const { numberToHex, toWei, toHex, toBN, toChecksumAddress } = require('web3-utils') const { netId, rpcUrl, privateKey, defaultGasPrice } = require('./config') const { fetchGasPrice, isValidProof, fetchDAIprice, isKnownContract } = require('./utils') const Web3 = require('web3') const express = require('express') const app = express() app.use(express.json()) app.use((err, req, res, next) => { if (err) { console.log('Invalid Request data') res.send('Invalid Request data') } else { next() } }) app.use(function(req, res, next) { res.header('Access-Control-Allow-Origin', '*') res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept') next() }) const web3 = new Web3(rpcUrl, null, { transactionConfirmationBlocks: 1 }) const account = web3.eth.accounts.privateKeyToAccount('0x' + privateKey) web3.eth.accounts.wallet.add('0x' + privateKey) web3.eth.defaultAccount = account.address const mixerABI = require('./abis/mixerABI.json') const gasPrices = { fast: defaultGasPrice } const ethPriceInDai = toWei('200') app.get('/', function (req, res) { // just for testing purposes res.send('This is tornado.cash Relayer service. Check the /status for settings') }) app.get('/status', function (req, res) { res.json({ relayerAddress: web3.eth.defaultAccount, gasPrices, netId, ethPriceInDai }) }) app.post('/relay', async (req, resp) => { let { valid , reason } = isValidProof(req.body.proof) if (!valid) { console.log('Proof is invalid:', reason) return resp.status(400).json({ error: 'Proof format is invalid' }) } let currency ( { valid, currency } = isKnownContract(req.body.contract)) if (!valid) { console.log('Contract does not exist:', req.body.contract) return resp.status(400).json({ error: 'This relayer does not support the token' }) } let { proof, publicSignals } = req.body.proof const args = { root: publicSignals[0], nullifierHash: publicSignals[1], recipient: toChecksumAddress(publicSignals[2]), relayer: toChecksumAddress(publicSignals[3]), fee: toBN(publicSignals[4]), refund: toBN(publicSignals[5]), } if (args.relayer !== web3.eth.defaultAccount) { console.log('This proof is for different relayer:', args.relayer) return resp.status(400).json({ error: 'Relayer address is invalid' }) } const expense = toBN(toWei(gasPrices.fast.toString(), 'gwei')).mul(toBN('1000000')) let desiredFee switch (currency) { case 'eth': { if (!args.refund.isZero()) { return resp.status(400).json({ error: 'Cannot send refund for eth currency.' }) } desiredFee = expense break } case 'dai': { desiredFee = expense.add(args.refund).mul(toBN(ethPriceInDai)).div(toBN(10 ** 18)) break } } if (args.fee.lt(desiredFee)) { console.log('Fee is too low') return resp.status(400).json({ error: 'Fee is too low. Try to resend.' }) } try { const mixer = new web3.eth.Contract(mixerABI, req.body.contract) const isSpent = await mixer.methods.isSpent(args.nullifierHash).call() if (isSpent) { return resp.status(400).json({ error: 'The note has been spent.' }) } const isKnownRoot = await mixer.methods.isKnownRoot(args.root).call() if (!isKnownRoot) { return resp.status(400).json({ error: 'The merkle root is too old or invalid.' }) } const gas = await mixer.methods.withdraw(proof, ...publicSignals).estimateGas({ value: args.refund }) const result = mixer.methods.withdraw(proof, ...publicSignals).send({ value: args.refund, gas: numberToHex(gas + 50000), gasPrice: toHex(toWei(gasPrices.fast.toString(), 'gwei')), // TODO: nonce }) result.once('transactionHash', function(hash){ resp.json({ txHash: hash }) }).on('error', function(e){ console.log(e) return resp.status(400).json({ error: 'Proof is malformed.' }) }) } catch (e) { console.log(e) return resp.status(400).json({ error: 'Proof is malformed or spent.' }) } }) app.listen(8000) if (Number(netId) === 1) { fetchGasPrice({ gasPrices }) fetchDAIprice({ ethPriceInDai, web3 }) console.log('Gas price oracle started.') }