backports: Use virtual transaction size in minimum fee calculation

CoinBlack@16ff90a

src/main.cpp

@@ -3810,7 +3810,7 @@ bool SignBlock(CBlock& block, CWallet& wallet, int64_t& nFees)
 // Blackcoin: GetMinFee
 CAmount GetMinFee(const CTransaction& tx, unsigned int nTimeTx)
 {
-    size_t nBytes = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
+    size_t nBytes = GetVirtualTransactionSize(tx);
     return GetMinFee(nBytes, nTimeTx);
 }
 
@@ -3834,6 +3834,18 @@ CAmount GetMinFee(size_t nBytes, uint32_t nTime)
     return nMinFee;
 }
 
+unsigned int nBytesPerSigOp = DEFAULT_BYTES_PER_SIGOP;
+
+int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost)
+{
+    return (std::max(nWeight, nSigOpCost * nBytesPerSigOp) + WITNESS_SCALE_FACTOR - 1) / WITNESS_SCALE_FACTOR;
+}
+
+int64_t GetVirtualTransactionSize(const CTransaction& tx, int64_t nSigOpCost)
+{
+    return GetVirtualTransactionSize(GetTransactionWeight(tx), nSigOpCost);
+}
+
 static bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex=NULL, bool fProofOfStake=true)
 {
     AssertLockHeld(cs_main);

src/main.h

@@ -490,6 +490,12 @@ bool SignBlock(CBlock& block, CWallet& wallet, int64_t& nFees);
 CAmount GetMinFee(const CTransaction& tx, unsigned int nTimeTx);
 CAmount GetMinFee(size_t nBytes, uint32_t nTime);
 
+/** Compute the virtual transaction size (weight reinterpreted as bytes). */
+int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost);
+int64_t GetVirtualTransactionSize(const CTransaction& tx, int64_t nSigOpCost = 0);
+
+extern unsigned int nBytesPerSigOp;
+
 /** Check a block is completely valid from start to finish (only works on top of our current best block, with cs_main held) */
 bool TestBlockValidity(CValidationState& state, const CChainParams& chainparams, const CBlock& block, CBlockIndex* pindexPrev, bool fCheckPOW = true, bool fCheckMerkleRoot = true, bool fCheckSig = true);
 

src/policy/policy.cpp

@@ -168,5 +168,3 @@ bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
 
     return true;
 }
-
-unsigned int nBytesPerSigOp = DEFAULT_BYTES_PER_SIGOP;

src/policy/policy.h

@@ -66,6 +66,4 @@ bool IsStandardTx(const CTransaction& tx, std::string& reason);
      */
 bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
 
-extern unsigned int nBytesPerSigOp;
-
 #endif // BITCOIN_POLICY_POLICY_H

src/primitives/transaction.cpp

@@ -155,3 +155,8 @@ std::string CTransaction::ToString() const
         str += "    " + vout[i].ToString() + "\n";
     return str;
 }
+
+int64_t GetTransactionWeight(const CTransaction& tx)
+{
+    return ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * (WITNESS_SCALE_FACTOR -1) + ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
+}

src/primitives/transaction.h

@@ -11,6 +11,10 @@
 #include "serialize.h"
 #include "uint256.h"
 
+static const int SERIALIZE_TRANSACTION_NO_WITNESS = 0x40000000;
+
+static const int WITNESS_SCALE_FACTOR = 4;
+
 /** An outpoint - a combination of a transaction hash and an index n into its vout */
 class COutPoint
 {
@@ -357,4 +361,7 @@ struct CMutableTransaction
     uint256 GetNormalizedHash() const;
 };
 
+/** Compute the weight of a transaction, as defined by BIP 141 */
+int64_t GetTransactionWeight(const CTransaction &tx);
+
 #endif // BITCOIN_PRIMITIVES_TRANSACTION_H