text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2019 The Llamacoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include <script/standard.h>
  
  #include <crypto/sha256.h>
  #include <pubkey.h>
  #include <script/script.h>
  
  typedef std::vector<unsigned char> valtype;
  
  bool fAcceptDatacarrier = DEFAULT_ACCEPT_DATACARRIER;
  unsigned nMaxDatacarrierBytes = MAX_OP_RETURN_RELAY;
  
  CScriptID::CScriptID(const CScript& in) : uint160(Hash160(in.begin(), in.end())) {}
  
  ScriptHash::ScriptHash(const CScript& in) : uint160(Hash160(in.begin(), in.end())) {}
  
  PKHash::PKHash(const CPubKey& pubkey) : uint160(pubkey.GetID()) {}
  
  WitnessV0ScriptHash::WitnessV0ScriptHash(const CScript& in)
  {
      CSHA256().Write(in.data(), in.size()).Finalize(begin());
  }
  
  const char* GetTxnOutputType(txnouttype t)
  {
      switch (t)
      {
      case TX_NONSTANDARD: return "nonstandard";
      case TX_PUBKEY: return "pubkey";
      case TX_PUBKEYHASH: return "pubkeyhash";
      case TX_SCRIPTHASH: return "scripthash";
      case TX_MULTISIG: return "multisig";
      case TX_NULL_DATA: return "nulldata";
      case TX_WITNESS_V0_KEYHASH: return "witness_v0_keyhash";
      case TX_WITNESS_V0_SCRIPTHASH: return "witness_v0_scripthash";
      case TX_WITNESS_UNKNOWN: return "witness_unknown";
      }
      return nullptr;
  }
  
  static bool MatchPayToPubkey(const CScript& script, valtype& pubkey)
  {
      if (script.size() == CPubKey::SIZE + 2 && script[0] == CPubKey::SIZE && script.back() == OP_CHECKSIG) {
          pubkey = valtype(script.begin() + 1, script.begin() + CPubKey::SIZE + 1);
          return CPubKey::ValidSize(pubkey);
      }
      if (script.size() == CPubKey::COMPRESSED_SIZE + 2 && script[0] == CPubKey::COMPRESSED_SIZE && script.back() == OP_CHECKSIG) {
          pubkey = valtype(script.begin() + 1, script.begin() + CPubKey::COMPRESSED_SIZE + 1);
          return CPubKey::ValidSize(pubkey);
      }
      return false;
  }
  
  static bool MatchPayToPubkeyHash(const CScript& script, valtype& pubkeyhash)
  {
      if (script.size() == 25 && script[0] == OP_DUP && script[1] == OP_HASH160 && script[2] == 20 && script[23] == OP_EQUALVERIFY && script[24] == OP_CHECKSIG) {
          pubkeyhash = valtype(script.begin () + 3, script.begin() + 23);
          return true;
      }
      return false;
  }
  
  /** Test for "small positive integer" script opcodes - OP_1 through OP_16. */
  static constexpr bool IsSmallInteger(opcodetype opcode)
  {
      return opcode >= OP_1 && opcode <= OP_16;
  }
  
  static bool MatchMultisig(const CScript& script, unsigned int& required, std::vector<valtype>& pubkeys)
  {
      opcodetype opcode;
      valtype data;
      CScript::const_iterator it = script.begin();
      if (script.size() < 1 || script.back() != OP_CHECKMULTISIG) return false;
  
      if (!script.GetOp(it, opcode, data) || !IsSmallInteger(opcode)) return false;
      required = CScript::DecodeOP_N(opcode);
      while (script.GetOp(it, opcode, data) && CPubKey::ValidSize(data)) {
          pubkeys.emplace_back(std::move(data));
      }
      if (!IsSmallInteger(opcode)) return false;
      unsigned int keys = CScript::DecodeOP_N(opcode);
      if (pubkeys.size() != keys || keys < required) return false;
      return (it + 1 == script.end());
  }
  
  txnouttype Solver(const CScript& scriptPubKey, std::vector<std::vector<unsigned char>>& vSolutionsRet)
  {
      vSolutionsRet.clear();
  
      // Shortcut for pay-to-script-hash, which are more constrained than the other types:
      // it is always OP_HASH160 20 [20 byte hash] OP_EQUAL
      if (scriptPubKey.IsPayToScriptHash())
      {
          std::vector<unsigned char> hashBytes(scriptPubKey.begin()+2, scriptPubKey.begin()+22);
          vSolutionsRet.push_back(hashBytes);
          return TX_SCRIPTHASH;
      }
  
      int witnessversion;
      std::vector<unsigned char> witnessprogram;
      if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
          if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_KEYHASH_SIZE) {
              vSolutionsRet.push_back(witnessprogram);
              return TX_WITNESS_V0_KEYHASH;
          }
          if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
              vSolutionsRet.push_back(witnessprogram);
              return TX_WITNESS_V0_SCRIPTHASH;
          }
          if (witnessversion != 0) {
              vSolutionsRet.push_back(std::vector<unsigned char>{(unsigned char)witnessversion});
              vSolutionsRet.push_back(std::move(witnessprogram));
              return TX_WITNESS_UNKNOWN;
          }
          return TX_NONSTANDARD;
      }
  
      // Provably prunable, data-carrying output
      //
      // So long as script passes the IsUnspendable() test and all but the first
      // byte passes the IsPushOnly() test we don't care what exactly is in the
      // script.
      if (scriptPubKey.size() >= 1 && scriptPubKey[0] == OP_RETURN && scriptPubKey.IsPushOnly(scriptPubKey.begin()+1)) {
          return TX_NULL_DATA;
      }
  
      std::vector<unsigned char> data;
      if (MatchPayToPubkey(scriptPubKey, data)) {
          vSolutionsRet.push_back(std::move(data));
          return TX_PUBKEY;
      }
  
      if (MatchPayToPubkeyHash(scriptPubKey, data)) {
          vSolutionsRet.push_back(std::move(data));
          return TX_PUBKEYHASH;
      }
  
      unsigned int required;
      std::vector<std::vector<unsigned char>> keys;
      if (MatchMultisig(scriptPubKey, required, keys)) {
          vSolutionsRet.push_back({static_cast<unsigned char>(required)}); // safe as required is in range 1..16
          vSolutionsRet.insert(vSolutionsRet.end(), keys.begin(), keys.end());
          vSolutionsRet.push_back({static_cast<unsigned char>(keys.size())}); // safe as size is in range 1..16
          return TX_MULTISIG;
      }
  
      vSolutionsRet.clear();
      return TX_NONSTANDARD;
  }
  
  bool ExtractDestination(const CScript& scriptPubKey, CTxDestination& addressRet)
  {
      std::vector<valtype> vSolutions;
      txnouttype whichType = Solver(scriptPubKey, vSolutions);
  
      if (whichType == TX_PUBKEY) {
          CPubKey pubKey(vSolutions[0]);
          if (!pubKey.IsValid())
              return false;
  
          addressRet = PKHash(pubKey);
          return true;
      }
      else if (whichType == TX_PUBKEYHASH)
      {
          addressRet = PKHash(uint160(vSolutions[0]));
          return true;
      }
      else if (whichType == TX_SCRIPTHASH)
      {
          addressRet = ScriptHash(uint160(vSolutions[0]));
          return true;
      } else if (whichType == TX_WITNESS_V0_KEYHASH) {
          WitnessV0KeyHash hash;
          std::copy(vSolutions[0].begin(), vSolutions[0].end(), hash.begin());
          addressRet = hash;
          return true;
      } else if (whichType == TX_WITNESS_V0_SCRIPTHASH) {
          WitnessV0ScriptHash hash;
          std::copy(vSolutions[0].begin(), vSolutions[0].end(), hash.begin());
          addressRet = hash;
          return true;
      } else if (whichType == TX_WITNESS_UNKNOWN) {
          WitnessUnknown unk;
          unk.version = vSolutions[0][0];
          std::copy(vSolutions[1].begin(), vSolutions[1].end(), unk.program);
          unk.length = vSolutions[1].size();
          addressRet = unk;
          return true;
      }
      // Multisig txns have more than one address...
      return false;
  }
  
  bool ExtractDestinations(const CScript& scriptPubKey, txnouttype& typeRet, std::vector<CTxDestination>& addressRet, int& nRequiredRet)
  {
      addressRet.clear();
      std::vector<valtype> vSolutions;
      typeRet = Solver(scriptPubKey, vSolutions);
      if (typeRet == TX_NONSTANDARD) {
          return false;
      } else if (typeRet == TX_NULL_DATA) {
          // This is data, not addresses
          return false;
      }
  
      if (typeRet == TX_MULTISIG)
      {
          nRequiredRet = vSolutions.front()[0];
          for (unsigned int i = 1; i < vSolutions.size()-1; i++)
          {
              CPubKey pubKey(vSolutions[i]);
              if (!pubKey.IsValid())
                  continue;
  
              CTxDestination address = PKHash(pubKey);
              addressRet.push_back(address);
          }
  
          if (addressRet.empty())
              return false;
      }
      else
      {
          nRequiredRet = 1;
          CTxDestination address;
          if (!ExtractDestination(scriptPubKey, address))
             return false;
          addressRet.push_back(address);
      }
  
      return true;
  }
  
  namespace
  {
  class CScriptVisitor : public boost::static_visitor<bool>
  {
  private:
      CScript *script;
  public:
      explicit CScriptVisitor(CScript *scriptin) { script = scriptin; }
  
      bool operator()(const CNoDestination &dest) const {
          script->clear();
          return false;
      }
  
      bool operator()(const PKHash &keyID) const {
          script->clear();
          *script << OP_DUP << OP_HASH160 << ToByteVector(keyID) << OP_EQUALVERIFY << OP_CHECKSIG;
          return true;
      }
  
      bool operator()(const ScriptHash &scriptID) const {
          script->clear();
          *script << OP_HASH160 << ToByteVector(scriptID) << OP_EQUAL;
          return true;
      }
  
      bool operator()(const WitnessV0KeyHash& id) const
      {
          script->clear();
          *script << OP_0 << ToByteVector(id);
          return true;
      }
  
      bool operator()(const WitnessV0ScriptHash& id) const
      {
          script->clear();
          *script << OP_0 << ToByteVector(id);
          return true;
      }
  
      bool operator()(const WitnessUnknown& id) const
      {
          script->clear();
          *script << CScript::EncodeOP_N(id.version) << std::vector<unsigned char>(id.program, id.program + id.length);
          return true;
      }
  };
  } // namespace
  
  CScript GetScriptForDestination(const CTxDestination& dest)
  {
      CScript script;
  
      boost::apply_visitor(CScriptVisitor(&script), dest);
      return script;
  }
  
  CScript GetScriptForRawPubKey(const CPubKey& pubKey)
  {
      return CScript() << std::vector<unsigned char>(pubKey.begin(), pubKey.end()) << OP_CHECKSIG;
  }
  
  CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys)
  {
      CScript script;
  
      script << CScript::EncodeOP_N(nRequired);
      for (const CPubKey& key : keys)
          script << ToByteVector(key);
      script << CScript::EncodeOP_N(keys.size()) << OP_CHECKMULTISIG;
      return script;
  }
  
  CScript GetScriptForWitness(const CScript& redeemscript)
  {
      std::vector<std::vector<unsigned char> > vSolutions;
      txnouttype typ = Solver(redeemscript, vSolutions);
      if (typ == TX_PUBKEY) {
          return GetScriptForDestination(WitnessV0KeyHash(Hash160(vSolutions[0].begin(), vSolutions[0].end())));
      } else if (typ == TX_PUBKEYHASH) {
          return GetScriptForDestination(WitnessV0KeyHash(vSolutions[0]));
      }
      return GetScriptForDestination(WitnessV0ScriptHash(redeemscript));
  }
  
  bool IsValidDestination(const CTxDestination& dest) {
      return dest.which() != 0;
  }
  