// Copyright (c) 2017-2021 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 <consensus/tx_check.h>

#include <consensus/amount.h>

#include <primitives/transaction.h>

#include <consensus/validation.h>

bool CheckTransaction(const CTransaction& tx, TxValidationState& state)

{

    // Basic checks that don't depend on any context

    if (tx.vin.empty())

        return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-vin-empty");

    if (tx.vout.empty())

        return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-vout-empty");

    // Size limits (this doesn't take the witness into account, as that hasn't been checked for malleability)

    if (::GetSerializeSize(TX_NO_WITNESS(tx)) * WITNESS_SCALE_FACTOR > MAX_BLOCK_WEIGHT) {

        return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-oversize");

    }

    // Check for negative or overflow output values (see CVE-2010-5139)

    CAmount nValueOut = 0;

    for (const auto& txout : tx.vout)

    {

        if (txout.nValue < 0)

            return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-vout-negative");

        if (txout.nValue > MAX_MONEY)

            return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-vout-toolarge");

        nValueOut += txout.nValue;

        if (!MoneyRange(nValueOut))

            return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-txouttotal-toolarge");

    }

    // Check for duplicate inputs (see CVE-2018-17144)

    // While Consensus::CheckTxInputs does check if all inputs of a tx are available, and UpdateCoins marks all inputs

    // of a tx as spent, it does not check if the tx has duplicate inputs.

    // Failure to run this check will result in either a crash or an inflation bug, depending on the implementation of

    // the underlying coins database.

    std::set<COutPoint> vInOutPoints;

    for (const auto& txin : tx.vin) {

        if (!vInOutPoints.insert(txin.prevout).second)

            return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-inputs-duplicate");

    }

    if (tx.IsCoinBase())

    {

        if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100)

            return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-cb-length");

    }

    else

    {

        for (const auto& txin : tx.vin)

            if (txin.prevout.IsNull())

                return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-prevout-null");

    }

    return true;

}