Restore original bytespersigop as bytespersigopstrict

Plus a bugfix to accurately count sigops for this purpose

src/init.cpp

@@ -447,6 +447,7 @@ std::string HelpMessage(HelpMessageMode mode)
     if (showDebug)
         strUsage += HelpMessageOpt("-acceptnonstdtxn", strprintf("Relay and mine \"non-standard\" transactions (%sdefault: %u)", "testnet/regtest only; ", !Params(CBaseChainParams::TESTNET).RequireStandard()));
     strUsage += HelpMessageOpt("-bytespersigop", strprintf(_("Equivalent bytes per sigop in transactions for relay and mining (default: %u)"), DEFAULT_BYTES_PER_SIGOP));
+    strUsage += HelpMessageOpt("-bytespersigopstrict", strprintf(_("Minimum bytes per sigop in transactions we relay and mine (default: %u)"), DEFAULT_BYTES_PER_SIGOP_STRICT));
     strUsage += HelpMessageOpt("-datacarrier", strprintf(_("Relay and mine data carrier transactions (default: %u)"), DEFAULT_ACCEPT_DATACARRIER));
     strUsage += HelpMessageOpt("-datacarriersize", strprintf(_("Maximum size of data in data carrier transactions we relay and mine (default: %u)"), MAX_OP_RETURN_RELAY));
     strUsage += HelpMessageOpt("-mempoolreplacement", strprintf(_("Enable transaction replacement in the memory pool (default: %u)"), DEFAULT_ENABLE_REPLACEMENT));

src/main.cpp

@@ -1046,6 +1046,34 @@ int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& i
     return nSigOps;
 }
 
+/** Compute accurate total signature operation cost of a transaction.
+ *  Not consensus-critical, since legacy sigops counting is always used in the protocol.
+ */
+int64_t GetAccurateTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, int flags)
+{
+    if (tx.IsCoinBase())
+        return 0;
+
+    unsigned int nSigOps = 0;
+    BOOST_FOREACH(const CTxIn& txin, tx.vin) {
+        nSigOps += txin.scriptSig.GetSigOpCount(false);
+    }
+
+    if (flags & SCRIPT_VERIFY_P2SH) {
+        nSigOps += GetP2SHSigOpCount(tx, inputs);
+    }
+
+    nSigOps *= WITNESS_SCALE_FACTOR;
+
+    if (flags & SCRIPT_VERIFY_WITNESS) {
+        for (unsigned int i = 0; i < tx.vin.size(); i++) {
+            const CTxOut &prevout = inputs.GetOutputFor(tx.vin[i]);
+            nSigOps += CountWitnessSigOps(tx.vin[i].scriptSig, prevout.scriptPubKey, i < tx.wit.vtxinwit.size() ? &tx.wit.vtxinwit[i].scriptWitness : NULL, flags);
+        }
+    }
+
+    return nSigOps;
+}
 
 
 
@@ -1296,7 +1324,10 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
         // itself can contain sigops MAX_STANDARD_TX_SIGOPS is less than
         // MAX_BLOCK_SIGOPS; we still consider this an invalid rather than
         // merely non-standard transaction.
-        if (nSigOpsCost > MAX_STANDARD_TX_SIGOPS_COST)
+        // To avoid rejecting low-sigop bare-multisig transactions, the sigops
+        // are counted a second time more accurately.
+        int64_t nAccurateSigOpsCost = GetAccurateTransactionSigOpCost(tx, view, STANDARD_SCRIPT_VERIFY_FLAGS);
+        if ((nSigOpsCost > MAX_STANDARD_TX_SIGOPS_COST) || (nBytesPerSigOpStrict && nAccurateSigOpsCost > nSize * WITNESS_SCALE_FACTOR / nBytesPerSigOpStrict))
             return state.DoS(0, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops", false,
                 strprintf("%d", nSigOpsCost));
 

src/policy/policy.cpp

@@ -155,6 +155,7 @@ bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
 }
 
 unsigned int nBytesPerSigOp = DEFAULT_BYTES_PER_SIGOP;
+unsigned int nBytesPerSigOpStrict = DEFAULT_BYTES_PER_SIGOP_STRICT;
 
 int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost)
 {

src/policy/policy.h

@@ -30,6 +30,8 @@ static const unsigned int MAX_STANDARD_TX_SIGOPS_COST = MAX_BLOCK_SIGOPS_COST/5;
 static const unsigned int DEFAULT_MAX_MEMPOOL_SIZE = 300;
 /** Default for -bytespersigop */
 static const unsigned int DEFAULT_BYTES_PER_SIGOP = 20;
+/** Default for -bytespersigopstrict */
+static const unsigned int DEFAULT_BYTES_PER_SIGOP_STRICT = 20;
 /**
  * Standard script verification flags that standard transactions will comply
  * with. However scripts violating these flags may still be present in valid
@@ -69,6 +71,7 @@ bool IsStandardTx(const CTransaction& tx, std::string& reason, const bool witnes
 bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
 
 extern unsigned int nBytesPerSigOp;
+extern unsigned int nBytesPerSigOpStrict;
 
 /** Compute the virtual transaction size (weight reinterpreted as bytes). */
 int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost);