Admincraft•7d 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

        })
    }

}

27 Replies

Admincraft Meta•7d 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•7d ago

Don't plugins declare their permissions in plugin.yml

duolingo se acercaOP•7d 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•7d ago

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

Mortis•7d ago

I might be wrong but pretty sure its basically grabbing it from tab completion then checking the commands permission from plugin.yml? thats probs at least partially how its done

duolingo se acercaOP•7d ago

Try the code above without any permission in plugin.yml

Mortis•7d ago

i know just stating partially thats how they likely do it

duolingo se acercaOP•7d ago

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

Mortis•7d ago

also it could just be the plugin listening into permission checks and caching it

duolingo se acercaOP•7d ago

After joining and running the command that required said permission, it was displayed on the editor (had to open a new one)

Mortis•7d ago

lp verbose does exist after all

duolingo se acercaOP•7d ago

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

duolingo se acercaOP•7d ago

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

duolingo se acercaOP•7d 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

Mortis•7d ago

because web editor is a web socket connection and you create a connection to the web editor and your server and upload permission to the web editor

Mortis•7d ago

https://github.com/LuckPerms/LuckPerms/blob/master/common/src/main/java/me/lucko/luckperms/common/api/implementation/ApiPlatform.java

GitHub

LuckPerms/common/src/main/java/me/lucko/luckperms/common/api/implem...

A permissions plugin for Minecraft servers. Contribute to LuckPerms/LuckPerms development by creating an account on GitHub.

duolingo se acercaOP•7d ago

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

Mortis•7d ago

tab completion?

duolingo se acercaOP•7d ago

I tried that and it lead me to AsyncPermissionRegistry 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

Mortis•7d ago

is that what you really want? just wondering whats your goal here

duolingo se acercaOP•7d ago

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

Mortis•7d ago

https://github.com/LuckPerms/LuckPerms/blob/master/common/src/main/java/me/lucko/luckperms/common/webeditor/WebEditorRequest.java ??

GitHub

LuckPerms/common/src/main/java/me/lucko/luckperms/common/webeditor/...

A permissions plugin for Minecraft servers. Contribute to LuckPerms/LuckPerms development by creating an account on GitHub.

Mortis•7d ago

https://github.com/LuckPerms/LuckPerms/blob/master/common/src/main/java/me/lucko/luckperms/common/model/PermissionHolder.java is interesting

GitHub

LuckPerms/common/src/main/java/me/lucko/luckperms/common/model/Perm...

A permissions plugin for Minecraft servers. Contribute to LuckPerms/LuckPerms development by creating an account on GitHub.

duolingo se acercaOP•7d ago

Just checking that one

Mortis•7d ago

https://github.com/LuckPerms/LuckPerms/blob/master/common/src/main/java/me/lucko/luckperms/common/commands/misc/EditorCommand.java when the editor command is ran

GitHub

LuckPerms/common/src/main/java/me/lucko/luckperms/common/commands/m...

A permissions plugin for Minecraft servers. Contribute to LuckPerms/LuckPerms development by creating an account on GitHub.

Mortis•7d ago

honestly think that should be enough idea to get how this works

duolingo se acercaOP•7d ago

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

Gaming

Programming

How LuckPerms "predicts" permissions

Did you find this page helpful?