const async = require('async') const EthQuery = require('eth-query') const ethUtil = require('ethereumjs-util') const Transaction = require('ethereumjs-tx') const normalize = require('eth-sig-util').normalize const BN = ethUtil.BN /* tx-utils are utility methods for Transaction manager its passed a provider and that is passed to ethquery and used to do things like calculate gas of a tx. */ module.exports = class txProviderUtils { constructor (provider) { this.provider = provider this.query = new EthQuery(provider) } analyzeGasUsage (txData, cb) { var self = this this.query.getBlockByNumber('latest', true, (err, block) => { if (err) return cb(err) async.waterfall([ self.estimateTxGas.bind(self, txData, block.gasLimit), self.setTxGas.bind(self, txData, block.gasLimit), ], cb) }) } estimateTxGas (txData, blockGasLimitHex, cb) { const txParams = txData.txParams // check if gasLimit is already specified txData.gasLimitSpecified = Boolean(txParams.gas) // if not, fallback to block gasLimit if (!txData.gasLimitSpecified) { txParams.gas = blockGasLimitHex } // run tx, see if it will OOG this.query.estimateGas(txParams, cb) } setTxGas (txData, blockGasLimitHex, estimatedGasHex, cb) { txData.estimatedGas = estimatedGasHex const txParams = txData.txParams // if gasLimit was specified and doesnt OOG, // use original specified amount if (txData.gasLimitSpecified) { txData.estimatedGas = txParams.gas cb() return } // if gasLimit not originally specified, // try adding an additional gas buffer to our estimation for safety const recommendedGasHex = this.addGasBuffer(txData.estimatedGas, blockGasLimitHex) txParams.gas = recommendedGasHex cb() return } addGasBuffer (initialGasLimitHex, blockGasLimitHex) { const initialGasLimitBn = hexToBn(initialGasLimitHex) const blockGasLimitBn = hexToBn(blockGasLimitHex) const bufferedGasLimitBn = initialGasLimitBn.muln(1.5) // if initialGasLimit is above blockGasLimit, dont modify it if (initialGasLimitBn.gt(blockGasLimitBn)) return bnToHex(initialGasLimitBn) // if bufferedGasLimit is below blockGasLimit, use bufferedGasLimit if (bufferedGasLimitBn.lt(blockGasLimitBn)) return bnToHex(bufferedGasLimitBn) // otherwise use blockGasLimit return bnToHex(blockGasLimitBn) } fillInTxParams (txParams, cb) { let fromAddress = txParams.from let reqs = {} if (isUndef(txParams.gas)) reqs.gas = (cb) => this.query.estimateGas(txParams, cb) if (isUndef(txParams.gasPrice)) reqs.gasPrice = (cb) => this.query.gasPrice(cb) if (isUndef(txParams.nonce)) reqs.nonce = (cb) => this.query.getTransactionCount(fromAddress, 'pending', cb) async.parallel(reqs, function(err, result) { if (err) return cb(err) // write results to txParams obj Object.assign(txParams, result) cb() }) } // builds ethTx from txParams object buildEthTxFromParams (txParams) { // apply gas multiplyer let gasPrice = hexToBn(txParams.gasPrice) // multiply and divide by 100 so as to add percision to integer mul txParams.gasPrice = ethUtil.intToHex(gasPrice.toNumber()) // normalize values txParams.to = normalize(txParams.to) txParams.from = normalize(txParams.from) txParams.value = normalize(txParams.value) txParams.data = normalize(txParams.data) txParams.gasLimit = normalize(txParams.gasLimit || txParams.gas) txParams.nonce = normalize(txParams.nonce) // build ethTx log.info(`Prepared tx for signing: ${JSON.stringify(txParams)}`) const ethTx = new Transaction(txParams) return ethTx } publishTransaction (rawTx, cb) { this.query.sendRawTransaction(rawTx, cb) } validateTxParams (txParams, cb) { if (('value' in txParams) && txParams.value.indexOf('-') === 0) { cb(new Error(`Invalid transaction value of ${txParams.value} not a positive number.`)) } else { cb() } } } // util function isUndef(value) { return value === undefined } function bnToHex(inputBn) { return ethUtil.addHexPrefix(inputBn.toString(16)) } function hexToBn(inputHex) { return new BN(ethUtil.stripHexPrefix(inputHex), 16) }