ssv-scanner miscounting validator_count in case of multiple events in the same block

[RaekwonIII]

Hello team, a query from a user triggered an investigation this morning, resulted in finding a. possible but in ssv-scanner.

the problem

The user lamented ssv-scanner reporting a validator count of 2, while his expectation was to have 4 validators assigned to his cluster:

massi@MacBook-Pro:~/dev/ssv-scanner|main ⇒  yarn cli cluster \
-n https://goerli.infura.io/v3/2a1be98f319e4b059b85f853a140b315 \
-ca 0xC3CD9A0aE89Fff83b71b58b6512D43F8a41f363D \
-oa 0xc97A3092dd785e1b65155Dd56664dD358B981e2d \
-oids 181,184,185,186
yarn run v1.22.19
$ node ./dist/tsc/src/cli.js cluster -n https://goerli.infura.io/v3/2a1be98f319e4b059b85f853a140b315 -ca 0xC3CD9A0aE89Fff83b71b58b6512D43F8a41f363D -oa 0xc97A3092dd785e1b65155Dd56664dD358B981e2d -oids 181,184,185,186

Scanning blockchain...
 ████████████████████████████████████████ 100% | ETA: 0s | 9738699/9738699
┌───────────┬──────────────────────────────────────────────┐
│  (index)  │                    Values                    │
├───────────┼──────────────────────────────────────────────┤
│   Owner   │ '0xc97A3092dd785e1b65155Dd56664dD358B981e2d' │
│ Operators │              '181,184,185,186'               │
│   Block   │                   9727805                    │
│   Data    │      '2,0,0,true,20000000000000000000'       │
└───────────┴──────────────────────────────────────────────┘
Cluster snapshot:
┌─────────────────┬────────────────────────┐
│     (index)     │         Values         │
├─────────────────┼────────────────────────┤
│ validatorCount  │          '2'           │
│ networkFeeIndex │          '0'           │
│      index      │          '0'           │
│     active      │          true          │
│     balance     │ '20000000000000000000' │
└─────────────────┴────────────────────────┘
{
  "block": 9727805,
  "cluster snapshot": {
    "validatorCount": "2",
    "networkFeeIndex": "0",
    "index": "0",
    "active": true,
    "balance": "20000000000000000000"
  },
  "cluster": [
    "2",
    "0",
    "0",
    true,
    "20000000000000000000"
  ]
}

For comparison, the SSV API "correctly" says there are 4 validators assigned to this cluster:

massi@MacBook-Pro:~/dev/ssv-scanner|main ⇒  curl -X 'GET' \
  'https://api.ssv.network/api/v4/prater/clusters/owner/0xc97A3092dd785e1b65155Dd56664dD358B981e2d?page=1&perPage=10' \
  -H 'accept: */*'

{
  "pagination": {
    "total": 1,
    "page": 1,
    "pages": 1,
    "per_page": 10
  },
  "clusters": [
    {
      "id": 14165,
      "id_str": "14165",
      "owner_address": "0xc97A3092dd785e1b65155Dd56664dD358B981e2d",
      "validator_count": 4,
      "network_fee_index": 0,
      "index": 0,
      "balance": "40000000000000000000",
      "active": true,
      "operators": [
        181,
        184,
        185,
        186
      ]
    }
  ]
}

A quick look at etherscan made us realize that he's not interacting directly with our contract, but with a contract of his own making:

https://goerli.etherscan.io/txs?a=0xc97A3092dd785e1b65155Dd56664dD358B981e2d

Thanks to the help of ssv-scan tool built by the community we found out that the user is experimenting with bulk calls to the contract:

https://testnet.ssvscan.io/account/0xc97a3092dd785e1b65155dd56664dd358b981e2d

And as you can see, 3 ValidatorAdded Events were triggered on the same block.

I took a look at the code responsible for cluster snapshot and it appears to me that it is overwriting the cluster snapshot based on the event's block number. But because the last 3 events have the same block number, it is not picking up the latest, so it's only counting up until 2 validators.

https://github.com/bloxapp/ssv-scanner/blob/main/src/lib/ClusterScanner/ClusterScanner.ts#L72