Merge pull request #420 from rnicoll/1.7-dev-change

Add support for sending change to a list of address(es)

src/init.cpp

@@ -2,6 +2,7 @@
 // Copyright (c) 2009-2014 The Bitcoin developers
 // Copyright (c) 2011-2013 The Litecoin developers
 // Copyright (c)      2014 The Inutoshi developers
+// Copyright (c)      2014 The Dogecoin developers
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -12,7 +13,9 @@
 #include "init.h"
 
 #include "addrman.h"
+#include "base58.h"
 #include "checkpoints.h"
+#include "key.h"
 #include "main.h"
 #include "miner.h"
 #include "net.h"
@@ -277,6 +280,7 @@ std::string HelpMessage(HelpMessageMode hmm)
     strUsage += "  -upgradewallet         " + _("Upgrade wallet to latest format") + "\n";
     strUsage += "  -wallet=<file>         " + _("Specify wallet file (within data directory)") + "\n";
     strUsage += "  -walletnotify=<cmd>    " + _("Execute command when a wallet transaction changes (%s in cmd is replaced by TxID)") + "\n";
+    strUsage += "  -change=<address>      " + _("Send change only to the specified address(es)") + "\n" +
     strUsage += "  -spendzeroconfchange   " + _("Spend unconfirmed change when sending transactions (default: 1)") + "\n";
 #endif
     strUsage += "\n" + _("Block creation options:") + "\n";
@@ -558,6 +562,20 @@ bool AppInit2(boost::thread_group& threadGroup)
         if (nTransactionFee > 25 * COIN)
             InitWarning(_("Warning: -paytxfee is set very high! This is the transaction fee you will pay if you send a transaction."));
     }
+    
+    if (mapArgs.count("-change"))
+    {
+        BOOST_FOREACH(std::string strChange, mapMultiArgs["-change"]) {
+            CBitcoinAddress address(strChange);
+            CKeyID keyID;
+            
+            if (!address.GetKeyID(keyID)) {
+                return InitError(strprintf(_("Bad -change address: '%s'"), strChange));
+            }
+            AddFixedChangeAddress(keyID);
+        }
+    }
+    
     bSpendZeroConfChange = GetArg("-spendzeroconfchange", true);
 
     strWalletFile = GetArg("-wallet", "wallet.dat");

src/wallet.cpp

@@ -1,5 +1,6 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2014 The Bitcoin developers
+// Copyright (c)      2014 The Dogecoin developers
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -18,6 +19,7 @@ using namespace std;
 // Settings
 int64_t nTransactionFee = 0;
 bool bSpendZeroConfChange = true;
+static std::vector<CKeyID> vChangeAddresses;
 
 //////////////////////////////////////////////////////////////////////////////
 //
@@ -1397,8 +1399,15 @@ bool CWallet::CreateTransaction(const vector<pair<CScript, int64_t> >& vecSend,
                     // coin control: send change to custom address
                     if (coinControl && !boost::get<CNoDestination>(&coinControl->destChange))
                         scriptChange.SetDestination(coinControl->destChange);
+                        
+                    // send change to one of the specified change addresses, if specified at init
+                    else if (vChangeAddresses.size())
+                    {
+                        CKeyID keyID = vChangeAddresses[GetRandInt(vChangeAddresses.size())];
+                        scriptChange.SetDestination(keyID);
+                    }
 
-                    // no coin control: send change to newly generated address
+                    // send change to newly generated address
                     else
                     {
                         // Note: We use a new key here to keep it from being obvious which side is the change.
@@ -2183,3 +2192,11 @@ bool CWallet::GetDestData(const CTxDestination &dest, const std::string &key, st
     }
     return false;
 }
+
+// Add an address to the list of fixed change addresses to use. Fixed
+// addresses can be used to reduce the pace at which wallets expand
+// due to number of change addresses
+void AddFixedChangeAddress(const CKeyID &changeAddress)
+{
+    vChangeAddresses.push_back(changeAddress);
+}

src/wallet.h

@@ -1,5 +1,6 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2013 The Bitcoin developers
+// Copyright (c)      2014 The Dogecoin developers
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #ifndef BITCOIN_WALLET_H
@@ -53,6 +54,9 @@ static void WriteOrderPos(const int64_t& nOrderPos, mapValue_t& mapValue)
     mapValue["n"] = i64tostr(nOrderPos);
 }
 
+// Add an address to the list of fixed change addresses to use.
+void AddFixedChangeAddress(const CKeyID &changeAddress);
+
 /** (client) version numbers for particular wallet features */
 enum WalletFeature
 {