Automatic Forwarder for ETH and ERC20 with ERC1167

Introduction

The general concept isn't new and on the Internet, it is possible to find many examples of non-custodial smart contracts. Problem is that they are usually in an old version of Solidity and they were made before ERC1167.

Our idea is based on the CoinBase blog post, but with a few fundamental changes.

First of all, the core of this idea is based on market standards. We took contracts and libraries from OpenZeppelin to ensure that we are not duplicating anything that we don’t have to.

The second thing is that the Forwarder smart contract in the blog post is prepared only for tokens, and initialization is based on a constructor that isn’t currently recommended.

The last thing is that our all concept is developed in Solidity 0.8.0, which implies the next positive changes.

To have better understanding of the conncept, please read

• Smart contract files
• Test files

Tech stack

NPM - dependency management

Truffle - project structure and cli management

OpenZeppelin - verified market standards

Ganache - for local tests

Environment

There are a few technical requirements before you start. Please install the following:

1. Node+NPM
2. Install trufflesuite, run in console npm install -g truffle
3. Install Ganache

When you will have all tools installed, please remember about running npm install in the project root catalog.

Detailed dependent libraries you will find in package.json

If you don't have any IDE, VSCode is simple, free, and good enough to project like this.

Truffle configuration file is prepared for local run - truffle-config.js

Commands

The full command reference is available here

Basic examples:

Compilation: truffle compile

Deployment/Migration: truffle migrate --network development

Run all local tests: truffle test

Run selected local tests: truffle test test/[FILENAME]

Verification with web3js and Ropsten test network

For external verification we will use infura and Ropsten network.

1. Make a copy of .example.secrets.json' with name .secrets.json` in the same catalog

2. Install Metamask at your local computer

3. Add some funds to the address in metamask using Ropsten faucet (https://faucet.ropsten.be/)

4. Copy mnemonic to variable MNEMONIC in `.secrets.json'

5. Create an account at https://infura.io/

6. Create a new project there and save project ID

7. Fill PROJECT_ID in .secrets.json with the value saved in INFURA

8. Deploy the project using the command truffle migrate --network ropsten

9. Save deployed smart contract addresses

10. Go to catalog test/client

11. Run npm install

12. Make a copy of .example.netfonig.json with the name .netconfig.json in the same catalog

13. Fill all fields in the configuration file

14. Initialize forwarder smart contract with command npm run init_test

15. To check factory methods run the command npm run factory_test