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 #ifndef BITCOIN_POLICY_POLICY_H
7 #define BITCOIN_POLICY_POLICY_H
8 9 #include <consensus/amount.h>
10 #include <consensus/consensus.h>
11 #include <consensus/validation.h>
12 #include <primitives/transaction.h>
13 #include <script/interpreter.h>
14 #include <script/solver.h>
15 #include <util/feefrac.h>
16 17 #include <cstdint>
18 #include <string>
19 20 class CCoinsViewCache;
21 class CFeeRate;
22 class CScript;
23 24 /** Default for -blockmaxweight, which controls the range of block weights the mining code will create **/
25 static constexpr unsigned int DEFAULT_BLOCK_MAX_WEIGHT{MAX_BLOCK_WEIGHT};
26 /** Default for -blockreservedweight **/
27 static constexpr unsigned int DEFAULT_BLOCK_RESERVED_WEIGHT{8000};
28 /** Default sigops cost to reserve for coinbase transaction outputs when creating block templates. */
29 static constexpr unsigned int DEFAULT_COINBASE_OUTPUT_MAX_ADDITIONAL_SIGOPS{400};
30 /** This accounts for the block header, var_int encoding of the transaction count and a minimally viable
31 * coinbase transaction. It adds an additional safety margin, because even with a thorough understanding
32 * of block serialization, it's easy to make a costly mistake when trying to squeeze every last byte.
33 * Setting a lower value is prevented at startup. */
34 static constexpr unsigned int MINIMUM_BLOCK_RESERVED_WEIGHT{2000};
35 /** Default for -blockmintxfee, which sets the minimum feerate for a transaction in blocks created by mining code **/
36 static constexpr unsigned int DEFAULT_BLOCK_MIN_TX_FEE{1};
37 /** The maximum weight for transactions we're willing to relay/mine */
38 static constexpr int32_t MAX_STANDARD_TX_WEIGHT{400000};
39 /** The minimum non-witness size for transactions we're willing to relay/mine: one larger than 64 */
40 static constexpr unsigned int MIN_STANDARD_TX_NONWITNESS_SIZE{65};
41 /** Maximum number of signature check operations in an IsStandard() P2SH script */
42 static constexpr unsigned int MAX_P2SH_SIGOPS{15};
43 /** The maximum number of sigops we're willing to relay/mine in a single tx */
44 static constexpr unsigned int MAX_STANDARD_TX_SIGOPS_COST{MAX_BLOCK_SIGOPS_COST/5};
45 /** The maximum number of potentially executed legacy signature operations in a single standard tx */
46 static constexpr unsigned int MAX_TX_LEGACY_SIGOPS{2'500};
47 /** Default for -incrementalrelayfee, which sets the minimum feerate increase for mempool limiting or replacement **/
48 static constexpr unsigned int DEFAULT_INCREMENTAL_RELAY_FEE{100};
49 /** Default for -bytespersigop */
50 static constexpr unsigned int DEFAULT_BYTES_PER_SIGOP{20};
51 /** Default for -permitbaremultisig */
52 static constexpr bool DEFAULT_PERMIT_BAREMULTISIG{true};
53 /** The maximum number of witness stack items in a standard P2WSH script */
54 static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEMS{100};
55 /** The maximum size in bytes of each witness stack item in a standard P2WSH script */
56 static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEM_SIZE{80};
57 /** The maximum size in bytes of each witness stack item in a standard BIP 342 script (Taproot, leaf version 0xc0) */
58 static constexpr unsigned int MAX_STANDARD_TAPSCRIPT_STACK_ITEM_SIZE{80};
59 /** The maximum size in bytes of a standard witnessScript */
60 static constexpr unsigned int MAX_STANDARD_P2WSH_SCRIPT_SIZE{3600};
61 /** The maximum size of a standard ScriptSig */
62 static constexpr unsigned int MAX_STANDARD_SCRIPTSIG_SIZE{1650};
63 /** Min feerate for defining dust.
64 * Changing the dust limit changes which transactions are
65 * standard and should be done with care and ideally rarely. It makes sense to
66 * only increase the dust limit after prior releases were already not creating
67 * outputs below the new threshold */
68 static constexpr unsigned int DUST_RELAY_TX_FEE{3000};
69 /** Default for -minrelaytxfee, minimum relay fee for transactions */
70 static constexpr unsigned int DEFAULT_MIN_RELAY_TX_FEE{100};
71 /** Maximum number of transactions per cluster (default) */
72 static constexpr unsigned int DEFAULT_CLUSTER_LIMIT{64};
73 /** Maximum size of cluster in virtual kilobytes */
74 static constexpr unsigned int DEFAULT_CLUSTER_SIZE_LIMIT_KVB{101};
75 /** Default for -limitancestorcount, max number of in-mempool ancestors */
76 static constexpr unsigned int DEFAULT_ANCESTOR_LIMIT{25};
77 /** Default for -limitdescendantcount, max number of in-mempool descendants */
78 static constexpr unsigned int DEFAULT_DESCENDANT_LIMIT{25};
79 /** Default for -datacarrier */
80 static const bool DEFAULT_ACCEPT_DATACARRIER = true;
81 /**
82 * Default setting for -datacarriersize in vbytes.
83 */
84 static const unsigned int MAX_OP_RETURN_RELAY = MAX_STANDARD_TX_WEIGHT / WITNESS_SCALE_FACTOR;
85 /**
86 * An extra transaction can be added to a package, as long as it only has one
87 * ancestor and is no larger than this. Not really any reason to make this
88 * configurable as it doesn't materially change DoS parameters.
89 */
90 static constexpr unsigned int EXTRA_DESCENDANT_TX_SIZE_LIMIT{10000};
91 92 /**
93 * Maximum number of ephemeral dust outputs allowed.
94 */
95 static constexpr unsigned int MAX_DUST_OUTPUTS_PER_TX{1};
96 97 /**
98 * Mandatory script verification flags that all new transactions must comply with for
99 * them to be valid.
100 *
101 * Note that this does not affect consensus validity; see GetBlockScriptFlags()
102 * for that.
103 */
104 static constexpr script_verify_flags MANDATORY_SCRIPT_VERIFY_FLAGS{SCRIPT_VERIFY_P2SH |
105 SCRIPT_VERIFY_DERSIG |
106 SCRIPT_VERIFY_NULLDUMMY |
107 SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY |
108 SCRIPT_VERIFY_CHECKSEQUENCEVERIFY |
109 SCRIPT_VERIFY_WITNESS |
110 SCRIPT_VERIFY_TAPROOT};
111 112 /**
113 * Standard script verification flags that standard transactions will comply
114 * with. However we do not ban/disconnect nodes that forward txs violating
115 * the additional (non-mandatory) rules here, to improve forwards and
116 * backwards compatibility.
117 */
118 static constexpr script_verify_flags STANDARD_SCRIPT_VERIFY_FLAGS{MANDATORY_SCRIPT_VERIFY_FLAGS |
119 SCRIPT_VERIFY_STRICTENC |
120 SCRIPT_VERIFY_MINIMALDATA |
121 SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS |
122 SCRIPT_VERIFY_CLEANSTACK |
123 SCRIPT_VERIFY_MINIMALIF |
124 SCRIPT_VERIFY_NULLFAIL |
125 SCRIPT_VERIFY_LOW_S |
126 SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM |
127 SCRIPT_VERIFY_WITNESS_PUBKEYTYPE |
128 SCRIPT_VERIFY_CONST_SCRIPTCODE |
129 SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_TAPROOT_VERSION |
130 SCRIPT_VERIFY_DISCOURAGE_OP_SUCCESS |
131 SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_PUBKEYTYPE};
132 133 /** For convenience, standard but not mandatory verify flags. */
134 static constexpr script_verify_flags STANDARD_NOT_MANDATORY_VERIFY_FLAGS{STANDARD_SCRIPT_VERIFY_FLAGS & ~MANDATORY_SCRIPT_VERIFY_FLAGS};
135 136 /** Used as the flags parameter to sequence and nLocktime checks in non-consensus code. */
137 static constexpr unsigned int STANDARD_LOCKTIME_VERIFY_FLAGS{LOCKTIME_VERIFY_SEQUENCE};
138 139 CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFee);
140 141 bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFee);
142 143 bool IsStandard(const CScript& scriptPubKey, TxoutType& whichType);
144 145 /** Get the vout index numbers of all dust outputs */
146 std::vector<uint32_t> GetDust(const CTransaction& tx, CFeeRate dust_relay_rate);
147 148 // Changing the default transaction version requires a two step process: first
149 // adapting relay policy by bumping TX_MAX_STANDARD_VERSION, and then later
150 // allowing the new transaction version in the wallet/RPC.
151 static constexpr decltype(CTransaction::version) TX_MIN_STANDARD_VERSION{1};
152 static constexpr decltype(CTransaction::version) TX_MAX_STANDARD_VERSION{3};
153 154 /**
155 * Check for standard transaction types
156 * @return True if all outputs (scriptPubKeys) use only standard transaction forms
157 */
158 bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_datacarrier_bytes, bool permit_bare_multisig, const CFeeRate& dust_relay_fee, std::string& reason);
159 /**
160 * Check for standard transaction types
161 * @param[in] mapInputs Map of previous transactions that have outputs we're spending
162 * @returns valid TxValidationState if all inputs (scriptSigs) use only standard transaction forms else returns
163 * invalid TxValidationState which states why the first invalid input is not standard
164 */
165 TxValidationState ValidateInputsStandardness(const CTransaction& tx, const CCoinsViewCache& mapInputs);
166 /**
167 * Check if the transaction is over standard P2WSH resources limit:
168 * 3600bytes witnessScript size, 80bytes per witness stack element, 100 witness stack elements
169 * These limits are adequate for multisignatures up to n-of-100 using OP_CHECKSIG, OP_ADD, and OP_EQUAL.
170 *
171 * Also enforce a maximum stack item size limit and no annexes for tapscript spends.
172 */
173 bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
174 /**
175 * Check whether this transaction spends any witness program but P2A, including not-yet-defined ones.
176 * May return `false` early for consensus-invalid transactions.
177 */
178 bool SpendsNonAnchorWitnessProg(const CTransaction& tx, const CCoinsViewCache& prevouts);
179 180 /** Compute the virtual transaction size (weight reinterpreted as bytes). */
181 int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost, unsigned int bytes_per_sigop);
182 int64_t GetVirtualTransactionSize(const CTransaction& tx, int64_t nSigOpCost, unsigned int bytes_per_sigop);
183 int64_t GetVirtualTransactionInputSize(const CTxIn& tx, int64_t nSigOpCost, unsigned int bytes_per_sigop);
184 185 static inline int64_t GetVirtualTransactionSize(const CTransaction& tx)
186 {
187 return GetVirtualTransactionSize(tx, 0, 0);
188 }
189 190 static inline int64_t GetVirtualTransactionInputSize(const CTxIn& tx)
191 {
192 return GetVirtualTransactionInputSize(tx, 0, 0);
193 }
194 195 int64_t GetSigOpsAdjustedWeight(int64_t weight, int64_t sigop_cost, unsigned int bytes_per_sigop);
196 197 static inline FeePerVSize ToFeePerVSize(FeePerWeight feerate) { return {feerate.fee, (feerate.size + WITNESS_SCALE_FACTOR - 1) / WITNESS_SCALE_FACTOR}; }
198 199 #endif // BITCOIN_POLICY_POLICY_H
200