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>
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.
PreconditionChecks(const CWallet & wallet,const CWalletTx & wtx,std::vector<bilingual_str> & errors)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
CheckFeeRate(const CWallet & wallet,const CWalletTx & wtx,const CFeeRate & newFeerate,const int64_t maxTxSize,std::vector<bilingual_str> & errors)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
EstimateFeeRate(const CWallet & wallet,const CWalletTx & wtx,const CAmount old_fee,CCoinControl & coin_control)114 static CFeeRate EstimateFeeRate(const CWallet& wallet, const CWalletTx& wtx, const CAmount old_fee, 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
TransactionCanBeBumped(const CWallet & wallet,const uint256 & txid)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
CreateRateBumpTransaction(CWallet & wallet,const uint256 & txid,const CCoinControl & coin_control,std::vector<bilingual_str> & errors,CAmount & old_fee,CAmount & new_fee,CMutableTransaction & mtx)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 /* FIXME: For Namecoin, this presumably strips off the name
182 prefix, and leads to an invalid tx. */
183 CTxDestination change_dest;
184 ExtractDestination(output.scriptPubKey, change_dest);
185 new_coin_control.destChange = change_dest;
186 }
187 }
188
189 isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
190 old_fee = wtx.GetDebit(filter) - wtx.tx->GetValueOut();
191
192 if (coin_control.m_feerate) {
193 // The user provided a feeRate argument.
194 // We calculate this here to avoid compiler warning on the cs_wallet lock
195 const int64_t maxTxSize = CalculateMaximumSignedTxSize(*wtx.tx, &wallet);
196 Result res = CheckFeeRate(wallet, wtx, *new_coin_control.m_feerate, maxTxSize, errors);
197 if (res != Result::OK) {
198 return res;
199 }
200 } else {
201 // The user did not provide a feeRate argument
202 new_coin_control.m_feerate = EstimateFeeRate(wallet, wtx, old_fee, new_coin_control);
203 }
204
205 // Fill in required inputs we are double-spending(all of them)
206 // N.B.: bip125 doesn't require all the inputs in the replaced transaction to be
207 // used in the replacement transaction, but it's very important for wallets to make
208 // sure that happens. If not, it would be possible to bump a transaction A twice to
209 // A2 and A3 where A2 and A3 don't conflict (or alternatively bump A to A2 and A2
210 // to A3 where A and A3 don't conflict). If both later get confirmed then the sender
211 // has accidentally double paid.
212 for (const auto& inputs : wtx.tx->vin) {
213 new_coin_control.Select(COutPoint(inputs.prevout));
214 }
215 new_coin_control.fAllowOtherInputs = true;
216
217 // We cannot source new unconfirmed inputs(bip125 rule 2)
218 new_coin_control.m_min_depth = 1;
219
220 CTransactionRef tx_new = MakeTransactionRef();
221 CAmount fee_ret;
222 int change_pos_in_out = -1; // No requested location for change
223 bilingual_str fail_reason;
224 FeeCalculation fee_calc_out;
225 if (!wallet.CreateTransaction(recipients, nullptr, tx_new, fee_ret, change_pos_in_out, fail_reason, new_coin_control, fee_calc_out, false)) {
226 errors.push_back(Untranslated("Unable to create transaction.") + Untranslated(" ") + fail_reason);
227 return Result::WALLET_ERROR;
228 }
229
230 // Write back new fee if successful
231 new_fee = fee_ret;
232
233 // Write back transaction
234 mtx = CMutableTransaction(*tx_new);
235 // Mark new tx not replaceable, if requested.
236 if (!coin_control.m_signal_bip125_rbf.get_value_or(wallet.m_signal_rbf)) {
237 for (auto& input : mtx.vin) {
238 if (input.nSequence < 0xfffffffe) input.nSequence = 0xfffffffe;
239 }
240 }
241
242 return Result::OK;
243 }
244
SignTransaction(CWallet & wallet,CMutableTransaction & mtx)245 bool SignTransaction(CWallet& wallet, CMutableTransaction& mtx) {
246 LOCK(wallet.cs_wallet);
247 return wallet.SignTransaction(mtx);
248 }
249
CommitTransaction(CWallet & wallet,const uint256 & txid,CMutableTransaction && mtx,std::vector<bilingual_str> & errors,uint256 & bumped_txid)250 Result CommitTransaction(CWallet& wallet, const uint256& txid, CMutableTransaction&& mtx, std::vector<bilingual_str>& errors, uint256& bumped_txid)
251 {
252 LOCK(wallet.cs_wallet);
253 if (!errors.empty()) {
254 return Result::MISC_ERROR;
255 }
256 auto it = txid.IsNull() ? wallet.mapWallet.end() : wallet.mapWallet.find(txid);
257 if (it == wallet.mapWallet.end()) {
258 errors.push_back(Untranslated("Invalid or non-wallet transaction id"));
259 return Result::MISC_ERROR;
260 }
261 CWalletTx& oldWtx = it->second;
262
263 // make sure the transaction still has no descendants and hasn't been mined in the meantime
264 Result result = PreconditionChecks(wallet, oldWtx, errors);
265 if (result != Result::OK) {
266 return result;
267 }
268
269 // commit/broadcast the tx
270 CTransactionRef tx = MakeTransactionRef(std::move(mtx));
271 mapValue_t mapValue = oldWtx.mapValue;
272 mapValue["replaces_txid"] = oldWtx.GetHash().ToString();
273
274 wallet.CommitTransaction(tx, std::move(mapValue), oldWtx.vOrderForm);
275
276 // mark the original tx as bumped
277 bumped_txid = tx->GetHash();
278 if (!wallet.MarkReplaced(oldWtx.GetHash(), bumped_txid)) {
279 // TODO: see if JSON-RPC has a standard way of returning a response
280 // along with an exception. It would be good to return information about
281 // wtxBumped to the caller even if marking the original transaction
282 // replaced does not succeed for some reason.
283 errors.push_back(Untranslated("Created new bumpfee transaction but could not mark the original transaction as replaced"));
284 }
285 return Result::OK;
286 }
287
288 } // namespace feebumper
289