Make CTransaction actually immutable

10 files changed, 131 insertions, 140 deletions

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 747167264b..b1283c236c 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1594,8 +1594,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
 
         deque<COutPoint> vWorkQueue;
         vector<uint256> vEraseQueue;
-        CTransaction tx;
-        vRecv >> tx;
+        CTransaction tx(deserialize, vRecv);
 
         CInv inv(MSG_TX, tx.GetHash());
         pfrom->AddInventoryKnown(inv);
diff --git a/src/primitives/transaction.cpp b/src/primitives/transaction.cpp
index 91f4d29488..11d7eace55 100644
--- a/src/primitives/transaction.cpp
+++ b/src/primitives/transaction.cpp
@@ -62,9 +62,9 @@ uint256 CMutableTransaction::GetHash() const
     return SerializeHash(*this, SER_GETHASH, SERIALIZE_TRANSACTION_NO_WITNESS);
 }
 
-void CTransaction::UpdateHash() const
+uint256 CTransaction::ComputeHash() const
 {
-    *const_cast<uint256*>(&hash) = SerializeHash(*this, SER_GETHASH, SERIALIZE_TRANSACTION_NO_WITNESS);
+    return SerializeHash(*this, SER_GETHASH, SERIALIZE_TRANSACTION_NO_WITNESS);
 }
 
 uint256 CTransaction::GetWitnessHash() const
@@ -72,25 +72,10 @@ uint256 CTransaction::GetWitnessHash() const
     return SerializeHash(*this, SER_GETHASH, 0);
 }
 
-CTransaction::CTransaction() : nVersion(CTransaction::CURRENT_VERSION), vin(), vout(), nLockTime(0) { }
-
-CTransaction::CTransaction(const CMutableTransaction &tx) : nVersion(tx.nVersion), vin(tx.vin), vout(tx.vout), wit(tx.wit), nLockTime(tx.nLockTime) {
-    UpdateHash();
-}
-
-CTransaction::CTransaction(CMutableTransaction &&tx) : nVersion(tx.nVersion), vin(std::move(tx.vin)), vout(std::move(tx.vout)), wit(std::move(tx.wit)), nLockTime(tx.nLockTime) {
-    UpdateHash();
-}
-
-CTransaction& CTransaction::operator=(const CTransaction &tx) {
-    *const_cast<int*>(&nVersion) = tx.nVersion;
-    *const_cast<std::vector<CTxIn>*>(&vin) = tx.vin;
-    *const_cast<std::vector<CTxOut>*>(&vout) = tx.vout;
-    *const_cast<CTxWitness*>(&wit) = tx.wit;
-    *const_cast<unsigned int*>(&nLockTime) = tx.nLockTime;
-    *const_cast<uint256*>(&hash) = tx.hash;
-    return *this;
-}
+/* For backward compatibility, the hash is initialized to 0. TODO: remove the need for this default constructor entirely. */
+CTransaction::CTransaction() : nVersion(CTransaction::CURRENT_VERSION), vin(), vout(), nLockTime(0), hash() {}
+CTransaction::CTransaction(const CMutableTransaction &tx) : nVersion(tx.nVersion), vin(tx.vin), vout(tx.vout), wit(tx.wit), nLockTime(tx.nLockTime), hash(ComputeHash()) {}
+CTransaction::CTransaction(CMutableTransaction &&tx) : nVersion(tx.nVersion), vin(std::move(tx.vin)), vout(std::move(tx.vout)), wit(std::move(tx.wit)), nLockTime(tx.nLockTime), hash(ComputeHash()) {}
 
 CAmount CTransaction::GetValueOut() const
 {
diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index 0fa85a1519..66fefafef5 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -286,73 +286,81 @@ struct CMutableTransaction;
  *   - CTxWitness wit;
  * - uint32_t nLockTime
  */
-template<typename Stream, typename Operation, typename TxType>
-inline void SerializeTransaction(TxType& tx, Stream& s, Operation ser_action) {
+template<typename Stream, typename TxType>
+inline void UnserializeTransaction(TxType& tx, Stream& s) {
     const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS);
 
-    READWRITE(*const_cast<int32_t*>(&tx.nVersion));
+    s >> tx.nVersion;
     unsigned char flags = 0;
-    if (ser_action.ForRead()) {
-        const_cast<std::vector<CTxIn>*>(&tx.vin)->clear();
-        const_cast<std::vector<CTxOut>*>(&tx.vout)->clear();
-        const_cast<CTxWitness*>(&tx.wit)->SetNull();
-        /* Try to read the vin. In case the dummy is there, this will be read as an empty vector. */
-        READWRITE(*const_cast<std::vector<CTxIn>*>(&tx.vin));
-        if (tx.vin.size() == 0 && fAllowWitness) {
-            /* We read a dummy or an empty vin. */
-            READWRITE(flags);
-            if (flags != 0) {
-                READWRITE(*const_cast<std::vector<CTxIn>*>(&tx.vin));
-                READWRITE(*const_cast<std::vector<CTxOut>*>(&tx.vout));
-            }
-        } else {
-            /* We read a non-empty vin. Assume a normal vout follows. */
-            READWRITE(*const_cast<std::vector<CTxOut>*>(&tx.vout));
-        }
-        if ((flags & 1) && fAllowWitness) {
-            /* The witness flag is present, and we support witnesses. */
-            flags ^= 1;
-            const_cast<CTxWitness*>(&tx.wit)->vtxinwit.resize(tx.vin.size());
-            READWRITE(tx.wit);
-        }
-        if (flags) {
-            /* Unknown flag in the serialization */
-            throw std::ios_base::failure("Unknown transaction optional data");
+    tx.vin.clear();
+    tx.vout.clear();
+    tx.wit.SetNull();
+    /* Try to read the vin. In case the dummy is there, this will be read as an empty vector. */
+    s >> tx.vin;
+    if (tx.vin.size() == 0 && fAllowWitness) {
+        /* We read a dummy or an empty vin. */
+        s >> flags;
+        if (flags != 0) {
+            s >> tx.vin;
+            s >> tx.vout;
         }
     } else {
-        // Consistency check
-        assert(tx.wit.vtxinwit.size() <= tx.vin.size());
-        if (fAllowWitness) {
-            /* Check whether witnesses need to be serialized. */
-            if (!tx.wit.IsNull()) {
-                flags |= 1;
-            }
-        }
-        if (flags) {
-            /* Use extended format in case witnesses are to be serialized. */
-            std::vector<CTxIn> vinDummy;
-            READWRITE(vinDummy);
-            READWRITE(flags);
+        /* We read a non-empty vin. Assume a normal vout follows. */
+        s >> tx.vout;
+    }
+    if ((flags & 1) && fAllowWitness) {
+        /* The witness flag is present, and we support witnesses. */
+        flags ^= 1;
+        tx.wit.vtxinwit.resize(tx.vin.size());
+        s >> tx.wit;
+    }
+    if (flags) {
+        /* Unknown flag in the serialization */
+        throw std::ios_base::failure("Unknown transaction optional data");
+    }
+    s >> tx.nLockTime;
+}
+
+template<typename Stream, typename TxType>
+inline void SerializeTransaction(const TxType& tx, Stream& s) {
+    const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS);
+
+    s << tx.nVersion;
+    unsigned char flags = 0;
+    // Consistency check
+    assert(tx.wit.vtxinwit.size() <= tx.vin.size());
+    if (fAllowWitness) {
+        /* Check whether witnesses need to be serialized. */
+        if (!tx.wit.IsNull()) {
+            flags |= 1;
         }
-        READWRITE(*const_cast<std::vector<CTxIn>*>(&tx.vin));
-        READWRITE(*const_cast<std::vector<CTxOut>*>(&tx.vout));
-        if (flags & 1) {
-            const_cast<CTxWitness*>(&tx.wit)->vtxinwit.resize(tx.vin.size());
-            READWRITE(tx.wit);
+    }
+    if (flags) {
+        /* Use extended format in case witnesses are to be serialized. */
+        std::vector<CTxIn> vinDummy;
+        s << vinDummy;
+        s << flags;
+    }
+    s << tx.vin;
+    s << tx.vout;
+    if (flags & 1) {
+        for (size_t i = 0; i < tx.vin.size(); i++) {
+            if (i < tx.wit.vtxinwit.size()) {
+                s << tx.wit.vtxinwit[i];
+            } else {
+                s << CTxInWitness();
+            }
         }
     }
-    READWRITE(*const_cast<uint32_t*>(&tx.nLockTime));
+    s << tx.nLockTime;
 }
 
+
 /** The basic transaction that is broadcasted on the network and contained in
  * blocks.  A transaction can contain multiple inputs and outputs.
  */
 class CTransaction
 {
-private:
-    /** Memory only. */
-    const uint256 hash;
-
 public:
     // Default transaction version.
     static const int32_t CURRENT_VERSION=1;
@@ -374,6 +382,13 @@ public:
     CTxWitness wit; // Not const: can change without invalidating the txid cache
     const uint32_t nLockTime;
 
+private:
+    /** Memory only. */
+    const uint256 hash;
+
+    uint256 ComputeHash() const;
+
+public:
     /** Construct a CTransaction that qualifies as IsNull() */
     CTransaction();
 
@@ -381,18 +396,13 @@ public:
     CTransaction(const CMutableTransaction &tx);
     CTransaction(CMutableTransaction &&tx);
 
-    CTransaction& operator=(const CTransaction& tx);
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action) {
-        SerializeTransaction(*this, s, ser_action);
-        if (ser_action.ForRead()) {
-            UpdateHash();
-        }
+    template <typename Stream>
+    inline void Serialize(Stream& s) const {
+        SerializeTransaction(*this, s);
     }
 
+    /** This deserializing constructor is provided instead of an Unserialize method.
+     *  Unserialize is not possible, since it would require overwriting const fields. */
     template <typename Stream>
     CTransaction(deserialize_type, Stream& s) : CTransaction(CMutableTransaction(deserialize, s)) {}
 
@@ -417,7 +427,7 @@ public:
 
     // Compute modified tx size for priority calculation (optionally given tx size)
     unsigned int CalculateModifiedSize(unsigned int nTxSize=0) const;
-    
+
     /**
      * Get the total transaction size in bytes, including witness data.
      * "Total Size" defined in BIP141 and BIP144.
@@ -441,8 +451,6 @@ public:
     }
 
     std::string ToString() const;
-
-    void UpdateHash() const;
 };
 
 /** A mutable version of CTransaction. */
@@ -457,11 +465,15 @@ struct CMutableTransaction
     CMutableTransaction();
     CMutableTransaction(const CTransaction& tx);
 
-    ADD_SERIALIZE_METHODS;
+    template <typename Stream>
+    inline void Serialize(Stream& s) const {
+        SerializeTransaction(*this, s);
+    }
 
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action) {
-        SerializeTransaction(*this, s, ser_action);
+
+    template <typename Stream>
+    inline void Unserialize(Stream& s) {
+        UnserializeTransaction(*this, s);
     }
 
     template <typename Stream>
diff --git a/src/script/bitcoinconsensus.cpp b/src/script/bitcoinconsensus.cpp
index 069ac55bfb..036d6ca7bf 100644
--- a/src/script/bitcoinconsensus.cpp
+++ b/src/script/bitcoinconsensus.cpp
@@ -85,8 +85,7 @@ static int verify_script(const unsigned char *scriptPubKey, unsigned int scriptP
     }
     try {
         TxInputStream stream(SER_NETWORK, PROTOCOL_VERSION, txTo, txToLen);
-        CTransaction tx;
-        stream >> tx;
+        CTransaction tx(deserialize, stream);
         if (nIn >= tx.vin.size())
             return set_error(err, bitcoinconsensus_ERR_TX_INDEX);
         if (GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION) != txToLen)
diff --git a/src/test/bloom_tests.cpp b/src/test/bloom_tests.cpp
index ffa1fb6ad0..b15ff9e44b 100644
--- a/src/test/bloom_tests.cpp
+++ b/src/test/bloom_tests.cpp
@@ -114,16 +114,14 @@ BOOST_AUTO_TEST_CASE(bloom_create_insert_key)
 BOOST_AUTO_TEST_CASE(bloom_match)
 {
     // Random real transaction (b4749f017444b051c44dfd2720e88f314ff94f3dd6d56d40ef65854fcd7fff6b)
-    CTransaction tx;
     CDataStream stream(ParseHex("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"), SER_DISK, CLIENT_VERSION);
-    stream >> tx;
+    CTransaction tx(deserialize, stream);
 
     // and one which spends it (e2769b09e784f32f62ef849763d4f45b98e07ba658647343b915ff832b110436)
     unsigned char ch[] = {0x01, 0x00, 0x00, 0x00, 0x01, 0x6b, 0xff, 0x7f, 0xcd, 0x4f, 0x85, 0x65, 0xef, 0x40, 0x6d, 0xd5, 0xd6, 0x3d, 0x4f, 0xf9, 0x4f, 0x31, 0x8f, 0xe8, 0x20, 0x27, 0xfd, 0x4d, 0xc4, 0x51, 0xb0, 0x44, 0x74, 0x01, 0x9f, 0x74, 0xb4, 0x00, 0x00, 0x00, 0x00, 0x8c, 0x49, 0x30, 0x46, 0x02, 0x21, 0x00, 0xda, 0x0d, 0xc6, 0xae, 0xce, 0xfe, 0x1e, 0x06, 0xef, 0xdf, 0x05, 0x77, 0x37, 0x57, 0xde, 0xb1, 0x68, 0x82, 0x09, 0x30, 0xe3, 0xb0, 0xd0, 0x3f, 0x46, 0xf5, 0xfc, 0xf1, 0x50, 0xbf, 0x99, 0x0c, 0x02, 0x21, 0x00, 0xd2, 0x5b, 0x5c, 0x87, 0x04, 0x00, 0x76, 0xe4, 0xf2, 0x53, 0xf8, 0x26, 0x2e, 0x76, 0x3e, 0x2d, 0xd5, 0x1e, 0x7f, 0xf0, 0xbe, 0x15, 0x77, 0x27, 0xc4, 0xbc, 0x42, 0x80, 0x7f, 0x17, 0xbd, 0x39, 0x01, 0x41, 0x04, 0xe6, 0xc2, 0x6e, 0xf6, 0x7d, 0xc6, 0x10, 0xd2, 0xcd, 0x19, 0x24, 0x84, 0x78, 0x9a, 0x6c, 0xf9, 0xae, 0xa9, 0x93, 0x0b, 0x94, 0x4b, 0x7e, 0x2d, 0xb5, 0x34, 0x2b, 0x9d, 0x9e, 0x5b, 0x9f, 0xf7, 0x9a, 0xff, 0x9a, 0x2e, 0xe1, 0x97, 0x8d, 0xd7, 0xfd, 0x01, 0xdf, 0xc5, 0x22, 0xee, 0x02, 0x28, 0x3d, 0x3b, 0x06, 0xa9, 0xd0, 0x3a, 0xcf, 0x80, 0x96, 0x96, 0x8d, 0x7d, 0xbb, 0x0f, 0x91, 0x78, 0xff, 0xff, 0xff, 0xff, 0x02, 0x8b, 0xa7, 0x94, 0x0e, 0x00, 0x00, 0x00, 0x00, 0x19, 0x76, 0xa9, 0x14, 0xba, 0xde, 0xec, 0xfd, 0xef, 0x05, 0x07, 0x24, 0x7f, 0xc8, 0xf7, 0x42, 0x41, 0xd7, 0x3b, 0xc0, 0x39, 0x97, 0x2d, 0x7b, 0x88, 0xac, 0x40, 0x94, 0xa8, 0x02, 0x00, 0x00, 0x00, 0x00, 0x19, 0x76, 0xa9, 0x14, 0xc1, 0x09, 0x32, 0x48, 0x3f, 0xec, 0x93, 0xed, 0x51, 0xf5, 0xfe, 0x95, 0xe7, 0x25, 0x59, 0xf2, 0xcc, 0x70, 0x43, 0xf9, 0x88, 0xac, 0x00, 0x00, 0x00, 0x00, 0x00};
     vector<unsigned char> vch(ch, ch + sizeof(ch) -1);
     CDataStream spendStream(vch, SER_DISK, CLIENT_VERSION);
-    CTransaction spendingTx;
-    spendStream >> spendingTx;
+    CTransaction spendingTx(deserialize, spendStream);
 
     CBloomFilter filter(10, 0.000001, 0, BLOOM_UPDATE_ALL);
     filter.insert(uint256S("0xb4749f017444b051c44dfd2720e88f314ff94f3dd6d56d40ef65854fcd7fff6b"));
diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp
index 3169afb13a..eb324d5a6b 100644
--- a/src/test/script_tests.cpp
+++ b/src/test/script_tests.cpp
@@ -276,7 +276,7 @@ private:
     //! The Witness embedded script
     CScript witscript;
     CScriptWitness scriptWitness;
-    CTransaction creditTx;
+    CTransactionRef creditTx;
     CMutableTransaction spendTx;
     bool havePush;
     std::vector<unsigned char> push;
@@ -319,8 +319,8 @@ public:
             redeemscript = scriptPubKey;
             scriptPubKey = CScript() << OP_HASH160 << ToByteVector(CScriptID(redeemscript)) << OP_EQUAL;
         }
-        creditTx = BuildCreditingTransaction(scriptPubKey, nValue);
-        spendTx = BuildSpendingTransaction(CScript(), CScriptWitness(), creditTx);
+        creditTx = MakeTransactionRef(BuildCreditingTransaction(scriptPubKey, nValue));
+        spendTx = BuildSpendingTransaction(CScript(), CScriptWitness(), *creditTx);
     }
 
     TestBuilder& ScriptError(ScriptError_t err)
@@ -421,7 +421,7 @@ public:
     {
         TestBuilder copy = *this; // Make a copy so we can rollback the push.
         DoPush();
-        DoTest(creditTx.vout[0].scriptPubKey, spendTx.vin[0].scriptSig, scriptWitness, flags, comment, scriptError, nValue);
+        DoTest(creditTx->vout[0].scriptPubKey, spendTx.vin[0].scriptSig, scriptWitness, flags, comment, scriptError, nValue);
         *this = copy;
         return *this;
     }
@@ -447,7 +447,7 @@ public:
             array.push_back(wit);
         }
         array.push_back(FormatScript(spendTx.vin[0].scriptSig));
-        array.push_back(FormatScript(creditTx.vout[0].scriptPubKey));
+        array.push_back(FormatScript(creditTx->vout[0].scriptPubKey));
         array.push_back(FormatScriptFlags(flags));
         array.push_back(FormatScriptError((ScriptError_t)scriptError));
         array.push_back(comment);
@@ -461,7 +461,7 @@ public:
 
     const CScript& GetScriptPubKey()
     {
-        return creditTx.vout[0].scriptPubKey;
+        return creditTx->vout[0].scriptPubKey;
     }
 };
 
diff --git a/src/test/serialize_tests.cpp b/src/test/serialize_tests.cpp
index bbadf57957..1dc86eb116 100644
--- a/src/test/serialize_tests.cpp
+++ b/src/test/serialize_tests.cpp
@@ -21,10 +21,10 @@ protected:
     bool boolval;
     std::string stringval;
     const char* charstrval;
-    CTransaction txval;
+    CTransactionRef txval;
 public:
     CSerializeMethodsTestSingle() = default;
-    CSerializeMethodsTestSingle(int intvalin, bool boolvalin, std::string stringvalin, const char* charstrvalin, CTransaction txvalin) : intval(intvalin), boolval(boolvalin), stringval(std::move(stringvalin)), charstrval(charstrvalin), txval(txvalin){}
+    CSerializeMethodsTestSingle(int intvalin, bool boolvalin, std::string stringvalin, const char* charstrvalin, CTransaction txvalin) : intval(intvalin), boolval(boolvalin), stringval(std::move(stringvalin)), charstrval(charstrvalin), txval(MakeTransactionRef(txvalin)){}
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
@@ -42,7 +42,7 @@ public:
                 boolval == rhs.boolval && \
                 stringval == rhs.stringval && \
                 strcmp(charstrval, rhs.charstrval) == 0 && \
-                txval == rhs.txval;
+                *txval == *rhs.txval;
     }
 };
 
diff --git a/src/test/sighash_tests.cpp b/src/test/sighash_tests.cpp
index 38d58e7ab0..a524f5b946 100644
--- a/src/test/sighash_tests.cpp
+++ b/src/test/sighash_tests.cpp
@@ -184,7 +184,7 @@ BOOST_AUTO_TEST_CASE(sighash_from_data)
         std::string raw_tx, raw_script, sigHashHex;
         int nIn, nHashType;
         uint256 sh;
-        CTransaction tx;
+        CTransactionRef tx;
         CScript scriptCode = CScript();
 
         try {
@@ -199,7 +199,7 @@ BOOST_AUTO_TEST_CASE(sighash_from_data)
           stream >> tx;
 
           CValidationState state;
-          BOOST_CHECK_MESSAGE(CheckTransaction(tx, state), strTest);
+          BOOST_CHECK_MESSAGE(CheckTransaction(*tx, state), strTest);
           BOOST_CHECK(state.IsValid());
 
           std::vector<unsigned char> raw = ParseHex(raw_script);
@@ -209,7 +209,7 @@ BOOST_AUTO_TEST_CASE(sighash_from_data)
           continue;
         }
 
-        sh = SignatureHash(scriptCode, tx, nIn, nHashType, 0, SIGVERSION_BASE);
+        sh = SignatureHash(scriptCode, *tx, nIn, nHashType, 0, SIGVERSION_BASE);
         BOOST_CHECK_MESSAGE(sh.GetHex() == sigHashHex, strTest);
     }
 }
diff --git a/src/test/transaction_tests.cpp b/src/test/transaction_tests.cpp
index 7b4763669a..ae5406ef7e 100644
--- a/src/test/transaction_tests.cpp
+++ b/src/test/transaction_tests.cpp
@@ -150,8 +150,7 @@ BOOST_AUTO_TEST_CASE(tx_valid)
 
             string transaction = test[1].get_str();
             CDataStream stream(ParseHex(transaction), SER_NETWORK, PROTOCOL_VERSION);
-            CTransaction tx;
-            stream >> tx;
+            CTransaction tx(deserialize, stream);
 
             CValidationState state;
             BOOST_CHECK_MESSAGE(CheckTransaction(tx, state), strTest);
@@ -236,8 +235,7 @@ BOOST_AUTO_TEST_CASE(tx_invalid)
 
             string transaction = test[1].get_str();
             CDataStream stream(ParseHex(transaction), SER_NETWORK, PROTOCOL_VERSION );
-            CTransaction tx;
-            stream >> tx;
+            CTransaction tx(deserialize, stream);
 
             CValidationState state;
             fValid = CheckTransaction(tx, state) && state.IsValid();
@@ -346,7 +344,7 @@ BOOST_AUTO_TEST_CASE(test_Get)
     BOOST_CHECK_EQUAL(coins.GetValueIn(t1), (50+21+22)*CENT);
 }
 
-void CreateCreditAndSpend(const CKeyStore& keystore, const CScript& outscript, CTransaction& output, CMutableTransaction& input, bool success = true)
+void CreateCreditAndSpend(const CKeyStore& keystore, const CScript& outscript, CTransactionRef& output, CMutableTransaction& input, bool success = true)
 {
     CMutableTransaction outputm;
     outputm.nVersion = 1;
@@ -360,22 +358,22 @@ void CreateCreditAndSpend(const CKeyStore& keystore, const CScript& outscript, C
     CDataStream ssout(SER_NETWORK, PROTOCOL_VERSION);
     ssout << outputm;
     ssout >> output;
-    assert(output.vin.size() == 1);
-    assert(output.vin[0] == outputm.vin[0]);
-    assert(output.vout.size() == 1);
-    assert(output.vout[0] == outputm.vout[0]);
-    assert(output.wit.vtxinwit.size() == 0);
+    assert(output->vin.size() == 1);
+    assert(output->vin[0] == outputm.vin[0]);
+    assert(output->vout.size() == 1);
+    assert(output->vout[0] == outputm.vout[0]);
+    assert(output->wit.vtxinwit.size() == 0);
 
     CMutableTransaction inputm;
     inputm.nVersion = 1;
     inputm.vin.resize(1);
-    inputm.vin[0].prevout.hash = output.GetHash();
+    inputm.vin[0].prevout.hash = output->GetHash();
     inputm.vin[0].prevout.n = 0;
     inputm.wit.vtxinwit.resize(1);
     inputm.vout.resize(1);
     inputm.vout[0].nValue = 1;
     inputm.vout[0].scriptPubKey = CScript();
-    bool ret = SignSignature(keystore, output, inputm, 0, SIGHASH_ALL);
+    bool ret = SignSignature(keystore, *output, inputm, 0, SIGHASH_ALL);
     assert(ret == success);
     CDataStream ssin(SER_NETWORK, PROTOCOL_VERSION);
     ssin << inputm;
@@ -393,11 +391,11 @@ void CreateCreditAndSpend(const CKeyStore& keystore, const CScript& outscript, C
     }
 }
 
-void CheckWithFlag(const CTransaction& output, const CMutableTransaction& input, int flags, bool success)
+void CheckWithFlag(const CTransactionRef& output, const CMutableTransaction& input, int flags, bool success)
 {
     ScriptError error;
     CTransaction inputi(input);
-    bool ret = VerifyScript(inputi.vin[0].scriptSig, output.vout[0].scriptPubKey, inputi.wit.vtxinwit.size() > 0 ? &inputi.wit.vtxinwit[0].scriptWitness : NULL, flags, TransactionSignatureChecker(&inputi, 0, output.vout[0].nValue), &error);
+    bool ret = VerifyScript(inputi.vin[0].scriptSig, output->vout[0].scriptPubKey, inputi.wit.vtxinwit.size() > 0 ? &inputi.wit.vtxinwit[0].scriptWitness : NULL, flags, TransactionSignatureChecker(&inputi, 0, output->vout[0].nValue), &error);
     assert(ret == success);
 }
 
@@ -466,10 +464,10 @@ BOOST_AUTO_TEST_CASE(test_big_witness_transaction) {
         assert(hashSigned);
     }
 
-    CTransaction tx;
     CDataStream ssout(SER_NETWORK, PROTOCOL_VERSION);
-    WithOrVersion(&ssout, 0) << mtx;
-    WithOrVersion(&ssout, 0) >> tx;
+    auto vstream = WithOrVersion(&ssout, 0);
+    vstream << mtx;
+    CTransaction tx(deserialize, vstream);
 
     // check all inputs concurrently, with the cache
     PrecomputedTransactionData txdata(tx);
@@ -547,7 +545,7 @@ BOOST_AUTO_TEST_CASE(test_witness)
     keystore2.AddCScript(GetScriptForWitness(scriptMulti));
     keystore2.AddKeyPubKey(key3, pubkey3);
 
-    CTransaction output1, output2;
+    CTransactionRef output1, output2;
     CMutableTransaction input1, input2;
     SignatureData sigdata;
 
@@ -639,8 +637,8 @@ BOOST_AUTO_TEST_CASE(test_witness)
     CheckWithFlag(output1, input1, 0, false);
     CreateCreditAndSpend(keystore2, scriptMulti, output2, input2, false);
     CheckWithFlag(output2, input2, 0, false);
-    BOOST_CHECK(output1 == output2);
-    UpdateTransaction(input1, 0, CombineSignatures(output1.vout[0].scriptPubKey, MutableTransactionSignatureChecker(&input1, 0, output1.vout[0].nValue), DataFromTransaction(input1, 0), DataFromTransaction(input2, 0)));
+    BOOST_CHECK(*output1 == *output2);
+    UpdateTransaction(input1, 0, CombineSignatures(output1->vout[0].scriptPubKey, MutableTransactionSignatureChecker(&input1, 0, output1->vout[0].nValue), DataFromTransaction(input1, 0), DataFromTransaction(input2, 0)));
     CheckWithFlag(output1, input1, STANDARD_SCRIPT_VERIFY_FLAGS, true);
 
     // P2SH 2-of-2 multisig
@@ -650,8 +648,8 @@ BOOST_AUTO_TEST_CASE(test_witness)
     CreateCreditAndSpend(keystore2, GetScriptForDestination(CScriptID(scriptMulti)), output2, input2, false);
     CheckWithFlag(output2, input2, 0, true);
     CheckWithFlag(output2, input2, SCRIPT_VERIFY_P2SH, false);
-    BOOST_CHECK(output1 == output2);
-    UpdateTransaction(input1, 0, CombineSignatures(output1.vout[0].scriptPubKey, MutableTransactionSignatureChecker(&input1, 0, output1.vout[0].nValue), DataFromTransaction(input1, 0), DataFromTransaction(input2, 0)));
+    BOOST_CHECK(*output1 == *output2);
+    UpdateTransaction(input1, 0, CombineSignatures(output1->vout[0].scriptPubKey, MutableTransactionSignatureChecker(&input1, 0, output1->vout[0].nValue), DataFromTransaction(input1, 0), DataFromTransaction(input2, 0)));
     CheckWithFlag(output1, input1, SCRIPT_VERIFY_P2SH, true);
     CheckWithFlag(output1, input1, STANDARD_SCRIPT_VERIFY_FLAGS, true);
 
@@ -662,8 +660,8 @@ BOOST_AUTO_TEST_CASE(test_witness)
     CreateCreditAndSpend(keystore2, GetScriptForWitness(scriptMulti), output2, input2, false);
     CheckWithFlag(output2, input2, 0, true);
     CheckWithFlag(output2, input2, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_WITNESS, false);
-    BOOST_CHECK(output1 == output2);
-    UpdateTransaction(input1, 0, CombineSignatures(output1.vout[0].scriptPubKey, MutableTransactionSignatureChecker(&input1, 0, output1.vout[0].nValue), DataFromTransaction(input1, 0), DataFromTransaction(input2, 0)));
+    BOOST_CHECK(*output1 == *output2);
+    UpdateTransaction(input1, 0, CombineSignatures(output1->vout[0].scriptPubKey, MutableTransactionSignatureChecker(&input1, 0, output1->vout[0].nValue), DataFromTransaction(input1, 0), DataFromTransaction(input2, 0)));
     CheckWithFlag(output1, input1, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_WITNESS, true);
     CheckWithFlag(output1, input1, STANDARD_SCRIPT_VERIFY_FLAGS, true);
 
@@ -674,8 +672,8 @@ BOOST_AUTO_TEST_CASE(test_witness)
     CreateCreditAndSpend(keystore2, GetScriptForDestination(CScriptID(GetScriptForWitness(scriptMulti))), output2, input2, false);
     CheckWithFlag(output2, input2, SCRIPT_VERIFY_P2SH, true);
     CheckWithFlag(output2, input2, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_WITNESS, false);
-    BOOST_CHECK(output1 == output2);
-    UpdateTransaction(input1, 0, CombineSignatures(output1.vout[0].scriptPubKey, MutableTransactionSignatureChecker(&input1, 0, output1.vout[0].nValue), DataFromTransaction(input1, 0), DataFromTransaction(input2, 0)));
+    BOOST_CHECK(*output1 == *output2);
+    UpdateTransaction(input1, 0, CombineSignatures(output1->vout[0].scriptPubKey, MutableTransactionSignatureChecker(&input1, 0, output1->vout[0].nValue), DataFromTransaction(input1, 0), DataFromTransaction(input2, 0)));
     CheckWithFlag(output1, input1, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_WITNESS, true);
     CheckWithFlag(output1, input1, STANDARD_SCRIPT_VERIFY_FLAGS, true);
 }
diff --git a/src/validation.cpp b/src/validation.cpp
index fe34565131..7eef14af2b 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -2859,8 +2859,9 @@ std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBloc
             out.scriptPubKey[5] = 0xed;
             memcpy(&out.scriptPubKey[6], witnessroot.begin(), 32);
             commitment = std::vector<unsigned char>(out.scriptPubKey.begin(), out.scriptPubKey.end());
-            const_cast<std::vector<CTxOut>*>(&block.vtx[0]->vout)->push_back(out);
-            block.vtx[0]->UpdateHash();
+            CMutableTransaction tx(*block.vtx[0]);
+            tx.vout.push_back(out);
+            block.vtx[0] = MakeTransactionRef(std::move(tx));
         }
     }
     UpdateUncommittedBlockStructures(block, pindexPrev, consensusParams);
@@ -4090,10 +4091,9 @@ bool LoadMempool(void)
         file >> num;
         double prioritydummy = 0;
         while (num--) {
-            CTransaction tx;
             int64_t nTime;
             int64_t nFeeDelta;
-            file >> tx;
+            CTransaction tx(deserialize, file);
             file >> nTime;
             file >> nFeeDelta;