Admincraft•2mo ago

How LuckPerms "predicts" permissions

This is not an issue, only something I was investigating for fun I've been curious about how LuckPerms manages to "predict" permissions the server has available. I made a very small single-file plugin to see this feature in action with just a single Permissible.hasPermission(String) function at the start of a command. Apparently before trying to execute the command, luckperms is not yet aware of this permission, however after trying it once and opening the editor, it does show as a possible permission to choose. This suggest that they might be caching permissions when Permissible.hasPermission(String) or similar functions are executed, however in their repo there isn't a clear reference to a cache on hasPermission, only on addPermission. I've been reading their repo for a while now, and learned a lot of how the plugin works but so far, no reference as how they resolve those permissions, closest I could find is AsyncPermissionRegistry but there's nothing suggesting a possible cache. This post is mostly for curiosity, if anyone had the same question and managed to find an answer before me. This is the example plugin I made to test this:

class CrappyPlugin : JavaPlugin() {

    lateinit var self: CrappyPlugin

    override fun onLoad() {
        this.self = this
    }

    override fun onEnable() {
        this.server.commandMap.register("example", object : Command("canexecute"), PluginIdentifiableCommand {
            override fun execute(
                sender: CommandSender,
                label: String,
                args: Array<out String>?
            ): Boolean {
                if (sender.hasPermission("example.canexecute.test")) {
                    sender.sendMessage("Yes, you can execute")
                    return true
                }
                sender.sendMessage("No, you can't execute")
                return false
            }

            override fun getPlugin() = self

        })
    }

}

class CrappyPlugin : JavaPlugin() {

    lateinit var self: CrappyPlugin

    override fun onLoad() {
        this.self = this
    }

    override fun onEnable() {
        this.server.commandMap.register("example", object : Command("canexecute"), PluginIdentifiableCommand {
            override fun execute(
                sender: CommandSender,
                label: String,
                args: Array<out String>?
            ): Boolean {
                if (sender.hasPermission("example.canexecute.test")) {
                    sender.sendMessage("Yes, you can execute")
                    return true
                }
                sender.sendMessage("No, you can't execute")
                return false
            }

            override fun getPlugin() = self

        })
    }

}

Solution:

I tried that and it lead me to AsyncPermissionRegistry

Jump to solution

9 Replies

Admincraft Meta•2mo ago

Thanks for asking your question!

Make sure to provide as much helpful information as possible such as logs/what you tried and what your exact issue is

Make sure to mark solved when issue is solved!!!

/close !close !solved !answered

Requested by duoslingo#0

Arthurmeade12•2mo ago

Don't plugins declare their permissions in plugin.yml

𝐁𝐢𝐪𝐮𝐚𝐭𝐞𝐫𝐧𝐢𝐨𝐧𝐬OP•2mo ago

No, try the code above as is without declaring anything in plugin.yml and Luckperms will be able to detect the permission regardless I mean, declare the main class, plugin name, etc. But no permissions

Arthurmeade12•2mo ago

Haha I trust you I don't know java Even though I probably should bc it's useful

𝐁𝐢𝐪𝐮𝐚𝐭𝐞𝐫𝐧𝐢𝐨𝐧𝐬OP•2mo ago

Try the code above without any permission in plugin.yml I feel is most likely cached I opened an editor before and after joining the server Before joining, the permission wasn't displayed in the editor After joining and running the command that required said permission, it was displayed on the editor (had to open a new one) Haven't try that before, but I don't think is likely that it mentiones the classes that are being called Or does it? I'll try

𝐁𝐢𝐪𝐮𝐚𝐭𝐞𝐫𝐧𝐢𝐨𝐧𝐬OP•2mo ago

Doesn't give that much insight on how lp does it

𝐁𝐢𝐪𝐮𝐚𝐭𝐞𝐫𝐧𝐢𝐨𝐧𝐬OP•2mo ago

I also took the chance to confirm, I opened one editor after joining the server but before executing that command. The editor is definitely only able to recognize it after the permission has been consulted Yh, but the point is where does it gets the permissions from in terms of code It's not on the plugin.yml, I haven't manually added them with Permissible.addPermission() it is registering the permission somewhere once its consulted

Solution

𝐁𝐢𝐪𝐮𝐚𝐭𝐞𝐫𝐧𝐢𝐨𝐧𝐬•2mo ago

I tried that and it lead me to AsyncPermissionRegistry

𝐁𝐢𝐪𝐮𝐚𝐭𝐞𝐫𝐧𝐢𝐨𝐧𝐬OP•2mo ago

I also tried looking into their hasPermission implementation and it lead me to PermissionCalculator But nothing that could potentially store the permission to send it to the editor Just to know what they did to store it I made something similar with a regular map And that left me wondering how they handled it Just checking that one Mostly, the issue is that when I look into those files I ran into a class that doesn't hold anything Well, I'm also just checking via github on the browser Maybe I should clone the repo and use the ide But idk, it is kinda fun investigating this way

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How LuckPerms "predicts" permissions

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