SkinKick - Auto-generated gist plugin stub by pmt.mcpe.me InstaPlugin

plugin.yml

---
name: SkinKick
author: PEMapModder
version: "1.0"
api:
- 1.13.0
main: PEMapModder\SkinKick\Main
commands:
  newskin:
    usage: /ns
    aliases: [ns]
  skinauth:
    description: Toggles/checks whether SkinAuth is enabled for you
    usage: /skinauth [t|f]
    aliases: [sa]
permissions: []
...

resources--config.yml

---
newskin-timeout: 300 # NOTE: the number is in seconds
newskin-description: Kicks you and lets you join with a new skin from the same IP within the next 5 minutes
kick-messages:
  newskin: "Please rejoin within 5 minutes with a different (or same) skin."
  newskin-diff-ip: Attempt to join server from a different IP address while in newskin mode
  diff-skin: "Your skin does not match the correct skin!"
...

src--PEMapModder--SkinKick--Main.php

<?php
namespace PEMapModder\SkinKick;

use pocketmine\Player;
use pocketmine\command\CommandSender;
use pocketmine\command\Command;
use pocketmine\event\Listener;
use pocketmine\event\player\PlayerLoginEvent;
use pocketmine\plugin\PluginBase;

class Main extends PluginBase implements Listener{
  public function onEnable(){
    $this->saveDefaultConfig();
    $this->getServer()->getPluginManager()->registerEvents($this, $this);
    @mkdir($this->getDataFolder() . "players/");
    $this->getCommand("newskin")->setDescription($this->getConfig()->get("newskin-description"));
  }
  public function onLogin(PlayerLoginEvent $event){
    $player = $event->getPlayer();
    $file = $this->getDataFolder() . "players/" . strtolower($player->getName()) . ".json";
    if(!is_file($file)){
      $config = new SkinConfig;
      $config->lastIp = $player->getAddress();
      $config->skin = base64_encode($player->getSkinData());
      $config->skinSlim = $player->isSkinSlim();
      file_put_contents($file, json_encode($config, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));
    }else{
      $config = SkinConfig::fromFile($file);
      if($config->newSkin < time()){
        if(base64_decode($config->skin) !== $player->getSkinData() or $config->skinSlim !== $player->isSkinSlim()){
          if($config->enforce){
            $event->setCancelled();
            $event->setKickMessage($this->getConfig()->getNested("kick-messages.diff-skin"), false);
            return;
          }
          $this->getLogger()->notice("{$player->getName()} is using a new skin, but (s)he is opt-out for SkinAuth!");
        }
        $config->lastIp = $player->getAddress();
        file_put_contents($file, json_encode($config, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));
      }else{
        if($player->getAddress() !== $config->lastIp){
          $event->setCancelled();
          $event->setKickMessage($this->getConfig()->getNested("kick-messages.newskin-diff-ip"), false);
          return;
        }
        $config->skin = base64_encode($player->getSkinData());
        $config->skinSlim = $player->isSkinSlim();
        $config->newSkin = 0;
        file_put_contents($file, json_encode($config, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));
      }
    }
  }

  public function onCommand(CommandSender $issuer, Command $cmd, $label, array $params){
    switch($cmd->getName()){
      case "newskin":
        if(!($issuer instanceof Player)){
          $issuer->sendMessage("Please run this command in-game.");
          return true;
        }
        $file = $this->getDataFolder() . "players/" . strtolower($issuer->getName()) . ".json";
        $config = SkinConfig::fromFile($file);
        $config->newSkin = time() + $this->getConfig()->get("newskin-timeout");
        file_put_contents($file, json_encode($config, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));
        $player->kick($this->getConfig()->getNested("kick-messages.newskin"), false);
        return true;
      case "skinauth":
        if(!($issuer instanceof Player)){
          $issuer->sendMessage("Please run this command in-game.");
          return true;
        }
        $file = $this->getDataFolder() . "players/" . strtolower($issuer->getName()) . ".json";
        $config = SkinConfig::fromFile($file);
        if(isset($params[0])){
          $opt = strtolower($params[0]);
          if($opt === "t" or $opt === "i" or $opt === "enable" or $opt === "on" or $opt === "in" or $opt === "true"){
            $optIn = true;
          }elseif($opt === "f" or $opt === "o" or $opt === "disable" or $opt === "off" or $opt === "off" or $opt === "false"){
            $optIn = false;
          }
        }
        if(!isset($optIn)){
          $inOut = $config->enforce ? "in" : "out";
          $reverse = $config->enforce ? "out" : "in";
          $reverseCmd = $config->enforce ? "/opt f" : "/opt t";
          $issuer->sendMessage("You are opt-$inOut to SkinAuth. Use `$reverseCmd` to opt-$reverse.");
          return true;
        }
        $config->enforce = $optIn;
        $inOut = $config->enforce ? "in" : "out";
        $reverse = $config->enforce ? "out" : "in";
        $reverseCmd = $config->enforce ? "/opt f" : "/opt t";
        $issuer->sendMessage("You are now opt-$inOut to SkinAuth. Use `$reverseCmd` to opt-$reverse.");
        return true;
    }
    return false;
  }
}

src--PEMapModder--SkinKick--SkinConfig.php

<?php
namespace PEMapModder\SkinKick;

class SkinConfig{
  /** @type bool */
  public $enforce = false;
  /** @type string */
  public $lastIp;
  /** @type string (base64-encoded) */
  public $skin;
  /** @type bool */
  public $skinSlim;
  /** @type int */
  public $newSkin = 0;
  
  public static function fromFile($file){
    $data = json_decode(file_get_contents($file));
    $self = new self;
    if(is_object($data)){
      foreach($data as $k => $v){
        $self->{$k} = $v;
      }
    }
    return $self;
  }
}

Awesome