text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2017 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #ifndef BITCOIN_POLICY_POLICY_H
  #define BITCOIN_POLICY_POLICY_H
  
  #include <consensus/consensus.h>
  #include <policy/feerate.h>
  #include <script/interpreter.h>
  #include <script/standard.h>
  
  #include <string>
  
  class CCoinsViewCache;
  class CTxOut;
  
  /** Default for -blockmaxweight, which controls the range of block weights the mining code will create **/
  static const unsigned int DEFAULT_BLOCK_MAX_WEIGHT = MAX_BLOCK_WEIGHT - 4000;
  /** Default for -blockmintxfee, which sets the minimum feerate for a transaction in blocks created by mining code **/
  static const unsigned int DEFAULT_BLOCK_MIN_TX_FEE = 1000;
  /** The maximum weight for transactions we're willing to relay/mine */
  static const unsigned int MAX_STANDARD_TX_WEIGHT = 400000;
  /** Maximum number of signature check operations in an IsStandard() P2SH script */
  static const unsigned int MAX_P2SH_SIGOPS = 15;
  /** The maximum number of sigops we're willing to relay/mine in a single tx */
  static const unsigned int MAX_STANDARD_TX_SIGOPS_COST = MAX_BLOCK_SIGOPS_COST/5;
  /** Default for -maxmempool, maximum megabytes of mempool memory usage */
  static const unsigned int DEFAULT_MAX_MEMPOOL_SIZE = 300;
  /** Default for -incrementalrelayfee, which sets the minimum feerate increase for mempool limiting or BIP 125 replacement **/
  static const unsigned int DEFAULT_INCREMENTAL_RELAY_FEE = 1000;
  /** Default for -bytespersigop */
  static const unsigned int DEFAULT_BYTES_PER_SIGOP = 20;
  /** The maximum number of witness stack items in a standard P2WSH script */
  static const unsigned int MAX_STANDARD_P2WSH_STACK_ITEMS = 100;
  /** The maximum size of each witness stack item in a standard P2WSH script */
  static const unsigned int MAX_STANDARD_P2WSH_STACK_ITEM_SIZE = 80;
  /** The maximum size of a standard witnessScript */
  static const unsigned int MAX_STANDARD_P2WSH_SCRIPT_SIZE = 3600;
  /** Min feerate for defining dust. Historically this has been based on the
   * minRelayTxFee, however changing the dust limit changes which transactions are
   * standard and should be done with care and ideally rarely. It makes sense to
   * only increase the dust limit after prior releases were already not creating
   * outputs below the new threshold */
  static const unsigned int DUST_RELAY_TX_FEE = 1000000;
  /**
   * Standard script verification flags that standard transactions will comply
   * with. However scripts violating these flags may still be present in valid
   * blocks and we must accept those blocks.
   */
  static constexpr unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY_FLAGS |
                                                               SCRIPT_VERIFY_DERSIG |
                                                               SCRIPT_VERIFY_STRICTENC |
                                                               SCRIPT_VERIFY_MINIMALDATA |
                                                               SCRIPT_VERIFY_NULLDUMMY |
                                                               SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS |
                                                               SCRIPT_VERIFY_CLEANSTACK |
                                                               SCRIPT_VERIFY_MINIMALIF |
                                                               SCRIPT_VERIFY_NULLFAIL |
                                                               SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY |
                                                               SCRIPT_VERIFY_CHECKSEQUENCEVERIFY |
                                                               SCRIPT_VERIFY_LOW_S |
                                                               SCRIPT_VERIFY_WITNESS |
                                                               SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM |
                                                               SCRIPT_VERIFY_WITNESS_PUBKEYTYPE;
  
  /** For convenience, standard but not mandatory verify flags. */
  static constexpr unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS = STANDARD_SCRIPT_VERIFY_FLAGS & ~MANDATORY_SCRIPT_VERIFY_FLAGS;
  
  /** Used as the flags parameter to sequence and nLocktime checks in non-consensus code. */
  static constexpr unsigned int STANDARD_LOCKTIME_VERIFY_FLAGS = LOCKTIME_VERIFY_SEQUENCE |
                                                                 LOCKTIME_MEDIAN_TIME_PAST;
  
  CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFee);
  
  bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFee);
  
  bool IsStandard(const CScript& scriptPubKey, txnouttype& whichType, const bool witnessEnabled = false);
      /**
       * Check for standard transaction types
       * @return True if all outputs (scriptPubKeys) use only standard transaction forms
       */
  bool IsStandardTx(const CTransaction& tx, std::string& reason, const bool witnessEnabled = false);
      /**
       * Check for standard transaction types
       * @param[in] mapInputs    Map of previous transactions that have outputs we're spending
       * @return True if all inputs (scriptSigs) use only standard transaction forms
       */
  bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
      /**
       * Check if the transaction is over standard P2WSH resources limit:
       * 3600bytes witnessScript size, 80bytes per witness stack element, 100 witness stack elements
       * These limits are adequate for multi-signature up to n-of-100 using OP_CHECKSIG, OP_ADD, and OP_EQUAL,
       */
  bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
  
  extern CFeeRate incrementalRelayFee;
  extern CFeeRate dustRelayFee;
  extern unsigned int nBytesPerSigOp;
  
  /** Compute the virtual transaction size (weight reinterpreted as bytes). */
  int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost);
  int64_t GetVirtualTransactionSize(const CTransaction& tx, int64_t nSigOpCost = 0);
  
  #endif // BITCOIN_POLICY_POLICY_H
  