No base-fee conversion in effective-gas-tip related methods

[ezdac]

Issue

We seem to have forgotten a lot of fee-currency conversions in EffectiveGasTip based calculations for fee-currency denominated transactions.

For most of the affected code, the tx.EffectiveGasTip(), tx.EffectiveGasTipCmp(),tx.EffectiveGasTipValue() methods are called to do some calculation (e.g. moving average) without considering wether the transaction is denominated in Celo or fee-currency.

tx.EffectiveGasTip()

A lot of calls to the tx.EffectiveGasTip() are affected, which are used e.g. here:

op-geth/miner/worker.go

Line 582 in a59c67f

minerFee, _ := tx.EffectiveGasTip(block.BaseFee())

op-geth/graphql/graphql.go

Line 371 in a59c67f

tip, err := tx.EffectiveGasTip(header.BaseFee)

op-geth/eth/gasprice/gasprice.go

Line 259 in a59c67f

func (oracle *Oracle) getBlockValues(ctx context.Context, blockNum uint64, limit int, ignoreUnder *big.Int, result chan results, quit chan struct{}) {

tx.EffectiveGasTipValue()

There is one usage of this method which is affected:

op-geth/eth/gasprice/optimism-gasprice.go

Lines 87 to 89 in a59c67f

	for i := range txs {
	tips[i] = txs[i].EffectiveGasTipValue(baseFee)
	}

tx.EffectiveGasTipCmp()

The entire function tx.EffectiveGasTipCmp() is compromised, whenever fee-currency and native transactions are compared:

op-geth/core/types/transaction.go

Lines 463 to 468 in a59c67f

	func (tx *Transaction) EffectiveGasTipCmp(other *Transaction, baseFee *big.Int) int {
	if baseFee == nil {
	return tx.GasTipCapCmp(other)
	}
	return tx.EffectiveGasTipValue(baseFee).Cmp(other.EffectiveGasTipValue(baseFee))
	}

This function however does not seem (yet) to be used in the op-geth codebase.

Severity

So far there seems to be no usage of those methods in EVM / state-transition related code, and the externally exposed affected surface consists of mostly convenience methods:

• FeeHistory will return incorrect gas price history
• SuggestGasTipCap will return incorrect gas-tip suggestions

op-geth/eth/api_backend.go

Lines 390 to 396 in a59c67f

	func (b *EthAPIBackend) SuggestGasTipCap(ctx context.Context) (*big.Int, error) {
	return b.gpo.SuggestTipCap(ctx)
	}
	func (b *EthAPIBackend) FeeHistory(ctx context.Context, blockCount uint64, lastBlock rpc.BlockNumber, rewardPercentiles []float64) (firstBlock *big.Int, reward [][]*big.Int, baseFee []*big.Int, gasUsedRatio []float64, baseFeePerBlobGas []*big.Int, blobGasUsedRatio []float64, err error) {
	return b.gpo.FeeHistory(ctx, blockCount, lastBlock, rewardPercentiles)
	}

Solution

For all calls to the aforementioned effective-gas-tip related methods, the passed in base-fee has to first be converted
to the transactions fee-currency when that transaction is a CIP-64 transaction.
When methods accumulate values between CIP-64 and Ethereum transactions, the accumulation has to be done in the same denomination.