From 7f66701020efbb6898278cf75e1e0712c78316a4 Mon Sep 17 00:00:00 2001
From: f139975 <f139975@mvrht.com>
Date: Mon, 18 Jul 2016 19:43:46 +0200
Subject: [PATCH] Fix counting of sigops cost in mempool check

The new "bytespersigop" limit introduced the side effect of making most multisig transactions non-standard.

This fixes the issue by accurately counting the sigops cost, solely for the newly introduced check.
---
 src/main.cpp | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/src/main.cpp b/src/main.cpp
index 73fbe53afb6..846646a4c5b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1047,6 +1047,34 @@ int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& i
     return nSigOps;
 }
 
+/** Compute accurate total signature operation cost of a transaction. */
+static int64_t GetAccurateTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, int flags)
+{
+    int64_t nSigOps = 0;
+    BOOST_FOREACH(const CTxIn& txin, tx.vin)
+    {
+        nSigOps += txin.scriptSig.GetSigOpCount(true);
+    }
+    BOOST_FOREACH(const CTxOut& txout, tx.vout)
+    {
+        nSigOps += txout.scriptPubKey.GetSigOpCount(true);
+    }
+    nSigOps *= WITNESS_SCALE_FACTOR;
+
+    if (tx.IsCoinBase())
+        return nSigOps;
+
+    if (flags & SCRIPT_VERIFY_P2SH) {
+        nSigOps += GetP2SHSigOpCount(tx, inputs) * WITNESS_SCALE_FACTOR;
+    }
+
+    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 +1324,11 @@ 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) || (nBytesPerSigOp && nSigOpsCost > nSize * WITNESS_SCALE_FACTOR / nBytesPerSigOp))
+        // To avoid making certain bare-multisig transactions non-standard,
+        // the sigops are counted a second time
+        int64_t nAccurateSigOpsCost = GetAccurateTransactionSigOpCost(tx, view, STANDARD_SCRIPT_VERIFY_FLAGS);
+
+        if ((nSigOpsCost > MAX_STANDARD_TX_SIGOPS_COST) || (nBytesPerSigOp && nAccurateSigOpsCost > nSize * WITNESS_SCALE_FACTOR / nBytesPerSigOp))
             return state.DoS(0, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops", false,
                 strprintf("%d", nSigOpsCost));