Branch data Line data Source code
1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
2 : : // Copyright (c) 2009-present The Bitcoin Core developers
3 : : // Distributed under the MIT software license, see the accompanying
4 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 : :
6 : : // NOTE: This file is intended to be customised by the end user, and includes only local node policy logic
7 : :
8 : : #include <policy/policy.h>
9 : :
10 : : #include <coins.h>
11 : : #include <consensus/amount.h>
12 : : #include <consensus/consensus.h>
13 : : #include <consensus/validation.h>
14 : : #include <policy/feerate.h>
15 : : #include <primitives/transaction.h>
16 : : #include <script/interpreter.h>
17 : : #include <script/script.h>
18 : : #include <script/solver.h>
19 : : #include <serialize.h>
20 : : #include <span.h>
21 : :
22 : : #include <algorithm>
23 : : #include <cstddef>
24 : : #include <vector>
25 : :
26 : 20951979 : CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFeeIn)
27 : : {
28 : : // "Dust" is defined in terms of dustRelayFee,
29 : : // which has units satoshis-per-kilobyte.
30 : : // If you'd pay more in fees than the value of the output
31 : : // to spend something, then we consider it dust.
32 : : // A typical spendable non-segwit txout is 34 bytes big, and will
33 : : // need a CTxIn of at least 148 bytes to spend:
34 : : // so dust is a spendable txout less than
35 : : // 182*dustRelayFee/1000 (in satoshis).
36 : : // 546 satoshis at the default rate of 3000 sat/kvB.
37 : : // A typical spendable segwit P2WPKH txout is 31 bytes big, and will
38 : : // need a CTxIn of at least 67 bytes to spend:
39 : : // so dust is a spendable txout less than
40 : : // 98*dustRelayFee/1000 (in satoshis).
41 : : // 294 satoshis at the default rate of 3000 sat/kvB.
42 [ + + ]: 20951979 : if (txout.scriptPubKey.IsUnspendable())
43 : : return 0;
44 : :
45 : 20922200 : size_t nSize = GetSerializeSize(txout);
46 : 20922200 : int witnessversion = 0;
47 : 20922200 : std::vector<unsigned char> witnessprogram;
48 : :
49 : : // Note this computation is for spending a Segwit v0 P2WPKH output (a 33 bytes
50 : : // public key + an ECDSA signature). For Segwit v1 Taproot outputs the minimum
51 : : // satisfaction is lower (a single BIP340 signature) but this computation was
52 : : // kept to not further reduce the dust level.
53 : : // See discussion in https://github.com/bitcoin/bitcoin/pull/22779 for details.
54 [ + - + + ]: 20922200 : if (txout.scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
55 : : // sum the sizes of the parts of a transaction input
56 : : // with 75% segwit discount applied to the script size.
57 : 20908569 : nSize += (32 + 4 + 1 + (107 / WITNESS_SCALE_FACTOR) + 4);
58 : : } else {
59 : 13631 : nSize += (32 + 4 + 1 + 107 + 4); // the 148 mentioned above
60 : : }
61 : :
62 [ + - ]: 20922200 : return dustRelayFeeIn.GetFee(nSize);
63 : 20922200 : }
64 : :
65 : 20949033 : bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFeeIn)
66 : : {
67 : 20949033 : return (txout.nValue < GetDustThreshold(txout, dustRelayFeeIn));
68 : : }
69 : :
70 : 6875738 : std::vector<uint32_t> GetDust(const CTransaction& tx, CFeeRate dust_relay_rate)
71 : : {
72 : 6875738 : std::vector<uint32_t> dust_outputs;
73 [ + + ]: 27440885 : for (uint32_t i{0}; i < tx.vout.size(); ++i) {
74 [ + - + + : 20565147 : if (IsDust(tx.vout[i], dust_relay_rate)) dust_outputs.push_back(i);
+ - ]
75 : : }
76 : 6875738 : return dust_outputs;
77 : 0 : }
78 : :
79 : 5125638 : bool IsStandard(const CScript& scriptPubKey, TxoutType& whichType)
80 : : {
81 : 5125638 : std::vector<std::vector<unsigned char> > vSolutions;
82 [ + - ]: 5125638 : whichType = Solver(scriptPubKey, vSolutions);
83 : :
84 [ + + ]: 5125638 : if (whichType == TxoutType::NONSTANDARD) {
85 : : return false;
86 [ + + ]: 5099857 : } else if (whichType == TxoutType::MULTISIG) {
87 [ + + ]: 3431 : unsigned char m = vSolutions.front()[0];
88 : 3431 : unsigned char n = vSolutions.back()[0];
89 : : // Support up to x-of-3 multisig txns as standard
90 [ + + ]: 3431 : if (n < 1 || n > 3)
91 : : return false;
92 [ - + ]: 1894 : if (m < 1 || m > n)
93 : 0 : return false;
94 : : }
95 : :
96 : : return true;
97 : 5125638 : }
98 : :
99 : 695064 : bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_datacarrier_bytes, bool permit_bare_multisig, const CFeeRate& dust_relay_fee, std::string& reason)
100 : : {
101 [ + + ]: 695064 : if (tx.version > TX_MAX_STANDARD_VERSION || tx.version < 1) {
102 : 20465 : reason = "version";
103 : 20465 : return false;
104 : : }
105 : :
106 : : // Extremely large transactions with lots of inputs can cost the network
107 : : // almost as much to process as they cost the sender in fees, because
108 : : // computing signature hashes is O(ninputs*txsize). Limiting transactions
109 : : // to MAX_STANDARD_TX_WEIGHT mitigates CPU exhaustion attacks.
110 : 674599 : unsigned int sz = GetTransactionWeight(tx);
111 [ + + ]: 674599 : if (sz > MAX_STANDARD_TX_WEIGHT) {
112 : 379 : reason = "tx-size";
113 : 379 : return false;
114 : : }
115 : :
116 [ + + ]: 4289947 : for (const CTxIn& txin : tx.vin)
117 : : {
118 : : // Biggest 'standard' txin involving only keys is a 15-of-15 P2SH
119 : : // multisig with compressed keys (remember the MAX_SCRIPT_ELEMENT_SIZE byte limit on
120 : : // redeemScript size). That works out to a (15*(33+1))+3=513 byte
121 : : // redeemScript, 513+1+15*(73+1)+3=1627 bytes of scriptSig, which
122 : : // we round off to 1650(MAX_STANDARD_SCRIPTSIG_SIZE) bytes for
123 : : // some minor future-proofing. That's also enough to spend a
124 : : // 20-of-20 CHECKMULTISIG scriptPubKey, though such a scriptPubKey
125 : : // is not considered standard.
126 [ + + + + ]: 3620777 : if (txin.scriptSig.size() > MAX_STANDARD_SCRIPTSIG_SIZE) {
127 : 97 : reason = "scriptsig-size";
128 : 97 : return false;
129 : : }
130 [ + + ]: 3620680 : if (!txin.scriptSig.IsPushOnly()) {
131 : 4953 : reason = "scriptsig-not-pushonly";
132 : 4953 : return false;
133 : : }
134 : : }
135 : :
136 [ + + ]: 669170 : unsigned int datacarrier_bytes_left = max_datacarrier_bytes.value_or(0);
137 : 669170 : TxoutType whichType;
138 [ + + ]: 5764755 : for (const CTxOut& txout : tx.vout) {
139 [ + + ]: 5121011 : if (!::IsStandard(txout.scriptPubKey, whichType)) {
140 : 25167 : reason = "scriptpubkey";
141 : 25167 : return false;
142 : : }
143 : :
144 [ + + ]: 5095844 : if (whichType == TxoutType::NULL_DATA) {
145 [ + + ]: 9718 : unsigned int size = txout.scriptPubKey.size();
146 [ + + ]: 9718 : if (size > datacarrier_bytes_left) {
147 : 17 : reason = "datacarrier";
148 : 17 : return false;
149 : : }
150 : 9701 : datacarrier_bytes_left -= size;
151 [ + + + + ]: 5086126 : } else if ((whichType == TxoutType::MULTISIG) && (!permit_bare_multisig)) {
152 : 242 : reason = "bare-multisig";
153 : 242 : return false;
154 : : }
155 : : }
156 : :
157 : : // Only MAX_DUST_OUTPUTS_PER_TX dust is permitted(on otherwise valid ephemeral dust)
158 [ + + ]: 643744 : if (GetDust(tx, dust_relay_fee).size() > MAX_DUST_OUTPUTS_PER_TX) {
159 : 725 : reason = "dust";
160 : 725 : return false;
161 : : }
162 : :
163 : : return true;
164 : : }
165 : :
166 : : /**
167 : : * Check transaction inputs.
168 : : *
169 : : * This does three things:
170 : : * * Prevents mempool acceptance of spends of future
171 : : * segwit versions we don't know how to validate
172 : : * * Mitigates a potential denial-of-service attack with
173 : : * P2SH scripts with a crazy number of expensive
174 : : * CHECKSIG/CHECKMULTISIG operations.
175 : : * * Prevents spends of unknown/irregular scriptPubKeys,
176 : : * which mitigates potential denial-of-service attacks
177 : : * involving expensive scripts and helps reserve them
178 : : * as potential new upgrade hooks.
179 : : *
180 : : * Note that only the non-witness portion of the transaction is checked here.
181 : : */
182 : 350326 : bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
183 : : {
184 [ + + ]: 350326 : if (tx.IsCoinBase()) {
185 : : return true; // Coinbases don't use vin normally
186 : : }
187 : :
188 [ + + ]: 1855189 : for (unsigned int i = 0; i < tx.vin.size(); i++) {
189 : 1507524 : const CTxOut& prev = mapInputs.AccessCoin(tx.vin[i].prevout).out;
190 : :
191 : 1507524 : std::vector<std::vector<unsigned char> > vSolutions;
192 [ + - ]: 1507524 : TxoutType whichType = Solver(prev.scriptPubKey, vSolutions);
193 [ + + ]: 1507524 : if (whichType == TxoutType::NONSTANDARD || whichType == TxoutType::WITNESS_UNKNOWN) {
194 : : // WITNESS_UNKNOWN failures are typically also caught with a policy
195 : : // flag in the script interpreter, but it can be helpful to catch
196 : : // this type of NONSTANDARD transaction earlier in transaction
197 : : // validation.
198 : : return false;
199 [ + + ]: 1505932 : } else if (whichType == TxoutType::SCRIPTHASH) {
200 : 3618 : std::vector<std::vector<unsigned char> > stack;
201 : : // convert the scriptSig into a stack, so we can inspect the redeemScript
202 [ + - + + ]: 3618 : if (!EvalScript(stack, tx.vin[i].scriptSig, SCRIPT_VERIFY_NONE, BaseSignatureChecker(), SigVersion::BASE))
203 : : return false;
204 [ + + ]: 2590 : if (stack.empty())
205 : : return false;
206 : 2584 : CScript subscript(stack.back().begin(), stack.back().end());
207 [ + - + + ]: 2584 : if (subscript.GetSigOpCount(true) > MAX_P2SH_SIGOPS) {
208 : 22 : return false;
209 : : }
210 : 3618 : }
211 : 1507524 : }
212 : :
213 : : return true;
214 : : }
215 : :
216 : 347195 : bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
217 : : {
218 [ + + ]: 347195 : if (tx.IsCoinBase())
219 : : return true; // Coinbases are skipped
220 : :
221 [ + + ]: 1929297 : for (unsigned int i = 0; i < tx.vin.size(); i++)
222 : : {
223 : : // We don't care if witness for this input is empty, since it must not be bloated.
224 : : // If the script is invalid without witness, it would be caught sooner or later during validation.
225 [ + + ]: 1583467 : if (tx.vin[i].scriptWitness.IsNull())
226 : 84221 : continue;
227 : :
228 : 1499246 : const CTxOut &prev = mapInputs.AccessCoin(tx.vin[i].prevout).out;
229 : :
230 : : // get the scriptPubKey corresponding to this input:
231 : 1499246 : CScript prevScript = prev.scriptPubKey;
232 : :
233 : : // witness stuffing detected
234 [ + - + + ]: 1499246 : if (prevScript.IsPayToAnchor()) {
235 : : return false;
236 : : }
237 : :
238 : 1499244 : bool p2sh = false;
239 [ + - + + ]: 1499244 : if (prevScript.IsPayToScriptHash()) {
240 : 57 : std::vector <std::vector<unsigned char> > stack;
241 : : // If the scriptPubKey is P2SH, we try to extract the redeemScript casually by converting the scriptSig
242 : : // into a stack. We do not check IsPushOnly nor compare the hash as these will be done later anyway.
243 : : // If the check fails at this stage, we know that this txid must be a bad one.
244 [ + - + + ]: 57 : if (!EvalScript(stack, tx.vin[i].scriptSig, SCRIPT_VERIFY_NONE, BaseSignatureChecker(), SigVersion::BASE))
245 : : return false;
246 [ + + ]: 42 : if (stack.empty())
247 : : return false;
248 : 40 : prevScript = CScript(stack.back().begin(), stack.back().end());
249 : 40 : p2sh = true;
250 : 57 : }
251 : :
252 : 1499227 : int witnessversion = 0;
253 : 1499227 : std::vector<unsigned char> witnessprogram;
254 : :
255 : : // Non-witness program must not be associated with any witness
256 [ + - + + ]: 1499227 : if (!prevScript.IsWitnessProgram(witnessversion, witnessprogram))
257 : : return false;
258 : :
259 : : // Check P2WSH standard limits
260 [ + + + + ]: 1498476 : if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
261 [ + + ]: 1494215 : if (tx.vin[i].scriptWitness.stack.back().size() > MAX_STANDARD_P2WSH_SCRIPT_SIZE)
262 : : return false;
263 [ + + ]: 1494100 : size_t sizeWitnessStack = tx.vin[i].scriptWitness.stack.size() - 1;
264 [ + + ]: 1494100 : if (sizeWitnessStack > MAX_STANDARD_P2WSH_STACK_ITEMS)
265 : : return false;
266 [ + + ]: 2120053 : for (unsigned int j = 0; j < sizeWitnessStack; j++) {
267 [ + + ]: 626410 : if (tx.vin[i].scriptWitness.stack[j].size() > MAX_STANDARD_P2WSH_STACK_ITEM_SIZE)
268 : : return false;
269 : : }
270 : : }
271 : :
272 : : // Check policy limits for Taproot spends:
273 : : // - MAX_STANDARD_TAPSCRIPT_STACK_ITEM_SIZE limit for stack item size
274 : : // - No annexes
275 [ + + + + : 1497904 : if (witnessversion == 1 && witnessprogram.size() == WITNESS_V1_TAPROOT_SIZE && !p2sh) {
+ - ]
276 : : // Taproot spend (non-P2SH-wrapped, version 1, witness program size 32; see BIP 341)
277 [ + + ]: 2182 : std::span stack{tx.vin[i].scriptWitness.stack};
278 [ + + + + : 2182 : if (stack.size() >= 2 && !stack.back().empty() && stack.back()[0] == ANNEX_TAG) {
+ + ]
279 : : // Annexes are nonstandard as long as no semantics are defined for them.
280 : : return false;
281 : : }
282 [ + + ]: 2180 : if (stack.size() >= 2) {
283 : : // Script path spend (2 or more stack elements after removing optional annex)
284 : 893 : const auto& control_block = SpanPopBack(stack);
285 : 893 : SpanPopBack(stack); // Ignore script
286 [ + + ]: 893 : if (control_block.empty()) return false; // Empty control block is invalid
287 [ + + ]: 891 : if ((control_block[0] & TAPROOT_LEAF_MASK) == TAPROOT_LEAF_TAPSCRIPT) {
288 : : // Leaf version 0xc0 (aka Tapscript, see BIP 342)
289 [ + + ]: 688 : for (const auto& item : stack) {
290 [ + + ]: 635 : if (item.size() > MAX_STANDARD_TAPSCRIPT_STACK_ITEM_SIZE) return false;
291 : : }
292 : : }
293 [ + - ]: 1287 : } else if (stack.size() == 1) {
294 : : // Key path spend (1 stack element after removing optional annex)
295 : : // (no policy rules apply)
296 : : } else {
297 : : // 0 stack elements; this is already invalid by consensus rules
298 : : return false;
299 : : }
300 : : }
301 : 1500579 : }
302 : : return true;
303 : : }
304 : :
305 : 1050093285 : int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost, unsigned int bytes_per_sigop)
306 : : {
307 [ + + ]: 1050093285 : return (std::max(nWeight, nSigOpCost * bytes_per_sigop) + WITNESS_SCALE_FACTOR - 1) / WITNESS_SCALE_FACTOR;
308 : : }
309 : :
310 : 30636 : int64_t GetVirtualTransactionSize(const CTransaction& tx, int64_t nSigOpCost, unsigned int bytes_per_sigop)
311 : : {
312 : 30636 : return GetVirtualTransactionSize(GetTransactionWeight(tx), nSigOpCost, bytes_per_sigop);
313 : : }
314 : :
315 : 66 : int64_t GetVirtualTransactionInputSize(const CTxIn& txin, int64_t nSigOpCost, unsigned int bytes_per_sigop)
316 : : {
317 : 66 : return GetVirtualTransactionSize(GetTransactionInputWeight(txin), nSigOpCost, bytes_per_sigop);
318 : : }
|
