Error parsing erc20 event log

[ssadler]

Ethers Version

6.3.0

Search Terms

event log

Describe the Problem

There is an exception parsing some (not all) erc20 event logs from Polygon.

This happens on both Infura and polygon-rpc.com endpoints.

Code Snippet

import { ethers } from 'ethers'                                                    
                                                                                   
import ierc20Abi from '@openzeppelin/contracts/build/contracts/IERC20.json'        
                                                                                   
let ierc20 = new ethers.Interface(ierc20Abi.abi)                                   
                                                                                   
async function main() {                                                            
  let provider = new ethers.JsonRpcProvider('https://polygon-rpc.com')             
                                                                                   
  let blockNum = 42689001                                                          
                                                                                   
    let logs = await provider.getLogs({fromBlock: blockNum, toBlock: blockNum})    
                                                                                   
    let events = logs.map((log) => {                                               
      try {                                                                        
        return ierc20.parseLog({ data: log.data, topics: log.topics.slice() })     
      } catch (e) {                                                                
        console.error("failed parsing log", e, log)                                
      }                                                                            
    }).filter((l) => !!l)                                                          
}                                                                                  
                                                                                   
main()

Contract ABI

{
  "_format": "hh-sol-artifact-1",
  "contractName": "IERC20",
  "sourceName": "contracts/token/ERC20/IERC20.sol",
  "abi": [
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "owner",
          "type": "address"
        },
        {
          "indexed": true,
          "internalType": "address",
          "name": "spender",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "value",
          "type": "uint256"
        }
      ],
      "name": "Approval",
      "type": "event"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "from",
          "type": "address"
        },
        {
          "indexed": true,
          "internalType": "address",
          "name": "to",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "value",
          "type": "uint256"
        }
      ],
      "name": "Transfer",
      "type": "event"
    },
    {
      "inputs": [
        {
          "internalType": "address",
          "name": "owner",
          "type": "address"
        },
        {
          "internalType": "address",
          "name": "spender",
          "type": "address"
        }
      ],
      "name": "allowance",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "stateMutability": "view",
      "type": "function"
    },
    {
      "inputs": [
        {
          "internalType": "address",
          "name": "spender",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "amount",
          "type": "uint256"
        }
      ],
      "name": "approve",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "inputs": [
        {
          "internalType": "address",
          "name": "account",
          "type": "address"
        }
      ],
      "name": "balanceOf",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "stateMutability": "view",
      "type": "function"
    },
    {
      "inputs": [],
      "name": "totalSupply",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "stateMutability": "view",
      "type": "function"
    },
    {
      "inputs": [
        {
          "internalType": "address",
          "name": "to",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "amount",
          "type": "uint256"
        }
      ],
      "name": "transfer",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "inputs": [
        {
          "internalType": "address",
          "name": "from",
          "type": "address"
        },
        {
          "internalType": "address",
          "name": "to",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "amount",
          "type": "uint256"
        }
      ],
      "name": "transferFrom",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "stateMutability": "nonpayable",
      "type": "function"
    }
  ],
  "bytecode": "0x",
  "deployedBytecode": "0x",
  "linkReferences": {},
  "deployedLinkReferences": {}
}

Errors

failed parsing log RangeError: data out-of-bounds (buffer=0x, length=0, offset=32, code=BUFFER_OVERRUN, version=6.3.0)
    at makeError (/node_modules/ethers/src.ts/utils/errors.ts:660:21)
    at assert (/node_modules/ethers/src.ts/utils/errors.ts:680:25)
    at Reader.#peekBytes (/node_modules/ethers/src.ts/abi/coders/abstract-coder.ts:419:23)
    at Reader.readBytes (/node_modules/ethers/src.ts/abi/coders/abstract-coder.ts:436:36)
    at Reader.readValue (/node_modules/ethers/src.ts/abi/coders/abstract-coder.ts:444:30)
    at NumberCoder.decode (/node_modules/ethers/src.ts/abi/coders/number.ts:54:33)
    at /node_modules/ethers/src.ts/abi/coders/array.ts:108:31
    at Array.forEach (<anonymous>)
    at unpack (/node_modules/ethers/src.ts/abi/coders/array.ts:86:12)
    at TupleCoder.decode (/node_modules/ethers/src.ts/abi/coders/tuple.ts:66:22) {
  code: 'BUFFER_OVERRUN',
  buffer: Uint8Array(0) [],
  length: 0,
  offset: 32
} Log {
  provider: JsonRpcProvider {},
  transactionHash: '0x3c2a0bfbf1ab5b345151da7afbc8d6a2751cf9db91585cebd282d7f05d966fad',
  blockHash: '0x850c5758aba451a963ff2510f133aec6e037a6f4b13afb9c9798147ce54c93fc',
  blockNumber: 42689001,
  removed: false,
  address: '0x5e6589b5C06096405BDBCe59821027C6854b1A44',
  data: '0x',
  topics: [
    '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
    '0x0000000000000000000000000000000000000000000000000000000000000000',
    '0x000000000000000000000000679a80fcee8f469f7e194433066d72db03d2f457',
    '0x000000000000000000000000000000000000000000000000000000000002e55a'
  ],
  index: 340,
  transactionIndex: 49
}

Environment

Altcoin - Please specify (e.g. Polygon)

Environment (Other)

Polygon

[ssadler]

This also happens with ethers js 5.7.2. Node version 18.12.0.

Edit: It appears that the empty log data is the issue; my guess is that it's a token transfer with 0 value? Polygonscan sees the same thing here.

There are also some events with no topics at all, which result in an error when calling parseLog. Not sure why there would be a log with no topics, but again, Polygonscan sees the same, for example event 199: https://polygonscan.com/tx/0x1f581d681b7fa6f13cd3f22953c84dfb9e322b77f0a3779102a198e690f82921#eventlog

[ricmoo]

No, there is an extra topic, so the Contract is using an indexed field for the uint. This is likely an ERC-721 log, not and ERC-20 log.

If the non-indexed value was 0, it would contain 32 bytes of 0 in the data and only have 3 topics.

[ssadler]

One more thing, there's a type error passing a log from getLogs to parseLog:

[ricmoo]

The log is incorrect for the ABI. The abi indicates Transfer(address indexed, address indexed, uint) but the log is for Transfer(address indexed, address indexed, uint indexed).

My guess is you are using the ERC-20 ABI for an ERC-721 contract.

Try updating the ABI to use ERC-721 and this log should parse fine. :)