Implementing base+wit/4 block size limit rule

Author: sipa

src/main.cpp

@@ -745,6 +745,7 @@ unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& in
 
 
 
+
 bool CheckTransaction(const CTransaction& tx, CValidationState &state)
 {
     // Basic checks that don't depend on any context
@@ -753,7 +754,7 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state)
     if (tx.vout.empty())
         return state.DoS(10, false, REJECT_INVALID, "bad-txns-vout-empty");
     // Size limits
-    if (::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION) > MAX_BLOCK_SIZE)
+    if (GetVirtualTransactionSize(tx) > MAX_BLOCK_SIZE)
         return state.DoS(100, false, REJECT_INVALID, "bad-txns-oversize");
 
     // Check for negative or overflow output values
@@ -2977,7 +2978,7 @@ bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bo
     // because we receive the wrong transactions for it.
 
     // Size limits
-    if (block.vtx.empty() || block.vtx.size() > MAX_BLOCK_SIZE || ::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION) > MAX_BLOCK_SIZE)
+    if (block.vtx.empty() || block.vtx.size() > MAX_BLOCK_SIZE || GetVirtualBlockSize(block) > MAX_BLOCK_SIZE)
         return state.DoS(100, error("CheckBlock(): size limits failed"),
                          REJECT_INVALID, "bad-blk-length");
 

src/primitives/block.cpp

@@ -31,3 +31,12 @@ std::string CBlock::ToString() const
     }
     return s.str();
 }
+
+size_t GetVirtualBlockSize(const CBlock& block)
+{
+    // The formula is: vsize = base_size + witness_size / 4.
+    // We can only serialize base or totalbase+witness, however, so the formula
+    // becomes: vsize = base_size + (total_size - base_size) / 4 or
+    // vsize = (total_size + 3 * base_size) / 4.
+    return (::GetSerializeSize(block, SER_NETWORK, 0) * 3 + ::GetSerializeSize(block, SER_NETWORK, SERIALIZE_TRANSACTION_WITNESS) + 3) / 4;
+}

src/primitives/block.h

@@ -155,4 +155,7 @@ struct CBlockLocator
     }
 };
 
+/** Compute the consensus-critical virtual block size. */
+size_t GetVirtualBlockSize(const CBlock& tx);
+
 #endif // BITCOIN_PRIMITIVES_BLOCK_H

src/primitives/transaction.cpp

@@ -148,3 +148,8 @@ std::string CTransaction::ToString() const
         str += "    " + vout[i].ToString() + "\n";
     return str;
 }
+
+size_t GetVirtualTransactionSize(const CTransaction& tx)
+{
+    return (::GetSerializeSize(tx, SER_NETWORK, 0) * 3 + ::GetSerializeSize(tx, SER_NETWORK, SERIALIZE_TRANSACTION_WITNESS) + 3) / 4;
+}

src/primitives/transaction.h

@@ -408,4 +408,7 @@ struct CMutableTransaction
     uint256 GetHash() const;
 };
 
+/** Compute the consensus-critical virtual transaction size. */
+size_t GetVirtualTransactionSize(const CTransaction& tx);
+
 #endif // BITCOIN_PRIMITIVES_TRANSACTION_H

src/test/mempool_tests.cpp

@@ -363,12 +363,12 @@ BOOST_AUTO_TEST_CASE(MempoolSizeLimitTest)
     BOOST_CHECK(pool.exists(tx2.GetHash()));
     BOOST_CHECK(pool.exists(tx3.GetHash()));
 
-    pool.TrimToSize(::GetSerializeSize(CTransaction(tx1), SER_NETWORK, PROTOCOL_VERSION)); // mempool is limited to tx1's size in memory usage, so nothing fits
+    pool.TrimToSize(GetVirtualTransactionSize(tx1)); // mempool is limited to tx1's size in memory usage, so nothing fits
     BOOST_CHECK(!pool.exists(tx1.GetHash()));
     BOOST_CHECK(!pool.exists(tx2.GetHash()));
     BOOST_CHECK(!pool.exists(tx3.GetHash()));
 
-    CFeeRate maxFeeRateRemoved(25000, ::GetSerializeSize(CTransaction(tx3), SER_NETWORK, PROTOCOL_VERSION) + ::GetSerializeSize(CTransaction(tx2), SER_NETWORK, PROTOCOL_VERSION));
+    CFeeRate maxFeeRateRemoved(25000, GetVirtualTransactionSize(tx3) + GetVirtualTransactionSize(tx2));
     BOOST_CHECK_EQUAL(pool.GetMinFee(1).GetFeePerK(), maxFeeRateRemoved.GetFeePerK() + 1000);
 
     CMutableTransaction tx4 = CMutableTransaction();

src/test/policyestimator_tests.cpp

@@ -50,7 +50,7 @@ BOOST_AUTO_TEST_CASE(BlockPolicyEstimates)
     tx.vin[0].scriptSig = garbage;
     tx.vout.resize(1);
     tx.vout[0].nValue=0LL;
-    CFeeRate baseRate(basefee, ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION));
+    CFeeRate baseRate(basefee, GetVirtualTransactionSize(tx));
 
     // Create a fake block
     std::vector<CTransaction> block;

src/txmempool.cpp

@@ -27,7 +27,7 @@ CTxMemPoolEntry::CTxMemPoolEntry(const CTransaction& _tx, const CAmount& _nFee,
     hadNoDependencies(poolHasNoInputsOf), inChainInputValue(_inChainInputValue),
     spendsCoinbase(_spendsCoinbase), sigOpCount(_sigOps)
 {
-    nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
+    nTxSize = GetVirtualTransactionSize(tx);
     nModSize = tx.CalculateModifiedSize(nTxSize);
     nUsageSize = RecursiveDynamicUsage(tx);
 

src/wallet/wallet.cpp

@@ -2173,7 +2173,7 @@ bool CWallet::CreateTransaction(const vector<CRecipient>& vecSend, CWalletTx& wt
                     nIn++;
                 }
 
-                unsigned int nBytes = ::GetSerializeSize(txNew, SER_NETWORK, PROTOCOL_VERSION);
+                unsigned int nBytes = GetVirtualTransactionSize(txNew);
 
                 // Remove scriptSigs if we used dummy signatures for fee calculation
                 if (!sign) {