import { BlockchainLifecycle } from '@0xproject/dev-utils'; import { Callback, ErrorCallback, NextCallback, Subprovider } from '@0xproject/subproviders'; import { Web3Wrapper } from '@0xproject/web3-wrapper'; import { CallData, JSONRPCRequestPayload, Provider, TxData } from 'ethereum-types'; import * as _ from 'lodash'; import { Lock } from 'semaphore-async-await'; import { constants } from './constants'; import { BlockParamLiteral } from './types'; interface MaybeFakeTxData extends TxData { isFakeTransaction?: boolean; } const BLOCK_GAS_LIMIT = 6000000; export interface TraceCollectionSubproviderConfig { shouldCollectTransactionTraces: boolean; shouldCollectCallTraces: boolean; shouldCollectGasEstimateTraces: boolean; } // Because there is no notion of a call trace in the Ethereum rpc - we collect them in a rather non-obvious/hacky way. // On each call - we create a snapshot, execute the call as a transaction, get the trace, revert the snapshot. // That allows us to avoid influencing test behaviour. /** * This class implements the [web3-provider-engine](https://github.com/MetaMask/provider-engine) subprovider interface. * It collects traces of all transactions that were sent and all calls that were executed through JSON RPC. It must * be extended by implementing the _recordTxTraceAsync method which is called for every transaction. */ export abstract class TraceCollectionSubprovider extends Subprovider { protected _web3Wrapper!: Web3Wrapper; // Lock is used to not accept normal transactions while doing call/snapshot magic because they'll be reverted later otherwise private readonly _lock = new Lock(); private readonly _defaultFromAddress: string; private _isEnabled = true; private readonly _config: TraceCollectionSubproviderConfig; /** * Instantiates a TraceCollectionSubprovider instance * @param defaultFromAddress default from address to use when sending transactions */ constructor(defaultFromAddress: string, config: TraceCollectionSubproviderConfig) { super(); this._defaultFromAddress = defaultFromAddress; this._config = config; } /** * Starts trace collection */ public start(): void { this._isEnabled = true; } /** * Stops trace collection */ public stop(): void { this._isEnabled = false; } /** * This method conforms to the web3-provider-engine interface. * It is called internally by the ProviderEngine when it is this subproviders * turn to handle a JSON RPC request. * @param payload JSON RPC payload * @param next Callback to call if this subprovider decides not to handle the request * @param end Callback to call if subprovider handled the request and wants to pass back the request. */ // tslint:disable-next-line:prefer-function-over-method async-suffix public async handleRequest(payload: JSONRPCRequestPayload, next: NextCallback, _end: ErrorCallback): Promise { if (this._isEnabled) { switch (payload.method) { case 'eth_sendTransaction': if (!this._config.shouldCollectTransactionTraces) { next(); } else { const txData = payload.params[0]; next(this._onTransactionSentAsync.bind(this, txData)); } return; case 'eth_call': if (!this._config.shouldCollectCallTraces) { next(); } else { const callData = payload.params[0]; next(this._onCallOrGasEstimateExecutedAsync.bind(this, callData)); } return; case 'eth_estimateGas': if (!this._config.shouldCollectGasEstimateTraces) { next(); } else { const estimateGasData = payload.params[0]; next(this._onCallOrGasEstimateExecutedAsync.bind(this, estimateGasData)); } return; default: next(); return; } } else { next(); return; } } /** * Set's the subprovider's engine to the ProviderEngine it is added to. * This is only called within the ProviderEngine source code, do not call * directly. */ public setEngine(engine: Provider): void { super.setEngine(engine); this._web3Wrapper = new Web3Wrapper(engine); } protected abstract async _recordTxTraceAsync( address: string, data: string | undefined, txHash: string, ): Promise; private async _onTransactionSentAsync( txData: MaybeFakeTxData, err: Error | null, txHash: string | undefined, cb: Callback, ): Promise { if (!txData.isFakeTransaction) { // This transaction is a usual transaction. Not a call executed as one. // And we don't want it to be executed within a snapshotting period await this._lock.acquire(); } const NULL_ADDRESS = '0x0'; if (_.isNull(err)) { const toAddress = _.isUndefined(txData.to) || txData.to === NULL_ADDRESS ? constants.NEW_CONTRACT : txData.to; await this._recordTxTraceAsync(toAddress, txData.data, txHash as string); } else { const latestBlock = await this._web3Wrapper.getBlockWithTransactionDataAsync(BlockParamLiteral.Latest); const transactions = latestBlock.transactions; for (const transaction of transactions) { const toAddress = _.isUndefined(txData.to) || txData.to === NULL_ADDRESS ? constants.NEW_CONTRACT : txData.to; await this._recordTxTraceAsync(toAddress, transaction.input, transaction.hash); } } if (!txData.isFakeTransaction) { // This transaction is a usual transaction. Not a call executed as one. // And we don't want it to be executed within a snapshotting period this._lock.release(); } cb(); } private async _onCallOrGasEstimateExecutedAsync( callData: Partial, _err: Error | null, _callResult: string, cb: Callback, ): Promise { await this._recordCallOrGasEstimateTraceAsync(callData); cb(); } private async _recordCallOrGasEstimateTraceAsync(callData: Partial): Promise { // We don't want other transactions to be exeucted during snashotting period, that's why we lock the // transaction execution for all transactions except our fake ones. await this._lock.acquire(); const blockchainLifecycle = new BlockchainLifecycle(this._web3Wrapper); await blockchainLifecycle.startAsync(); const fakeTxData: MaybeFakeTxData = { gas: BLOCK_GAS_LIMIT, isFakeTransaction: true, // This transaction (and only it) is allowed to come through when the lock is locked ...callData, from: callData.from || this._defaultFromAddress, }; try { const txHash = await this._web3Wrapper.sendTransactionAsync(fakeTxData); await this._web3Wrapper.awaitTransactionMinedAsync(txHash, 0); } catch (err) { // Even if this transaction failed - we've already recorded it's trace. _.noop(); } await blockchainLifecycle.revertAsync(); this._lock.release(); } }