With a custom paymaster

This PR adds a custom paymaster to accept gas payments.

README.md

@@ -1,13 +1,14 @@
 # GSN v3 integration workshop
 
-### (This branch already contains frontend and contract integration with GSN)
+### (This branch adds a custom paymaster to our GSN-enabled sample)
 
 This sample dapp emits an event with the last account that clicked on the "capture the flag" button. We will integrate
 this dapp to work gaslessly with GSN v3. This will allow an externally owned account without ETH to capture the flag by
 signing a meta transaction.
 
 ### To run the sample:
 
+
 1. first clone and `yarn install`
 2. run `yarn gsn-with-ganache` to start a node, and also deploy GSN contracts and start a relayer service.
 3. Make sure you have Metamask installed, and pointing to "localhost"
@@ -17,8 +18,8 @@ signing a meta transaction.
 
 You can see the integrations as GitHub pull requests:
 
-1. (this branch) [Basic: Minimum viable GSN integration](https://github.com/opengsn/workshop/pull/1/files)
-2. [Advanced: Write your own custom Paymaster](https://github.com/opengsn/workshop/pull/2/files_)
+1. [Basic: Minimum viable GSN integration](https://github.com/opengsn/workshop/pull/1/files)
+2. (this branch) [Advanced: Write your own custom Paymaster](https://github.com/opengsn/workshop/pull/2/files_)
 
 Note: on testnet we maintain a public service "pay for everything" paymaster so writing your own is not strictly
 required. On mainnet, you need a custom paymaster, such as a token paymaster that allow users to pay for gas in tokens,

contracts/ImportArtifacts.sol

@@ -0,0 +1,6 @@
+//SPDX-License-Identifier: MIT
+pragma solidity ^0.8.7;
+
+//"import" it into our project for Truffle to generate artifacts
+import "@opengsn/paymasters/contracts/WhitelistPaymaster.sol";
+

migrations/2_deploy_contracts.js

@@ -1,8 +1,27 @@
 const CaptureTheFlag = artifacts.require('CaptureTheFlag')
+const WhitelistPaymaster = artifacts.require('WhitelistPaymaster')
 
-module.exports = async function (deployer) {
+module.exports = async function (deployer, network, accounts) {
     const forwarder = require('../build/gsn/Forwarder').address
     await deployer.deploy(CaptureTheFlag, forwarder)
 
     console.log(`Deployed CTF at ${CaptureTheFlag.address} with forwarder ${forwarder}`)
+
+    await deployer.deploy(WhitelistPaymaster)
+    const relayHubAddress = require('../build/gsn/RelayHub.json').address
+    const paymaster = await WhitelistPaymaster.deployed()
+    await paymaster.setRelayHub(relayHubAddress)
+    await paymaster.setTrustedForwarder(forwarder)
+
+    // This is the first ganache address, when started with "ganache-cli -d"
+    // you can add your metamask address here.
+    await paymaster.whitelistSender('0x90F8bf6A479f320ead074411a4B0e7944Ea8c9C1')
+
+
+    // you can also add addresses by running `truffle console` and then running:
+    // const pm = await WhitelistPaymaster.deployed()
+    // pm.whitelistSender('0x90F8bf6A479f320ead074411a4B0e7944Ea8c9C1')
+
+    await web3.eth.sendTransaction({from: accounts[0], to: paymaster.address, value: 1e18})
+    console.log(`1 ETH deposited to Paymaster(${WhitelistPaymaster.address})`)
 }

package.json

@@ -6,6 +6,7 @@
   "dependencies": {
     "@opengsn/contracts": "^3.0.0-beta.1",
     "@opengsn/dev": "^3.0.0-beta.1",
+    "@opengsn/paymasters": "^3.0.0-beta.1",
     "@opengsn/provider": "^3.0.0-beta.1",
     "browserify": "^17.0.0",
     "ethers": "^5.6.8",
@@ -14,8 +15,8 @@
     "serve": "^13.0.0"
   },
   "scripts": {
-    "ganache": "yarn run ganache-cli -d --networkId 1337 --chainId 1337",
-    "gsn-with-ganache": "run-with-testrpc -d --networkId 1337 --chainId 1337 'gsn start'",
+    "ganache": "yarn run ganache-cli -d --chainId 1337",
+    "gsn-with-ganache": "run-with-testrpc -d --chainId 1337 'gsn start'",
     "test": "truffle test",
     "compile": "truffle compile",
     "build": "./ui/build.sh",

test/testcontracts.js

@@ -2,24 +2,31 @@ const {RelayProvider} = require('@opengsn/provider')
 const {GsnTestEnvironment} = require('@opengsn/dev')
 
 const CaptureTheFlag = artifacts.require('CaptureTheFlag')
+const WhitelistPaymaster = artifacts.require('WhitelistPaymaster')
 
 const ZERO_ADDRESS = '0x0000000000000000000000000000000000000000'
 
 contract("CaptureTheFlag", async accounts => {
 
     let account
     let captureFlagContract
+    let whitelistPaymaster
 
     before(async () => {
-        const {forwarderAddress, paymasterAddress} = GsnTestEnvironment.loadDeployment()
+        const {forwarderAddress, relayHubAddress} = GsnTestEnvironment.loadDeployment()
+
+        const whitelistPaymaster = await WhitelistPaymaster.new()
+        await whitelistPaymaster.setTrustedForwarder(forwarderAddress)
+        await whitelistPaymaster.setRelayHub(relayHubAddress)
+        await web3.eth.sendTransaction({from: accounts[0], to: whitelistPaymaster.address, value: 1e18})
 
         captureFlagContract = await CaptureTheFlag.new(forwarderAddress);
 
         const gsnProvider = await RelayProvider.newProvider({
             provider: web3.currentProvider,
             config: {
                 loggerConfiguration: {logLevel: 'error'},
-                paymasterAddress,
+                paymasterAddress: whitelistPaymaster.address,
                 //these 2 params are needed only for ganache:
                 methodSuffix: '',
                 jsonStringifyRequest: false,
@@ -33,6 +40,8 @@ contract("CaptureTheFlag", async accounts => {
         // default ganache accounts all have eth.
         // test from a different account, without any eth
         account = gsnProvider.newAccount().address
+
+        await whitelistPaymaster.whitelistSender(account)
     })
 
     it('Runs with GSN', async () => {
@@ -41,4 +50,13 @@ contract("CaptureTheFlag", async accounts => {
         assert.equal(res.logs[0].args.previousHolder, ZERO_ADDRESS, "Wrong previous flag holder");
         assert.equal(res.logs[0].args.currentHolder, account, "Wrong current flag holder");
     });
+
+    it('Paymaster should reject different account', async () => {
+        await captureFlagContract.captureTheFlag({from: accounts[2]})
+            .then(() => {
+                throw new Error('should revert')
+            })
+            .catch(() => {
+            })
+    });
 });

ui/index.js

@@ -1,7 +1,8 @@
 const ethers = require('ethers')
 const {RelayProvider} = require('@opengsn/provider')
+let whitelistPaymasterAddress
 
-const paymasterAddress = require('../build/gsn/Paymaster').address
+const WhitelistPaymasterArtifact = require('../build/contracts/WhitelistPaymaster.json')
 const contractArtifact = require('../build/contracts/CaptureTheFlag.json')
 const contractAbi = contractArtifact.abi
 
@@ -24,11 +25,14 @@ async function initContract() {
     })
     const networkId = await window.ethereum.request({method: 'net_version'})
 
+    whitelistPaymasterAddress = WhitelistPaymasterArtifact.networks[networkId].address
+    console.log('Using whitelistPaymaster at', whitelistPaymasterAddress)
+
     gsnProvider = await RelayProvider.newProvider({
         provider: window.ethereum,
         config: {
-            loggerConfiguration: {logLevel: 'debug'},
-            paymasterAddress
+            //loggerConfiguration: { logLevel: 'error' },
+            paymasterAddress: whitelistPaymasterAddress
         }
     }).init()