UI to alert of respend attempt affecting wallet.

Respend transactions that conflict with transactions already in the
wallet are added to it.  They are not displayed unless they also involve
the wallet, or get into a block.  If they do not involve the wallet,
they continue not to affect balance.

Transactions that involve the wallet, and have conflicting non-equivalent
transactions, are highlighted in red.  When the conflict first occurs, a
modal dialog is thrown.

CWallet::SyncMetaData is changed to sync only to equivalent transactions.

When a conflict is added to the wallet, counter nConflictsReceived is
incremented.  This acts like a change in active block height for the
purpose of triggering UI updates.

src/qt/guiconstants.h

@@ -23,6 +23,10 @@ static const int STATUSBAR_ICONSIZE = 16;
 #define COLOR_NEGATIVE QColor(255, 0, 0)
 /* Transaction list -- bare address (without label) */
 #define COLOR_BAREADDRESS QColor(140, 140, 140)
+/* Transaction list -- has conflicting transactions */
+#define COLOR_HASCONFLICTING Qt::white;
+/* Transaction list -- has conflicting transactions - background */
+#define COLOR_HASCONFLICTING_BG QColor(192, 0, 0)
 
 /* Tooltips longer than this (in characters) are converted into rich text,
    so that they can be word-wrapped.

src/qt/transactionfilterproxy.cpp

@@ -24,7 +24,7 @@ TransactionFilterProxy::TransactionFilterProxy(QObject *parent) :
     typeFilter(ALL_TYPES),
     minAmount(0),
     limitRows(-1),
-    showInactive(true)
+    showInactive(false)
 {
 }
 
@@ -39,7 +39,7 @@ bool TransactionFilterProxy::filterAcceptsRow(int sourceRow, const QModelIndex &
     qint64 amount = llabs(index.data(TransactionTableModel::AmountRole).toLongLong());
     int status = index.data(TransactionTableModel::StatusRole).toInt();
 
-    if(!showInactive && status == TransactionStatus::Conflicted)
+    if(!showInactive && status == TransactionStatus::Conflicted && type == TransactionRecord::Other)
         return false;
     if(!(TYPE(type) & typeFilter))
         return false;

src/qt/transactionrecord.cpp

@@ -170,6 +170,8 @@ void TransactionRecord::updateStatus(const CWalletTx &wtx)
     status.depth = wtx.GetDepthInMainChain();
     status.cur_num_blocks = chainActive.Height();
 
+    status.hasConflicting = false;
+
     if (!IsFinalTx(wtx, chainActive.Height() + 1))
     {
         if (wtx.nLockTime < LOCKTIME_THRESHOLD)
@@ -213,6 +215,7 @@ void TransactionRecord::updateStatus(const CWalletTx &wtx)
         if (status.depth < 0)
         {
             status.status = TransactionStatus::Conflicted;
+            status.hasConflicting = !(wtx.GetConflicts(false).empty());
         }
         else if (GetAdjustedTime() - wtx.nTimeReceived > 2 * 60 && wtx.GetRequestCount() == 0)
         {
@@ -221,6 +224,7 @@ void TransactionRecord::updateStatus(const CWalletTx &wtx)
         else if (status.depth == 0)
         {
             status.status = TransactionStatus::Unconfirmed;
+            status.hasConflicting = !(wtx.GetConflicts(false).empty());
         }
         else if (status.depth < RecommendedNumConfirmations)
         {
@@ -231,13 +235,13 @@ void TransactionRecord::updateStatus(const CWalletTx &wtx)
             status.status = TransactionStatus::Confirmed;
         }
     }
-
 }
 
-bool TransactionRecord::statusUpdateNeeded()
+bool TransactionRecord::statusUpdateNeeded(int64_t nConflictsReceived)
 {
     AssertLockHeld(cs_main);
-    return status.cur_num_blocks != chainActive.Height();
+    return (status.cur_num_blocks != chainActive.Height() ||
+            status.cur_num_conflicts != nConflictsReceived);
 }
 
 QString TransactionRecord::getTxID() const

src/qt/transactionrecord.h

@@ -20,7 +20,8 @@ class TransactionStatus
 public:
     TransactionStatus():
         countsForBalance(false), sortKey(""),
-        matures_in(0), status(Offline), depth(0), open_for(0), cur_num_blocks(-1)
+        matures_in(0), status(Offline), hasConflicting(false), depth(0), open_for(0), cur_num_blocks(-1),
+        cur_num_conflicts(-1)
     { }
 
     enum Status {
@@ -51,6 +52,10 @@ class TransactionStatus
     /** @name Reported status
        @{*/
     Status status;
+
+    // Has conflicting transactions spending same prevout
+    bool hasConflicting;
+
     qint64 depth;
     qint64 open_for; /**< Timestamp if status==OpenUntilDate, otherwise number
                       of additional blocks that need to be mined before
@@ -59,6 +64,10 @@ class TransactionStatus
 
     /** Current number of blocks (to know whether cached status is still valid) */
     int cur_num_blocks;
+
+    /** Number of conflicts received into wallet as of last status update */
+    int64_t cur_num_conflicts;
+
 };
 
 /** UI model for a transaction. A core transaction can be represented by multiple UI transactions if it has
@@ -133,7 +142,7 @@ class TransactionRecord
 
     /** Return whether a status update is needed.
      */
-    bool statusUpdateNeeded();
+    bool statusUpdateNeeded(int64_t nConflictsReceived);
 };
 
 #endif // TRANSACTIONRECORD_H

src/qt/transactiontablemodel.cpp

@@ -168,8 +168,7 @@ class TransactionTablePriv
                 parent->endRemoveRows();
                 break;
             case CT_UPDATED:
-                // Miscellaneous updates -- nothing to do, status update will take care of this, and is only computed for
-                // visible transactions.
+                emit parent->dataChanged(parent->index(lowerIndex, parent->Status), parent->index(upperIndex-1, parent->Amount));
                 break;
             }
         }
@@ -190,20 +189,21 @@ class TransactionTablePriv
             // stuck if the core is holding the locks for a longer time - for
             // example, during a wallet rescan.
             //
-            // If a status update is needed (blocks came in since last check),
-            //  update the status of this transaction from the wallet. Otherwise,
+            // If a status update is needed (blocks or conflicts came in since last check),
+            // update the status of this transaction from the wallet. Otherwise,
             // simply re-use the cached status.
             TRY_LOCK(cs_main, lockMain);
             if(lockMain)
             {
                 TRY_LOCK(wallet->cs_wallet, lockWallet);
-                if(lockWallet && rec->statusUpdateNeeded())
+                if(lockWallet && rec->statusUpdateNeeded(wallet->nConflictsReceived))
                 {
                     std::map<uint256, CWalletTx>::iterator mi = wallet->mapWallet.find(rec->hash);
 
                     if(mi != wallet->mapWallet.end())
                     {
                         rec->updateStatus(mi->second);
+                        rec->status.cur_num_conflicts = wallet->nConflictsReceived;
                     }
                 }
             }
@@ -363,6 +363,8 @@ QString TransactionTableModel::formatTxType(const TransactionRecord *wtx) const
         return tr("Payment to yourself");
     case TransactionRecord::Generated:
         return tr("Mined");
+    case TransactionRecord::Other:
+        return tr("Other");
     default:
         return QString();
     }
@@ -535,7 +537,13 @@ QVariant TransactionTableModel::data(const QModelIndex &index, int role) const
         return formatTooltip(rec);
     case Qt::TextAlignmentRole:
         return column_alignments[index.column()];
+    case Qt::BackgroundColorRole:
+    	if (rec->status.hasConflicting)
+            return COLOR_HASCONFLICTING_BG;
+    	break;
     case Qt::ForegroundRole:
+        if (rec->status.hasConflicting)
+            return COLOR_HASCONFLICTING;
         // Non-confirmed (but not immature) as transactions are grey
         if(!rec->status.countsForBalance && rec->status.status != TransactionStatus::Immature)
         {

src/qt/walletmodel.cpp

@@ -138,6 +138,14 @@ void WalletModel::checkBalanceChanged()
 
 void WalletModel::updateTransaction(const QString &hash, int status)
 {
+	if (status == CT_GOT_CONFLICT)
+	{
+	    emit message(tr("Conflict Received"),
+	    	         tr("WARNING: Transaction may never be confirmed. Its input was seen being spent by another transaction on the network. Wait for confirmation!"),
+	          		CClientUIInterface::MSG_WARNING);
+		return;
+	}
+
     if(transactionTableModel)
         transactionTableModel->updateTransaction(hash, status);
 

src/ui_interface.h

@@ -21,7 +21,8 @@ enum ChangeType
 {
     CT_NEW,
     CT_UPDATED,
-    CT_DELETED
+    CT_DELETED,
+    CT_GOT_CONFLICT
 };
 
 /** Signals for UI communication. */

src/wallet.cpp

@@ -256,7 +256,7 @@ bool CWallet::SetMaxVersion(int nVersion)
     return true;
 }
 
-set<uint256> CWallet::GetConflicts(const uint256& txid) const
+set<uint256> CWallet::GetConflicts(const uint256& txid, bool includeEquivalent) const
 {
     set<uint256> result;
     AssertLockHeld(cs_wallet);
@@ -274,7 +274,8 @@ set<uint256> CWallet::GetConflicts(const uint256& txid) const
             continue;  // No conflict if zero or one spends
         range = mapTxSpends.equal_range(txin.prevout);
         for (TxSpends::const_iterator it = range.first; it != range.second; ++it)
-            result.insert(it->second);
+            if (includeEquivalent || !wtx.IsEquivalentTo(mapWallet.at(it->second)))
+                result.insert(it->second);
     }
     return result;
 }
@@ -303,6 +304,7 @@ void CWallet::SyncMetaData(pair<TxSpends::iterator, TxSpends::iterator> range)
         const uint256& hash = it->second;
         CWalletTx* copyTo = &mapWallet[hash];
         if (copyFrom == copyTo) continue;
+        if (!copyFrom->IsEquivalentTo(*copyTo)) continue;
         copyTo->mapValue = copyFrom->mapValue;
         copyTo->vOrderForm = copyFrom->vOrderForm;
         // fTimeReceivedIsTxTime not copied on purpose
@@ -588,6 +590,20 @@ bool CWallet::AddToWallet(const CWalletTx& wtxIn, bool fFromLoadWallet)
         // Notify UI of new or updated transaction
         NotifyTransactionChanged(this, hash, fInsertedNew ? CT_NEW : CT_UPDATED);
 
+        // Notifications for existing transactions that now have conflicts with this one
+        if (fInsertedNew)
+        {
+            BOOST_FOREACH(const uint256& conflictHash, wtxIn.GetConflicts(false))
+            {
+                CWalletTx& txConflict = mapWallet[conflictHash];
+                NotifyTransactionChanged(this, conflictHash, CT_UPDATED); //Updates UI table
+                if (IsFromMe(txConflict) || IsMine(txConflict))
+                {
+                    NotifyTransactionChanged(this, conflictHash, CT_GOT_CONFLICT);  //Throws dialog
+                }
+            }
+        }
+
         // notify an external script when a wallet transaction comes in or is updated
         std::string strCmd = GetArg("-walletnotify", "");
 
@@ -610,7 +626,12 @@ bool CWallet::AddToWalletIfInvolvingMe(const CTransaction& tx, const CBlock* pbl
         AssertLockHeld(cs_wallet);
         bool fExisted = mapWallet.count(tx.GetHash());
         if (fExisted && !fUpdate) return false;
-        if (fExisted || IsMine(tx) || IsFromMe(tx))
+
+        bool fIsConflicting = IsConflicting(tx);
+        if (fIsConflicting)
+        	nConflictsReceived++;
+
+        if (fExisted || IsMine(tx) || IsFromMe(tx) || fIsConflicting)
         {
             CWalletTx wtx(this,tx);
             // Get merkle branch if transaction was found in a block
@@ -896,7 +917,7 @@ void CWallet::ReacceptWalletTransactions()
 
         int nDepth = wtx.GetDepthInMainChain();
 
-        if (!wtx.IsCoinBase() && nDepth < 0)
+        if (!wtx.IsCoinBase() && nDepth < 0 && (IsMine(wtx) || IsFromMe(wtx)))
         {
             // Try to add to memory pool
             LOCK(mempool.cs);
@@ -916,13 +937,13 @@ void CWalletTx::RelayWalletTransaction()
     }
 }
 
-set<uint256> CWalletTx::GetConflicts() const
+set<uint256> CWalletTx::GetConflicts(bool includeEquivalent) const
 {
     set<uint256> result;
     if (pwallet != NULL)
     {
         uint256 myHash = GetHash();
-        result = pwallet->GetConflicts(myHash);
+        result = pwallet->GetConflicts(myHash, includeEquivalent);
         result.erase(myHash);
     }
     return result;

src/wallet.h

@@ -141,6 +141,9 @@ class CWallet : public CCryptoKeyStore, public CWalletInterface
     MasterKeyMap mapMasterKeys;
     unsigned int nMasterKeyMaxID;
 
+    // Increment to cause UI refresh, similar to new block
+    int64_t nConflictsReceived;
+
     CWallet()
     {
         SetNull();
@@ -163,6 +166,7 @@ class CWallet : public CCryptoKeyStore, public CWalletInterface
         nNextResend = 0;
         nLastResend = 0;
         nTimeFirstKey = 0;
+        nConflictsReceived = 0;
     }
 
     std::map<uint256, CWalletTx> mapWallet;
@@ -305,6 +309,13 @@ class CWallet : public CCryptoKeyStore, public CWalletInterface
     {
         return (GetDebit(tx) > 0);
     }
+    bool IsConflicting(const CTransaction& tx) const
+    {
+  	    BOOST_FOREACH(const CTxIn& txin, tx.vin)
+    	    if (mapTxSpends.count(txin.prevout))
+    	        return true;
+   	    return false;
+    }
     int64_t GetDebit(const CTransaction& tx) const
     {
         int64_t nDebit = 0;
@@ -377,7 +388,7 @@ class CWallet : public CCryptoKeyStore, public CWalletInterface
     int GetVersion() { LOCK(cs_wallet); return nWalletVersion; }
 
     // Get wallet transactions that conflict with given transaction (spend same outputs)
-    std::set<uint256> GetConflicts(const uint256& txid) const;
+    std::set<uint256> GetConflicts(const uint256& txid, bool includeEquivalent) const;
 
     /** Address book entry changed.
      * @note called with lock cs_wallet held.
@@ -699,7 +710,7 @@ class CWalletTx : public CMerkleTx
 
     void RelayWalletTransaction();
 
-    std::set<uint256> GetConflicts() const;
+    std::set<uint256> GetConflicts(bool includeEquivalent=true) const;
 };