1 // Copyright (c) 2021-2022 The Limenka developers
2 // Distributed under the MIT software license, see the accompanying
3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 5 #include <consensus/amount.h>
6 #include <policy/fees.h>
7 #include <script/solver.h>
8 #include <validation.h>
9 #include <wallet/coincontrol.h>
10 #include <wallet/spend.h>
11 #include <wallet/test/util.h>
12 #include <wallet/test/wallet_test_fixture.h>
13 14 #include <boost/test/unit_test.hpp>
15 #include <test/util/boost_no_print_int128.h>
16 17 namespace wallet {
18 BOOST_FIXTURE_TEST_SUITE(spend_tests, WalletTestingSetup)
19 20 BOOST_FIXTURE_TEST_CASE(SubtractFee, TestChain100Setup)
21 {
22 CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
23 auto wallet = CreateSyncedWallet(*m_node.chain, WITH_LOCK(Assert(m_node.chainman)->GetMutex(), return m_node.chainman->ActiveChain()), coinbaseKey);
24 25 // Check that a subtract-from-recipient transaction slightly less than the
26 // coinbase input amount does not create a change output (because it would
27 // be uneconomical to add and spend the output), and make sure it pays the
28 // leftover input amount which would have been change to the recipient
29 // instead of the miner.
30 auto check_tx = [&wallet](CAmount leftover_input_amount) {
31 CRecipient recipient{PubKeyDestination({}), 50 * COIN - leftover_input_amount, /*subtract_fee=*/true};
32 CCoinControl coin_control;
33 coin_control.m_feerate.emplace(10000);
34 coin_control.fOverrideFeeRate = true;
35 // We need to use a change type with high cost of change so that the leftover amount will be dropped to fee instead of added as a change output
36 coin_control.m_change_type = OutputType::LEGACY;
37 auto res = CreateTransaction(*wallet, {recipient}, /*change_pos=*/std::nullopt, coin_control);
38 BOOST_CHECK(res);
39 const auto& txr = *res;
40 BOOST_CHECK_EQUAL(txr.tx->vout.size(), 1);
41 BOOST_CHECK_EQUAL(txr.tx->vout[0].nValue, recipient.nAmount + leftover_input_amount - txr.fee);
42 BOOST_CHECK_GT(txr.fee, 0);
43 return txr.fee;
44 };
45 46 // Send full input amount to recipient, check that only nonzero fee is
47 // subtracted (to_reduce == fee).
48 const CAmount fee{check_tx(0)};
49 50 // Send slightly less than full input amount to recipient, check leftover
51 // input amount is paid to recipient not the miner (to_reduce == fee - 123)
52 BOOST_CHECK_EQUAL(fee, check_tx(123));
53 54 // Send full input minus fee amount to recipient, check leftover input
55 // amount is paid to recipient not the miner (to_reduce == 0)
56 BOOST_CHECK_EQUAL(fee, check_tx(fee));
57 58 // Send full input minus more than the fee amount to recipient, check
59 // leftover input amount is paid to recipient not the miner (to_reduce ==
60 // -123). This overpays the recipient instead of overpaying the miner more
61 // than double the necessary fee.
62 BOOST_CHECK_EQUAL(fee, check_tx(fee + 123));
63 }
64 65 BOOST_FIXTURE_TEST_CASE(wallet_duplicated_preset_inputs_test, TestChain100Setup)
66 {
67 // Verify that the wallet's Coin Selection process does not include pre-selected inputs twice in a transaction.
68 69 // Add 4 spendable UTXO, 50 BTC each, to the wallet (total balance 200 BTC)
70 for (int i = 0; i < 4; i++) CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
71 auto wallet = CreateSyncedWallet(*m_node.chain, WITH_LOCK(Assert(m_node.chainman)->GetMutex(), return m_node.chainman->ActiveChain()), coinbaseKey);
72 73 LOCK(wallet->cs_wallet);
74 auto available_coins = AvailableCoins(*wallet);
75 std::vector<COutput> coins = available_coins.All();
76 // Preselect the first 3 UTXO (150 BTC total)
77 std::set<COutPoint> preset_inputs = {coins[0].outpoint, coins[1].outpoint, coins[2].outpoint};
78 79 // Try to create a tx that spends more than what preset inputs + wallet selected inputs are covering for.
80 // The wallet can cover up to 200 BTC, and the tx target is 299 BTC.
81 std::vector<CRecipient> recipients{{*Assert(wallet->GetNewDestination(OutputType::BECH32, "dummy")),
82 /*nAmount=*/299 * COIN, /*fSubtractFeeFromAmount=*/true}};
83 CCoinControl coin_control;
84 coin_control.m_allow_other_inputs = true;
85 for (const auto& outpoint : preset_inputs) {
86 coin_control.Select(outpoint);
87 }
88 89 // Attempt to send 299 BTC from a wallet that only has 200 BTC. The wallet should exclude
90 // the preset inputs from the pool of available coins, realize that there is not enough
91 // money to fund the 299 BTC payment, and fail with "Insufficient funds".
92 //
93 // Even with SFFO, the wallet can only afford to send 200 BTC.
94 // If the wallet does not properly exclude preset inputs from the pool of available coins
95 // prior to coin selection, it may create a transaction that does not fund the full payment
96 // amount or, through SFFO, incorrectly reduce the recipient's amount by the difference
97 // between the original target and the wrongly counted inputs (in this case 99 BTC)
98 // so that the recipient's amount is no longer equal to the user's selected target of 299 BTC.
99 100 // First case, use 'subtract_fee_from_outputs=true'
101 BOOST_CHECK(!CreateTransaction(*wallet, recipients, /*change_pos=*/std::nullopt, coin_control));
102 103 // Second case, don't use 'subtract_fee_from_outputs'.
104 recipients[0].fSubtractFeeFromAmount = false;
105 BOOST_CHECK(!CreateTransaction(*wallet, recipients, /*change_pos=*/std::nullopt, coin_control));
106 }
107 108 BOOST_AUTO_TEST_SUITE_END()
109 } // namespace wallet
110