1 // Copyright (c) 2017-2020 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 <interfaces/chain.h>
6 #include <policy/fees.h>
7 #include <policy/policy.h>
8 #include <util/moneystr.h>
9 #include <util/rbf.h>
10 #include <util/system.h>
11 #include <util/translation.h>
12 #include <wallet/coincontrol.h>
13 #include <wallet/feebumper.h>
14 #include <wallet/fees.h>
ExternalSignerScriptPubKeyMan(WalletStorage & storage,WalletDescriptor & descriptor)15 #include <wallet/wallet.h>
16
17 //! Check whether transaction has descendant in wallet or mempool, or has been
18 //! mined, or conflicts with a mined transaction. Return a feebumper::Result.
19 static feebumper::Result PreconditionChecks(const CWallet& wallet, const CWalletTx& wtx, std::vector<bilingual_str>& errors) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
20 {
21 if (wallet.HasWalletSpend(wtx.GetHash())) {
22 errors.push_back(Untranslated("Transaction has descendants in the wallet"));
23 return feebumper::Result::INVALID_PARAMETER;
24 }
25
26 {
27 if (wallet.chain().hasDescendantsInMempool(wtx.GetHash())) {
28 errors.push_back(Untranslated("Transaction has descendants in the mempool"));
29 return feebumper::Result::INVALID_PARAMETER;
30 }
31 }
32
33 if (wtx.GetDepthInMainChain() != 0) {
34 errors.push_back(Untranslated("Transaction has been mined, or is conflicted with a mined transaction"));
35 return feebumper::Result::WALLET_ERROR;
36 }
37
38 if (!SignalsOptInRBF(*wtx.tx)) {
39 errors.push_back(Untranslated("Transaction is not BIP 125 replaceable"));
40 return feebumper::Result::WALLET_ERROR;
41 }
42
43 if (wtx.mapValue.count("replaced_by_txid")) {
44 errors.push_back(strprintf(Untranslated("Cannot bump transaction %s which was already bumped by transaction %s"), wtx.GetHash().ToString(), wtx.mapValue.at("replaced_by_txid")));
45 return feebumper::Result::WALLET_ERROR;
46 }
47
48 // check that original tx consists entirely of our inputs
49 // if not, we can't bump the fee, because the wallet has no way of knowing the value of the other inputs (thus the fee)
50 isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
51 if (!wallet.IsAllFromMe(*wtx.tx, filter)) {
52 errors.push_back(Untranslated("Transaction contains inputs that don't belong to this wallet"));
53 return feebumper::Result::WALLET_ERROR;
54 }
55
56
57 return feebumper::Result::OK;
58 }
59
60 //! Check if the user provided a valid feeRate
61 static feebumper::Result CheckFeeRate(const CWallet& wallet, const CWalletTx& wtx, const CFeeRate& newFeerate, const int64_t maxTxSize, std::vector<bilingual_str>& errors)
62 {
63 // check that fee rate is higher than mempool's minimum fee
64 // (no point in bumping fee if we know that the new tx won't be accepted to the mempool)
65 // This may occur if the user set fee_rate or paytxfee too low, if fallbackfee is too low, or, perhaps,
66 // in a rare situation where the mempool minimum fee increased significantly since the fee estimation just a
67 // moment earlier. In this case, we report an error to the user, who may adjust the fee.
68 CFeeRate minMempoolFeeRate = wallet.chain().mempoolMinFee();
69
70 if (newFeerate.GetFeePerK() < minMempoolFeeRate.GetFeePerK()) {
71 errors.push_back(strprintf(
72 Untranslated("New fee rate (%s) is lower than the minimum fee rate (%s) to get into the mempool -- "),
73 FormatMoney(newFeerate.GetFeePerK()),
74 FormatMoney(minMempoolFeeRate.GetFeePerK())));
75 return feebumper::Result::WALLET_ERROR;
76 }
77
78 CAmount new_total_fee = newFeerate.GetFee(maxTxSize);
79
80 CFeeRate incrementalRelayFee = std::max(wallet.chain().relayIncrementalFee(), CFeeRate(WALLET_INCREMENTAL_RELAY_FEE));
81
82 // Given old total fee and transaction size, calculate the old feeRate
83 isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
84 CAmount old_fee = wtx.GetDebit(filter) - wtx.tx->GetValueOut();
85 const int64_t txSize = GetVirtualTransactionSize(*(wtx.tx));
86 CFeeRate nOldFeeRate(old_fee, txSize);
87 // Min total fee is old fee + relay fee
88 CAmount minTotalFee = nOldFeeRate.GetFee(maxTxSize) + incrementalRelayFee.GetFee(maxTxSize);
89
90 if (new_total_fee < minTotalFee) {
91 errors.push_back(strprintf(Untranslated("Insufficient total fee %s, must be at least %s (oldFee %s + incrementalFee %s)"),
92 FormatMoney(new_total_fee), FormatMoney(minTotalFee), FormatMoney(nOldFeeRate.GetFee(maxTxSize)), FormatMoney(incrementalRelayFee.GetFee(maxTxSize))));
93 return feebumper::Result::INVALID_PARAMETER;
94 }
95
96 CAmount requiredFee = GetRequiredFee(wallet, maxTxSize);
97 if (new_total_fee < requiredFee) {
98 errors.push_back(strprintf(Untranslated("Insufficient total fee (cannot be less than required fee %s)"),
99 FormatMoney(requiredFee)));
100 return feebumper::Result::INVALID_PARAMETER;
101 }
102
103 // Check that in all cases the new fee doesn't violate maxTxFee
104 const CAmount max_tx_fee = wallet.m_default_max_tx_fee;
105 if (new_total_fee > max_tx_fee) {
106 errors.push_back(strprintf(Untranslated("Specified or calculated fee %s is too high (cannot be higher than -maxtxfee %s)"),
107 FormatMoney(new_total_fee), FormatMoney(max_tx_fee)));
108 return feebumper::Result::WALLET_ERROR;
109 }
110
111 return feebumper::Result::OK;
112 }
113
114 static CFeeRate EstimateFeeRate(const CWallet& wallet, const CWalletTx& wtx, const CAmount old_fee, const CCoinControl& coin_control)
115 {
116 // Get the fee rate of the original transaction. This is calculated from
117 // the tx fee/vsize, so it may have been rounded down. Add 1 satoshi to the
118 // result.
119 int64_t txSize = GetVirtualTransactionSize(*(wtx.tx));
120 CFeeRate feerate(old_fee, txSize);
121 feerate += CFeeRate(1);
122
123 // The node has a configurable incremental relay fee. Increment the fee by
124 // the minimum of that and the wallet's conservative
125 // WALLET_INCREMENTAL_RELAY_FEE value to future proof against changes to
126 // network wide policy for incremental relay fee that our node may not be
127 // aware of. This ensures we're over the required relay fee rate
128 // (BIP 125 rule 4). The replacement tx will be at least as large as the
129 // original tx, so the total fee will be greater (BIP 125 rule 3)
130 CFeeRate node_incremental_relay_fee = wallet.chain().relayIncrementalFee();
131 CFeeRate wallet_incremental_relay_fee = CFeeRate(WALLET_INCREMENTAL_RELAY_FEE);
132 feerate += std::max(node_incremental_relay_fee, wallet_incremental_relay_fee);
133
134 // Fee rate must also be at least the wallet's GetMinimumFeeRate
135 CFeeRate min_feerate(GetMinimumFeeRate(wallet, coin_control, /* feeCalc */ nullptr));
136
137 // Set the required fee rate for the replacement transaction in coin control.
138 return std::max(feerate, min_feerate);
139 }
140
141 namespace feebumper {
142
143 bool TransactionCanBeBumped(const CWallet& wallet, const uint256& txid)
144 {
145 LOCK(wallet.cs_wallet);
146 const CWalletTx* wtx = wallet.GetWalletTx(txid);
147 if (wtx == nullptr) return false;
148
149 std::vector<bilingual_str> errors_dummy;
150 feebumper::Result res = PreconditionChecks(wallet, *wtx, errors_dummy);
151 return res == feebumper::Result::OK;
152 }
153
154 Result CreateRateBumpTransaction(CWallet& wallet, const uint256& txid, const CCoinControl& coin_control, std::vector<bilingual_str>& errors,
155 CAmount& old_fee, CAmount& new_fee, CMutableTransaction& mtx)
156 {
157 // We are going to modify coin control later, copy to re-use
158 CCoinControl new_coin_control(coin_control);
159
160 LOCK(wallet.cs_wallet);
161 errors.clear();
162 auto it = wallet.mapWallet.find(txid);
163 if (it == wallet.mapWallet.end()) {
164 errors.push_back(Untranslated("Invalid or non-wallet transaction id"));
165 return Result::INVALID_ADDRESS_OR_KEY;
166 }
167 const CWalletTx& wtx = it->second;
168
169 Result result = PreconditionChecks(wallet, wtx, errors);
170 if (result != Result::OK) {
171 return result;
172 }
173
174 // Fill in recipients(and preserve a single change key if there is one)
175 std::vector<CRecipient> recipients;
176 for (const auto& output : wtx.tx->vout) {
177 if (!wallet.IsChange(output)) {
178 CRecipient recipient = {output.scriptPubKey, output.nValue, false};
179 recipients.push_back(recipient);
180 } else {
181 CTxDestination change_dest;
182 ExtractDestination(output.scriptPubKey, change_dest);
183 new_coin_control.destChange = change_dest;
184 }
185 }
186
187 isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
188 old_fee = wtx.GetDebit(filter) - wtx.tx->GetValueOut();
189
190 if (coin_control.m_feerate) {
191 // The user provided a feeRate argument.
192 // We calculate this here to avoid compiler warning on the cs_wallet lock
193 const int64_t maxTxSize{CalculateMaximumSignedTxSize(*wtx.tx, &wallet).vsize};
194 Result res = CheckFeeRate(wallet, wtx, *new_coin_control.m_feerate, maxTxSize, errors);
195 if (res != Result::OK) {
196 return res;
197 }
198 } else {
199 // The user did not provide a feeRate argument
200 new_coin_control.m_feerate = EstimateFeeRate(wallet, wtx, old_fee, new_coin_control);
201 }
202
203 // Fill in required inputs we are double-spending(all of them)
204 // N.B.: bip125 doesn't require all the inputs in the replaced transaction to be
205 // used in the replacement transaction, but it's very important for wallets to make
206 // sure that happens. If not, it would be possible to bump a transaction A twice to
207 // A2 and A3 where A2 and A3 don't conflict (or alternatively bump A to A2 and A2
208 // to A3 where A and A3 don't conflict). If both later get confirmed then the sender
209 // has accidentally double paid.
210 for (const auto& inputs : wtx.tx->vin) {
211 new_coin_control.Select(COutPoint(inputs.prevout));
212 }
213 new_coin_control.fAllowOtherInputs = true;
214
215 // We cannot source new unconfirmed inputs(bip125 rule 2)
216 new_coin_control.m_min_depth = 1;
217
218 CTransactionRef tx_new;
219 CAmount fee_ret;
220 int change_pos_in_out = -1; // No requested location for change
221 bilingual_str fail_reason;
222 FeeCalculation fee_calc_out;
223 if (!wallet.CreateTransaction(recipients, tx_new, fee_ret, change_pos_in_out, fail_reason, new_coin_control, fee_calc_out, false)) {
224 errors.push_back(Untranslated("Unable to create transaction.") + Untranslated(" ") + fail_reason);
225 return Result::WALLET_ERROR;
226 }
227
228 // Write back new fee if successful
229 new_fee = fee_ret;
230
231 // Write back transaction
232 mtx = CMutableTransaction(*tx_new);
233 // Mark new tx not replaceable, if requested.
234 if (!coin_control.m_signal_bip125_rbf.value_or(wallet.m_signal_rbf)) {
235 for (auto& input : mtx.vin) {
236 if (input.nSequence < 0xfffffffe) input.nSequence = 0xfffffffe;
237 }
238 }
239
240 return Result::OK;
241 }
242
243 bool SignTransaction(CWallet& wallet, CMutableTransaction& mtx) {
244 LOCK(wallet.cs_wallet);
245 return wallet.SignTransaction(mtx);
246 }
247
248 Result CommitTransaction(CWallet& wallet, const uint256& txid, CMutableTransaction&& mtx, std::vector<bilingual_str>& errors, uint256& bumped_txid)
249 {
250 LOCK(wallet.cs_wallet);
251 if (!errors.empty()) {
252 return Result::MISC_ERROR;
253 }
254 auto it = txid.IsNull() ? wallet.mapWallet.end() : wallet.mapWallet.find(txid);
255 if (it == wallet.mapWallet.end()) {
256 errors.push_back(Untranslated("Invalid or non-wallet transaction id"));
257 return Result::MISC_ERROR;
258 }
259 const CWalletTx& oldWtx = it->second;
260
261 // make sure the transaction still has no descendants and hasn't been mined in the meantime
262 Result result = PreconditionChecks(wallet, oldWtx, errors);
263 if (result != Result::OK) {
264 return result;
265 }
266
267 // commit/broadcast the tx
268 CTransactionRef tx = MakeTransactionRef(std::move(mtx));
269 mapValue_t mapValue = oldWtx.mapValue;
270 mapValue["replaces_txid"] = oldWtx.GetHash().ToString();
271
272 wallet.CommitTransaction(tx, std::move(mapValue), oldWtx.vOrderForm);
273
274 // mark the original tx as bumped
275 bumped_txid = tx->GetHash();
276 if (!wallet.MarkReplaced(oldWtx.GetHash(), bumped_txid)) {
277 // TODO: see if JSON-RPC has a standard way of returning a response
278 // along with an exception. It would be good to return information about
279 // wtxBumped to the caller even if marking the original transaction
280 // replaced does not succeed for some reason.
281 errors.push_back(Untranslated("Created new bumpfee transaction but could not mark the original transaction as replaced"));
282 }
283 return Result::OK;
284 }
285
286 } // namespace feebumper
287