580,15 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
             }
         } else {
             assert(IsTransactionReason(state.GetReason()));
-            if (!tx.HasWitness() && state.GetReason() != ValidationInvalidReason::TX_WITNESS_MUTATED) {
+            if ((!tx.HasWitness() && state.GetReason() != ValidationInvalidReason::TX_WITNESS_MUTATED) ||
+                    state.GetReason() == ValidationInvalidReason::TX_INPUTS_NOT_STANDARD) {
                 // Do not use rejection cache for witness transactions or
                 // witness-stripped transactions, as they can have been malleated.
                 // See https://github.com/bitcoin/bitcoin/issues/8279 for details.
+                // However, if the transaction failed for TX_INPUTS_NOT_STANDARD,
+                // then we know that the witness was irrelevant to the policy
+                // failure, since this check depends only on the txid
+                // (the scriptPubKey being spent is covered by the txid).
                 assert(recentRejects);
                 recentRejects->insert(tx.GetHash());
                 if (RecursiveDynamicUsage(*ptx) < 100000) {