execute fee check logic in deliverTX

[yaruwangway]

Summary

Present gaia fee antehandler checks the fees only in checkTx. The fee antehandler checks:

if msgs are bypass msgs and the bypass msgs gas usage is within bypass gas limit.
if the paid fee is in the denom required.
if paidFee amount >= required Fee amount (required fee takes the higher fee between mininum-gas-price in app.toml and global fee).
The above fee checks can prevent malicious tx submitters, but it cannot prevent malicious validator.

The solution is to do fee check logic in deliverTx as well, this requires determinism of the fee check result, therefore, the fee check will also run in deliverTx.

In order to make deliverTx deterministic, the deliverTX checks the fee against global fee, while checkTX is checking fees against combinedFees (global fee and local min-gas-price in app.toml).

This means:

• local min-gas-price higher than global fee, if paidfee can pass CheckTx, it can also pass DeliverTX.
• local min-gas-price higher than global fee, if paidfee cannot pass CheckTx, it get rejected.
• local min-gas-price lower than global fee, if paidfee can pass CheckTx, it can also pass DeliverTX.
• local min-gas-price lower than global fee, if paidfee cannot pass CheckTx, it get rejected.

Please note, the above mentioned refactor is Consensus breaking !!!

Problem Definition

Proposal

• remove the checkTX condition here so that the fee check will run both in CheckTX and DeliverTX.
• if CheckTX, check paid fees against combinedFees, if DeliverTx, check paid fees against globalfees, eeCoinsNonZeroDenom.IsAnyGTE(nonZeroCoinGlobalFeeReq) .

	nonZeroCoinGlobalFeeReq, _ := splitFees(requiredGlobalFees)
	if ctx.IsCheckTx() {
		if !feeCoinsNoZeroDenom.DenomsSubsetOf(nonZeroCoinFeesReq) {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrInsufficientFee, "fee is not a subset of required fees; got %s, required: %s", feeCoins, combinedFeeRequirement)
		}
	} else {
		// deliverTx
		if !feeCoinsNoZeroDenom.DenomsSubsetOf(nonZeroCoinGlobalFeeReq) {
			return ctx, sdkerrors.Wrapf(sdkerrors.ErrInsufficientFee, "fee is not a subset of required fees; got %s, required: %s", feeCoins, combinedFeeRequirement)
		}
	}
	

• no need to switch conditions (CheckTX/DeliverTX) for check against zeroCoinFeesDenomReq, due to zeroCoinFeesDenomReq can be only from zero coins in globalfee.

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