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Multicall Contract

What is EIP-2930?​

EIP-2930 allows users to define addresses and storage slots for a transaction.

https://eips.ethereum.org/EIPS/eip-2930

Why is EIP-2930 important?​

Sphinx 1.X has automated the accessList for Shardeum RPC nodes to route shards.

Therefore, you no longer need to specify the accessList for these networks with automated accessList generation.

This document is useful for:

-educational purposes
-situations where the automated accessList fails and you need to specify the accessList directly

Where is EIP-2930 data located for a transaction?​

The accessList transaction parameter is where the EIP-2930 address and storage slot data goes.

How do I define an accessList for an EIP-2930 transaction?​

Based on the EIP-2930 specification, the general syntax should be:

-the address [20 bytes]

-then the storage slots being accessed at that address [32 bytes]

Example:

    [
        [
            "0xde0b295669a9fd93d5f28d9ec85e40f4cb697bae",
            [
                "0x0000000000000000000000000000000000000000000000000000000000000003",
                "0x0000000000000000000000000000000000000000000000000000000000000007"
            ]
        ],
        [
            "0xbb9bc244d798123fde783fcc1c72d3bb8c189413",
            []
        ]
    ]

EIP-2930 Optional:​

Transfer SHM on Shardeum Between Wallets:​

Send an EIP-2930 transaction with an accessList address that has no storage:

const Web3 = require('web3')
const ethers = require("ethers")

const rpcURL = "https://sphinx.shardeum.org/"
const web3 = new Web3(rpcURL)

const provider = new ethers.providers.JsonRpcProvider(rpcURL)
const signer = new ethers.Wallet(Buffer.from(process.env.devTestnetPrivateKey, 'hex'), provider);
console.log("User wallet address: " + signer.address)

const transferToWallet = new ethers.Wallet(Buffer.from(process.env.devTestnetPrivateKeyTwo, 'hex'), provider);
console.log("transferToWallet address: " + transferToWallet.address)

createAndSendTx();

async function createAndSendTx() {

    const chainIdConnected = await web3.eth.getChainId();
    console.log("chainIdConnected: "+ chainIdConnected)

    const oneEtherInWeiSHM = "1000000000000000000"
    console.log("oneEtherInWeiSHM: " + oneEtherInWeiSHM)

    const userBalance = await provider.getBalance(signer.address);
    console.log("User Balance [Shardeum SHM]" )
    console.log(ethers.utils.formatEther(userBalance))

    const receiverBalance = await provider.getBalance(transferToWallet.address);
    console.log("Receiver Balance [Shardeum SHM]" )
    console.log(ethers.utils.formatEther(receiverBalance))

    const txCount = await provider.getTransactionCount(signer.address);

    const tx = signer.sendTransaction({
          chainId: chainIdConnected,
          to: transferToWallet.address,
          nonce:    web3.utils.toHex(txCount),
          gasLimit: web3.utils.toHex(300000), // Raise the gas limit to a much higher amount
          gasPrice: web3.utils.toHex(web3.utils.toWei('30', 'gwei')),
          value: oneEtherInWeiSHM,
          type: 1,
          accessList: [
            {
              address: transferToWallet.address,
              storageKeys: []
            }
          ]

    });

    console.log("WAIT FOR TX RECEIPT: ")
    await tx
    console.log("TX RECEIPT: ")
    console.log(tx)

}

Contracts contractToCall and Multicall:​

// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

contract contractToCall {

    uint public slot0; //uint is 32 bytes and fills a 32 byte slot. //Do not set 0 manually it wastes gas!

    function set(uint x) public {
        slot0 = x;
    }

}

contract Multicall {

    contractToCall public callContractToCall;

    constructor(address setCallOne) {
        callContractToCall = contractToCall(setCallOne);
    }

    function multiCallRead() public view returns(uint) {
        return callContractToCall.slot0();
    }

    function multiCallWrite(uint x) public {
        callContractToCall.set(x);
    }

}

contractToCall (Single Address):​

Send an EIP-2930 transaction with a accessList. The accessList contains the contract's address and accessed storage slot (or slots). In this case, it will be storage slot0, because it is a single uint storage variable (uint = 256 bits = 32 bytes) which is modified when we call "set(uint)".

const Web3 = require('web3')
const ethers = require("ethers")

const rpcURL = "https://sphinx.shardeum.org/"
const web3 = new Web3(rpcURL)

const provider = new ethers.providers.JsonRpcProvider(rpcURL)
const signer = new ethers.Wallet(Buffer.from(process.env.devTestnetPrivateKey, 'hex'), provider);
console.log("User wallet address: " + signer.address)

const simpleStorageAddress = '0xE8eb488bEe284ed5b9657D5fc928f90F40BC2d57'
const simpleStorageABI = [{"inputs":[{"internalType":"uint256","name":"x","type":"uint256"}],"name":"set","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"slot0","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"}]

const simpleStorageDeployed = new web3.eth.Contract(simpleStorageABI, simpleStorageAddress)

createAndSendTx();

async function createAndSendTx() {

    const chainIdConnected = await web3.eth.getChainId();
    console.log("chainIdConnected: "+ chainIdConnected)

    const slot0 = await simpleStorageDeployed.methods.slot0().call()
    console.log("slot0: "+ slot0)

    const unixTime = Date.now();
    console.log("UNIX TIME: " + unixTime)

    const txCount = await provider.getTransactionCount(signer.address);

    const tx = signer.sendTransaction({
          chainId: chainIdConnected,
          to: simpleStorageAddress,
          nonce:    web3.utils.toHex(txCount),
          gasLimit: web3.utils.toHex(300000), // Raise the gas limit to a much higher amount
          gasPrice: web3.utils.toHex(web3.utils.toWei('30', 'gwei')),
          data: simpleStorageDeployed.methods.set(unixTime).encodeABI(),
          type: 1,
          accessList: [
            {
              address: simpleStorageAddress,
              storageKeys: [
                "0x0000000000000000000000000000000000000000000000000000000000000000",
              ]
            }
          ]

    });

    console.log("WAIT FOR TX RECEIPT: ")
    await tx
    console.log("TX RECEIPT: ")
    console.log(tx)

}

Multicall Storage Read:​

Reading contract states cross shard does not need an accessList.

For example, ERC-20 multicall:

tokenObject.totalSupply()

will work with no accessList cross shard.

EIP-2930 Required:​

Multicall Storage Write:​

Writing contract states cross shard requires an accessList.

For example, ERC-20 multicall:

tokenObject.transfer(recipient, amount)

will require an accessList to work cross shard.

Contract Multicall can change states in other contracts (in this case contractToCall). For sharded Shardeum networks, we need to specify the addresses and storage slots being called outside "from" and "to" in the transaction.

Sphinx 1.X Address codeHash in storage slots:​

Sphinx 1.X will not need the codeHash in storage slots for each corresponding externally called address.

In Solidity, you can get an address codeHash from a deployed contract on the matching network [along with checking if an address is a contract]. You can also get an address codeHash with the ethers library.

Solidity codeHash example:​

// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

contract addressCodeHash { //From https://soliditydeveloper.com/extcodehash

    function getCodeHash(address account) public view returns (bytes32) {

        bytes32 codeHash;    
        assembly { codeHash := extcodehash(account) }

        return (codeHash);
    }

    function isContractBasedOnHash(address account) public view returns (bool) {
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;

        bytes32 codeHash;    
        assembly { codeHash := extcodehash(account) }

        return (codeHash != accountHash && codeHash != 0x0);
    }

    function isContractBasedOnSize(address addr) public view returns (bool) {
        uint size;
        assembly { size := extcodesize(addr) }
        return size > 0;
    }

}

EIP-2930 accessList transactions for Multicall contract to modify slot0 in contractToCall:​

const Web3 = require('web3')
const ethers = require("ethers")

const rpcURL = "https://sphinx.shardeum.org/"
const web3 = new Web3(rpcURL)

const provider = new ethers.providers.JsonRpcProvider(rpcURL)
const signer = new ethers.Wallet(Buffer.from(process.env.devTestnetPrivateKey, 'hex'), provider);
console.log("User wallet address: " + signer.address)

const contractAddress_JS = '0xb1fEf690f84241738b188eF8b88e52B2cc59AbD2'
const contractABI_JS = [{"inputs":[{"internalType":"uint256","name":"x","type":"uint256"}],"name":"multiCallWrite","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"setCallOne","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"inputs":[],"name":"callContractToCall","outputs":[{"internalType":"contractcontractToCall","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"multiCallRead","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"}]

const contractDefined_JS = new web3.eth.Contract(contractABI_JS, contractAddress_JS)

createAndSendTx();

async function createAndSendTx() {

    const chainIdConnected = await web3.eth.getChainId();
    console.log("chainIdConnected: "+ chainIdConnected)

    const slot0 = await contractDefined_JS.methods.multiCallRead().call()
    console.log("slot0: "+ slot0)

    const contractOneAddress = await contractDefined_JS.methods.callContractToCall().call()
    console.log("contractOneAddress: "+ contractOneAddress)

    const codeHash = await provider.getCode(contractOneAddress)
    console.log("contractOneAddress codeHash: " + codeHash)

    const unixTime = Date.now();
    console.log("UNIX TIME: " + unixTime)

    const txCount = await provider.getTransactionCount(signer.address);

    const tx = signer.sendTransaction({
        chainId: chainIdConnected,
        to: contractAddress_JS,
        nonce:    web3.utils.toHex(txCount),
        gasLimit: web3.utils.toHex(2100000), // Raise the gas limit to a much higher amount
        gasPrice: web3.utils.toHex(web3.utils.toWei('30', 'gwei')),
        data: contractDefined_JS.methods.multiCallWrite(unixTime).encodeABI(),
        type: 1,
        accessList: [
          {
            address: contractOneAddress, //Contract address we are calling from the "to" contract at some point.
            storageKeys: [
              "0x0000000000000000000000000000000000000000000000000000000000000000",
              codeHash, //Code hash from EXTCODEHASH https://blog.finxter.com/how-to-find-out-if-an-ethereum-address-is-a-contract/
            ]
          }
        ]

    });

    console.log("WAIT FOR TX RECEIPT: ")
    await tx
    console.log("TX RECEIPT: ")
    console.log(tx)

}

How can I create an EIP-2930 accessList easily?​

EIP-2930 accessList simulator​

Tool generates accessList with 91% accuracy:

https://github.com/alexchenzl/predict-al

EIP-2930 accessList generation for swap transactions can be found in this GitHub repository:

https://github.com/shardeum-globalswap/interface/tree/support-eip2930