Add mininput to deal with dust spam.

By default, mininput is set to 0.0001. This means that create transaction will
ignore any transactions with an output value less than 0.0001. You can override
the default by passing in -mininput on startup or by calling setmininput.

src/db.cpp

@@ -803,6 +803,7 @@ bool CWalletDB::LoadWallet(CWallet* pwallet)
                 if (strKey == "fGenerateBitcoins")  ssValue >> fGenerateBitcoins;
 #endif
                 if (strKey == "nTransactionFee")    ssValue >> nTransactionFee;
+                if (strKey == "nMinimumInputValue") ssValue >> nMinimumInputValue;
                 if (strKey == "fLimitProcessors")   ssValue >> fLimitProcessors;
                 if (strKey == "nLimitProcessors")   ssValue >> nLimitProcessors;
                 if (strKey == "fMinimizeToTray")    ssValue >> fMinimizeToTray;
@@ -821,6 +822,7 @@ bool CWalletDB::LoadWallet(CWallet* pwallet)
     printf("nFileVersion = %d\n", nFileVersion);
     printf("fGenerateBitcoins = %d\n", fGenerateBitcoins);
     printf("nTransactionFee = %"PRI64d"\n", nTransactionFee);
+    printf("nMinimumInputValue = %"PRI64d"\n", nMinimumInputValue);
     printf("fMinimizeToTray = %d\n", fMinimizeToTray);
     printf("fMinimizeOnClose = %d\n", fMinimizeOnClose);
     printf("fUseProxy = %d\n", fUseProxy);

src/init.cpp

@@ -186,6 +186,7 @@ bool AppInit2(int argc, char* argv[])
 #endif
 #endif
             "  -paytxfee=<amt>  \t  "   + _("Fee per KB to add to transactions you send\n") +
+            "  -mininput=<amt>  \t  "   + _("When creating transactions, ignore inputs with value less than this (default: 0.0001)\n") +
 #ifdef GUI
             "  -server          \t\t  " + _("Accept command line and JSON-RPC commands\n") +
 #endif
@@ -512,6 +513,15 @@ bool AppInit2(int argc, char* argv[])
             wxMessageBox(_("Warning: -paytxfee is set very high.  This is the transaction fee you will pay if you send a transaction."), "Bitcoin", wxOK | wxICON_EXCLAMATION);
     }
 
+    if (mapArgs.count("-mininput"))
+    {
+        if (!ParseMoney(mapArgs["-mininput"], nMinimumInputValue))
+        {
+            wxMessageBox(_("Invalid amount for -mininput=<amount>"), "Litecoin");
+            return false;
+        }
+    }
+
     if (fHaveUPnP)
     {
 #if USE_UPNP

src/main.cpp

@@ -56,6 +56,7 @@ int64 nHPSTimerStart;
 // Settings
 int fGenerateBitcoins = false;
 int64 nTransactionFee = 0;
+int64 nMinimumInputValue = CENT / 100;
 int fLimitProcessors = false;
 int nLimitProcessors = 1;
 int fMinimizeToTray = true;

src/main.h

@@ -72,6 +72,7 @@ extern std::set<CWallet*> setpwalletRegistered;
 // Settings
 extern int fGenerateBitcoins;
 extern int64 nTransactionFee;
+extern int64 nMinimumInputValue;
 extern int fLimitProcessors;
 extern int nLimitProcessors;
 extern int fMinimizeToTray;

src/rpc.cpp

@@ -453,6 +453,7 @@ Value getinfo(const Array& params, bool fHelp)
     obj.push_back(Pair("testnet",       fTestNet));
     obj.push_back(Pair("keypoololdest", (boost::int64_t)pwalletMain->GetOldestKeyPoolTime()));
     obj.push_back(Pair("paytxfee",      ValueFromAmount(nTransactionFee)));
+    obj.push_back(Pair("mininput",      ValueFromAmount(nMinimumInputValue)));
     obj.push_back(Pair("errors",        GetWarnings("statusbar")));
     return obj;
 }
@@ -651,6 +652,22 @@ Value settxfee(const Array& params, bool fHelp)
     return true;
 }
 
+Value setmininput(const Array& params, bool fHelp)
+{
+    if (fHelp || params.size() < 1 || params.size() > 1)
+        throw runtime_error(
+            "setmininput <amount>\n"
+            "<amount> is a real and is rounded to the nearest 0.00000001");
+
+    // Amount
+    int64 nAmount = 0;
+    if (params[0].get_real() != 0.0)
+        nAmount = AmountFromValue(params[0]);        // rejects 0.0 amounts
+
+    nMinimumInputValue = nAmount;
+    return true;
+}
+
 Value sendtoaddress(const Array& params, bool fHelp)
 {
     if (fHelp || params.size() < 2 || params.size() > 4)
@@ -2012,6 +2029,7 @@ pair<string, rpcfn_type> pCallTable[] =
     make_pair("listaccounts",          &listaccounts),
     make_pair("settxfee",              &settxfee),
     make_pair("getmemorypool",         &getmemorypool),
+    make_pair("setmininput",           &setmininput),
 };
 map<string, rpcfn_type> mapCallTable(pCallTable, pCallTable + sizeof(pCallTable)/sizeof(pCallTable[0]));
 
@@ -2656,6 +2674,7 @@ int CommandLineRPC(int argc, char *argv[])
         if (strMethod == "sendtoaddress"          && n > 1) ConvertTo<double>(params[1]);
         if (strMethod == "settxfee"               && n > 0) ConvertTo<double>(params[0]);
         if (strMethod == "getamountreceived"      && n > 1) ConvertTo<boost::int64_t>(params[1]); // deprecated
+        if (strMethod == "setmininput"            && n > 0) ConvertTo<double>(params[0]);
         if (strMethod == "getreceivedbyaddress"   && n > 1) ConvertTo<boost::int64_t>(params[1]);
         if (strMethod == "getreceivedbyaccount"   && n > 1) ConvertTo<boost::int64_t>(params[1]);
         if (strMethod == "getreceivedbylabel"     && n > 1) ConvertTo<boost::int64_t>(params[1]); // deprecated

src/wallet.cpp

@@ -621,7 +621,9 @@ bool CWallet::SelectCoinsMinConf(int64 nTargetValue, int nConfMine, int nConfThe
 
                 int64 n = pcoin->vout[i].nValue;
 
-                if (n <= 0)
+                // If output is less than minimum value, then don't include transaction.
+                // This is to help deal with dust spam clogging up create transactions.
+                if (n <= 0 || n < nMinimumInputValue)
                     continue;
 
                 pair<int64,pair<const CWalletTx*,unsigned int> > coin = make_pair(n,make_pair(pcoin,i));