Make TxData functions public

[fedekunze]

Rationale

Why should this feature exist?

The existing TxData interface defines its functions as unexported, making it impossible to provide our own implementation of these methods.

go-ethereum/core/types/transaction.go

Lines 68 to 88 in 3b05318

	// TxData is the underlying data of a transaction.
	//
	// This is implemented by DynamicFeeTx, LegacyTx and AccessListTx.
	type TxData interface {
	txType() byte // returns the type ID
	copy() TxData // creates a deep copy and initializes all fields
	chainID() *big.Int
	accessList() AccessList
	data() []byte
	gas() uint64
	gasPrice() *big.Int
	gasTipCap() *big.Int
	gasFeeCap() *big.Int
	value() *big.Int
	nonce() uint64
	to() *common.Address
	rawSignatureValues() (v, r, s *big.Int)
	setSignatureValues(chainID, v, r, s *big.Int)
	}

What are the use-cases?

Our use case is that we need to implement the TxData implementation as a proto.Any that can support all the concrete implementations of the tx data: LegacyTxType, AccessListTxType and DynamicFeeTxType. We want our TxData interface to embed the TxData interface from geth so that we are able to reduce maintenance.

Implementation

Do you have ideas regarding the implementation of this feature?
Make the TxData functions public.

Are you willing to implement this feature?

Yes

[fedekunze]

cc @s1na

[s1na]

Hey @fedekunze. I had a quick look and it seems in the lifetime of #21502 these accessor methods started out as public methods but were made private in lightclient@389f039#diff-8fb609018eccff10931645347515b8ecc194992cc4ef9e84ebdea87682dd50c3.

I know in general that the core/types API has been usually kinda stable and it's changed with care which I guess is the reason why these TxData methods were made private. But I can bring this up for discussion and if there was agreement on exporting them make a PR to address it.

[fedekunze]

Thanks @s1na, here's our PR to add support for proto.Any if you need more context: evmos/ethermint#220

[ligi]

Can you elaborate why you need to serialize tx.data and not the raw bytes of the transaction that already cares for the transaction type and has a spec (EIP)

[fjl]

We expose TxData for only one reason: making creation of types.Transaction from Go code more convenient. The methods of TxData are an internal implementation detail and will never be stable API. It's not a good idea to send these fields over protocol buffers. If your app needs to send/receive Ethereum transactions over protocol buffers, it should accept them as opaque binary data, which can be parsed by Transaction.UnmarshalBinary.