golang ethereum client: github.com/ethereum/go-ethereum cannot subscribe to log events via websocket

[nikolas-digitalBabylon]

Description

As a golang application Developer, I want subscribe to smart-contract event logs via websocket api so that i receive push events

Acceptance Criteria

• Besu RPC node is compatible with ethereum golang client websocket API

Steps to Reproduce (Bug)

1. Import github.com/ethereum/go-ethereum eth client
2. Try to create a subscription for smart contract log events with the client reaching the Besu ws port

Expected behavior:
Application should receive push events as emitted by deployed smart contracts

Actual behavior:
Application Besu node returns an error upon subscription

Frequency:
Always

Versions

• Software version:
  Modified sample network from commit b9bfa831194763f18cc99deca235ffe754b66aae , Date: Mon Jan 27 18:52:10 2020 +1000

• Docker Version: 19.03.8

• OS: Latest Ubuntu LTS (18.04).

• golang ethereum client: github.com/ethereum/go-ethereum v1.9.12

Additional Information

Capturing the websocket packages transmitted with the standard golang ethereum client reveals a payload of:
{"jsonrpc":"2.0","id":1,"method":"eth_subscribe","params":["logs",{"address":["0xb9a219631aed55ebc3d998f17c3840b7ec39c0cc"],"fromBlock":"0x0","toBlock":"latest","topics":null}]}\n to which the Besu node responds with {"jsonrpc":"2.0","id":1,"error":{"code":-32600,"message":"Invalid Request"}}

I implemented an own client that submits {"id":123,"method":"eth_subscribe","params":["logs",{"address":"0xb9a219631aed55ebc3d998f17c3840b7ec39c0cc"}]}\n and works as expected. I can then receive and decode events.

One important difference to notice, is that the standard ethereum client transmits an array of contract addresses.

[shemnon]

My instinct says we are not playing well with the null "topics" argument. Thanks for the JSON-RPC, this will help a lot.

[shemnon]

The problem was different. geth does not follow it's own published spec for this API (https://github.com/ethereum/go-ethereum/wiki/RPC-PUB-SUB#logs or https://geth.ethereum.org/docs/rpc/pubsub) and includes fromBlock and toBlock in the subscription arguments. Only address and topics are documented.

[RatanRSur]

Thanks for the bug report and repro! The fix should be in the master branch now.