Transaction fee restrictions with solidity

Question

Can I restrict transaction fee (gas price) for the payable method of the crowdsale contract. And if I can, how?

And one more question, if I restrict fee and call revert() - this transaction will be declined in the memepool and will be not mined at all, or not?

Thanks!

Answer 1

There's no way to stop a transaction from being mined, but you can check the gas price using tx.gasprice and not process transactions that are above a certain gas price, e.g.

function() payable {
    require(tx.gasprice<30000000000); //30000000000 is 30 gwei
                                      //if gas price is higher than it, the tx will fail
    doOtherProcessing();
}

Note that this will refund any unused gas. If you change require to assert, then it wont refund the unused gas.