When querying 1.21.1 Servers, response contains unexpected characters.

[Mx772]

When doing a simple query like:

import mc from "minecraftstatuspinger";

// All The Mods 10 - 1.21.1
let result = await mc.lookup({ host: "10.g.akliz.net" });
console.log(result);

Getting the error:

undefined:1
{
    "favicon": "LongBase64",
    "isModded": true,
    "description": "A Minecraft Server",
    "players": {
        "max": 20,
        "online": 6,
        "sample": [
        ]
    },
    "version": {
        "name": "1.21.1",
        "protocol": 767
    },
    "preventsChatReports": true
}V{
    "releaseType": "unknown",
    "projectId": 925200,
    "name": "All The Mods 10",
    "version": "2.36"
}

SyntaxError: Unexpected non-whitespace character after JSON at position 6108 (line 1 column 6109)
    at JSON.parse (<anonymous>)
    at new ServerStatus (file:////node_modules/.pnpm/minecraftstatuspinger@1.2.1/node_modules/minecraftstatuspinger/dist/types.js:29:36)
    at Socket.<anonymous> (file:////node_modules/.pnpm/minecraftstatuspinger@1.2.1/node_modules/minecraftstatuspinger/dist/index.js:64:36)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

Note the 'V' between json objects.

Doing the same for a 1.20.1 server returns valid results like:

import mc from "minecraftstatuspinger";

// All the Mods 9  - 1.20.1
let result = await mc.lookup({ host: "atm9nf.g.akliz.net" });
console.log(result);    

I was able to replicate it on other versions of node as well.

Tested:

Node.js v22.8.0
Node.js v18.20.7
Node.js v22.14.0

I haven't touched node in quite a bit, so I could 100% be doing something wrong here. But the fact it breaks on the newer versions makes me assume it's something like the response changing as you demonstrated here:
https://pinger.floppa.hair/responses/

[woodendoors7]

I've not been able to test yet, but are you sure it happens on all 1.12.1 servers, or just that one? It could as well be mods messing it up.

[Mx772]

All the servers I tested were 1.21.1 modded, but with different modpacks. I can test later with an unmodded one.

The weird part is it seems to work with homepage but I'm not sure of their implementation. I was just trying to query and log which failed.

[woodendoors7]

I have finally got around to testing it, and it seems to be caused by Better Compatibility Checker. Instead of adding a new JSON field into the status response packet JSON, it adds an entirely new string containing a 'JSON response'. The V (and other letters) in your example response should be the packet ID and varint length of the field in binary, incorrectly being parsed as UTF.

My code is at fault - the JSON response field is prefixed with a length, but instead of cutting off the buffer at that length, I keep the rest in the final output. This is normally fine if the server behaves as intended, but it may include non-standard fields added by various mods. It's probably why homepage works - it cuts it off as you should, and ignores anything that goes after it.

Expect a patch soon, and thanks for bringing this to my attention. 🙏

[Mx772]

Appreciate you looking into it! It was on my weekend plans but I hadn't gotten around to it yet. I figured it was something weird with Json parsing so that makes sense.