Eth API: On revert, return data in the error

[Stebalien]

Checklist

• This is not a new feature or an enhancement to the Filecoin protocol. If it is, please open an FIP issue.
• This is not a new feature request. If it is, please file a feature request instead.
• This is not brainstorming ideas. If you have an idea you'd like to discuss, please open a new discussion on the lotus forum and select the category as Ideas.
• I have a specific, actionable, and well motivated improvement to propose.

Lotus component

• lotus daemon - chain sync
• lotus miner - mining and block production
• lotus miner/worker - sealing
• lotus miner - proving(WindowPoSt)
• lotus miner/market - storage deal
• lotus miner/market - retrieval deal
• lotus miner/market - data transfer
• lotus client
• lotus JSON-RPC API
• lotus message management (mpool)
• Other

Improvement Suggestion

JSON-RPC supports an optional data field in errors to return additional information. Furthermore, it looks like Ethereum clients use this field to return "revert reasons".

Specifically, we have an error type defined here:

https://github.com/filecoin-project/go-jsonrpc/blob/787a96afc5da60084c97b597b61f0fad18c65a3d/handler.go#L68-L72

type respError struct {
	Code    ErrorCode       `json:"code"`
	Message string          `json:"message"`
	Meta    json.RawMessage `json:"meta,omitempty"`
}

We should extend this to:

type respError struct {
	Code    ErrorCode       `json:"code"`
	Message string          `json:"message"`
	Meta    json.RawMessage `json:"meta,omitempty"`
	Data    json.RawMessage `json:"data,omitempty"`
}

And provide a way to return said data from a JSON-RPC method. Likely the best way is to define interface { ErrorData() interface{} }.

[Stebalien]

See https://www.jsonrpc.org/specification#error_object

[aarshkshah1992]

@virajbhartiya This will be a fun one and has been a long pending ask from users. Want to pick this up ?
Will need changes to Lotus and https://github.com/filecoin-project/go-jsonrpc.

[aarshkshah1992]

@Stebalien Which ETH APIs should be returning reverted reason in the data field ? Is it the eth_call and eth_estimateGas APIs only ?

[aarshkshah1992]

@virajbhartiya is picking this up.

[Stebalien]

@Stebalien Which ETH APIs should be returning reverted reason in the data field ? Is the eth_call and eth_estimateGas APIs only ?

As far as I know, yes.