classic-relayer/index.js

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2019-07-18 08:43:26 -04:00
const { fetchGasPrice, isValidProof } = require('./utils')
const { numberToHex, toWei, toHex } = require('web3-utils')
const express = require('express')
const app = express()
app.use(express.json())
const { netId, rpcUrl, privateKey, mixerAddress, defaultGasPrice } = require('./env.json')
const Web3 = require('web3')
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('./mixerABI.json')
const mixer = new web3.eth.Contract(mixerABI, mixerAddress)
const gasPrices = { fast: defaultGasPrice }
app.get('/', function (req, res) {
// just for testing purposes
res.send(`Tornado mixer relayer. Gas Price is ${JSON.stringify(gasPrices)}`)
})
app.post('/relay', async (req, resp) => {
const { valid , reason } = isValidProof(req.body)
if (!valid) {
console.log('Proof is invalid:', reason)
return resp.status(400).send('Proof is invalid')
}
let { pi_a, pi_b, pi_c, publicSignals } = req.body
// TODO
// if (bigInt(proof.publicSignals[3]) < getMinimumFee()) {
// resp.status(403).send('Fee is too low')
// }
try {
const nullifier = publicSignals[1]
const isSpent = await mixer.methods.isSpent(nullifier).call()
if (isSpent) {
throw new Error('The note has been spent')
}
const gas = await mixer.methods.withdraw(pi_a, pi_b, pi_c, publicSignals).estimateGas()
const result = mixer.methods.withdraw(pi_a, pi_b, pi_c, publicSignals).send({
gas: numberToHex(gas + 50000),
gasPrice: toHex(toWei(gasPrices.fast.toString(), 'gwei')),
// TODO: nonce
})
result.once('transactionHash', function(hash){
resp.send({ transaction: hash })
}).on('error', function(e){
console.log(e)
resp.status(400).send('Proof is malformed')
})
} catch (e) {
console.log(e)
resp.status(400).send('Proof is malformed or spent')
}
})
app.listen(8000)
if (netId === 1) {
fetchGasPrice({ gasPrices })
console.log('Gas price oracle started.')
}