1  // Copyright (c) 2009-2010 Satoshi Nakamoto
  2  // Copyright (c) 2009-2022 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 <primitives/transaction.h>
 12  #include <script/interpreter.h>
 13  #include <script/solver.h>
 14  
 15  #include <cstdint>
 16  #include <string>
 17  
 18  class CCoinsViewCache;
 19  class CFeeRate;
 20  class CScript;
 21  
 22  /** Default for -blockmaxweight, which controls the range of block weights the mining code will create **/
 23  static constexpr unsigned int DEFAULT_BLOCK_MAX_WEIGHT{MAX_BLOCK_WEIGHT - 4000};
 24  /** Default for -blockmintxfee, which sets the minimum feerate for a transaction in blocks created by mining code **/
 25  static constexpr unsigned int DEFAULT_BLOCK_MIN_TX_FEE{1000};
 26  /** The maximum weight for transactions we're willing to relay/mine */
 27  static constexpr int32_t MAX_STANDARD_TX_WEIGHT{400000};
 28  /** The minimum non-witness size for transactions we're willing to relay/mine: one larger than 64  */
 29  static constexpr unsigned int MIN_STANDARD_TX_NONWITNESS_SIZE{65};
 30  /** Maximum number of signature check operations in an IsStandard() P2SH script */
 31  static constexpr unsigned int MAX_P2SH_SIGOPS{15};
 32  /** The maximum number of sigops we're willing to relay/mine in a single tx */
 33  static constexpr unsigned int MAX_STANDARD_TX_SIGOPS_COST{MAX_BLOCK_SIGOPS_COST/5};
 34  /** Default for -incrementalrelayfee, which sets the minimum feerate increase for mempool limiting or replacement **/
 35  static constexpr unsigned int DEFAULT_INCREMENTAL_RELAY_FEE{1000};
 36  /** Default for -bytespersigop */
 37  static constexpr unsigned int DEFAULT_BYTES_PER_SIGOP{20};
 38  /** Default for -permitbaremultisig */
 39  static constexpr bool DEFAULT_PERMIT_BAREMULTISIG{true};
 40  /** The maximum number of witness stack items in a standard P2WSH script */
 41  static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEMS{100};
 42  /** The maximum size in bytes of each witness stack item in a standard P2WSH script */
 43  static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEM_SIZE{80};
 44  /** The maximum size in bytes of each witness stack item in a standard BIP 342 script (Taproot, leaf version 0xc0) */
 45  static constexpr unsigned int MAX_STANDARD_TAPSCRIPT_STACK_ITEM_SIZE{80};
 46  /** The maximum size in bytes of a standard witnessScript */
 47  static constexpr unsigned int MAX_STANDARD_P2WSH_SCRIPT_SIZE{3600};
 48  /** The maximum size of a standard ScriptSig */
 49  static constexpr unsigned int MAX_STANDARD_SCRIPTSIG_SIZE{1650};
 50  /** Min feerate for defining dust.
 51   * Changing the dust limit changes which transactions are
 52   * standard and should be done with care and ideally rarely. It makes sense to
 53   * only increase the dust limit after prior releases were already not creating
 54   * outputs below the new threshold */
 55  static constexpr unsigned int DUST_RELAY_TX_FEE{3000};
 56  /** Default for -minrelaytxfee, minimum relay fee for transactions */
 57  static constexpr unsigned int DEFAULT_MIN_RELAY_TX_FEE{1000};
 58  /** Default for -limitancestorcount, max number of in-mempool ancestors */
 59  static constexpr unsigned int DEFAULT_ANCESTOR_LIMIT{25};
 60  /** Default for -limitancestorsize, maximum kilobytes of tx + all in-mempool ancestors */
 61  static constexpr unsigned int DEFAULT_ANCESTOR_SIZE_LIMIT_KVB{101};
 62  /** Default for -limitdescendantcount, max number of in-mempool descendants */
 63  static constexpr unsigned int DEFAULT_DESCENDANT_LIMIT{25};
 64  /** Default for -limitdescendantsize, maximum kilobytes of in-mempool descendants */
 65  static constexpr unsigned int DEFAULT_DESCENDANT_SIZE_LIMIT_KVB{101};
 66  /** Default for -datacarrier */
 67  static const bool DEFAULT_ACCEPT_DATACARRIER = true;
 68  /**
 69   * Default setting for -datacarriersize. 80 bytes of data, +1 for OP_RETURN,
 70   * +2 for the pushdata opcodes.
 71   */
 72  static const unsigned int MAX_OP_RETURN_RELAY = 83;
 73  /**
 74   * An extra transaction can be added to a package, as long as it only has one
 75   * ancestor and is no larger than this. Not really any reason to make this
 76   * configurable as it doesn't materially change DoS parameters.
 77   */
 78  static constexpr unsigned int EXTRA_DESCENDANT_TX_SIZE_LIMIT{10000};
 79  
 80  
 81  /**
 82   * Mandatory script verification flags that all new transactions must comply with for
 83   * them to be valid. Failing one of these tests may trigger a DoS ban;
 84   * see CheckInputScripts() for details.
 85   *
 86   * Note that this does not affect consensus validity; see GetBlockScriptFlags()
 87   * for that.
 88   */
 89  static constexpr unsigned int MANDATORY_SCRIPT_VERIFY_FLAGS{SCRIPT_VERIFY_P2SH |
 90                                                               SCRIPT_VERIFY_DERSIG |
 91                                                               SCRIPT_VERIFY_NULLDUMMY |
 92                                                               SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY |
 93                                                               SCRIPT_VERIFY_CHECKSEQUENCEVERIFY |
 94                                                               SCRIPT_VERIFY_WITNESS |
 95                                                               SCRIPT_VERIFY_TAPROOT};
 96  
 97  /**
 98   * Standard script verification flags that standard transactions will comply
 99   * with. However we do not ban/disconnect nodes that forward txs violating
100   * the additional (non-mandatory) rules here, to improve forwards and
101   * backwards compatibility.
102   */
103  static constexpr unsigned int STANDARD_SCRIPT_VERIFY_FLAGS{MANDATORY_SCRIPT_VERIFY_FLAGS |
104                                                               SCRIPT_VERIFY_STRICTENC |
105                                                               SCRIPT_VERIFY_MINIMALDATA |
106                                                               SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS |
107                                                               SCRIPT_VERIFY_CLEANSTACK |
108                                                               SCRIPT_VERIFY_MINIMALIF |
109                                                               SCRIPT_VERIFY_NULLFAIL |
110                                                               SCRIPT_VERIFY_LOW_S |
111                                                               SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM |
112                                                               SCRIPT_VERIFY_WITNESS_PUBKEYTYPE |
113                                                               SCRIPT_VERIFY_CONST_SCRIPTCODE |
114                                                               SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_TAPROOT_VERSION |
115                                                               SCRIPT_VERIFY_DISCOURAGE_OP_SUCCESS |
116                                                               SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_PUBKEYTYPE};
117  
118  /** For convenience, standard but not mandatory verify flags. */
119  static constexpr unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS{STANDARD_SCRIPT_VERIFY_FLAGS & ~MANDATORY_SCRIPT_VERIFY_FLAGS};
120  
121  /** Used as the flags parameter to sequence and nLocktime checks in non-consensus code. */
122  static constexpr unsigned int STANDARD_LOCKTIME_VERIFY_FLAGS{LOCKTIME_VERIFY_SEQUENCE};
123  
124  CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFee);
125  
126  bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFee);
127  
128  bool IsStandard(const CScript& scriptPubKey, const std::optional<unsigned>& max_datacarrier_bytes, TxoutType& whichType);
129  
130  
131  // Changing the default transaction version requires a two step process: first
132  // adapting relay policy by bumping TX_MAX_STANDARD_VERSION, and then later
133  // allowing the new transaction version in the wallet/RPC.
134  static constexpr decltype(CTransaction::nVersion) TX_MAX_STANDARD_VERSION{2};
135  
136  /**
137  * Check for standard transaction types
138  * @return True if all outputs (scriptPubKeys) use only standard transaction forms
139  */
140  bool IsStandardTx(const CTransaction& tx, const std::optional<unsigned>& max_datacarrier_bytes, bool permit_bare_multisig, const CFeeRate& dust_relay_fee, std::string& reason);
141  /**
142  * Check for standard transaction types
143  * @param[in] mapInputs       Map of previous transactions that have outputs we're spending
144  * @return True if all inputs (scriptSigs) use only standard transaction forms
145  */
146  bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
147  /**
148  * Check if the transaction is over standard P2WSH resources limit:
149  * 3600bytes witnessScript size, 80bytes per witness stack element, 100 witness stack elements
150  * These limits are adequate for multisignatures up to n-of-100 using OP_CHECKSIG, OP_ADD, and OP_EQUAL.
151  *
152  * Also enforce a maximum stack item size limit and no annexes for tapscript spends.
153  */
154  bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
155  
156  /** Compute the virtual transaction size (weight reinterpreted as bytes). */
157  int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost, unsigned int bytes_per_sigop);
158  int64_t GetVirtualTransactionSize(const CTransaction& tx, int64_t nSigOpCost, unsigned int bytes_per_sigop);
159  int64_t GetVirtualTransactionInputSize(const CTxIn& tx, int64_t nSigOpCost, unsigned int bytes_per_sigop);
160  
161  static inline int64_t GetVirtualTransactionSize(const CTransaction& tx)
162  {
163      return GetVirtualTransactionSize(tx, 0, 0);
164  }
165  
166  static inline int64_t GetVirtualTransactionInputSize(const CTxIn& tx)
167  {
168      return GetVirtualTransactionInputSize(tx, 0, 0);
169  }
170  
171  #endif // BITCOIN_POLICY_POLICY_H