rpc: add an include_change parameter to listsinceblock

It's useful for an external application tracking coins to not be limited
by our change detection. For instance, for a watchonly wallet with two
descriptors a transaction from one to the other would be considered a
change output and not be included in the result (if the address was not
generated by this wallet).

Author: darosior

src/rpc/client.cpp

@@ -74,6 +74,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "listsinceblock", 1, "target_confirmations" },
     { "listsinceblock", 2, "include_watchonly" },
     { "listsinceblock", 3, "include_removed" },
+    { "listsinceblock", 4, "include_change" },
     { "sendmany", 1, "amounts" },
     { "sendmany", 2, "minconf" },
     { "sendmany", 4, "subtractfeefrom" },

src/wallet/receive.cpp

@@ -223,7 +223,8 @@ CAmount CachedTxGetAvailableCredit(const CWallet& wallet, const CWalletTx& wtx,
 
 void CachedTxGetAmounts(const CWallet& wallet, const CWalletTx& wtx,
                   std::list<COutputEntry>& listReceived,
-                  std::list<COutputEntry>& listSent, CAmount& nFee, const isminefilter& filter)
+                  std::list<COutputEntry>& listSent, CAmount& nFee, const isminefilter& filter,
+                  bool include_change)
 {
     nFee = 0;
     listReceived.clear();
@@ -248,8 +249,7 @@ void CachedTxGetAmounts(const CWallet& wallet, const CWalletTx& wtx,
         //   2) the output is to us (received)
         if (nDebit > 0)
         {
-            // Don't report 'change' txouts
-            if (OutputIsChange(wallet, txout))
+            if (!include_change && OutputIsChange(wallet, txout))
                 continue;
         }
         else if (!(fIsMine & filter))

src/wallet/receive.h

@@ -44,7 +44,8 @@ struct COutputEntry
 void CachedTxGetAmounts(const CWallet& wallet, const CWalletTx& wtx,
                         std::list<COutputEntry>& listReceived,
                         std::list<COutputEntry>& listSent,
-                        CAmount& nFee, const isminefilter& filter);
+                        CAmount& nFee, const isminefilter& filter,
+                        bool include_change);
 bool CachedTxIsFromMe(const CWallet& wallet, const CWalletTx& wtx, const isminefilter& filter);
 bool CachedTxIsTrusted(const CWallet& wallet, const CWalletTx& wtx, std::set<uint256>& trusted_parents) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet);
 bool CachedTxIsTrusted(const CWallet& wallet, const CWalletTx& wtx);

src/wallet/rpc/transactions.cpp

@@ -315,13 +315,16 @@ static void MaybePushAddress(UniValue & entry, const CTxDestination &dest)
  * @param  filter_label   Optional label string to filter incoming transactions.
  */
 template <class Vec>
-static void ListTransactions(const CWallet& wallet, const CWalletTx& wtx, int nMinDepth, bool fLong, Vec& ret, const isminefilter& filter_ismine, const std::string* filter_label) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
+static void ListTransactions(const CWallet& wallet, const CWalletTx& wtx, int nMinDepth, bool fLong,
+                             Vec& ret, const isminefilter& filter_ismine, const std::string* filter_label,
+                             bool include_change = false)
+    EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
 {
     CAmount nFee;
     std::list<COutputEntry> listReceived;
     std::list<COutputEntry> listSent;
 
-    CachedTxGetAmounts(wallet, wtx, listReceived, listSent, nFee, filter_ismine);
+    CachedTxGetAmounts(wallet, wtx, listReceived, listSent, nFee, filter_ismine, include_change);
 
     bool involvesWatchonly = CachedTxIsFromMe(wallet, wtx, ISMINE_WATCH_ONLY);
 
@@ -548,6 +551,7 @@ RPCHelpMan listsinceblock()
                     {"include_watchonly", RPCArg::Type::BOOL, RPCArg::DefaultHint{"true for watch-only wallets, otherwise false"}, "Include transactions to watch-only addresses (see 'importaddress')"},
                     {"include_removed", RPCArg::Type::BOOL, RPCArg::Default{true}, "Show transactions that were removed due to a reorg in the \"removed\" array\n"
                                                                        "(not guaranteed to work on pruned nodes)"},
+                    {"include_change", RPCArg::Type::BOOL, RPCArg::Default{false}, "Also add entries for change outputs.\n"},
                 },
                 RPCResult{
                     RPCResult::Type::OBJ, "", "",
@@ -628,6 +632,7 @@ RPCHelpMan listsinceblock()
     }
 
     bool include_removed = (request.params[3].isNull() || request.params[3].get_bool());
+    bool include_change = (!request.params[4].isNull() && request.params[4].get_bool());
 
     int depth = height ? wallet.GetLastBlockHeight() + 1 - *height : -1;
 
@@ -637,7 +642,7 @@ RPCHelpMan listsinceblock()
         const CWalletTx& tx = pairWtx.second;
 
         if (depth == -1 || abs(wallet.GetTxDepthInMainChain(tx)) < depth) {
-            ListTransactions(wallet, tx, 0, true, transactions, filter, nullptr /* filter_label */);
+            ListTransactions(wallet, tx, 0, true, transactions, filter, nullptr /* filter_label */, /*include_change=*/include_change);
         }
     }
 
@@ -654,7 +659,7 @@ RPCHelpMan listsinceblock()
             if (it != wallet.mapWallet.end()) {
                 // We want all transactions regardless of confirmation count to appear here,
                 // even negative confirmation ones, hence the big negative.
-                ListTransactions(wallet, it->second, -100000000, true, removed, filter, nullptr /* filter_label */);
+                ListTransactions(wallet, it->second, -100000000, true, removed, filter, nullptr /* filter_label */, /*include_change=*/include_change);
             }
         }
         blockId = block.hashPrevBlock;

test/functional/wallet_listsinceblock.py

@@ -41,6 +41,7 @@ def run_test(self):
         self.double_spends_filtered()
         self.test_targetconfirmations()
         self.test_desc()
+        self.test_send_to_self()
 
     def test_no_blockhash(self):
         self.log.info("Test no blockhash")
@@ -423,6 +424,27 @@ def test_desc(self):
         coin_b = next(c for c in coins if c["amount"] == 2)
         assert_equal(coin_b["parent_descs"][0], multi_b)
 
+    def test_send_to_self(self):
+        """We can make listsinceblock output our change outputs."""
+        self.log.info("Test the inclusion of change outputs in the output.")
+
+        # Create a UTxO paying to one of our change addresses.
+        block_hash = self.nodes[2].getbestblockhash()
+        addr = self.nodes[2].getrawchangeaddress()
+        self.nodes[2].sendtoaddress(addr, 1)
+
+        # If we don't list change, we won't have an entry for it.
+        coins = self.nodes[2].listsinceblock(blockhash=block_hash)["transactions"]
+        assert not any(c["address"] == addr for c in coins)
+
+        # Now if we list change, we'll get both the send (to a change address) and
+        # the actual change.
+        res = self.nodes[2].listsinceblock(blockhash=block_hash, include_change=True)
+        coins = [entry for entry in res["transactions"] if entry["category"] == "receive"]
+        assert_equal(len(coins), 2)
+        assert any(c["address"] == addr for c in coins)
+        assert all(self.nodes[2].getaddressinfo(c["address"])["ischange"] for c in coins)
+
 
 if __name__ == '__main__':
     ListSinceBlockTest().main()