Add COutput::fSafe member for safe handling of unconfirmed outputs

This exposes a value computed in CWallet::AvailableCoins so it can used for
other things, like inclusion in listunspent output.

src/bench/coin_selection.cpp

@@ -20,7 +20,7 @@ static void addCoin(const CAmount& nValue, const CWallet& wallet, std::vector<CO
     CWalletTx* wtx = new CWalletTx(&wallet, MakeTransactionRef(std::move(tx)));
 
     int nAge = 6 * 24;
-    COutput output(wtx, nInput, nAge, true, true);
+    COutput output(wtx, nInput, nAge, true /* spendable */, true /* solvable */, true /* safe */);
     vCoins.push_back(output);
 }
 

src/qt/walletmodel.cpp

@@ -580,7 +580,7 @@ void WalletModel::getOutputs(const std::vector<COutPoint>& vOutpoints, std::vect
         if (!wallet->mapWallet.count(outpoint.hash)) continue;
         int nDepth = wallet->mapWallet[outpoint.hash].GetDepthInMainChain();
         if (nDepth < 0) continue;
-        COutput out(&wallet->mapWallet[outpoint.hash], outpoint.n, nDepth, true, true);
+        COutput out(&wallet->mapWallet[outpoint.hash], outpoint.n, nDepth, true /* spendable */, true /* solvable */, true /* safe */);
         vOutputs.push_back(out);
     }
 }
@@ -607,7 +607,7 @@ void WalletModel::listCoins(std::map<QString, std::vector<COutput> >& mapCoins)
         if (!wallet->mapWallet.count(outpoint.hash)) continue;
         int nDepth = wallet->mapWallet[outpoint.hash].GetDepthInMainChain();
         if (nDepth < 0) continue;
-        COutput out(&wallet->mapWallet[outpoint.hash], outpoint.n, nDepth, true, true);
+        COutput out(&wallet->mapWallet[outpoint.hash], outpoint.n, nDepth, true /* spendable */, true /* solvable */, true /* safe */);
         if (outpoint.n < out.tx->tx->vout.size() && wallet->IsMine(out.tx->tx->vout[outpoint.n]) == ISMINE_SPENDABLE)
             vCoins.push_back(out);
     }
@@ -619,7 +619,7 @@ void WalletModel::listCoins(std::map<QString, std::vector<COutput> >& mapCoins)
         while (wallet->IsChange(cout.tx->tx->vout[cout.i]) && cout.tx->tx->vin.size() > 0 && wallet->IsMine(cout.tx->tx->vin[0]))
         {
             if (!wallet->mapWallet.count(cout.tx->tx->vin[0].prevout.hash)) break;
-            cout = COutput(&wallet->mapWallet[cout.tx->tx->vin[0].prevout.hash], cout.tx->tx->vin[0].prevout.n, 0, true, true);
+            cout = COutput(&wallet->mapWallet[cout.tx->tx->vin[0].prevout.hash], cout.tx->tx->vin[0].prevout.n, 0 /* depth */, true /* spendable */, true /* solvable */, true /* safe */);
         }
 
         CTxDestination address;

src/wallet/test/wallet_tests.cpp

@@ -54,7 +54,7 @@ static void add_coin(const CAmount& nValue, int nAge = 6*24, bool fIsFromMe = fa
         wtx->fDebitCached = true;
         wtx->nDebitCached = 1;
     }
-    COutput output(wtx.get(), nInput, nAge, true, true);
+    COutput output(wtx.get(), nInput, nAge, true /* spendable */, true /* solvable */, true /* safe */);
     vCoins.push_back(output);
     wtxn.emplace_back(std::move(wtx));
 }

src/wallet/wallet.cpp

@@ -1946,7 +1946,7 @@ CAmount CWallet::GetImmatureWatchOnlyBalance() const
     return nTotal;
 }
 
-void CWallet::AvailableCoins(std::vector<COutput>& vCoins, bool fOnlyConfirmed, const CCoinControl *coinControl, bool fIncludeZeroValue) const
+void CWallet::AvailableCoins(std::vector<COutput>& vCoins, bool fOnlySafe, const CCoinControl *coinControl, bool fIncludeZeroValue) const
 {
     vCoins.clear();
 
@@ -1960,9 +1960,6 @@ void CWallet::AvailableCoins(std::vector<COutput>& vCoins, bool fOnlyConfirmed,
             if (!CheckFinalTx(*pcoin))
                 continue;
 
-            if (fOnlyConfirmed && !pcoin->IsTrusted())
-                continue;
-
             if (pcoin->IsCoinBase() && pcoin->GetBlocksToMaturity() > 0)
                 continue;
 
@@ -1975,6 +1972,8 @@ void CWallet::AvailableCoins(std::vector<COutput>& vCoins, bool fOnlyConfirmed,
             if (nDepth == 0 && !pcoin->InMempool())
                 continue;
 
+            bool safeTx = pcoin->IsTrusted();
+
             // We should not consider coins from transactions that are replacing
             // other transactions.
             //
@@ -1990,8 +1989,8 @@ void CWallet::AvailableCoins(std::vector<COutput>& vCoins, bool fOnlyConfirmed,
             // be a 1-block reorg away from the chain where transactions A and C
             // were accepted to another chain where B, B', and C were all
             // accepted.
-            if (nDepth == 0 && fOnlyConfirmed && pcoin->mapValue.count("replaces_txid")) {
+            if (nDepth == 0 && pcoin->mapValue.count("replaces_txid")) {
-                continue;
+                safeTx = false;
             }
 
             // Similarly, we should not consider coins from transactions that
@@ -2002,7 +2001,11 @@ void CWallet::AvailableCoins(std::vector<COutput>& vCoins, bool fOnlyConfirmed,
             // intending to replace A', but potentially resulting in a scenario
             // where A, A', and D could all be accepted (instead of just B and
             // D, or just A and A' like the user would want).
-            if (nDepth == 0 && fOnlyConfirmed && pcoin->mapValue.count("replaced_by_txid")) {
+            if (nDepth == 0 && pcoin->mapValue.count("replaced_by_txid")) {
+                safeTx = false;
+            }
+
+            if (fOnlySafe && !safeTx) {
                 continue;
             }
 
@@ -2014,7 +2017,7 @@ void CWallet::AvailableCoins(std::vector<COutput>& vCoins, bool fOnlyConfirmed,
                         vCoins.push_back(COutput(pcoin, i, nDepth,
                                                  ((mine & ISMINE_SPENDABLE) != ISMINE_NO) ||
                                                   (coinControl && coinControl->fAllowWatchOnly && (mine & ISMINE_WATCH_SOLVABLE) != ISMINE_NO),
-                                                 (mine & (ISMINE_SPENDABLE | ISMINE_WATCH_SOLVABLE)) != ISMINE_NO));
+                                                 (mine & (ISMINE_SPENDABLE | ISMINE_WATCH_SOLVABLE)) != ISMINE_NO, safeTx));
             }
         }
     }

src/wallet/wallet.h

@@ -466,12 +466,23 @@ public:
     const CWalletTx *tx;
     int i;
     int nDepth;
+
+    /** Whether we have the private keys to spend this output */
     bool fSpendable;
+
+    /** Whether we know how to spend this output, ignoring the lack of keys */
     bool fSolvable;
 
-    COutput(const CWalletTx *txIn, int iIn, int nDepthIn, bool fSpendableIn, bool fSolvableIn)
+    /**
+     * Whether this output is considered safe to spend. Unconfirmed transactions
+     * from outside keys and unconfirmed replacement transactions are considered
+     * unsafe and will not be used to fund new spending transactions.
+     */
+    bool fSafe;
+
+    COutput(const CWalletTx *txIn, int iIn, int nDepthIn, bool fSpendableIn, bool fSolvableIn, bool fSafeIn)
     {
-        tx = txIn; i = iIn; nDepth = nDepthIn; fSpendable = fSpendableIn; fSolvable = fSolvableIn;
+        tx = txIn; i = iIn; nDepth = nDepthIn; fSpendable = fSpendableIn; fSolvable = fSolvableIn; fSafe = fSafeIn;
     }
 
     std::string ToString() const;
@@ -740,7 +751,7 @@ public:
     /**
      * populate vCoins with vector of available COutputs.
      */
-    void AvailableCoins(std::vector<COutput>& vCoins, bool fOnlyConfirmed=true, const CCoinControl *coinControl = NULL, bool fIncludeZeroValue=false) const;
+    void AvailableCoins(std::vector<COutput>& vCoins, bool fOnlySafe=true, const CCoinControl *coinControl = NULL, bool fIncludeZeroValue=false) const;
 
     /**
      * Shuffle and select coins until nTargetValue is reached while avoiding