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