text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2016 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_SCRIPT_SCRIPT_H
  #define BITCOIN_SCRIPT_SCRIPT_H
  
  #include <crypto/common.h>
  #include <prevector.h>
  #include <serialize.h>
  
  #include <cassert>
  #include <climits>
  #include <cstdint>
  #include <cstring>
  #include <limits>
  #include <stdexcept>
  #include <string>
  #include <vector>
  
  // Maximum number of bytes pushable to the stack
  static const unsigned int MAX_SCRIPT_ELEMENT_SIZE = 520;
  
  // Maximum number of non-push operations per script
  static const int MAX_OPS_PER_SCRIPT = 201;
  
  // Maximum number of public keys per multisig
  static const int MAX_PUBKEYS_PER_MULTISIG = 20;
  
  // Maximum script length in bytes
  static const int MAX_SCRIPT_SIZE = 10000;
  
  // Maximum number of values on script interpreter stack
  static const int MAX_STACK_SIZE = 1000;
  
  // Threshold for nLockTime: below this value it is interpreted as block number,
  // otherwise as UNIX timestamp. Thresold is Tue Nov 5 00:53:20 1985 UTC
  static const unsigned int LOCKTIME_THRESHOLD = 500000000;
  
  template <typename T> std::vector<uint8_t> ToByteVector(const T &in) {
      return std::vector<uint8_t>(in.begin(), in.end());
  }
  
  /** Script opcodes */
  enum opcodetype {
      // push value
      OP_0 = 0x00,
      OP_FALSE = OP_0,
      OP_PUSHDATA1 = 0x4c,
      OP_PUSHDATA2 = 0x4d,
      OP_PUSHDATA4 = 0x4e,
      OP_1NEGATE = 0x4f,
      OP_RESERVED = 0x50,
      OP_1 = 0x51,
      OP_TRUE = OP_1,
      OP_2 = 0x52,
      OP_3 = 0x53,
      OP_4 = 0x54,
      OP_5 = 0x55,
      OP_6 = 0x56,
      OP_7 = 0x57,
      OP_8 = 0x58,
      OP_9 = 0x59,
      OP_10 = 0x5a,
      OP_11 = 0x5b,
      OP_12 = 0x5c,
      OP_13 = 0x5d,
      OP_14 = 0x5e,
      OP_15 = 0x5f,
      OP_16 = 0x60,
  
      // control
      OP_NOP = 0x61,
      OP_VER = 0x62,
      OP_IF = 0x63,
      OP_NOTIF = 0x64,
      OP_VERIF = 0x65,
      OP_VERNOTIF = 0x66,
      OP_ELSE = 0x67,
      OP_ENDIF = 0x68,
      OP_VERIFY = 0x69,
      OP_RETURN = 0x6a,
  
      // stack ops
      OP_TOALTSTACK = 0x6b,
      OP_FROMALTSTACK = 0x6c,
      OP_2DROP = 0x6d,
      OP_2DUP = 0x6e,
      OP_3DUP = 0x6f,
      OP_2OVER = 0x70,
      OP_2ROT = 0x71,
      OP_2SWAP = 0x72,
      OP_IFDUP = 0x73,
      OP_DEPTH = 0x74,
      OP_DROP = 0x75,
      OP_DUP = 0x76,
      OP_NIP = 0x77,
      OP_OVER = 0x78,
      OP_PICK = 0x79,
      OP_ROLL = 0x7a,
      OP_ROT = 0x7b,
      OP_SWAP = 0x7c,
      OP_TUCK = 0x7d,
  
      // splice ops
      OP_CAT = 0x7e,
      OP_SPLIT = 0x7f,   // after monolith upgrade (May 2018)
      OP_NUM2BIN = 0x80, // after monolith upgrade (May 2018)
      OP_BIN2NUM = 0x81, // after monolith upgrade (May 2018)
      OP_SIZE = 0x82,
  
      // bit logic
      OP_INVERT = 0x83,
      OP_AND = 0x84,
      OP_OR = 0x85,
      OP_XOR = 0x86,
      OP_EQUAL = 0x87,
      OP_EQUALVERIFY = 0x88,
      OP_RESERVED1 = 0x89,
      OP_RESERVED2 = 0x8a,
  
      // numeric
      OP_1ADD = 0x8b,
      OP_1SUB = 0x8c,
      OP_2MUL = 0x8d,
      OP_2DIV = 0x8e,
      OP_NEGATE = 0x8f,
      OP_ABS = 0x90,
      OP_NOT = 0x91,
      OP_0NOTEQUAL = 0x92,
  
      OP_ADD = 0x93,
      OP_SUB = 0x94,
      OP_MUL = 0x95,
      OP_DIV = 0x96,
      OP_MOD = 0x97,
      OP_LSHIFT = 0x98,
      OP_RSHIFT = 0x99,
  
      OP_BOOLAND = 0x9a,
      OP_BOOLOR = 0x9b,
      OP_NUMEQUAL = 0x9c,
      OP_NUMEQUALVERIFY = 0x9d,
      OP_NUMNOTEQUAL = 0x9e,
      OP_LESSTHAN = 0x9f,
      OP_GREATERTHAN = 0xa0,
      OP_LESSTHANOREQUAL = 0xa1,
      OP_GREATERTHANOREQUAL = 0xa2,
      OP_MIN = 0xa3,
      OP_MAX = 0xa4,
  
      OP_WITHIN = 0xa5,
  
      // crypto
      OP_RIPEMD160 = 0xa6,
      OP_SHA1 = 0xa7,
      OP_SHA256 = 0xa8,
      OP_HASH160 = 0xa9,
      OP_HASH256 = 0xaa,
      OP_CODESEPARATOR = 0xab,
      OP_CHECKSIG = 0xac,
      OP_CHECKSIGVERIFY = 0xad,
      OP_CHECKMULTISIG = 0xae,
      OP_CHECKMULTISIGVERIFY = 0xaf,
  
      // expansion
      OP_NOP1 = 0xb0,
      OP_CHECKLOCKTIMEVERIFY = 0xb1,
      OP_NOP2 = OP_CHECKLOCKTIMEVERIFY,
      OP_CHECKSEQUENCEVERIFY = 0xb2,
      OP_NOP3 = OP_CHECKSEQUENCEVERIFY,
      OP_NOP4 = 0xb3,
      OP_NOP5 = 0xb4,
      OP_NOP6 = 0xb5,
      OP_NOP7 = 0xb6,
      OP_NOP8 = 0xb7,
      OP_NOP9 = 0xb8,
      OP_NOP10 = 0xb9,
  
      // More crypto
      OP_CHECKDATASIG = 0xba,
      OP_CHECKDATASIGVERIFY = 0xbb,
  
      // The first op_code value after all defined opcodes
      FIRST_UNDEFINED_OP_VALUE,
  
      // multi-byte opcodes
      OP_PREFIX_BEGIN = 0xf0,
      OP_PREFIX_END = 0xf7,
  
      OP_INVALIDOPCODE = 0xff,
  };
  
  const char *GetOpName(opcodetype opcode);
  
  /**
   * Check whether the given stack element data would be minimally pushed using
   * the given opcode.
   */
  bool CheckMinimalPush(const std::vector<uint8_t> &data, opcodetype opcode);
  
  class scriptnum_error : public std::runtime_error {
  public:
      explicit scriptnum_error(const std::string &str)
          : std::runtime_error(str) {}
  };
  
  class CScriptNum {
      /**
       * Numeric opcodes (OP_1ADD, etc) are restricted to operating on 4-byte
       * integers. The semantics are subtle, though: operands must be in the range
       * [-2^31 +1...2^31 -1], but results may overflow (and are valid as long as
       * they are not used in a subsequent numeric operation). CScriptNum enforces
       * those semantics by storing results as an int64 and allowing out-of-range
       * values to be returned as a vector of bytes but throwing an exception if
       * arithmetic is done or the result is interpreted as an integer.
       */
  public:
      static const size_t MAXIMUM_ELEMENT_SIZE = 4;
  
      explicit CScriptNum(const int64_t &n) { m_value = n; }
  
      explicit CScriptNum(const std::vector<uint8_t> &vch, bool fRequireMinimal,
                          const size_t nMaxNumSize = MAXIMUM_ELEMENT_SIZE) {
          if (vch.size() > nMaxNumSize) {
              throw scriptnum_error("script number overflow");
          }
          if (fRequireMinimal && !IsMinimallyEncoded(vch, nMaxNumSize)) {
              throw scriptnum_error("non-minimally encoded script number");
          }
          m_value = set_vch(vch);
      }
  
      static bool IsMinimallyEncoded(
          const std::vector<uint8_t> &vch,
          const size_t nMaxNumSize = CScriptNum::MAXIMUM_ELEMENT_SIZE);
  
      static bool MinimallyEncode(std::vector<uint8_t> &data);
  
      inline bool operator==(const int64_t &rhs) const { return m_value == rhs; }
      inline bool operator!=(const int64_t &rhs) const { return m_value != rhs; }
      inline bool operator<=(const int64_t &rhs) const { return m_value <= rhs; }
      inline bool operator<(const int64_t &rhs) const { return m_value < rhs; }
      inline bool operator>=(const int64_t &rhs) const { return m_value >= rhs; }
      inline bool operator>(const int64_t &rhs) const { return m_value > rhs; }
  
      inline bool operator==(const CScriptNum &rhs) const {
          return operator==(rhs.m_value);
      }
      inline bool operator!=(const CScriptNum &rhs) const {
          return operator!=(rhs.m_value);
      }
      inline bool operator<=(const CScriptNum &rhs) const {
          return operator<=(rhs.m_value);
      }
      inline bool operator<(const CScriptNum &rhs) const {
          return operator<(rhs.m_value);
      }
      inline bool operator>=(const CScriptNum &rhs) const {
          return operator>=(rhs.m_value);
      }
      inline bool operator>(const CScriptNum &rhs) const {
          return operator>(rhs.m_value);
      }
  
      inline CScriptNum operator+(const int64_t &rhs) const {
          return CScriptNum(m_value + rhs);
      }
      inline CScriptNum operator-(const int64_t &rhs) const {
          return CScriptNum(m_value - rhs);
      }
      inline CScriptNum operator+(const CScriptNum &rhs) const {
          return operator+(rhs.m_value);
      }
      inline CScriptNum operator-(const CScriptNum &rhs) const {
          return operator-(rhs.m_value);
      }
  
      inline CScriptNum operator/(const int64_t &rhs) const {
          return CScriptNum(m_value / rhs);
      }
      inline CScriptNum operator/(const CScriptNum &rhs) const {
          return operator/(rhs.m_value);
      }
  
      inline CScriptNum operator%(const int64_t &rhs) const {
          return CScriptNum(m_value % rhs);
      }
      inline CScriptNum operator%(const CScriptNum &rhs) const {
          return operator%(rhs.m_value);
      }
  
      inline CScriptNum &operator+=(const CScriptNum &rhs) {
          return operator+=(rhs.m_value);
      }
      inline CScriptNum &operator-=(const CScriptNum &rhs) {
          return operator-=(rhs.m_value);
      }
  
      inline CScriptNum operator&(const int64_t &rhs) const {
          return CScriptNum(m_value & rhs);
      }
      inline CScriptNum operator&(const CScriptNum &rhs) const {
          return operator&(rhs.m_value);
      }
  
      inline CScriptNum &operator&=(const CScriptNum &rhs) {
          return operator&=(rhs.m_value);
      }
  
      inline CScriptNum operator-() const {
          assert(m_value != std::numeric_limits<int64_t>::min());
          return CScriptNum(-m_value);
      }
  
      inline CScriptNum &operator=(const int64_t &rhs) {
          m_value = rhs;
          return *this;
      }
  
      inline CScriptNum &operator+=(const int64_t &rhs) {
          assert(
              rhs == 0 ||
              (rhs > 0 && m_value <= std::numeric_limits<int64_t>::max() - rhs) ||
              (rhs < 0 && m_value >= std::numeric_limits<int64_t>::min() - rhs));
          m_value += rhs;
          return *this;
      }
  
      inline CScriptNum &operator-=(const int64_t &rhs) {
          assert(
              rhs == 0 ||
              (rhs > 0 && m_value >= std::numeric_limits<int64_t>::min() + rhs) ||
              (rhs < 0 && m_value <= std::numeric_limits<int64_t>::max() + rhs));
          m_value -= rhs;
          return *this;
      }
  
      inline CScriptNum &operator&=(const int64_t &rhs) {
          m_value &= rhs;
          return *this;
      }
  
      int getint() const {
          if (m_value > std::numeric_limits<int>::max()) {
              return std::numeric_limits<int>::max();
          } else if (m_value < std::numeric_limits<int>::min()) {
              return std::numeric_limits<int>::min();
          }
          return m_value;
      }
  
      std::vector<uint8_t> getvch() const { return serialize(m_value); }
  
      static std::vector<uint8_t> serialize(const int64_t &value) {
          if (value == 0) {
              return {};
          }
  
          std::vector<uint8_t> result;
          const bool neg = value < 0;
          uint64_t absvalue = neg ? -value : value;
  
          while (absvalue) {
              result.push_back(absvalue & 0xff);
              absvalue >>= 8;
          }
  
          // - If the most significant byte is >= 0x80 and the value is positive,
          // push a new zero-byte to make the significant byte < 0x80 again.
          // - If the most significant byte is >= 0x80 and the value is negative,
          // push a new 0x80 byte that will be popped off when converting to an
          // integral.
          // - If the most significant byte is < 0x80 and the value is negative,
          // add 0x80 to it, since it will be subtracted and interpreted as a
          // negative when converting to an integral.
          if (result.back() & 0x80) {
              result.push_back(neg ? 0x80 : 0);
          } else if (neg) {
              result.back() |= 0x80;
          }
  
          return result;
      }
  
  private:
      static int64_t set_vch(const std::vector<uint8_t> &vch) {
          if (vch.empty()) {
              return 0;
          }
  
          int64_t result = 0;
          for (size_t i = 0; i != vch.size(); ++i) {
              result |= int64_t(vch[i]) << 8 * i;
          }
  
          // If the input vector's most significant byte is 0x80, remove it from
          // the result's msb and return a negative.
          if (vch.back() & 0x80) {
              return -int64_t(result & ~(0x80ULL << (8 * (vch.size() - 1))));
          }
  
          return result;
      }
  
      int64_t m_value;
  };
  
  /**
   * We use a prevector for the script to reduce the considerable memory overhead
   * of vectors in cases where they normally contain a small number of small
   * elements. Tests in October 2015 showed use of this reduced dbcache memory
   * usage by 23% and made an initial sync 13% faster.
   */
  typedef prevector<28, uint8_t> CScriptBase;
  
  bool GetScriptOp(CScriptBase::const_iterator &pc,
                   CScriptBase::const_iterator end, opcodetype &opcodeRet,
                   std::vector<uint8_t> *pvchRet);
  
  /** Serialized script, used inside transaction inputs and outputs */
  class CScript : public CScriptBase {
  protected:
      CScript &push_int64(int64_t n) {
          if (n == -1 || (n >= 1 && n <= 16)) {
              push_back(n + (OP_1 - 1));
          } else if (n == 0) {
              push_back(OP_0);
          } else {
              *this << CScriptNum::serialize(n);
          }
          return *this;
      }
  
  public:
      CScript() {}
      CScript(const_iterator pbegin, const_iterator pend)
          : CScriptBase(pbegin, pend) {}
      CScript(std::vector<uint8_t>::const_iterator pbegin,
              std::vector<uint8_t>::const_iterator pend)
          : CScriptBase(pbegin, pend) {}
      CScript(const uint8_t *pbegin, const uint8_t *pend)
          : CScriptBase(pbegin, pend) {}
  
      ADD_SERIALIZE_METHODS;
  
      template <typename Stream, typename Operation>
      inline void SerializationOp(Stream &s, Operation ser_action) {
          READWRITEAS(CScriptBase, *this);
      }
  
      CScript &operator+=(const CScript &b) {
          reserve(size() + b.size());
          insert(end(), b.begin(), b.end());
          return *this;
      }
  
      friend CScript operator+(const CScript &a, const CScript &b) {
          CScript ret = a;
          ret += b;
          return ret;
      }
  
      CScript(int64_t b) { operator<<(b); }
  
      explicit CScript(opcodetype b) { operator<<(b); }
      explicit CScript(const CScriptNum &b) { operator<<(b); }
      explicit CScript(const std::vector<uint8_t> &b) { operator<<(b); }
  
      CScript &operator<<(int64_t b) { return push_int64(b); }
  
      CScript &operator<<(opcodetype opcode) {
          if (opcode < 0 || opcode > 0xff) {
              throw std::runtime_error("CScript::operator<<(): invalid opcode");
          }
          insert(end(), uint8_t(opcode));
          return *this;
      }
  
      CScript &operator<<(const CScriptNum &b) {
          *this << b.getvch();
          return *this;
      }
  
      CScript &operator<<(const std::vector<uint8_t> &b) {
          if (b.size() < OP_PUSHDATA1) {
              insert(end(), uint8_t(b.size()));
          } else if (b.size() <= 0xff) {
              insert(end(), OP_PUSHDATA1);
              insert(end(), uint8_t(b.size()));
          } else if (b.size() <= 0xffff) {
              insert(end(), OP_PUSHDATA2);
              uint8_t _data[2];
              WriteLE16(_data, b.size());
              insert(end(), _data, _data + sizeof(_data));
          } else {
              insert(end(), OP_PUSHDATA4);
              uint8_t _data[4];
              WriteLE32(_data, b.size());
              insert(end(), _data, _data + sizeof(_data));
          }
          insert(end(), b.begin(), b.end());
          return *this;
      }
  
      CScript &operator<<(const CScript &b) {
          // I'm not sure if this should push the script or concatenate scripts.
          // If there's ever a use for pushing a script onto a script, delete this
          // member fn.
          assert(!"Warning: Pushing a CScript onto a CScript with << is probably "
                  "not intended, use + to concatenate!");
          return *this;
      }
  
      bool GetOp(const_iterator &pc, opcodetype &opcodeRet,
                 std::vector<uint8_t> &vchRet) const {
          return GetScriptOp(pc, end(), opcodeRet, &vchRet);
      }
  
      bool GetOp(const_iterator &pc, opcodetype &opcodeRet) const {
          return GetScriptOp(pc, end(), opcodeRet, nullptr);
      }
  
      /** Encode/decode small integers: */
      static int DecodeOP_N(opcodetype opcode) {
          if (opcode == OP_0) {
              return 0;
          }
  
          assert(opcode >= OP_1 && opcode <= OP_16);
          return int(opcode) - int(OP_1 - 1);
      }
      static opcodetype EncodeOP_N(int n) {
          assert(n >= 0 && n <= 16);
          if (n == 0) {
              return OP_0;
          }
  
          return (opcodetype)(OP_1 + n - 1);
      }
  
      /**
       * Pre-version-0.6, Bitcoin always counted CHECKMULTISIGs as 20 sigops. With
       * pay-to-script-hash, that changed: CHECKMULTISIGs serialized in scriptSigs
       * are counted more accurately, assuming they are of the form
       *  ... OP_N CHECKMULTISIG ...
       */
      uint32_t GetSigOpCount(uint32_t flags, bool fAccurate) const;
  
      /**
       * Accurately count sigOps, including sigOps in pay-to-script-hash
       * transactions:
       */
      uint32_t GetSigOpCount(uint32_t flags, const CScript &scriptSig) const;
  
      bool IsPayToPublicKeyHash() const;
  
      bool IsPayToScriptHash() const;
      bool IsCommitment(const std::vector<uint8_t> &data) const;
      bool IsWitnessProgram(int &version, std::vector<uint8_t> &program) const;
      bool IsWitnessProgram() const;
  
      /**
       * Called by IsStandardTx and P2SH/BIP62 VerifyScript (which makes it
       * consensus-critical).
       */
      bool IsPushOnly(const_iterator pc) const;
      bool IsPushOnly() const;
  
      /**
       * Returns whether the script is guaranteed to fail at execution, regardless
       * of the initial stack. This allows outputs to be pruned instantly when
       * entering the UTXO set.
       */
      bool IsUnspendable() const {
          return (size() > 0 && *begin() == OP_RETURN) ||
                 (size() > MAX_SCRIPT_SIZE);
      }
  
      void clear() {
          // The default prevector::clear() does not release memory
          CScriptBase::clear();
          shrink_to_fit();
      }
  };
  
  class CReserveScript {
  public:
      CScript reserveScript;
      virtual void KeepScript() {}
      CReserveScript() {}
      virtual ~CReserveScript() {}
  };
  
  #endif // BITCOIN_SCRIPT_SCRIPT_H
  