[wallet] Add GetLegacyBalance method to simplify getbalance RPC

This adds a simpler new implementation of getbalance logic along with asserts
to confirm it behaves identically to the old logic. The old logic is removed in
the next commit.

1 files changed, 58 insertions, 0 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index b63171c4b6..cd94eefb20 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1975,6 +1975,49 @@ CAmount CWallet::GetImmatureWatchOnlyBalance() const
     return nTotal;
 }
 
+// Calculate total balance in a different way from GetBalance. The biggest
+// difference is that GetBalance sums up all unspent TxOuts paying to the
+// wallet, while this sums up both spent and unspent TxOuts paying to the
+// wallet, and then subtracts the values of TxIns spending from the wallet. This
+// also has fewer restrictions on which unconfirmed transactions are considered
+// trusted.
+CAmount CWallet::GetLegacyBalance(const isminefilter& filter, int minDepth, const std::string* account) const
+{
+    LOCK2(cs_main, cs_wallet);
+
+    CAmount balance = 0;
+    for (const auto& entry : mapWallet) {
+        const CWalletTx& wtx = entry.second;
+        const int depth = wtx.GetDepthInMainChain();
+        if (depth < 0 || !CheckFinalTx(*wtx.tx) || wtx.GetBlocksToMaturity() > 0) {
+            continue;
+        }
+
+        // Loop through tx outputs and add incoming payments. For outgoing txs,
+        // treat change outputs specially, as part of the amount debited.
+        CAmount debit = wtx.GetDebit(filter);
+        const bool outgoing = debit > 0;
+        for (const CTxOut& out : wtx.tx->vout) {
+            if (outgoing && IsChange(out)) {
+                debit -= out.nValue;
+            } else if (IsMine(out) & filter && depth >= minDepth && (!account || *account == GetAccountName(out.scriptPubKey))) {
+                balance += out.nValue;
+            }
+        }
+
+        // For outgoing txs, subtract amount debited.
+        if (outgoing && (!account || *account == wtx.strFromAccount)) {
+            balance -= debit;
+        }
+    }
+
+    if (account) {
+        balance += CWalletDB(*dbw).GetAccountCreditDebit(*account);
+    }
+
+    return balance;
+}
+
 void CWallet::AvailableCoins(std::vector<COutput>& vCoins, bool fOnlySafe, const CCoinControl *coinControl, bool fIncludeZeroValue) const
 {
     vCoins.clear();
@@ -2911,6 +2954,21 @@ bool CWallet::DelAddressBook(const CTxDestination& address)
     return CWalletDB(*dbw).EraseName(CBitcoinAddress(address).ToString());
 }
 
+const std::string& CWallet::GetAccountName(const CScript& scriptPubKey) const
+{
+    CTxDestination address;
+    if (ExtractDestination(scriptPubKey, address) && !scriptPubKey.IsUnspendable()) {
+        auto mi = mapAddressBook.find(address);
+        if (mi != mapAddressBook.end()) {
+            return mi->second.name;
+        }
+    }
+    // A scriptPubKey that doesn't have an entry in the address book is
+    // associated with the default account ("").
+    const static std::string DEFAULT_ACCOUNT_NAME;
+    return DEFAULT_ACCOUNT_NAME;
+}
+
 bool CWallet::SetDefaultKey(const CPubKey &vchPubKey)
 {
     if (!CWalletDB(*dbw).WriteDefaultKey(vchPubKey))