script.cpp

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <script/script.h>

#include <hash.h>
#include <util/strencodings.h>

#include <string>

CScriptID::CScriptID(const CScript& in) : BaseHash(Hash160(in)) {}

std::string GetOpName(opcodetype opcode)
{
    switch (opcode)
    {
    // push value
    case OP_0                      : return "0";
    case OP_PUSHDATA1              : return "OP_PUSHDATA1";
    case OP_PUSHDATA2              : return "OP_PUSHDATA2";
    case OP_PUSHDATA4              : return "OP_PUSHDATA4";
    case OP_1NEGATE                : return "-1";
    case OP_RESERVED               : return "OP_RESERVED";
    case OP_1                      : return "1";
    case OP_2                      : return "2";
    case OP_3                      : return "3";
    case OP_4                      : return "4";
    case OP_5                      : return "5";
    case OP_6                      : return "6";
    case OP_7                      : return "7";
    case OP_8                      : return "8";
    case OP_9                      : return "9";
    case OP_10                     : return "10";
    case OP_11                     : return "11";
    case OP_12                     : return "12";
    case OP_13                     : return "13";
    case OP_14                     : return "14";
    case OP_15                     : return "15";
    case OP_16                     : return "16";

    // control
    case OP_NOP                    : return "OP_NOP";
    case OP_VER                    : return "OP_VER";
    case OP_IF                     : return "OP_IF";
    case OP_NOTIF                  : return "OP_NOTIF";
    case OP_VERIF                  : return "OP_VERIF";
    case OP_VERNOTIF               : return "OP_VERNOTIF";
    case OP_ELSE                   : return "OP_ELSE";
    case OP_ENDIF                  : return "OP_ENDIF";
    case OP_VERIFY                 : return "OP_VERIFY";
    case OP_RETURN                 : return "OP_RETURN";

    // stack ops
    case OP_TOALTSTACK             : return "OP_TOALTSTACK";
    case OP_FROMALTSTACK           : return "OP_FROMALTSTACK";
    case OP_2DROP                  : return "OP_2DROP";
    case OP_2DUP                   : return "OP_2DUP";
    case OP_3DUP                   : return "OP_3DUP";
    case OP_2OVER                  : return "OP_2OVER";
    case OP_2ROT                   : return "OP_2ROT";
    case OP_2SWAP                  : return "OP_2SWAP";
    case OP_IFDUP                  : return "OP_IFDUP";
    case OP_DEPTH                  : return "OP_DEPTH";
    case OP_DROP                   : return "OP_DROP";
    case OP_DUP                    : return "OP_DUP";
    case OP_NIP                    : return "OP_NIP";
    case OP_OVER                   : return "OP_OVER";
    case OP_PICK                   : return "OP_PICK";
    case OP_ROLL                   : return "OP_ROLL";
    case OP_ROT                    : return "OP_ROT";
    case OP_SWAP                   : return "OP_SWAP";
    case OP_TUCK                   : return "OP_TUCK";

    // splice ops
    case OP_CAT                    : return "OP_CAT";
    case OP_SUBSTR                 : return "OP_SUBSTR";
    case OP_LEFT                   : return "OP_LEFT";
    case OP_RIGHT                  : return "OP_RIGHT";
    case OP_SIZE                   : return "OP_SIZE";

    // bit logic
    case OP_INVERT                 : return "OP_INVERT";
    case OP_AND                    : return "OP_AND";
    case OP_OR                     : return "OP_OR";
    case OP_XOR                    : return "OP_XOR";
    case OP_EQUAL                  : return "OP_EQUAL";
    case OP_EQUALVERIFY            : return "OP_EQUALVERIFY";
    case OP_RESERVED1              : return "OP_RESERVED1";
    case OP_RESERVED2              : return "OP_RESERVED2";

    // numeric
    case OP_1ADD                   : return "OP_1ADD";
    case OP_1SUB                   : return "OP_1SUB";
    case OP_2MUL                   : return "OP_2MUL";
    case OP_2DIV                   : return "OP_2DIV";
    case OP_NEGATE                 : return "OP_NEGATE";
    case OP_ABS                    : return "OP_ABS";
    case OP_NOT                    : return "OP_NOT";
    case OP_0NOTEQUAL              : return "OP_0NOTEQUAL";
    case OP_ADD                    : return "OP_ADD";
    case OP_SUB                    : return "OP_SUB";
    case OP_MUL                    : return "OP_MUL";
    case OP_DIV                    : return "OP_DIV";
    case OP_MOD                    : return "OP_MOD";
    case OP_LSHIFT                 : return "OP_LSHIFT";
    case OP_RSHIFT                 : return "OP_RSHIFT";
    case OP_BOOLAND                : return "OP_BOOLAND";
    case OP_BOOLOR                 : return "OP_BOOLOR";
    case OP_NUMEQUAL               : return "OP_NUMEQUAL";
    case OP_NUMEQUALVERIFY         : return "OP_NUMEQUALVERIFY";
    case OP_NUMNOTEQUAL            : return "OP_NUMNOTEQUAL";
    case OP_LESSTHAN               : return "OP_LESSTHAN";
    case OP_GREATERTHAN            : return "OP_GREATERTHAN";
    case OP_LESSTHANOREQUAL        : return "OP_LESSTHANOREQUAL";
    case OP_GREATERTHANOREQUAL     : return "OP_GREATERTHANOREQUAL";
    case OP_MIN                    : return "OP_MIN";
    case OP_MAX                    : return "OP_MAX";
    case OP_WITHIN                 : return "OP_WITHIN";

    // crypto
    case OP_RIPEMD160              : return "OP_RIPEMD160";
    case OP_SHA1                   : return "OP_SHA1";
    case OP_SHA256                 : return "OP_SHA256";
    case OP_HASH160                : return "OP_HASH160";
    case OP_HASH256                : return "OP_HASH256";
    case OP_CODESEPARATOR          : return "OP_CODESEPARATOR";
    case OP_CHECKSIG               : return "OP_CHECKSIG";
    case OP_CHECKSIGVERIFY         : return "OP_CHECKSIGVERIFY";
    case OP_CHECKMULTISIG          : return "OP_CHECKMULTISIG";
    case OP_CHECKMULTISIGVERIFY    : return "OP_CHECKMULTISIGVERIFY";

    // expansion
    case OP_NOP1                   : return "OP_NOP1";
    case OP_CHECKLOCKTIMEVERIFY    : return "OP_CHECKLOCKTIMEVERIFY";
    case OP_CHECKSEQUENCEVERIFY    : return "OP_CHECKSEQUENCEVERIFY";
    case OP_NOP4                   : return "OP_NOP4";
    case OP_NOP5                   : return "OP_NOP5";
    case OP_NOP6                   : return "OP_NOP6";
    case OP_NOP7                   : return "OP_NOP7";
    case OP_NOP8                   : return "OP_NOP8";
    case OP_NOP9                   : return "OP_NOP9";
    case OP_NOP10                  : return "OP_NOP10";

    // Opcode added by BIP 342 (Tapscript)
    case OP_CHECKSIGADD            : return "OP_CHECKSIGADD";

    case OP_INVALIDOPCODE          : return "OP_INVALIDOPCODE";

    default:
        return "OP_UNKNOWN";
    }
}

unsigned int CScript::GetSigOpCount(bool fAccurate) const
{
    unsigned int n = 0;
    const_iterator pc = begin();
    opcodetype lastOpcode = OP_INVALIDOPCODE;
    while (pc < end())
    {
        opcodetype opcode;
        if (!GetOp(pc, opcode))
            break;
        if (opcode == OP_CHECKSIG || opcode == OP_CHECKSIGVERIFY)
            n++;
        else if (opcode == OP_CHECKMULTISIG || opcode == OP_CHECKMULTISIGVERIFY)
        {
            if (fAccurate && lastOpcode >= OP_1 && lastOpcode <= OP_16)
                n += DecodeOP_N(lastOpcode);
            else
                n += MAX_PUBKEYS_PER_MULTISIG;
        }
        lastOpcode = opcode;
    }
    return n;
}

unsigned int CScript::GetSigOpCount(const CScript& scriptSig) const
{
    if (!IsPayToScriptHash())
        return GetSigOpCount(true);

    // This is a pay-to-script-hash scriptPubKey;
    // get the last item that the scriptSig
    // pushes onto the stack:
    const_iterator pc = scriptSig.begin();
    std::vector<unsigned char> vData;
    while (pc < scriptSig.end())
    {
        opcodetype opcode;
        if (!scriptSig.GetOp(pc, opcode, vData))
            return 0;
        if (opcode > OP_16)
            return 0;
    }

    CScript subscript(vData.begin(), vData.end());
    return subscript.GetSigOpCount(true);
}

bool CScript::IsPayToScriptHash() const
{
    // Extra-fast test for pay-to-script-hash CScripts:
    return (this->size() == 23 &&
            (*this)[0] == OP_HASH160 &&
            (*this)[1] == 0x14 &&
            (*this)[22] == OP_EQUAL);
}

bool CScript::IsPayToWitnessScriptHash() const
{
    // Extra-fast test for pay-to-witness-script-hash CScripts:
    return (this->size() == 34 &&
            (*this)[0] == OP_0 &&
            (*this)[1] == 0x20);
}

// A witness program is any valid CScript that consists of a 1-byte push opcode
// followed by a data push between 2 and 40 bytes.
bool CScript::IsWitnessProgram(int& version, std::vector<unsigned char>& program) const
{
    if (this->size() < 4 || this->size() > 42) {
        return false;
    }
    if ((*this)[0] != OP_0 && ((*this)[0] < OP_1 || (*this)[0] > OP_16)) {
        return false;
    }
    if ((size_t)((*this)[1] + 2) == this->size()) {
        version = DecodeOP_N((opcodetype)(*this)[0]);
        program = std::vector<unsigned char>(this->begin() + 2, this->end());
        return true;
    }
    return false;
}

bool CScript::IsPushOnly(const_iterator pc) const
{
    while (pc < end())
    {
        opcodetype opcode;
        if (!GetOp(pc, opcode))
            return false;
        // Note that IsPushOnly() *does* consider OP_RESERVED to be a
        // push-type opcode, however execution of OP_RESERVED fails, so
        // it's not relevant to P2SH/BIP62 as the scriptSig would fail prior to
        // the P2SH special validation code being executed.
        if (opcode > OP_16)
            return false;
    }
    return true;
}

bool CScript::IsPushOnly() const
{
    return this->IsPushOnly(begin());
}

std::string CScriptWitness::ToString() const
{
    std::string ret = "CScriptWitness(";
    for (unsigned int i = 0; i < stack.size(); i++) {
        if (i) {
            ret += ", ";
        }
        ret += HexStr(stack[i]);
    }
    return ret + ")";
}

bool CScript::HasValidOps() const
{
    CScript::const_iterator it = begin();
    while (it < end()) {
        opcodetype opcode;
        std::vector<unsigned char> item;
        if (!GetOp(it, opcode, item) || opcode > MAX_OPCODE || item.size() > MAX_SCRIPT_ELEMENT_SIZE) {
            return false;
        }
    }
    return true;
}

bool GetScriptOp(CScriptBase::const_iterator& pc, CScriptBase::const_iterator end, opcodetype& opcodeRet, std::vector<unsigned char>* pvchRet)
{
    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 = static_cast<opcodetype>(opcode);
    return true;
}

bool IsOpSuccess(const opcodetype& opcode)
{
    return opcode == 80 || opcode == 98 || (opcode >= 126 && opcode <= 129) ||
           (opcode >= 131 && opcode <= 134) || (opcode >= 137 && opcode <= 138) ||
           (opcode >= 141 && opcode <= 142) || (opcode >= 149 && opcode <= 153) ||
           (opcode >= 187 && opcode <= 254);
}

bool CheckMinimalPush(const std::vector<unsigned char>& data, opcodetype opcode) {
    // Excludes OP_1NEGATE, OP_1-16 since they are by definition minimal
    assert(0 <= opcode && opcode <= OP_PUSHDATA4);
    if (data.size() == 0) {
        // Should have used OP_0.
        return opcode == OP_0;
    } else if (data.size() == 1 && data[0] >= 1 && data[0] <= 16) {
        // Should have used OP_1 .. OP_16.
        return false;
    } else if (data.size() == 1 && data[0] == 0x81) {
        // Should have used OP_1NEGATE.
        return false;
    } else if (data.size() <= 75) {
        // Must have used a direct push (opcode indicating number of bytes pushed + those bytes).
        return opcode == data.size();
    } else if (data.size() <= 255) {
        // Must have used OP_PUSHDATA.
        return opcode == OP_PUSHDATA1;
    } else if (data.size() <= 65535) {
        // Must have used OP_PUSHDATA2.
        return opcode == OP_PUSHDATA2;
    }
    return true;
}