BDSX - parse the Login Packet

example.ts

import * as jwt from 'jsonwebtoken'; // npm i --save jsonwebtoken

class LoginPacket {
    protocolVersion: number
    chainData: any
    clientData: ClientData
    extraData: ExtraData
}

enum InputMode {
    Mouse = 1,
    Touch,
    Gamepad,
    MotionController
}

// https://github.com/Sandertv/gophertunnel/blob/master/minecraft/protocol/login/data.go#L73
// This isnt complete but you should be able to figure it out from the link above
class ClientData {
    DefaultInputMode: InputMode
    CurrentInputMode: InputMode
}

class ExtraData {
    XUID: String
    identity: String
    displayName: String
    titleId: String
}

function readLoginPacket(ptr: NativePointer, size: number): LoginPacket {
    let loginPacket = new LoginPacket()
    ptr.move(1); // the first byte is the packet id
    loginPacket.protocolVersion = ptr.readInt32();
    let chainRaw = Buffer.from(ptr.readBuffer(ptr.readVarUint()))
    let chainLength = chainRaw.readInt32LE()
    let chainString = chainRaw.toString("utf8", 4, chainLength+4)
    loginPacket.chainData = JSON.parse(chainString);
    for (let token of loginPacket.chainData.chain) {
        let payload = jwt.decode(token)!
        if (Object.keys(payload).includes("extraData")) {
            loginPacket.extraData = (payload as any).extraData
        }
        console.log(payload)
    }
    let tokenString = chainRaw.toString("utf8", chainLength+8)
    loginPacket.clientData = jwt.decode(tokenString)! as ClientData
    console.log(loginPacket.clientData.CurrentInputMode)
    return loginPacket
}
netevent.raw(PacketId.Login).on((ptr, size, networkIdentifier, packetId) => {
    let packet = readLoginPacket(ptr, size);
})