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
20class CCoinsViewCache;
21class CFeeRate;
22class CScript;
23
24/** Default for -blockmaxweight, which controls the range of block weights the mining code will create **/
25inline constexpr unsigned int DEFAULT_BLOCK_MAX_WEIGHT{MAX_BLOCK_WEIGHT};
26/** Default for -blockreservedweight **/
27inline constexpr unsigned int DEFAULT_BLOCK_RESERVED_WEIGHT{8000};
28/** Default sigops cost to reserve for coinbase transaction outputs when creating block templates. */
29inline 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. */
34inline 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 **/
36inline constexpr unsigned int DEFAULT_BLOCK_MIN_TX_FEE{1};
37/** The maximum weight for transactions we're willing to relay/mine */
38inline constexpr int32_t MAX_STANDARD_TX_WEIGHT{400'000};
39/** The minimum non-witness size for transactions we're willing to relay/mine: one larger than 64  */
40inline constexpr unsigned int MIN_STANDARD_TX_NONWITNESS_SIZE{65};
41/** Maximum number of signature check operations in an IsStandard() P2SH script */
42inline constexpr unsigned int MAX_P2SH_SIGOPS{15};
43/** The maximum number of sigops we're willing to relay/mine in a single tx */
44inline 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 */
46inline constexpr unsigned int MAX_TX_LEGACY_SIGOPS{2'500};
47/** Default for -incrementalrelayfee, which sets the minimum feerate increase for mempool limiting or replacement **/
48inline constexpr unsigned int DEFAULT_INCREMENTAL_RELAY_FEE{100};
49/** Default for -bytespersigop */
50inline constexpr unsigned int DEFAULT_BYTES_PER_SIGOP{20};
51/** Default for -permitbaremultisig */
52inline constexpr bool DEFAULT_PERMIT_BAREMULTISIG{true};
53/** The maximum number of witness stack items in a standard P2WSH script */
54inline 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 */
56inline 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) */
58inline constexpr unsigned int MAX_STANDARD_TAPSCRIPT_STACK_ITEM_SIZE{80};
59/** The maximum size in bytes of a standard witnessScript */
60inline constexpr unsigned int MAX_STANDARD_P2WSH_SCRIPT_SIZE{3600};
61/** The maximum size of a standard ScriptSig */
62inline 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 */
68inline constexpr unsigned int DUST_RELAY_TX_FEE{3000};
69/** Default for -minrelaytxfee, minimum relay fee for transactions */
70inline constexpr unsigned int DEFAULT_MIN_RELAY_TX_FEE{100};
71/** Maximum number of transactions per cluster (default) */
72inline constexpr unsigned int DEFAULT_CLUSTER_LIMIT{64};
73/** Maximum size of cluster in virtual kilobytes */
74inline constexpr unsigned int DEFAULT_CLUSTER_SIZE_LIMIT_KVB{101};
75/** Default for -limitancestorcount, max number of in-mempool ancestors */
76inline constexpr unsigned int DEFAULT_ANCESTOR_LIMIT{25};
77/** Default for -limitdescendantcount, max number of in-mempool descendants */
78inline constexpr unsigned int DEFAULT_DESCENDANT_LIMIT{25};
79/** Default for -datacarrier */
80inline constexpr bool DEFAULT_ACCEPT_DATACARRIER = true;
81/**
82 * Default setting for -datacarriersize in vbytes.
83 */
84inline constexpr 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 */
90inline constexpr unsigned int EXTRA_DESCENDANT_TX_SIZE_LIMIT{10'000};
91
92/**
93 * Maximum number of ephemeral dust outputs allowed.
94 */
95inline 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 */
104inline 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 */
118inline 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. */
134inline 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. */
137inline constexpr unsigned int STANDARD_LOCKTIME_VERIFY_FLAGS{LOCKTIME_VERIFY_SEQUENCE};
138
139CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFee);
140
141bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFee);
142
143bool IsStandard(const CScript& scriptPubKey, TxoutType& whichType);
144
145/** Get the vout index numbers of all dust outputs */
146std::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.
151inline constexpr decltype(CTransaction::version) TX_MIN_STANDARD_VERSION{1};
152inline 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*/
158bool 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 */
165TxValidationState 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*/
173bool 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 */
178bool SpendsNonAnchorWitnessProg(const CTransaction& tx, const CCoinsViewCache& prevouts);
179
180/** Compute the virtual transaction size (weight reinterpreted as bytes). */
181int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost, unsigned int bytes_per_sigop);
182int64_t GetVirtualTransactionSize(const CTransaction& tx, int64_t nSigOpCost, unsigned int bytes_per_sigop);
183int64_t GetVirtualTransactionInputSize(const CTxIn& tx, int64_t nSigOpCost, unsigned int bytes_per_sigop);
184
185static inline int64_t GetVirtualTransactionSize(const CTransaction& tx)
186{
187    return GetVirtualTransactionSize(tx, 0, 0);
188}
189
190static inline int64_t GetVirtualTransactionInputSize(const CTxIn& tx)
191{
192    return GetVirtualTransactionInputSize(tx, 0, 0);
193}
194
195int64_t GetSigOpsAdjustedWeight(int64_t weight, int64_t sigop_cost, unsigned int bytes_per_sigop);
196
197static 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