Zero Cost EthereumTransaction on Success

[Nana-EC]

Description:
On many EVM chains execution costs are fully captured in gas. Thus submitting transactions to execution nodes bears no
cost to the relay node. On Hedera it is necessary to charge a fee for EthereumTransaction HAPI submissions (just like
all other HAPI transactions).

This HIP suggests the network logic not charge successful EthereumTransaction submissions, but instead only charge the
regular HAPI fee for badly formed transactions.

Related issue(s):

Fixes #1083

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

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[Neurone]

on Success
[...]
2. As a relay operator I will pay the HAPI transaction fee for EthereumTransaction submissions that fail.

I think referring to success/failure can be misleading in the HIP's title and description. I suggest using something like well-formed, formally valid, etc.

• If the EthereumTransaction succeeds, do not charge the AccountId submitter
• If the EthereumTransaction fails, charge the AccountId submitter

I recommend dropping the success/failure wording and clearly stating the list of results for which the submitter will be charged $0.0001 (e.g., WRONG_NONCE, INVALID_SIGNATURE, etc.).

Any results not in the list above will be free for the submitter, whether it's an EVM error or not (e.g., CONTRACT_REVERT_EXECUTED, SUCCESS, etc.).

[rbair23]

@Neurone I agree, the text has been updated, but I think it would benefit from being even more precise.

[quiet-node]

This indeed highlights a list of prechecks performed by the Relay to validate transactions and reject them if any conditions are met, ensuring they are not forwarded to the network unnecessarily, thus avoiding charges. Notably, the Hedera JSON-RPC Relay already handles and rejects these scenarios. However, there are additional prechecks currently performed by the Relay that are not mentioned here:

• Transaction type
• Gas price
• Gas limit
• Chain ID
• Value
• calldata size (not exceed 128KB maximum)

I recommend considering these prechecks and including them in this HIP for greater clarity and completeness.

[rbair23]

I agree, thank you @quiet-node! Can you please reply to this comment with a suggested replacement (you can click the icon of a document with the + and - signs within it to offer a suggestion) and we will get it applied to the HIP text.

[stoqnkpL]

If a precheck is performed by the Relay, doesn't this mean that if it fails, the Relay will never send a transaction to a Hedera node, meaning the relay account can never be charged for it?

[Nana-EC]

Correct.
A relay will only submit to a CN a transaction that passes it's prechecks.
If it fails it is in the best interest of the relay to not submit to a CN otherwise it will be charged.

[Nana-EC]

@Neurone added an explicit clarification of response codes.
For not it's probably better to not the cases for which no charge to the relay account is made.
Listing the cases where it will may be lengthy and that list may grow over time, but the non charged cases are less likely to grow

[Neurone]

Hi Nana, good. Listing the cases for which the operator is not charged is perfectly fine and clear, thanks.

[rbair23]

Suggested change

	On Ethereum, all execution costs are paid for by the 'sender' who created, signed, and submitted the transaction. Hedera
	follows a similar approach for all `ContractCallTransaction`s but also charges an additional fee for each
	`EthereumTransaction` submitted via JSON-RPC relays. This fee serves as a defense against a malicious JSON-RPC relay that
	might send malformed transactions to the network, where there would be no one to pay for the processing of those transactions.
	This fee is unnecessary for successful transactions since the intrinsic gas fee covers the base costs (gossip & consensus).
	Therefore, this HIP proposes that the fee for submitting `EthereumTransactions` to the network should only be charged if the
	JSON-RPC relay submits a transaction that fails due diligence checks, such that the EOA cannot be charged for the overhead
	of gossip and consensus.
	On Ethereum, all execution costs are paid for by the 'sender' who created, signed, and submitted the transaction.
	Hedera follows a similar approach for `ContractCallTransaction`s. However, Hedera charges an additional fee for
	each `EthereumTransaction` submitted via JSON-RPC relays. This fee serves as a defense against a malicious
	JSON-RPC relay that might send malformed transactions to the network, where there would be no one to pay for
	the processing of those transactions.
	This fee is unnecessary for successful transactions since the intrinsic gas fee covers the base costs (gossip &
	consensus). Therefore, this HIP proposes that the fee for submitting `EthereumTransactions` to the network
	should only be charged if the JSON-RPC relay submits a transaction that fails due diligence checks, such that the
	EOA cannot be charged for the overhead of gossip and consensus.

[Nana-EC]

Changes applied