web3-provider-engine/dist/es5/subproviders/nonce-tracker.js

A JavaScript library for composing Ethereum provider objects using middleware modules

"use strict";

var inherits = require('util').inherits;
var _require = require('@ethereumjs/tx'),
  TransactionFactory = _require.TransactionFactory;
var ethUtil = require('@ethereumjs/util');
var Subprovider = require('./subprovider.js');
var blockTagForPayload = require('../util/rpc-cache-utils').blockTagForPayload;
module.exports = NonceTrackerSubprovider;

// handles the following RPC methods:
//   eth_getTransactionCount (pending only)
//
// observes the following RPC methods:
//   eth_sendRawTransaction
//   evm_revert (to clear the nonce cache)

inherits(NonceTrackerSubprovider, Subprovider);
function NonceTrackerSubprovider() {
  var self = this;
  self.nonceCache = {};
}
NonceTrackerSubprovider.prototype.handleRequest = function (payload, next, end) {
  var self = this;
  switch (payload.method) {
    case 'eth_getTransactionCount':
      var blockTag = blockTagForPayload(payload);
      var address = payload.params[0].toLowerCase();
      var cachedResult = self.nonceCache[address];
      // only handle requests against the 'pending' blockTag
      if (blockTag === 'pending') {
        // has a result
        if (cachedResult) {
          end(null, cachedResult);
          // fallthrough then populate cache
        } else {
          next(function (err, result, cb) {
            if (err) return cb();
            if (self.nonceCache[address] === undefined) {
              self.nonceCache[address] = result;
            }
            cb();
          });
        }
      } else {
        next();
      }
      return;
    case 'eth_sendRawTransaction':
      // allow the request to continue normally
      next(function (err, result, cb) {
        // only update local nonce if tx was submitted correctly
        if (err) return cb();
        // parse raw tx
        var rawTx = payload.params[0];
        var rawData = Buffer.from(ethUtil.stripHexPrefix(rawTx), 'hex');
        var tx = TransactionFactory.fromSerializedData(rawData);
        // extract address
        var address = tx.getSenderAddress().toString('hex').toLowerCase();
        // extract nonce and increment
        var nonce = ethUtil.bufferToInt(tx.nonce);
        nonce++;
        // hexify and normalize
        var hexNonce = nonce.toString(16);
        if (hexNonce.length % 2) hexNonce = '0' + hexNonce;
        hexNonce = '0x' + hexNonce;
        // dont update our record on the nonce until the submit was successful
        // update cache
        self.nonceCache[address] = hexNonce;
        cb();
      });
      return;

    // Clear cache on a testrpc revert
    case 'evm_revert':
      self.nonceCache = {};
      next();
      return;
    default:
      next();
      return;
  }
};