Method CheckTxInputs

src/consensus/tx_verify.cpp:164–214

}

bool Consensus::CheckTxInputs(const CTransaction& tx, TxValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee)
{
    // are the actual inputs available?
    if (!inputs.HaveInputs(tx)) {
        return state.Invalid(TxValidationResult::TX_MISSING_INPUTS, "bad-txns-inputs-missingorspent",
                         strprintf("%s: inputs missing/spent", __func__));
    }

    CAmount nValueIn = 0;
    for (unsigned int i = 0; i < tx.vin.size(); ++i) {
        const COutPoint &prevout = tx.vin[i].prevout;
        const Coin& coin = inputs.AccessCoin(prevout);
        assert(!coin.IsSpent());

        // If prev is coinbase, check that it's matured
        if (coin.IsCoinBase() && nSpendHeight - coin.nHeight < COINBASE_MATURITY) {
            return state.Invalid(TxValidationResult::TX_PREMATURE_SPEND, "bad-txns-premature-spend-of-coinbase",
                strprintf("tried to spend coinbase at depth %d", nSpendHeight - coin.nHeight));
        }

        // Check for negative or overflow input values
        nValueIn += coin.out.nValue;
        if (!MoneyRange(coin.out.nValue) || !MoneyRange(nValueIn)) {
            return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-inputvalues-outofrange");
        }
    }

    // `tx.GetValueOut()` won't throw in validation paths because output-range checks run first
    // (`bad-txns-vout-negative`, `bad-txns-vout-toolarge`, `bad-txns-txouttotal-toolarge`):
    // * `MemPoolAccept::PreChecks`: `CheckTransaction()` is called before this method;
    // * `Chainstate::ConnectBlock`: `CheckTransaction()` is called via `CheckBlock()` before this method.
    const CAmount value_out = tx.GetValueOut();
    if (nValueIn < value_out) {
        return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-in-belowout",
            strprintf("value in (%s) < value out (%s)", FormatMoney(nValueIn), FormatMoney(value_out)));
    }

    // Tally transaction fees
    const CAmount txfee_aux = nValueIn - value_out;
    if (!MoneyRange(txfee_aux)) {
        // Unreachable, given the following preconditions:
        // * `value_out` comes from `tx.GetValueOut()`, which throws unless `MoneyRange(value_out)` and asserts `MoneyRange(nValueOut)` on return.
        // * `MoneyRange(nValueIn)` was enforced in the input loop.
        // * `nValueIn < value_out` was handled above, so `nValueIn >= value_out` here (and `txfee_aux >= 0`).
        // Therefore `0 <= txfee_aux = nValueIn - value_out <= nValueIn <= MAX_MONEY`.
        return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-fee-outofrange");
    }

    txfee = txfee_aux;
    return true;
}