Uniswap V3: decode exactInput paths

08_decodeExactInputPath.js

const hashes = [
    '0x04fffe0fb9d0ac806b0f3c329a83d8dd5ddcd598ee82779043d83802d6ee784a',
    '0x8df99a1c9bbbf7cda5a9f1bc11d3b3cd0c6d99f31039396a29779fea252960f6',
    '0x3f94bc2af1300a01827e59a745b05af8517ae4fc5e25ee1add9789d19c9bfd00',
    '0x68cf26f581d6c0add08c9fcf9b1d4d31cff660d8bfb6b7d9e3636a7aa1e0a91f',
    '0xed797fb4d05950dca9279c55f2436211a3eb585f1f20877e7384017500951fe4',
    '0x7596c887baea532f2a2370af06d1990dac8be04f68e8f906dd82025d2ce42ad7',
    '0x8892ffda5398dbf54d0fb6bc4d2bbdbc31de250f633cf1becc568a92fbe63c51',
    '0x9219aa3bc64b325f84f9e3c101e602c83f65f61272a982c8f2fd1c55874ecc6d',
    '0x81995eb1d1a62c3dbdb817663e39b40d235861e4ee6513962299d8a15905dded',
    '0xd9727c3b97e878ed32c9cf8f4203bf5c4a0bfb37027ccd944f550b2024f4152d',
    '0x496226187f9b7810f9d64530cd57163c1ce15cf85119e6da85e7f91ba2dee0a7',
    '0x779bcb8991a8a66fd0ce2b3328b71791f71a8878d24d2acce5dbc22d27cb538f',
]

const ethers = require("ethers")

require('dotenv').config()
const provider = new ethers.providers.JsonRpcProvider(process.env.INFURA_URL)

const swapRouter02Abi = [
    // copy from https://etherscan.io/address/0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45
]

const contractInterface = new ethers.utils.Interface(swapRouter02Abi);

const main = () => {
    hashes.forEach(async (hash) => {
        const tx = await provider.getTransaction(hash)

        const data = tx.data
        const decodedData = contractInterface.parseTransaction({ data: data })

        // console.log('------')
        // console.log(decodedData)

        const params = decodedData.args.params
        const path = params.path
        decodePath(path)
    })
}


const decodePath = (path) => {
    const decodedPath = []

    const pathData = path.slice(2)

    let idx = 0;
    let inputToken

    inputToken = `0x${pathData.slice(idx, idx + 40)}`
    idx += 40;

    while (idx < pathData.length) {
        const fee = parseInt(pathData.slice(idx, idx + 6), 16)
        idx += 6;

        const outputToken = `0x${pathData.slice(idx, idx + 40)}`
        idx += 40;

        decodedPath.push({ inputToken: inputToken, fee, outputToken: outputToken })

        inputToken = outputToken
    }

    console.log(decodedPath)
}


main()

/*
    node scripts/08_decodeExactInputPath.js
 */

hardhat.config.js

require("@nomiclabs/hardhat-waffle");
require('dotenv').config()

/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
  solidity: "0.8.18",
  networks: {
    hardhat: {
      forking: {
        url: process.env.INFURA_URL
      }
    }
  }
};

package.json

{
  "name": "YouTubeTutorials",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@nomiclabs/hardhat-ethers": "^2.2.3",
    "@nomiclabs/hardhat-waffle": "^2.0.6",
    "@types/sinon-chai": "^3.2.9",
    "@uniswap/sdk": "^3.0.3",
    "@uniswap/sdk-core": "^4.0.2",
    "@uniswap/universal-router-sdk": "^1.5.7",
    "@uniswap/v3-core": "^1.0.1",
    "@uniswap/v3-periphery": "^1.4.3",
    "@uniswap/v3-sdk": "^3.9.0",
    "dotenv": "^16.3.1",
    "ethereum-waffle": "^4.0.10",
    "ethers": "^5.7.2",
    "hardhat": "^2.14.0"
  }
}