Wallet/RPC: Allow specifying min & max chain depth for inputs used by fund calls

Enables users to craft BIP-125 replacements with changes to the output
list, ensuring that if additional funds are needed they will be added.

5 files changed, 170 insertions, 1 deletions

diff --git a/doc/release-notes-25375.md b/doc/release-notes-25375.md
new file mode 100644
index 0000000000..24605b12f0
--- /dev/null
+++ b/doc/release-notes-25375.md
@@ -0,0 +1,10 @@
+Updated RPCs
+--------
+
+The `minconf` option, which allows a user to specify the minimum number
+of confirmations a UTXO being spent has, and the `maxconf` option,
+which allows specifying the maximum number of confirmations, have been
+added to the following RPCs:
+- `fundrawtransaction`
+- `send`
+- `walletcreatefundedpsbt`
diff --git a/src/wallet/rpc/spend.cpp b/src/wallet/rpc/spend.cpp
index be1ad37592..280d6a8061 100644
--- a/src/wallet/rpc/spend.cpp
+++ b/src/wallet/rpc/spend.cpp
@@ -528,6 +528,8 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
                 {"replaceable", UniValueType(UniValue::VBOOL)},
                 {"conf_target", UniValueType(UniValue::VNUM)},
                 {"estimate_mode", UniValueType(UniValue::VSTR)},
+                {"minconf", UniValueType(UniValue::VNUM)},
+                {"maxconf", UniValueType(UniValue::VNUM)},
                 {"input_weights", UniValueType(UniValue::VARR)},
             },
             true, true);
@@ -593,6 +595,22 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
         if (options.exists("replaceable")) {
             coinControl.m_signal_bip125_rbf = options["replaceable"].get_bool();
         }
+
+        if (options.exists("minconf")) {
+            coinControl.m_min_depth = options["minconf"].getInt<int>();
+
+            if (coinControl.m_min_depth < 0) {
+                throw JSONRPCError(RPC_INVALID_PARAMETER, "Negative minconf");
+            }
+        }
+
+        if (options.exists("maxconf")) {
+            coinControl.m_max_depth = options["maxconf"].getInt<int>();
+
+            if (coinControl.m_max_depth < coinControl.m_min_depth) {
+                throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("maxconf can't be lower than minconf: %d < %d", coinControl.m_max_depth, coinControl.m_min_depth));
+            }
+        }
         SetFeeEstimateMode(wallet, coinControl, options["conf_target"], options["estimate_mode"], options["fee_rate"], override_min_fee);
       }
     } else {
@@ -744,6 +762,8 @@ RPCHelpMan fundrawtransaction()
                             {"include_unsafe", RPCArg::Type::BOOL, RPCArg::Default{false}, "Include inputs that are not safe to spend (unconfirmed transactions from outside keys and unconfirmed replacement transactions).\n"
                                                           "Warning: the resulting transaction may become invalid if one of the unsafe inputs disappears.\n"
                                                           "If that happens, you will need to fund the transaction with different inputs and republish it."},
+                            {"minconf", RPCArg::Type::NUM, RPCArg::Default{0}, "If add_inputs is specified, require inputs with at least this many confirmations."},
+                            {"maxconf", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "If add_inputs is specified, require inputs with at most this many confirmations."},
                             {"changeAddress", RPCArg::Type::STR, RPCArg::DefaultHint{"automatic"}, "The bitcoin address to receive the change"},
                             {"changePosition", RPCArg::Type::NUM, RPCArg::DefaultHint{"random"}, "The index of the change output"},
                             {"change_type", RPCArg::Type::STR, RPCArg::DefaultHint{"set by -changetype"}, "The output type to use. Only valid if changeAddress is not specified. Options are \"legacy\", \"p2sh-segwit\", \"bech32\", and \"bech32m\"."},
@@ -1147,6 +1167,8 @@ RPCHelpMan send()
                     {"include_unsafe", RPCArg::Type::BOOL, RPCArg::Default{false}, "Include inputs that are not safe to spend (unconfirmed transactions from outside keys and unconfirmed replacement transactions).\n"
                                                           "Warning: the resulting transaction may become invalid if one of the unsafe inputs disappears.\n"
                                                           "If that happens, you will need to fund the transaction with different inputs and republish it."},
+                    {"minconf", RPCArg::Type::NUM, RPCArg::Default{0}, "If add_inputs is specified, require inputs with at least this many confirmations."},
+                    {"maxconf", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "If add_inputs is specified, require inputs with at most this many confirmations."},
                     {"add_to_wallet", RPCArg::Type::BOOL, RPCArg::Default{true}, "When false, returns a serialized transaction which will not be added to the wallet or broadcast"},
                     {"change_address", RPCArg::Type::STR, RPCArg::DefaultHint{"automatic"}, "The bitcoin address to receive the change"},
                     {"change_position", RPCArg::Type::NUM, RPCArg::DefaultHint{"random"}, "The index of the change output"},
@@ -1603,6 +1625,8 @@ RPCHelpMan walletcreatefundedpsbt()
                             {"include_unsafe", RPCArg::Type::BOOL, RPCArg::Default{false}, "Include inputs that are not safe to spend (unconfirmed transactions from outside keys and unconfirmed replacement transactions).\n"
                                                           "Warning: the resulting transaction may become invalid if one of the unsafe inputs disappears.\n"
                                                           "If that happens, you will need to fund the transaction with different inputs and republish it."},
+                            {"minconf", RPCArg::Type::NUM, RPCArg::Default{0}, "If add_inputs is specified, require inputs with at least this many confirmations."},
+                            {"maxconf", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "If add_inputs is specified, require inputs with at most this many confirmations."},
                             {"changeAddress", RPCArg::Type::STR, RPCArg::DefaultHint{"automatic"}, "The bitcoin address to receive the change"},
                             {"changePosition", RPCArg::Type::NUM, RPCArg::DefaultHint{"random"}, "The index of the change output"},
                             {"change_type", RPCArg::Type::STR, RPCArg::DefaultHint{"set by -changetype"}, "The output type to use. Only valid if changeAddress is not specified. Options are \"legacy\", \"p2sh-segwit\", \"bech32\", and \"bech32m\"."},
diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
index a50e0fb244..58a80e37a2 100755
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -36,6 +36,7 @@ from test_framework.util import (
     assert_approx,
     assert_equal,
     assert_greater_than,
+    assert_greater_than_or_equal,
     assert_raises_rpc_error,
     find_output,
     find_vout_for_address,
@@ -106,6 +107,65 @@ class PSBTTest(BitcoinTestFramework):
         self.connect_nodes(0, 1)
         self.connect_nodes(0, 2)
 
+    def test_input_confs_control(self):
+        self.nodes[0].createwallet("minconf")
+        wallet = self.nodes[0].get_wallet_rpc("minconf")
+
+        # Fund the wallet with different chain heights
+        for _ in range(2):
+            self.nodes[1].sendmany("", {wallet.getnewaddress():1, wallet.getnewaddress():1})
+            self.generate(self.nodes[1], 1)
+
+        unconfirmed_txid = wallet.sendtoaddress(wallet.getnewaddress(), 0.5)
+
+        self.log.info("Crafting PSBT using an unconfirmed input")
+        target_address = self.nodes[1].getnewaddress()
+        psbtx1 = wallet.walletcreatefundedpsbt([], {target_address: 0.1}, 0, {'fee_rate': 1, 'maxconf': 0})['psbt']
+
+        # Make sure we only had the one input
+        tx1_inputs = self.nodes[0].decodepsbt(psbtx1)['tx']['vin']
+        assert_equal(len(tx1_inputs), 1)
+
+        utxo1 = tx1_inputs[0]
+        assert_equal(unconfirmed_txid, utxo1['txid'])
+
+        signed_tx1 = wallet.walletprocesspsbt(psbtx1)['psbt']
+        final_tx1 = wallet.finalizepsbt(signed_tx1)['hex']
+        txid1 = self.nodes[0].sendrawtransaction(final_tx1)
+
+        mempool = self.nodes[0].getrawmempool()
+        assert txid1 in mempool
+
+        self.log.info("Fail to craft a new PSBT that sends more funds with add_inputs = False")
+        assert_raises_rpc_error(-4, "The preselected coins total amount does not cover the transaction target. Please allow other inputs to be automatically selected or include more coins manually", wallet.walletcreatefundedpsbt, [{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': False})
+
+        self.log.info("Fail to craft a new PSBT with minconf above highest one")
+        assert_raises_rpc_error(-4, "Insufficient funds", wallet.walletcreatefundedpsbt, [{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': True, 'minconf': 3, 'fee_rate': 10})
+
+        self.log.info("Fail to broadcast a new PSBT with maxconf 0 due to BIP125 rules to verify it actually chose unconfirmed outputs")
+        psbt_invalid = wallet.walletcreatefundedpsbt([{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': True, 'maxconf': 0, 'fee_rate': 10})['psbt']
+        signed_invalid = wallet.walletprocesspsbt(psbt_invalid)['psbt']
+        final_invalid = wallet.finalizepsbt(signed_invalid)['hex']
+        assert_raises_rpc_error(-26, "bad-txns-spends-conflicting-tx", self.nodes[0].sendrawtransaction, final_invalid)
+
+        self.log.info("Craft a replacement adding inputs with highest confs possible")
+        psbtx2 = wallet.walletcreatefundedpsbt([{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': True, 'minconf': 2, 'fee_rate': 10})['psbt']
+        tx2_inputs = self.nodes[0].decodepsbt(psbtx2)['tx']['vin']
+        assert_greater_than_or_equal(len(tx2_inputs), 2)
+        for vin in tx2_inputs:
+            if vin['txid'] != unconfirmed_txid:
+                assert_greater_than_or_equal(self.nodes[0].gettxout(vin['txid'], vin['vout'])['confirmations'], 2)
+
+        signed_tx2 = wallet.walletprocesspsbt(psbtx2)['psbt']
+        final_tx2 = wallet.finalizepsbt(signed_tx2)['hex']
+        txid2 = self.nodes[0].sendrawtransaction(final_tx2)
+
+        mempool = self.nodes[0].getrawmempool()
+        assert txid1 not in mempool
+        assert txid2 in mempool
+
+        wallet.unloadwallet()
+
     def assert_change_type(self, psbtx, expected_type):
         """Assert that the given PSBT has a change output with the given type."""
 
@@ -514,6 +574,8 @@ class PSBTTest(BitcoinTestFramework):
         # TODO: Re-enable this for segwit v1
         # self.test_utxo_conversion()
 
+        self.test_input_confs_control()
+
         # Test that psbts with p2pkh outputs are created properly
         p2pkh = self.nodes[0].getnewaddress(address_type='legacy')
         psbt = self.nodes[1].walletcreatefundedpsbt([], [{p2pkh : 1}], 0, {"includeWatching" : True}, True)
diff --git a/test/functional/wallet_fundrawtransaction.py b/test/functional/wallet_fundrawtransaction.py
index 98b0f70b01..29ddb77b41 100755
--- a/test/functional/wallet_fundrawtransaction.py
+++ b/test/functional/wallet_fundrawtransaction.py
@@ -148,6 +148,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         self.test_external_inputs()
         self.test_22670()
         self.test_feerate_rounding()
+        self.test_input_confs_control()
 
     def test_change_position(self):
         """Ensure setting changePosition in fundraw with an exact match is handled properly."""
@@ -1403,6 +1404,66 @@ class RawTransactionsTest(BitcoinTestFramework):
         rawtx = w.createrawtransaction(inputs=[], outputs=[{self.nodes[0].getnewaddress(address_type="bech32"): 1 - 0.00000202}])
         assert_raises_rpc_error(-4, "Insufficient funds", w.fundrawtransaction, rawtx, {"fee_rate": 1.85})
 
+    def test_input_confs_control(self):
+        self.nodes[0].createwallet("minconf")
+        wallet = self.nodes[0].get_wallet_rpc("minconf")
+
+        # Fund the wallet with different chain heights
+        for _ in range(2):
+            self.nodes[2].sendmany("", {wallet.getnewaddress():1, wallet.getnewaddress():1})
+            self.generate(self.nodes[2], 1)
+
+        unconfirmed_txid = wallet.sendtoaddress(wallet.getnewaddress(), 0.5)
+
+        self.log.info("Crafting TX using an unconfirmed input")
+        target_address = self.nodes[2].getnewaddress()
+        raw_tx1 = wallet.createrawtransaction([], {target_address: 0.1}, 0, True)
+        funded_tx1 = wallet.fundrawtransaction(raw_tx1, {'fee_rate': 1, 'maxconf': 0})['hex']
+
+        # Make sure we only had the one input
+        tx1_inputs = self.nodes[0].decoderawtransaction(funded_tx1)['vin']
+        assert_equal(len(tx1_inputs), 1)
+
+        utxo1 = tx1_inputs[0]
+        assert unconfirmed_txid == utxo1['txid']
+
+        final_tx1 = wallet.signrawtransactionwithwallet(funded_tx1)['hex']
+        txid1 = self.nodes[0].sendrawtransaction(final_tx1)
+
+        mempool = self.nodes[0].getrawmempool()
+        assert txid1 in mempool
+
+        self.log.info("Fail to craft a new TX with minconf above highest one")
+        # Create a replacement tx to 'final_tx1' that has 1 BTC target instead of 0.1.
+        raw_tx2 = wallet.createrawtransaction([{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1})
+        assert_raises_rpc_error(-4, "Insufficient funds", wallet.fundrawtransaction, raw_tx2, {'add_inputs': True, 'minconf': 3, 'fee_rate': 10})
+
+        self.log.info("Fail to broadcast a new TX with maxconf 0 due to BIP125 rules to verify it actually chose unconfirmed outputs")
+        # Now fund 'raw_tx2' to fulfill the total target (1 BTC) by using all the wallet unconfirmed outputs.
+        # As it was created with the first unconfirmed output, 'raw_tx2' only has 0.1 BTC covered (need to fund 0.9 BTC more).
+        # So, the selection process, to cover the amount, will pick up the 'final_tx1' output as well, which is an output of the tx that this
+        # new tx is replacing!. So, once we send it to the mempool, it will return a "bad-txns-spends-conflicting-tx"
+        # because the input will no longer exist once the first tx gets replaced by this new one).
+        funded_invalid = wallet.fundrawtransaction(raw_tx2, {'add_inputs': True, 'maxconf': 0, 'fee_rate': 10})['hex']
+        final_invalid = wallet.signrawtransactionwithwallet(funded_invalid)['hex']
+        assert_raises_rpc_error(-26, "bad-txns-spends-conflicting-tx", self.nodes[0].sendrawtransaction, final_invalid)
+
+        self.log.info("Craft a replacement adding inputs with highest depth possible")
+        funded_tx2 = wallet.fundrawtransaction(raw_tx2, {'add_inputs': True, 'minconf': 2, 'fee_rate': 10})['hex']
+        tx2_inputs = self.nodes[0].decoderawtransaction(funded_tx2)['vin']
+        assert_greater_than_or_equal(len(tx2_inputs), 2)
+        for vin in tx2_inputs:
+            if vin['txid'] != unconfirmed_txid:
+                assert_greater_than_or_equal(self.nodes[0].gettxout(vin['txid'], vin['vout'])['confirmations'], 2)
+
+        final_tx2 = wallet.signrawtransactionwithwallet(funded_tx2)['hex']
+        txid2 = self.nodes[0].sendrawtransaction(final_tx2)
+
+        mempool = self.nodes[0].getrawmempool()
+        assert txid1 not in mempool
+        assert txid2 in mempool
+
+        wallet.unloadwallet()
 
 if __name__ == '__main__':
     RawTransactionsTest().main()
diff --git a/test/functional/wallet_send.py b/test/functional/wallet_send.py
index 424834323f..ac3ec06eec 100755
--- a/test/functional/wallet_send.py
+++ b/test/functional/wallet_send.py
@@ -45,7 +45,7 @@ class WalletSendTest(BitcoinTestFramework):
                   conf_target=None, estimate_mode=None, fee_rate=None, add_to_wallet=None, psbt=None,
                   inputs=None, add_inputs=None, include_unsafe=None, change_address=None, change_position=None, change_type=None,
                   include_watching=None, locktime=None, lock_unspents=None, replaceable=None, subtract_fee_from_outputs=None,
-                  expect_error=None, solving_data=None):
+                  expect_error=None, solving_data=None, minconf=None):
         assert (amount is None) != (data is None)
 
         from_balance_before = from_wallet.getbalances()["mine"]["trusted"]
@@ -106,6 +106,8 @@ class WalletSendTest(BitcoinTestFramework):
             options["subtract_fee_from_outputs"] = subtract_fee_from_outputs
         if solving_data is not None:
             options["solving_data"] = solving_data
+        if minconf is not None:
+            options["minconf"] = minconf
 
         if len(options.keys()) == 0:
             options = None
@@ -487,6 +489,16 @@ class WalletSendTest(BitcoinTestFramework):
         res = self.test_send(from_wallet=w5, to_wallet=w0, amount=1, include_unsafe=True)
         assert res["complete"]
 
+        self.log.info("Minconf")
+        self.nodes[1].createwallet(wallet_name="minconfw")
+        minconfw= self.nodes[1].get_wallet_rpc("minconfw")
+        self.test_send(from_wallet=w0, to_wallet=minconfw, amount=2)
+        self.generate(self.nodes[0], 3)
+        self.test_send(from_wallet=minconfw, to_wallet=w0, amount=1, minconf=4, expect_error=(-4, "Insufficient funds"))
+        self.test_send(from_wallet=minconfw, to_wallet=w0, amount=1, minconf=-4, expect_error=(-8, "Negative minconf"))
+        res = self.test_send(from_wallet=minconfw, to_wallet=w0, amount=1, minconf=3)
+        assert res["complete"]
+
         self.log.info("External outputs")
         eckey = ECKey()
         eckey.generate()