shakedex-scan-plugin.js

// Based on: https://gist.github.com/pinheadmz/b51a6ee3c1b414bd7d053951b83f6162

// USAGE: hsd --log-console=false --plugins=/path/to/this/file/shakedex-scan-plugin.js

'use strict';

const layout = require('hsd/lib/blockchain/layout');
const TXMeta = require('hsd/lib/primitives/txmeta');
const { LOCKTIME_FLAG } = require('hsd/lib/protocol/consensus');

const plugin = exports;


class Plugin {
  constructor(node) {
    this.chain = node.chain;

    // Run after chain is ready
    this.chain.once('tip', async (entry) => {
      console.log('::: Scan for shakedex v1 transfers with bad locktime :::');
      this.run();
    });

  }

  async run() {
    const start = Date.now();
    let total = 0;        // Total number of txs scanned
    let matches = [];     // Matched txs

    // Extended txs iterator
    const iter = this.chain.db.db.iterator({
      gte: layout.t.min(),
      lte: layout.t.max(),
      values: true,
    });

    while (await iter.next()) {
      total++;
      if (total % 100000 === 0) console.log('Scanned', total, 'txs.')

      const { value } = iter;
      const meta = TXMeta.decode(value);
      const tx = meta.tx;

      // Skip if coinbase
      if (tx.isCoinbase()) continue;

      // Skip if no locktime
      if (tx.locktime === 0) continue;

      // Skip if seq not final
      for (const input of tx.inputs) {
        if (input.sequence !== 0xFFFFFFFF) continue;
      }
      // if (tx.inputs[0].sequence !== 0xFFFFFFFF) continue;

      let mtp;

      // locktime check
      if (tx.locktime & LOCKTIME_FLAG) {
        // time based locktime
        // -> don't care because shakedex v1 marks it as height, not time
        // -> even if the value is time
        continue;

      } else {
        // height based locktime
        // -> consider value as time, not height because shakedex v1

        const entry = await this.chain.getEntryByHash(meta.block);
        mtp = await this.chain.getMedianTime(entry);

        if (tx.locktime < mtp) {
          // Time has passed locktime, it's fine
          continue;
        }
      }

      // Locktime is in the future, log it.
      const match = {
        height: meta.height,
        block: meta.block.toString('hex'),
        txhash: tx.hash().toString('hex'),
        namehash: tx.outputs[0].covenant.getHash(0).toString('hex'),
        validAfter: new Date(tx.locktime * 1000),
        boughtAt: new Date(mtp * 1000),
        difference: `${((tx.locktime - mtp) / 60).toFixed(2)} minutes`,
      };
      matches.push(match);
      console.log(`Possible exploit ${matches.length}:`, match);
    }

    console.log('DONE.');
    console.log(`elapsed time: ${Date.now() - start} ms`);
    console.log(`Scanned txs: ${total}\tMatches found: ${matches.length}`);

    console.table(matches);
  }
}

plugin.id = 'shakedex-scan';
plugin.init = function init(node) {
  return new Plugin(node);
};