Added eth namespace apis Call, EstimateGas

[aeharvlee]

Proposed changes

This PR implemented Eth namespace APIs Call and EstimateGas.

Ethereum Source Code links

• Call
• EstimateGas

Review Points

1. State Override feature

• Ethereum introduced State Override option at Call api.
  • Now user can override the state ephemerally prior to executing the call.
  • Related docs with detailed description: https://geth.ethereum.org/docs/rpc/ns-eth
  • Related PR: eth/tracer: extend call tracer ethereum/go-ethereum#22245

2. Differences from Klaytn

• Ethereum's Call and EstimateGas basically checks if caller (= the from address) has enough balance to proceeds call if user specified gas and gasPrice field.
  • Checks balance of caller is higher than gas * gasPrice.

For this, I moved logic adding balance of caller from GetEVM to out of it because both klay_call and eth_call are now using same API but works differently.

Klaytn add gasFee by default before proceeding call and estimateGas.

3. Differences from Ethereum implementation

• Removed ExecutionResult struct

  • There is no easy way to classify whether the error returned from TransitionDb in Klaytn is vmError or consensusError or just simple error can be detected before executing EVM (e.g. user specify gas limit which is lower than intrinsicGas).
  • Ethereum uses ExecutionResult because they can specify that errors in their codebase, but this is not adaptable to current Klaytn codebase.
    We can apply this changes maybe later.

• AccessList is not supported yet

  • AccessList is not supported yet in Klaytn, so it does not process with it even though user passes AccessList as parameter.

How to test this PR

First, please clone my origin repo.

1. Build ken with source codes related with this PR.

• Run make ken

2. Run ken

• In my case, I tested with CN 1 - PN 1 - EN 1 in my local.
• Please note that you should enable eth namepsace to RPC_API and WS_API in kend.conf

Prepare the test

Click to expand

Bytecode

To test State Override feature, I compiled simple storage contract and got bytecode to use.

Storage.bin-runtime: 6080604052600436106049576000357c0100000000000000000000000000000000000000000000000000000000900463ffffffff1680632e64cec114604e5780636057361d146076575b600080fd5b348015605957600080fd5b50606060a0565b6040518082815260200191505060405180910390f35b348015608157600080fd5b50609e6004803603810190808035906020019092919050505060a9565b005b60008054905090565b80600081905550505600a165627a7a723058207783dba41884f73679e167576362b7277f88458815141651f48ca38c25b498f80029

I used $ docker run -v /Users/denver.lee/playground/solidity/storage:/sol ethereum/solc:0.4.24 --asm --abi --bin --bin-runtime --metadata --overwrite -o /sol/output /sol/storage.sol to compile below Storage contract code.

pragma solidity ^0.4.24;

/**
 * @title Storage
 * @dev Store & retrieve value in a variable
 */
contract Storage {

    uint256 number;

    /**
     * @dev Store value in variable
     * @param num value to store
     */
    function store(uint256 num) public {
        number = num;
    }

    /**
     * @dev Return value 
     * @return value of 'number'
     */
    function retrieve() public view returns (uint256){
        return number;
    }
}

ABI Set to test function call of KIP-7

> totalSupplyAbi
{ name: 'totalSupply', type: 'function', inputs: [] }
> caver.abi.encodeFunctionCall(totalSupplyAbi, [])
'0x18160ddd' 

> balanceOfAbi
{
  constant: true,
  inputs: [ { internalType: 'address', name: 'account', type: 'address' } ],
  name: 'balanceOf',
  outputs: [ { internalType: 'uint256', name: '', type: 'uint256' } ],
  payable: false,
  stateMutability: 'view',
  type: 'function'
}
> caver.abi.encodeFunctionCall(balanceOfAbi, ["0xca7a99380131e6c76cfa622396347107aeedca2d"])
'0x70a08231000000000000000000000000ca7a99380131e6c76cfa622396347107aeedca2d'

> retrieveAbi
{ name: 'retrieve', type: 'function', inputs: [] }
> caver.abi.encodeFunctionCall(retrieveAbiObj, [])
'0x2e64cec1'

Test Call

Click to expand

I tested this api in the following order.

1. Deploy KIP-7 contract.
2. Call KIP-7 contract functions totalSupply and balanceOf to check whether call is working or not.
3. State Override already deployed KIP-7 contract account by replacing it's code with runtime bytecode of Storage.sol and call retrieve function of Storage.sol.

Here is the my test scenario info below.

• KIP-7 Contract address: 0xbE3892d33620bE5aca8c75D39e7401871194d290
• Deployer address: 0xca7a99380131e6c76cfa622396347107aeedca2d

Call totalSupply()

➜  corecell curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0", "method": "eth_call", "params": [{"from": "0xca7a99380131e6c76cfa622396347107aeedca2d", "to": "0xbE3892d33620bE5aca8c75D39e7401871194d290", "data": "0x18160ddd"}, "latest"], "id": 1}' http://localhost:8551

{"jsonrpc":"2.0","id":1,"result":"0x0000000000000000000000000000000000000000000000000de0b6b3a7640000"}

Call balanceOf("0xca7a99380131e6c76cfa622396347107aeedca2d")

➜  corecell curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0", "method": "eth_call", "params": [{"from": "0xca7a99380131e6c76cfa622396347107aeedca2d", "to": "0xbE3892d33620bE5aca8c75D39e7401871194d290", "data": "0x70a08231000000000000000000000000ca7a99380131e6c76cfa622396347107aeedca2d"}, "latest"], "id": 1}' http://localhost:8551

{"jsonrpc":"2.0","id":1,"result":"0x0000000000000000000000000000000000000000000000000de0b6b3a763ffff"}

State Override with Storage.sol and Call retrieve

➜  corecell curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0", "method": "eth_call", "params": [{"from": "0xca7a99380131e6c76cfa622396347107aeedca2d", "to": "0xbE3892d33620bE5aca8c75D39e7401871194d290", "data": "0x2e64cec1"}, "latest", {"0xbE3892d33620bE5aca8c75D39e7401871194d290": {"code":"0x6080604052600436106049576000357c0100000000000000000000000000000000000000000000000000000000900463ffffffff1680632e64cec114604e5780636057361d146076575b600080fd5b348015605957600080fd5b50606060a0565b6040518082815260200191505060405180910390f35b348015608157600080fd5b50609e6004803603810190808035906020019092919050505060a9565b005b60008054905090565b80600081905550505600a165627a7a723058207783dba41884f73679e167576362b7277f88458815141651f48ca38c25b498f80029"}}], "id": 1}' http://localhost:8551

{"jsonrpc":"2.0","id":1,"result":"0x0000000000000000000000000000000000000000000000000000000000000000"}

Call with gas and gasPrice but balance is not enough
Balance of caller 0xe2df3753d74bebd8c4ccdbd5320b36e5ef8ca08d: 0.

➜  corecell curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0", "method": "eth_call", "params": [{"from": "0xe2df3753d74bebd8c4ccdbd5320b36e5ef8ca08d", "to": "0xbE3892d33620bE5aca8c75D39e7401871194d290", "data": "0x70a08231000000000000000000000000ca7a99380131e6c76cfa622396347107aeedca2d", "gas": "0x99999", "gasPrice": "0x1"}, "latest"], "id": 1}' http://localhost:8551
{"jsonrpc":"2.0","id":1,"error":{"code":-32000,"message":"err: insufficient balance of the fee payer to pay for gas (supplied gas 629145)"}}

Call with gas and gasPrice but balance is not enough -> Using State Override to cover this
But if we use State Override we can use it. Let's override state with balance 0x99999.

➜  corecell curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0", "method": "eth_call", "params": [{"from": "0xe2df3753d74bebd8c4ccdbd5320b36e5ef8ca08d", "to": "0xbE3892d33620bE5aca8c75D39e7401871194d290", "data": "0x70a08231000000000000000000000000ca7a99380131e6c76cfa622396347107aeedca2d", "gas": "0x99999", "gasPrice": "0x1"}, "latest", {"0xe2df3753d74bebd8c4ccdbd5320b36e5ef8ca08d": {"balance": "0x99999"}}], "id": 1}' http://localhost:8551

{"jsonrpc":"2.0","id":1,"result":"0x0000000000000000000000000000000000000000000000000de0b6b3a763ffff"}

Test EstimateGas

Click to expand

Estimate Gas with gas and gasPrice. Caller balance is enough to call it.
Balance of caller 0xca7a99380131e6c76cfa622396347107aeedca2d: 9.99999999999999999999999999999999097166e+49

➜  corecell curl -H "Content-Type: application/json" --data '{"jsonrpc": "2.0", "method": "eth_estimateGas", "params": [{"from": "0xca7a99380131e6c76cfa622396347107aeedca2d", "to": "0x87ac99835e67168d4f9a40580f8f5c33550ba88b", "gas": "0x100000", "gasPrice": "0x5d21dba00", "value": "0x0", "data": "0x8ada066e"}], "id": 1}' http://localhost:8551

{"jsonrpc":"2.0","id":1,"result":"0x5398"}

Estimate Gas with gas and gasPrice but Caller balance is not enough.
Balance of caller 0xe2df3753d74bebd8c4ccdbd5320b36e5ef8ca08d: 0

➜  corecell curl -H "Content-Type: application/json" --data '{"jsonrpc": "2.0", "method": "eth_estimateGas", "params": [{"from": "0xe2df3753d74bebd8c4ccdbd5320b36e5ef8ca08d", "to": "0x87ac99835e67168d4f9a40580f8f5c33550ba88b", "gas": "0x100000", "gasPrice": "0x5d21dba00", "value": "0x0", "data": "0x8ada066e"}], "id": 1}' http://localhost:8551

{"jsonrpc":"2.0","id":1,"error":{"code":-32000,"message":"insufficient funds for transfer"}}

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Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[jimni1222]

Please resolve conflicts

[aidan-kwon]

I think it's good except for the comment I leaved

[aidan-kwon]

@jeongkyun-oh @yoomee1313 PTAL