Merge pull request #6088

2085895 fundrawtransaction tests (Jonas Schnelli)
21bbd92 Add fundrawtransaction RPC method (Matt Corallo)
1e0d1a2 Add FundTransaction method to wallet (Matt Corallo)
2d84e22 Small tweaks to CCoinControl for fundrawtransaction (Matt Corallo)
9b4e7d9 Add DummySignatureCreator which just creates zeroed sigs (Pieter Wuille)

10 files changed, 230 insertions, 14 deletions

diff --git a/src/coincontrol.h b/src/coincontrol.h
index 92fae9847c..3e8de83c39 100644
--- a/src/coincontrol.h
+++ b/src/coincontrol.h
@@ -12,6 +12,8 @@ class CCoinControl
 {
 public:
     CTxDestination destChange;
+    //! If false, allows unselected inputs, but requires all selected inputs be used
+    bool fAllowOtherInputs;
 
     CCoinControl()
     {
@@ -21,6 +23,7 @@ public:
     void SetNull()
     {
         destChange = CNoDestination();
+        fAllowOtherInputs = false;
         setSelected.clear();
     }
 
@@ -50,7 +53,7 @@ public:
         setSelected.clear();
     }
 
-    void ListSelected(std::vector<COutPoint>& vOutpoints)
+    void ListSelected(std::vector<COutPoint>& vOutpoints) const
     {
         vOutpoints.assign(setSelected.begin(), setSelected.end());
     }
diff --git a/src/rpcclient.cpp b/src/rpcclient.cpp
index 1d94e4f61b..4c6b47e4a0 100644
--- a/src/rpcclient.cpp
+++ b/src/rpcclient.cpp
@@ -78,6 +78,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "signrawtransaction", 1 },
     { "signrawtransaction", 2 },
     { "sendrawtransaction", 1 },
+    { "fundrawtransaction", 1 },
     { "gettxout", 1 },
     { "gettxout", 2 },
     { "gettxoutproof", 0 },
diff --git a/src/rpcserver.cpp b/src/rpcserver.cpp
index 6d089c6738..2f28971589 100644
--- a/src/rpcserver.cpp
+++ b/src/rpcserver.cpp
@@ -320,6 +320,9 @@ static const CRPCCommand vRPCCommands[] =
     { "rawtransactions",    "getrawtransaction",      &getrawtransaction,      true  },
     { "rawtransactions",    "sendrawtransaction",     &sendrawtransaction,     false },
     { "rawtransactions",    "signrawtransaction",     &signrawtransaction,     false }, /* uses wallet if enabled */
+#ifdef ENABLE_WALLET
+    { "rawtransactions",    "fundrawtransaction",     &fundrawtransaction,     false },
+#endif
 
     /* Utility functions */
     { "util",               "createmultisig",         &createmultisig,         true  },
diff --git a/src/rpcserver.h b/src/rpcserver.h
index d08ae72f5c..45af10c2a8 100644
--- a/src/rpcserver.h
+++ b/src/rpcserver.h
@@ -221,6 +221,7 @@ extern UniValue listlockunspent(const UniValue& params, bool fHelp);
 extern UniValue createrawtransaction(const UniValue& params, bool fHelp);
 extern UniValue decoderawtransaction(const UniValue& params, bool fHelp);
 extern UniValue decodescript(const UniValue& params, bool fHelp);
+extern UniValue fundrawtransaction(const UniValue& params, bool fHelp);
 extern UniValue signrawtransaction(const UniValue& params, bool fHelp);
 extern UniValue sendrawtransaction(const UniValue& params, bool fHelp);
 extern UniValue gettxoutproof(const UniValue& params, bool fHelp);
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index eab629cd91..4543ca303f 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -275,3 +275,39 @@ CScript CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecke
 
     return CombineSignatures(scriptPubKey, checker, txType, vSolutions, stack1, stack2);
 }
+
+namespace {
+/** Dummy signature checker which accepts all signatures. */
+class DummySignatureChecker : public BaseSignatureChecker
+{
+public:
+    DummySignatureChecker() {}
+
+    bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode) const
+    {
+        return true;
+    }
+};
+const DummySignatureChecker dummyChecker;
+}
+
+const BaseSignatureChecker& DummySignatureCreator::Checker() const
+{
+    return dummyChecker;
+}
+
+bool DummySignatureCreator::CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode) const
+{
+    // Create a dummy signature that is a valid DER-encoding
+    vchSig.assign(72, '\000');
+    vchSig[0] = 0x30;
+    vchSig[1] = 69;
+    vchSig[2] = 0x02;
+    vchSig[3] = 33;
+    vchSig[4] = 0x01;
+    vchSig[4 + 33] = 0x02;
+    vchSig[5 + 33] = 32;
+    vchSig[6 + 33] = 0x01;
+    vchSig[6 + 33 + 32] = SIGHASH_ALL;
+    return true;
+}
diff --git a/src/script/sign.h b/src/script/sign.h
index 0c4cf61e5e..13f45007dd 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -43,6 +43,14 @@ public:
     bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode) const;
 };
 
+/** A signature creator that just produces 72-byte empty signatyres. */
+class DummySignatureCreator : public BaseSignatureCreator {
+public:
+    DummySignatureCreator(const CKeyStore* keystoreIn) : BaseSignatureCreator(keystoreIn) {}
+    const BaseSignatureChecker& Checker() const;
+    bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode) const;
+};
+
 /** Produce a script signature using a generic signature creator. */
 bool ProduceSignature(const BaseSignatureCreator& creator, const CScript& scriptPubKey, CScript& scriptSig);
 
diff --git a/src/test/rpc_wallet_tests.cpp b/src/test/rpc_wallet_tests.cpp
index a72b656100..9368963ff2 100644
--- a/src/test/rpc_wallet_tests.cpp
+++ b/src/test/rpc_wallet_tests.cpp
@@ -217,6 +217,12 @@ BOOST_AUTO_TEST_CASE(rpc_wallet)
     UniValue arr = retValue.get_array();
     BOOST_CHECK(arr.size() > 0);
     BOOST_CHECK(CBitcoinAddress(arr[0].get_str()).Get() == demoAddress.Get());
+
+    /*********************************
+     * 	     fundrawtransaction
+     *********************************/
+    BOOST_CHECK_THROW(CallRPC("fundrawtransaction 28z"), runtime_error);
+    BOOST_CHECK_THROW(CallRPC("fundrawtransaction 01000000000180969800000000001976a91450ce0a4b0ee0ddeb633da85199728b940ac3fe9488ac00000000"), runtime_error);
 }
 
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 5404dd4aa0..8d88933878 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2361,3 +2361,57 @@ UniValue listunspent(const UniValue& params, bool fHelp)
 
     return results;
 }
+
+UniValue fundrawtransaction(const UniValue& params, bool fHelp)
+{
+    if (!EnsureWalletIsAvailable(fHelp))
+        return NullUniValue;
+
+    if (fHelp || params.size() != 1)
+        throw runtime_error(
+                            "fundrawtransaction \"hexstring\"\n"
+                            "\nAdd inputs to a transaction until it has enough in value to meet its out value.\n"
+                            "This will not modify existing inputs, and will add one change output to the outputs.\n"
+                            "Note that inputs which were signed may need to be resigned after completion since in/outputs have been added.\n"
+                            "The inputs added will not be signed, use signrawtransaction for that.\n"
+                            "\nArguments:\n"
+                            "1. \"hexstring\"    (string, required) The hex string of the raw transaction\n"
+                            "\nResult:\n"
+                            "{\n"
+                            "  \"hex\":       \"value\", (string)  The resulting raw transaction (hex-encoded string)\n"
+                            "  \"fee\":       n,         (numeric) The fee added to the transaction\n"
+                            "  \"changepos\": n          (numeric) The position of the added change output, or -1\n"
+                            "}\n"
+                            "\"hex\"             \n"
+                            "\nExamples:\n"
+                            "\nCreate a transaction with no inputs\n"
+                            + HelpExampleCli("createrawtransaction", "\"[]\" \"{\\\"myaddress\\\":0.01}\"") +
+                            "\nAdd sufficient unsigned inputs to meet the output value\n"
+                            + HelpExampleCli("fundrawtransaction", "\"rawtransactionhex\"") +
+                            "\nSign the transaction\n"
+                            + HelpExampleCli("signrawtransaction", "\"fundedtransactionhex\"") +
+                            "\nSend the transaction\n"
+                            + HelpExampleCli("sendrawtransaction", "\"signedtransactionhex\"")
+                            );
+
+    RPCTypeCheck(params, boost::assign::list_of(UniValue::VSTR));
+
+    // parse hex string from parameter
+    CTransaction origTx;
+    if (!DecodeHexTx(origTx, params[0].get_str()))
+        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
+
+    CMutableTransaction tx(origTx);
+    CAmount nFee;
+    string strFailReason;
+    int nChangePos = -1;
+    if(!pwalletMain->FundTransaction(tx, nFee, nChangePos, strFailReason))
+        throw JSONRPCError(RPC_INTERNAL_ERROR, strFailReason);
+
+    UniValue result(UniValue::VOBJ);
+    result.push_back(Pair("hex", EncodeHexTx(tx)));
+    result.push_back(Pair("changepos", nChangePos));
+    result.push_back(Pair("fee", ValueFromAmount(nFee)));
+
+    return result;
+}
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 3f12d88e79..eee57900b5 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1509,7 +1509,7 @@ void CWallet::AvailableCoins(vector<COutput>& vCoins, bool fOnlyConfirmed, const
                 isminetype mine = IsMine(pcoin->vout[i]);
                 if (!(IsSpent(wtxid, i)) && mine != ISMINE_NO &&
                     !IsLockedCoin((*it).first, i) && (pcoin->vout[i].nValue > 0 || fIncludeZeroValue) &&
-                    (!coinControl || !coinControl->HasSelected() || coinControl->IsSelected((*it).first, i)))
+                    (!coinControl || !coinControl->HasSelected() || coinControl->fAllowOtherInputs || coinControl->IsSelected((*it).first, i)))
                         vCoins.push_back(COutput(pcoin, i, nDepth, (mine & ISMINE_SPENDABLE) != ISMINE_NO));
             }
         }
@@ -1669,25 +1669,108 @@ bool CWallet::SelectCoins(const CAmount& nTargetValue, set<pair<const CWalletTx*
     AvailableCoins(vCoins, true, coinControl);
 
     // coin control -> return all selected outputs (we want all selected to go into the transaction for sure)
-    if (coinControl && coinControl->HasSelected())
+    if (coinControl && coinControl->HasSelected() && !coinControl->fAllowOtherInputs)
     {
         BOOST_FOREACH(const COutput& out, vCoins)
         {
-            if(!out.fSpendable)
-                continue;
+            if (!out.fSpendable)
+                 continue;
             nValueRet += out.tx->vout[out.i].nValue;
             setCoinsRet.insert(make_pair(out.tx, out.i));
         }
         return (nValueRet >= nTargetValue);
     }
 
-    return (SelectCoinsMinConf(nTargetValue, 1, 6, vCoins, setCoinsRet, nValueRet) ||
-            SelectCoinsMinConf(nTargetValue, 1, 1, vCoins, setCoinsRet, nValueRet) ||
-            (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue, 0, 1, vCoins, setCoinsRet, nValueRet)));
+    // calculate value from preset inputs and store them
+    set<pair<const CWalletTx*, uint32_t> > setPresetCoins;
+    CAmount nValueFromPresetInputs = 0;
+
+    std::vector<COutPoint> vPresetInputs;
+    if (coinControl)
+        coinControl->ListSelected(vPresetInputs);
+    BOOST_FOREACH(const COutPoint& outpoint, vPresetInputs)
+    {
+        map<uint256, CWalletTx>::const_iterator it = mapWallet.find(outpoint.hash);
+        if (it != mapWallet.end())
+        {
+            const CWalletTx* pcoin = &it->second;
+            // Clearly invalid input, fail
+            if (pcoin->vout.size() <= outpoint.n)
+                return false;
+            nValueFromPresetInputs += pcoin->vout[outpoint.n].nValue;
+            setPresetCoins.insert(make_pair(pcoin, outpoint.n));
+        } else
+            return false; // TODO: Allow non-wallet inputs
+    }
+
+    // remove preset inputs from vCoins
+    for (vector<COutput>::iterator it = vCoins.begin(); it != vCoins.end() && coinControl && coinControl->HasSelected();)
+    {
+        if (setPresetCoins.count(make_pair(it->tx, it->i)))
+            it = vCoins.erase(it);
+        else
+            ++it;
+    }
+
+    bool res = nTargetValue <= nValueFromPresetInputs ||
+        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 1, 6, vCoins, setCoinsRet, nValueRet) ||
+        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 1, 1, vCoins, setCoinsRet, nValueRet) ||
+        (bSpendZeroConfChange && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, 0, 1, vCoins, setCoinsRet, nValueRet));
+
+    // because SelectCoinsMinConf clears the setCoinsRet, we now add the possible inputs to the coinset
+    setCoinsRet.insert(setPresetCoins.begin(), setPresetCoins.end());
+
+    // add preset inputs to the total value selected
+    nValueRet += nValueFromPresetInputs;
+
+    return res;
 }
 
-bool CWallet::CreateTransaction(const vector<CRecipient>& vecSend,
-                                CWalletTx& wtxNew, CReserveKey& reservekey, CAmount& nFeeRet, int& nChangePosRet, std::string& strFailReason, const CCoinControl* coinControl)
+bool CWallet::FundTransaction(CMutableTransaction& tx, CAmount &nFeeRet, int& nChangePosRet, std::string& strFailReason)
+{
+    vector<CRecipient> vecSend;
+
+    // Turn the txout set into a CRecipient vector
+    BOOST_FOREACH(const CTxOut& txOut, tx.vout)
+    {
+        CRecipient recipient = {txOut.scriptPubKey, txOut.nValue, false};
+        vecSend.push_back(recipient);
+    }
+
+    CCoinControl coinControl;
+    coinControl.fAllowOtherInputs = true;
+    BOOST_FOREACH(const CTxIn& txin, tx.vin)
+        coinControl.Select(txin.prevout);
+
+    CReserveKey reservekey(this);
+    CWalletTx wtx;
+    if (!CreateTransaction(vecSend, wtx, reservekey, nFeeRet, nChangePosRet, strFailReason, &coinControl, false))
+        return false;
+
+    if (nChangePosRet != -1)
+        tx.vout.insert(tx.vout.begin() + nChangePosRet, wtx.vout[nChangePosRet]);
+
+    // Add new txins (keeping original txin scriptSig/order)
+    BOOST_FOREACH(const CTxIn& txin, wtx.vin)
+    {
+        bool found = false;
+        BOOST_FOREACH(const CTxIn& origTxIn, tx.vin)
+        {
+            if (txin.prevout.hash == origTxIn.prevout.hash && txin.prevout.n == origTxIn.prevout.n)
+            {
+                found = true;
+                break;
+            }
+        }
+        if (!found)
+            tx.vin.push_back(txin);
+    }
+
+    return true;
+}
+
+bool CWallet::CreateTransaction(const vector<CRecipient>& vecSend, CWalletTx& wtxNew, CReserveKey& reservekey, CAmount& nFeeRet,
+                                int& nChangePosRet, std::string& strFailReason, const CCoinControl* coinControl, bool sign)
 {
     CAmount nValue = 0;
     unsigned int nSubtractFeeFromAmount = 0;
@@ -1890,23 +1973,43 @@ bool CWallet::CreateTransaction(const vector<CRecipient>& vecSend,
 
                 // Sign
                 int nIn = 0;
+                CTransaction txNewConst(txNew);
                 BOOST_FOREACH(const PAIRTYPE(const CWalletTx*,unsigned int)& coin, setCoins)
-                    if (!SignSignature(*this, *coin.first, txNew, nIn++))
+                {
+                    bool signSuccess;
+                    const CScript& scriptPubKey = coin.first->vout[coin.second].scriptPubKey;
+                    CScript& scriptSigRes = txNew.vin[nIn].scriptSig;
+                    if (sign)
+                        signSuccess = ProduceSignature(TransactionSignatureCreator(this, &txNewConst, nIn, SIGHASH_ALL), scriptPubKey, scriptSigRes);
+                    else
+                        signSuccess = ProduceSignature(DummySignatureCreator(this), scriptPubKey, scriptSigRes);
+
+                    if (!signSuccess)
                     {
                         strFailReason = _("Signing transaction failed");
                         return false;
                     }
+                    nIn++;
+                }
+
+                unsigned int nBytes = ::GetSerializeSize(txNew, SER_NETWORK, PROTOCOL_VERSION);
+
+                // Remove scriptSigs if we used dummy signatures for fee calculation
+                if (!sign) {
+                    BOOST_FOREACH (CTxIn& vin, txNew.vin)
+                        vin.scriptSig = CScript();
+                }
 
                 // Embed the constructed transaction data in wtxNew.
                 *static_cast<CTransaction*>(&wtxNew) = CTransaction(txNew);
 
                 // Limit size
-                unsigned int nBytes = ::GetSerializeSize(*(CTransaction*)&wtxNew, SER_NETWORK, PROTOCOL_VERSION);
                 if (nBytes >= MAX_STANDARD_TX_SIZE)
                 {
                     strFailReason = _("Transaction too large");
                     return false;
                 }
+
                 dPriority = wtxNew.ComputePriority(dPriority, nBytes);
 
                 // Can we complete this as a free transaction?
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 9f3f08d117..b6a8e8671f 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -625,8 +625,9 @@ public:
     CAmount GetWatchOnlyBalance() const;
     CAmount GetUnconfirmedWatchOnlyBalance() const;
     CAmount GetImmatureWatchOnlyBalance() const;
-    bool CreateTransaction(const std::vector<CRecipient>& vecSend,
-                           CWalletTx& wtxNew, CReserveKey& reservekey, CAmount& nFeeRet, int& nChangePosRet, std::string& strFailReason, const CCoinControl *coinControl = NULL);
+    bool FundTransaction(CMutableTransaction& tx, CAmount& nFeeRet, int& nChangePosRet, std::string& strFailReason);
+    bool CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletTx& wtxNew, CReserveKey& reservekey, CAmount& nFeeRet, int& nChangePosRet,
+                           std::string& strFailReason, const CCoinControl *coinControl = NULL, bool sign = true);
     bool CommitTransaction(CWalletTx& wtxNew, CReserveKey& reservekey);
 
     static CFeeRate minTxFee;