How to programmatically check the type of Ethereum node/backend that I'm connected to using Go?

Question

I'm aware that I can do this using CURL like so:

curl -H "Content-Type: application/json" -X POST --data '{"jsonrpc":"2.0","method":"web3_clientVersion","params":[],"id":67}' https://the-node-ip-address:8545

Which return the following output:

{"jsonrpc":"2.0","id":67,"result":"Geth/v1.8.22-omnibus-260f7fbd/linux-amd64/go1.11.1"}

OR

{"jsonrpc":"2.0","result":"Parity-Ethereum//v2.2.11-stable-8e31051-20190220/x86_64-linux-gnu/rustc1.32.0","id":67}

Is there a way to do this using any package from go-ethereum project? All I have with me is a node RPC URL i.e. http://123.45.678.912:8545 and I want to check if it's a Geth node or Parity node using Golang without needing to convert the CURL above to Go code.

I'm looking for something like this:

import "github.com/ethereum/go-ethereum/ethclient"
...
client := ethclient.Dial("http://123.45.678.912:8545")
clientType := client.Xxx() // <-- I need this method and it should return "Geth" or "Parity"

What is the method for Xxx() above?

Answer 1

The ethclient package doesn't provide a method for that but you can use the rpc package to do what you need. Here's a working example:

package main

import (
    "fmt"

    "github.com/ethereum/go-ethereum/rpc"
)

func main() {
    client, err := rpc.DialHTTP("https://mainnet.infura.io")
    if err != nil {
        panic(err)
    }

    var res string
    req := struct {
        To   string `json:"to"`
        Data string `json:"data"`
    }{}

    if err := client.Call(&res, "web3_clientVersion", req, "latest"); err != nil {
        panic(err)
    }

    fmt.Println(res) // Geth/v1.8.22-omnibus-260f7fbd/linux-amd64/go1.11.1
}