text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2015 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 <assert.h>
  #include <climits>
  #include <limits>
  #include <stdexcept>
  #include <stdint.h>
  #include <string.h>
  #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;
  
  // Threshold for nLockTime: below this value it is interpreted as block number,
  // otherwise as UNIX timestamp.
  static const unsigned int LOCKTIME_THRESHOLD = 500000000; // Tue Nov  5 00:53:20 1985 UTC
  
  template <typename T>
  std::vector<unsigned char> ToByteVector(const T& in)
  {
      return std::vector<unsigned char>(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_SUBSTR = 0x7f,
      OP_LEFT = 0x80,
      OP_RIGHT = 0x81,
      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,
  
  
      // template matching params
      OP_SMALLINTEGER = 0xfa,
      OP_PUBKEYS = 0xfb,
      OP_PUBKEYHASH = 0xfd,
      OP_PUBKEY = 0xfe,
  
      OP_INVALIDOPCODE = 0xff,
  
      // zerocoin params
      OP_ZEROCOINMINT = 0xc1,
      OP_ZEROCOINSPEND = 0xc2,
  };
  
  const char* GetOpName(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:
  
      explicit CScriptNum(const int64_t& n)
      {
          m_value = n;
      }
  
      static const size_t nDefaultMaxNumSize = 4;
  
      explicit CScriptNum(const std::vector<unsigned char>& vch, bool fRequireMinimal,
                          const size_t nMaxNumSize = nDefaultMaxNumSize)
      {
          if (vch.size() > nMaxNumSize) {
              throw scriptnum_error("script number overflow");
          }
          if (fRequireMinimal && vch.size() > 0) {
              // Check that the number is encoded with the minimum possible
              // number of bytes.
              //
              // If the most-significant-byte - excluding the sign bit - is zero
              // then we're not minimal. Note how this test also rejects the
              // negative-zero encoding, 0x80.
              if ((vch.back() & 0x7f) == 0) {
                  // One exception: if there's more than one byte and the most
                  // significant bit of the second-most-significant-byte is set
                  // it would conflict with the sign bit. An example of this case
                  // is +-255, which encode to 0xff00 and 0xff80 respectively.
                  // (big-endian).
                  if (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0) {
                      throw scriptnum_error("non-minimally encoded script number");
                  }
              }
          }
          m_value = set_vch(vch);
      }
  
      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 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<unsigned char> getvch() const
      {
          return serialize(m_value);
      }
  
      static std::vector<unsigned char> serialize(const int64_t& value)
      {
          if(value == 0)
              return std::vector<unsigned char>();
  
          std::vector<unsigned char> 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<unsigned char>& vch)
      {
        if (vch.empty())
            return 0;
  
        int64_t result = 0;
        for (size_t i = 0; i != vch.size(); ++i)
            result |= static_cast<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;
  };
  
  typedef prevector<28, unsigned char> CScriptBase;
  
  /** 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 CScript& b) : CScriptBase(b.begin(), b.end()) { }
      CScript(const_iterator pbegin, const_iterator pend) : CScriptBase(pbegin, pend) { }
      CScript(std::vector<unsigned char>::const_iterator pbegin, std::vector<unsigned char>::const_iterator pend) : CScriptBase(pbegin, pend) { }
      CScript(const unsigned char* pbegin, const unsigned char* pend) : CScriptBase(pbegin, pend) { }
  
      CScript& operator+=(const CScript& b)
      {
          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<unsigned char>& 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(), (unsigned char)opcode);
          return *this;
      }
  
      CScript& operator<<(const CScriptNum& b)
      {
          *this << b.getvch();
          return *this;
      }
  
      CScript& operator<<(const std::vector<unsigned char>& b)
      {
          if (b.size() < OP_PUSHDATA1)
          {
              insert(end(), (unsigned char)b.size());
          }
          else if (b.size() <= 0xff)
          {
              insert(end(), OP_PUSHDATA1);
              insert(end(), (unsigned char)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(iterator& pc, opcodetype& opcodeRet, std::vector<unsigned char>& vchRet)
      {
           // Wrapper so it can be called with either iterator or const_iterator
           const_iterator pc2 = pc;
           bool fRet = GetOp2(pc2, opcodeRet, &vchRet);
           pc = begin() + (pc2 - begin());
           return fRet;
      }
  
      bool GetOp(iterator& pc, opcodetype& opcodeRet)
      {
           const_iterator pc2 = pc;
           bool fRet = GetOp2(pc2, opcodeRet, NULL);
           pc = begin() + (pc2 - begin());
           return fRet;
      }
  
      bool GetOp(const_iterator& pc, opcodetype& opcodeRet, std::vector<unsigned char>& vchRet) const
      {
          return GetOp2(pc, opcodeRet, &vchRet);
      }
  
      bool GetOp(const_iterator& pc, opcodetype& opcodeRet) const
      {
          return GetOp2(pc, opcodeRet, NULL);
      }
  
      bool GetOp2(const_iterator& pc, opcodetype& opcodeRet, std::vector<unsigned char>* pvchRet) const
      {
          opcodeRet = OP_INVALIDOPCODE;
          if (pvchRet)
              pvchRet->clear();
          if (pc >= end())
              return false;
  
          // Read instruction
          if (end() - pc < 1)
              return false;
          unsigned int opcode = *pc++;
  
          // Immediate operand
          if (opcode <= OP_PUSHDATA4)
          {
              unsigned int nSize = 0;
              if (opcode < OP_PUSHDATA1)
              {
                  nSize = opcode;
              }
              else if (opcode == OP_PUSHDATA1)
              {
                  if (end() - pc < 1)
                      return false;
                  nSize = *pc++;
              }
              else if (opcode == OP_PUSHDATA2)
              {
                  if (end() - pc < 2)
                      return false;
                  nSize = ReadLE16(&pc[0]);
                  pc += 2;
              }
              else if (opcode == OP_PUSHDATA4)
              {
                  if (end() - pc < 4)
                      return false;
                  nSize = ReadLE32(&pc[0]);
                  pc += 4;
              }
              if (end() - pc < 0 || (unsigned int)(end() - pc) < nSize)
                  return false;
              if (pvchRet)
                  pvchRet->assign(pc, pc + nSize);
              pc += nSize;
          }
  
          opcodeRet = (opcodetype)opcode;
          return true;
      }
  
      /** 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);
      }
  
      int FindAndDelete(const CScript& b)
      {
          int nFound = 0;
          if (b.empty())
              return nFound;
          CScript result;
          iterator pc = begin(), pc2 = begin();
          opcodetype opcode;
          do
          {
              result.insert(result.end(), pc2, pc);
              while (static_cast<size_t>(end() - pc) >= b.size() && std::equal(b.begin(), b.end(), pc))
              {
                  pc = pc + b.size();
                  ++nFound;
              }
              pc2 = pc;
          }
          while (GetOp(pc, opcode));
  
          if (nFound > 0) {
              result.insert(result.end(), pc2, end());
              *this = result;
          }
  
          return nFound;
      }
      int Find(opcodetype op) const
      {
          int nFound = 0;
          opcodetype opcode;
          for (const_iterator pc = begin(); pc != end() && GetOp(pc, opcode);)
              if (opcode == op)
                  ++nFound;
          return nFound;
      }
  
      /**
       * 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 ...
       */
      unsigned int GetSigOpCount(bool fAccurate) const;
  
      /**
       * Accurately count sigOps, including sigOps in
       * pay-to-script-hash transactions:
       */
      unsigned int GetSigOpCount(const CScript& scriptSig) const;
  
      bool IsPayToPublicKeyHash() const;
  
      bool IsNormalPaymentScript() const;
  
      bool IsPayToScriptHash() const;
      bool IsPayToWitnessScriptHash() const;
      bool IsWitnessProgram(int& version, std::vector<unsigned char>& program) const;
      
      bool IsZerocoinMint() const;
      bool IsZerocoinSpend() const;
      // Called by IsStandardTx.
      bool HasCanonicalPushes() 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 std::vector::clear() does not release memory.
          CScriptBase().swap(*this);
      }
  };
  
  struct CScriptWitness
  {
      // Note that this encodes the data elements being pushed, rather than
      // encoding them as a CScript that pushes them.
      std::vector<std::vector<unsigned char> > stack;
  
      // Some compilers complain without a default constructor
      CScriptWitness() { }
  
      bool IsNull() const { return stack.empty(); }
  
      std::string ToString() const;
  };
  
  class CReserveScript
  {
  public:
      CScript reserveScript;
      virtual void KeepScript() {}
      CReserveScript() {}
      virtual ~CReserveScript() {}
  };
  
  #endif // BITCOIN_SCRIPT_SCRIPT_H
  