interpreter.h

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Copyright (c) 2017-2019 The Raven Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef RAVEN_SCRIPT_INTERPRETER_H
#define RAVEN_SCRIPT_INTERPRETER_H

#include "script_error.h"
#include "primitives/transaction.h"

#include <vector>
#include <stdint.h>
#include <string>

class CPubKey;

class CScript;

class CTransaction;

class uint256;

enum
{
    SIGHASH_ALL = 1,
    SIGHASH_NONE = 2,
    SIGHASH_SINGLE = 3,
    SIGHASH_ANYONECANPAY = 0x80,
};

enum
{
    SCRIPT_VERIFY_NONE = 0,

    // Evaluate P2SH subscripts (softfork safe, BIP16).
            SCRIPT_VERIFY_P2SH = (1U << 0),

    // Passing a non-strict-DER signature or one with undefined hashtype to a checksig operation causes script failure.
    // Evaluating a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) by checksig causes script failure.
    // (softfork safe, but not used or intended as a consensus rule).
            SCRIPT_VERIFY_STRICTENC = (1U << 1),

    // Passing a non-strict-DER signature to a checksig operation causes script failure (softfork safe, BIP62 rule 1)
            SCRIPT_VERIFY_DERSIG = (1U << 2),

    // Passing a non-strict-DER signature or one with S > order/2 to a checksig operation causes script failure
    // (softfork safe, BIP62 rule 5).
            SCRIPT_VERIFY_LOW_S = (1U << 3),

    // verify dummy stack item consumed by CHECKMULTISIG is of zero-length (softfork safe, BIP62 rule 7).
            SCRIPT_VERIFY_NULLDUMMY = (1U << 4),

    // Using a non-push operator in the scriptSig causes script failure (softfork safe, BIP62 rule 2).
            SCRIPT_VERIFY_SIGPUSHONLY = (1U << 5),

    // Require minimal encodings for all push operations (OP_0... OP_16, OP_1NEGATE where possible, direct
    // pushes up to 75 bytes, OP_PUSHDATA up to 255 bytes, OP_PUSHDATA2 for anything larger). Evaluating
    // any other push causes the script to fail (BIP62 rule 3).
    // In addition, whenever a stack element is interpreted as a number, it must be of minimal length (BIP62 rule 4).
    // (softfork safe)
            SCRIPT_VERIFY_MINIMALDATA = (1U << 6),

    // Discourage use of NOPs reserved for upgrades (NOP1-10)
    //
    // Provided so that nodes can avoid accepting or mining transactions
    // containing executed NOP's whose meaning may change after a soft-fork,
    // thus rendering the script invalid; with this flag set executing
    // discouraged NOPs fails the script. This verification flag will never be
    // a mandatory flag applied to scripts in a block. NOPs that are not
    // executed, e.g.  within an unexecuted IF ENDIF block, are *not* rejected.
            SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1U << 7),

    // Require that only a single stack element remains after evaluation. This changes the success criterion from
    // "At least one stack element must remain, and when interpreted as a boolean, it must be true" to
    // "Exactly one stack element must remain, and when interpreted as a boolean, it must be true".
    // (softfork safe, BIP62 rule 6)
    // Note: CLEANSTACK should never be used without P2SH or WITNESS.
            SCRIPT_VERIFY_CLEANSTACK = (1U << 8),

    // Verify CHECKLOCKTIMEVERIFY
    //
    // See BIP65 for details.
            SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY = (1U << 9),

    // support CHECKSEQUENCEVERIFY opcode
    //
    // See BIP112 for details
            SCRIPT_VERIFY_CHECKSEQUENCEVERIFY = (1U << 10),

    // Support segregated witness
    //
            SCRIPT_VERIFY_WITNESS = (1U << 11),

    // Making v1-v16 witness program non-standard
    //
            SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM = (1U << 12),

    // Segwit script only: Require the argument of OP_IF/NOTIF to be exactly 0x01 or empty vector
    //
            SCRIPT_VERIFY_MINIMALIF = (1U << 13),

    // Signature(s) must be empty vector if an CHECK(MULTI)SIG operation failed
    //
            SCRIPT_VERIFY_NULLFAIL = (1U << 14),

    // Public keys in segregated witness scripts must be compressed
    //
            SCRIPT_VERIFY_WITNESS_PUBKEYTYPE = (1U << 15),
};

bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError *serror);

struct PrecomputedTransactionData
{
    uint256 hashPrevouts, hashSequence, hashOutputs;
    bool ready = false;

    explicit PrecomputedTransactionData(const CTransaction &tx);
};

enum SigVersion
{
    SIGVERSION_BASE = 0,
    SIGVERSION_WITNESS_V0 = 1,
};

uint256 SignatureHash(const CScript &scriptCode, const CTransaction &txTo, unsigned int nIn, int nHashType, const CAmount &amount, SigVersion sigversion, const PrecomputedTransactionData *cache = nullptr);

class BaseSignatureChecker
{
public:
    virtual bool CheckSig(const std::vector<unsigned char> &scriptSig, const std::vector<unsigned char> &vchPubKey, const CScript &scriptCode, SigVersion sigversion) const
    {
        return false;
    }

    virtual bool CheckLockTime(const CScriptNum &nLockTime) const
    {
        return false;
    }

    virtual bool CheckSequence(const CScriptNum &nSequence) const
    {
        return false;
    }

    virtual ~BaseSignatureChecker() {}
};

class TransactionSignatureChecker : public BaseSignatureChecker
{
private:
    const CTransaction *txTo;
    unsigned int nIn;
    const CAmount amount;
    const PrecomputedTransactionData *txdata;

protected:
    virtual bool VerifySignature(const std::vector<unsigned char> &vchSig, const CPubKey &vchPubKey, const uint256 &sighash) const;

public:
    TransactionSignatureChecker(const CTransaction *txToIn, unsigned int nInIn, const CAmount &amountIn) : txTo(txToIn), nIn(nInIn), amount(amountIn), txdata(nullptr) {}

    TransactionSignatureChecker(const CTransaction *txToIn, unsigned int nInIn, const CAmount &amountIn, const PrecomputedTransactionData &txdataIn) : txTo(txToIn), nIn(nInIn), amount(amountIn), txdata(&txdataIn) {}

    bool CheckSig(const std::vector<unsigned char> &scriptSig, const std::vector<unsigned char> &vchPubKey, const CScript &scriptCode, SigVersion sigversion) const override;

    bool CheckLockTime(const CScriptNum &nLockTime) const override;

    bool CheckSequence(const CScriptNum &nSequence) const override;
};

class MutableTransactionSignatureChecker : public TransactionSignatureChecker
{
private:
    const CTransaction txTo;

public:
    MutableTransactionSignatureChecker(const CMutableTransaction *txToIn, unsigned int nInIn, const CAmount &amountIn) : TransactionSignatureChecker(&txTo, nInIn, amountIn), txTo(*txToIn) {}
};

bool EvalScript(std::vector<std::vector<unsigned char> > &stack, const CScript &script, unsigned int flags, const BaseSignatureChecker &checker, SigVersion sigversion, ScriptError *error = nullptr);

bool VerifyScript(const CScript &scriptSig, const CScript &scriptPubKey, const CScriptWitness *witness, unsigned int flags, const BaseSignatureChecker &checker, ScriptError *serror = nullptr);

size_t CountWitnessSigOps(const CScript &scriptSig, const CScript &scriptPubKey, const CScriptWitness *witness, unsigned int flags);

#endif // RAVEN_SCRIPT_INTERPRETER_H