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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<void> {
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.
* @param engine The ProviderEngine this subprovider is added to
*/
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<void>;
private async _onTransactionSentAsync(
txData: MaybeFakeTxData,
err: Error | null,
txHash: string | undefined,
cb: Callback,
): Promise<void> {
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<CallData>,
_err: Error | null,
_callResult: string,
cb: Callback,
): Promise<void> {
await this._recordCallOrGasEstimateTraceAsync(callData);
cb();
}
private async _recordCallOrGasEstimateTraceAsync(callData: Partial<CallData>): Promise<void> {
// 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();
}
}
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