1 // Copyright (c) 2021-present 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 <key.h>
7 #include <policy/fees/block_policy_estimator.h>
8 #include <script/solver.h>
9 #include <validation.h>
10 #include <wallet/coincontrol.h>
11 #include <wallet/spend.h>
12 #include <wallet/test/util.h>
13 #include <wallet/test/wallet_test_fixture.h>
14 15 #include <boost/test/unit_test.hpp>
16 17 namespace wallet {
18 BOOST_FIXTURE_TEST_SUITE(spend_tests, WalletTestingSetup)
19 20 BOOST_AUTO_TEST_CASE(max_signed_input_size_uses_external_outpoint)
21 {
22 const CKey key{GenerateRandomKey()};
23 FillableSigningProvider provider;
24 BOOST_REQUIRE(provider.AddKey(key));
25 26 const CTxOut txout{COIN, GetScriptForDestination(PKHash{key.GetPubKey()})};
27 const COutPoint outpoint{Txid{}, 0};
28 CCoinControl coin_control;
29 coin_control.Select(outpoint).SetTxOut(txout);
30 31 const int low_r{CalculateMaximumSignedInputSize(txout, COutPoint{}, &provider, /*can_grind_r=*/true, &coin_control)};
32 const int high_r{CalculateMaximumSignedInputSize(txout, outpoint, &provider, /*can_grind_r=*/true, &coin_control)};
33 BOOST_CHECK_EQUAL(high_r, low_r + 1);
34 }
35 36 BOOST_FIXTURE_TEST_CASE(SubtractFee, TestChain100Setup)
37 {
38 CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
39 auto wallet = CreateSyncedWallet(*m_node.chain, WITH_LOCK(Assert(m_node.chainman)->GetMutex(), return m_node.chainman->ActiveChain()), coinbaseKey);
40 41 // Check that a subtract-from-recipient transaction slightly less than the
42 // coinbase input amount does not create a change output (because it would
43 // be uneconomical to add and spend the output), and make sure it pays the
44 // leftover input amount which would have been change to the recipient
45 // instead of the miner.
46 auto check_tx = [&wallet](CAmount leftover_input_amount) {
47 CRecipient recipient{PubKeyDestination({}), 50 * COIN - leftover_input_amount, /*subtract_fee=*/true};
48 CCoinControl coin_control;
49 coin_control.m_feerate.emplace(10000);
50 coin_control.fOverrideFeeRate = true;
51 // 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
52 coin_control.m_change_type = OutputType::LEGACY;
53 auto res = CreateTransaction(*wallet, {recipient}, /*change_pos=*/std::nullopt, coin_control);
54 BOOST_CHECK(res);
55 const auto& txr = *res;
56 BOOST_CHECK_EQUAL(txr.tx->vout.size(), 1);
57 BOOST_CHECK_EQUAL(txr.tx->vout[0].nValue, recipient.nAmount + leftover_input_amount - txr.fee);
58 BOOST_CHECK_GT(txr.fee, 0);
59 return txr.fee;
60 };
61 62 // Send full input amount to recipient, check that only nonzero fee is
63 // subtracted (to_reduce == fee).
64 const CAmount fee{check_tx(0)};
65 66 // Send slightly less than full input amount to recipient, check leftover
67 // input amount is paid to recipient not the miner (to_reduce == fee - 123)
68 BOOST_CHECK_EQUAL(fee, check_tx(123));
69 70 // Send full input minus fee amount to recipient, check leftover input
71 // amount is paid to recipient not the miner (to_reduce == 0)
72 BOOST_CHECK_EQUAL(fee, check_tx(fee));
73 74 // Send full input minus more than the fee amount to recipient, check
75 // leftover input amount is paid to recipient not the miner (to_reduce ==
76 // -123). This overpays the recipient instead of overpaying the miner more
77 // than double the necessary fee.
78 BOOST_CHECK_EQUAL(fee, check_tx(fee + 123));
79 }
80 81 BOOST_FIXTURE_TEST_CASE(wallet_duplicated_preset_inputs_test, TestChain100Setup)
82 {
83 // Verify that the wallet's Coin Selection process does not include pre-selected inputs twice in a transaction.
84 85 // Add 4 spendable UTXO, 50 BTC each, to the wallet (total balance 200 BTC)
86 for (int i = 0; i < 4; i++) CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
87 auto wallet = CreateSyncedWallet(*m_node.chain, WITH_LOCK(Assert(m_node.chainman)->GetMutex(), return m_node.chainman->ActiveChain()), coinbaseKey);
88 89 LOCK(wallet->cs_wallet);
90 auto available_coins = AvailableCoins(*wallet);
91 std::vector<COutput> coins = available_coins.All();
92 // Preselect the first 3 UTXO (150 BTC total)
93 std::set<COutPoint> preset_inputs = {coins[0].outpoint, coins[1].outpoint, coins[2].outpoint};
94 95 // Try to create a tx that spends more than what preset inputs + wallet selected inputs are covering for.
96 // The wallet can cover up to 200 BTC, and the tx target is 299 BTC.
97 std::vector<CRecipient> recipients{{*Assert(wallet->GetNewDestination(OutputType::BECH32, "dummy")),
98 /*nAmount=*/299 * COIN, /*fSubtractFeeFromAmount=*/true}};
99 CCoinControl coin_control;
100 coin_control.m_allow_other_inputs = true;
101 for (const auto& outpoint : preset_inputs) {
102 coin_control.Select(outpoint);
103 }
104 105 // Attempt to send 299 BTC from a wallet that only has 200 BTC. The wallet should exclude
106 // the preset inputs from the pool of available coins, realize that there is not enough
107 // money to fund the 299 BTC payment, and fail with "Insufficient funds".
108 //
109 // Even with SFFO, the wallet can only afford to send 200 BTC.
110 // If the wallet does not properly exclude preset inputs from the pool of available coins
111 // prior to coin selection, it may create a transaction that does not fund the full payment
112 // amount or, through SFFO, incorrectly reduce the recipient's amount by the difference
113 // between the original target and the wrongly counted inputs (in this case 99 BTC)
114 // so that the recipient's amount is no longer equal to the user's selected target of 299 BTC.
115 116 // First case, use 'subtract_fee_from_outputs=true'
117 BOOST_CHECK(!CreateTransaction(*wallet, recipients, /*change_pos=*/std::nullopt, coin_control));
118 119 // Second case, don't use 'subtract_fee_from_outputs'.
120 recipients[0].fSubtractFeeFromAmount = false;
121 BOOST_CHECK(!CreateTransaction(*wallet, recipients, /*change_pos=*/std::nullopt, coin_control));
122 }
123 124 BOOST_AUTO_TEST_SUITE_END()
125 } // namespace wallet
126