eth,internal: add eth_chainId method to PublicEthereumApi JSONRPC

[whilei]

I'm stealing @sorpaas words from his congruent Parity client PR:

Currently although we can use net_version RPC call to get the
current network ID, there's no RPC for querying the chain ID. This
makes it impossible to determine the current actual blockchain using
the RPC. An ETH/ETC client can accidentally connect to an ETC/ETH RPC
endpoint without knowing it unless it tries to sign a transaction or
it fetch a transaction that is known to have signed with a chain
ID. This has since caused trouble for application developers, such as
MetaMask, to add multi-chain support.

Recently merged the same endpoint to ETC's go-ethereum: ethereumproject/go-ethereum#336

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[karalabe]

Would be nice to have an EIP for it before adding methods to the standardized eth_ namespace.

[tcz001]

Good to see this, I was facing with same problem when using Web3js, which was using the net_getId by default, just created a EIP694

[whilei]

Please find an EIP PR here: ethereum/EIPs#695

[bas-vk]

The proper way to retrieve the chainID is:

if config := api.e.chainConfig; config.IsEIP155(api.e.blockchain.CurrentBlock().Number()) {
		chainID = config.ChainId
}

Although the EIP is not finalized it is likely that a QUANTITY is returned. You can return one the of integer types in the hexutil package for that. They will take care of the appropiate encoding that is used for quantity types.

[holiman]

Parity just added this method aswell, looks good to me.
Actually, hold that. How will this respond when doing e.g. a full-sync, before reaching EIP-155?

x

[whilei]

It will return hexutil.Uint(new(big.Int)) == 0x0, which does not conflict with any existing chainId in EIP155.

[frankiebee]

whats the status on this? seems like a stale PR. did chainId make it in somewhere else?

[turbobit]

ESN ( https://ethersocial.org ) using customized RPC-API for using Metamask.
api : https://api-meta.esn.gonspool.com
api return RPC call "net_version" as chainId value "31102"
"chainId 31102 " is ESN's chainid.

by using this customized RPC-API.
i am sucess send a coin with

• metamask
• myetherwallet + metamask
  ex ) https://escblock.gonsmine.com/tx/0x7c3992eb93a1f858da755bda36824bde60aa340545c83c4127c968add1b5fcae

[fjl]

Closing in favor of #17617