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import * as _ from 'lodash';
import { BlockParamLiteral, JSONRPCRequestPayload } from 'ethereum-types';
import EthereumTx = require('ethereumjs-tx');
import ethUtil = require('ethereumjs-util');
import providerEngineUtils = require('@dexon-foundation/web3-provider-engine/util/rpc-cache-utils');
import { Callback, ErrorCallback, NextCallback, NonceSubproviderErrors } from '../types';
import { Subprovider } from './subprovider';
const NONCE_TOO_LOW_ERROR_MESSAGE = 'Transaction nonce is too low';
/**
* This class implements the [web3-provider-engine](https://github.com/MetaMask/provider-engine) subprovider interface.
* It is heavily inspired by the [NonceSubprovider](https://github.com/MetaMask/provider-engine/blob/master/subproviders/nonce-tracker.js).
* We added the additional feature of clearing the cached nonce value when a `nonce value too low` error occurs.
*/
export class NonceTrackerSubprovider extends Subprovider {
private readonly _nonceCache: { [address: string]: string } = {};
private static _reconstructTransaction(payload: JSONRPCRequestPayload): EthereumTx {
const raw = payload.params[0];
if (_.isUndefined(raw)) {
throw new Error(NonceSubproviderErrors.EmptyParametersFound);
}
const rawData = ethUtil.toBuffer(raw);
const transaction = new EthereumTx(rawData);
return transaction;
}
private static _determineAddress(payload: JSONRPCRequestPayload): string {
let address: string;
switch (payload.method) {
case 'eth_getTransactionCount':
address = payload.params[0].toLowerCase();
return address;
case 'eth_sendRawTransaction':
const transaction = NonceTrackerSubprovider._reconstructTransaction(payload);
const addressRaw = transaction
.getSenderAddress()
.toString('hex')
.toLowerCase();
address = `0x${addressRaw}`;
return address;
default:
throw new Error(NonceSubproviderErrors.CannotDetermineAddressFromPayload);
}
}
/**
* 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:async-suffix
public async handleRequest(payload: JSONRPCRequestPayload, next: NextCallback, end: ErrorCallback): Promise<void> {
switch (payload.method) {
case 'eth_getTransactionCount':
const requestDefaultBlock = providerEngineUtils.blockTagForPayload(payload);
if (requestDefaultBlock === BlockParamLiteral.Pending) {
const address = NonceTrackerSubprovider._determineAddress(payload);
const cachedResult = this._nonceCache[address];
if (!_.isUndefined(cachedResult)) {
return end(null, cachedResult);
} else {
return next((requestError: Error | null, requestResult: any, cb: Callback) => {
if (_.isNull(requestError)) {
this._nonceCache[address] = requestResult as string;
}
cb();
});
}
} else {
return next();
}
case 'eth_sendRawTransaction':
return next((sendTransactionError: Error | null, _txResult: any, cb: Callback) => {
if (_.isNull(sendTransactionError)) {
this._handleSuccessfulTransaction(payload);
} else {
this._handleSendTransactionError(payload, sendTransactionError);
}
cb();
});
default:
return next();
}
}
private _handleSuccessfulTransaction(payload: JSONRPCRequestPayload): void {
const address = NonceTrackerSubprovider._determineAddress(payload);
const transaction = NonceTrackerSubprovider._reconstructTransaction(payload);
// Increment the nonce from the previous successfully submitted transaction
let nonce = ethUtil.bufferToInt(transaction.nonce);
nonce++;
const hexBase = 16;
let nextHexNonce = nonce.toString(hexBase);
if (nextHexNonce.length % 2) {
nextHexNonce = `0${nextHexNonce}`;
}
const nextPrefixedHexNonce = `0x${nextHexNonce}`;
this._nonceCache[address] = nextPrefixedHexNonce;
}
private _handleSendTransactionError(payload: JSONRPCRequestPayload, err: Error): void {
const address = NonceTrackerSubprovider._determineAddress(payload);
if (this._nonceCache[address] && _.includes(err.message, NONCE_TOO_LOW_ERROR_MESSAGE)) {
delete this._nonceCache[address];
}
}
}
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