Ability to ignore IsStandardTx rejection reasons

Author: luke-jr

src/policy/policy.cpp

@@ -67,6 +67,10 @@ bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFeeIn)
     return (txout.nValue < GetDustThreshold(txout, dustRelayFeeIn));
 }
 
+/**
+ * Note this must assign whichType even if returning false, in case
+ * IsStandardTx ignores the "scriptpubkey" rejection.
+ */
 bool IsStandard(const CScript& scriptPubKey, const std::optional<unsigned>& max_datacarrier_bytes, TxoutType& whichType)
 {
     std::vector<std::vector<unsigned char> > vSolutions;
@@ -91,11 +95,27 @@ bool IsStandard(const CScript& scriptPubKey, const std::optional<unsigned>& max_
     return true;
 }
 
-bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_datacarrier_bytes, bool permit_bare_multisig, const CFeeRate& dust_relay_fee, std::string& reason)
+static inline bool MaybeReject_(std::string& out_reason, const std::string& reason, const std::string& reason_prefix, const ignore_rejects_type& ignore_rejects) {
+    if (ignore_rejects.count(reason_prefix + reason)) {
+        return false;
+    }
+
+    out_reason = reason_prefix + reason;
+    return true;
+}
+
+#define MaybeReject(reason)  do {  \
+    if (MaybeReject_(out_reason, reason, reason_prefix, ignore_rejects)) {  \
+        return false;  \
+    }  \
+} while(0)
+
+bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_datacarrier_bytes, bool permit_bare_multisig, const CFeeRate& dust_relay_fee, std::string& out_reason, const ignore_rejects_type& ignore_rejects)
 {
+    const std::string reason_prefix;
+
     if (tx.version > TX_MAX_STANDARD_VERSION || tx.version < 1) {
-        reason = "version";
-        return false;
+        MaybeReject("version");
     }
 
     // Extremely large transactions with lots of inputs can cost the network
@@ -104,8 +124,7 @@ bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_dat
     // to MAX_STANDARD_TX_WEIGHT mitigates CPU exhaustion attacks.
     unsigned int sz = GetTransactionWeight(tx);
     if (sz > MAX_STANDARD_TX_WEIGHT) {
-        reason = "tx-size";
-        return false;
+        MaybeReject("tx-size");
     }
 
     for (const CTxIn& txin : tx.vin)
@@ -119,41 +138,39 @@ bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_dat
         // 20-of-20 CHECKMULTISIG scriptPubKey, though such a scriptPubKey
         // is not considered standard.
         if (txin.scriptSig.size() > MAX_STANDARD_SCRIPTSIG_SIZE) {
-            reason = "scriptsig-size";
-            return false;
+            MaybeReject("scriptsig-size");
         }
         if (!txin.scriptSig.IsPushOnly()) {
-            reason = "scriptsig-not-pushonly";
-            return false;
+            MaybeReject("scriptsig-not-pushonly");
         }
     }
 
     unsigned int nDataOut = 0;
     TxoutType whichType;
     for (const CTxOut& txout : tx.vout) {
         if (!::IsStandard(txout.scriptPubKey, max_datacarrier_bytes, whichType)) {
-            reason = "scriptpubkey";
             if (whichType == TxoutType::WITNESS_UNKNOWN) {
-                reason += "-unknown-witnessversion";
+                MaybeReject("scriptpubkey-unknown-witnessversion");
+            } else {
+                MaybeReject("scriptpubkey");
             }
-            return false;
         }
 
-        if (whichType == TxoutType::NULL_DATA)
+        if (whichType == TxoutType::NULL_DATA) {
             nDataOut++;
+            continue;
+        }
         else if ((whichType == TxoutType::MULTISIG) && (!permit_bare_multisig)) {
-            reason = "bare-multisig";
-            return false;
-        } else if (IsDust(txout, dust_relay_fee)) {
-            reason = "dust";
-            return false;
+            MaybeReject("bare-multisig");
+        }
+        if (IsDust(txout, dust_relay_fee)) {
+            MaybeReject("dust");
         }
     }
 
     // only one OP_RETURN txout is permitted
     if (nDataOut > 1) {
-        reason = "multi-op-return";
-        return false;
+        MaybeReject("multi-op-return");
     }
 
     return true;

src/policy/policy.h

@@ -141,7 +141,7 @@ static constexpr decltype(CTransaction::version) TX_MAX_STANDARD_VERSION{3};
 * Check for standard transaction types
 * @return True if all outputs (scriptPubKeys) use only standard transaction forms
 */
-bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_datacarrier_bytes, bool permit_bare_multisig, const CFeeRate& dust_relay_fee, std::string& reason);
+bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_datacarrier_bytes, bool permit_bare_multisig, const CFeeRate& dust_relay_fee, std::string& out_reason, const ignore_rejects_type& ignore_rejects=empty_ignore_rejects);
 /**
 * Check for standard transaction types
 * @param[in] mapInputs       Map of previous transactions that have outputs we're spending

src/validation.cpp

@@ -810,7 +810,7 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
 
     // Rather not work on nonstandard transactions (unless -testnet/-regtest)
     std::string reason;
-    if (m_pool.m_opts.require_standard && !IsStandardTx(tx, m_pool.m_opts.max_datacarrier_bytes, m_pool.m_opts.permit_bare_multisig, m_pool.m_opts.dust_relay_feerate, reason)) {
+    if (m_pool.m_opts.require_standard && !IsStandardTx(tx, m_pool.m_opts.max_datacarrier_bytes, m_pool.m_opts.permit_bare_multisig, m_pool.m_opts.dust_relay_feerate, reason, ignore_rejects)) {
         return state.Invalid(TxValidationResult::TX_NOT_STANDARD, reason);
     }