PHP method to implement anti-hotlink cracking for images [solve the problem of anti-hotlinking for images/reverse proxy]

<?php
 class ImgBridge{
  private $water=&#39;&#39;;
  private $imgUrl=&#39;&#39;; 
  private $referer=&#39;&#39;;
  private $ua=&#39;MQQBrowser/26 Mozilla/5.0 (Linux; U; Android 2.3.7; zh-cn; MB200 Build/GRJ22; CyanogenMod-7) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1&#39;;
  private $imgCode=&#39;&#39;;
  private $imgHeader=&#39;&#39;;
  private $imgBody=&#39;&#39;;
  private $imgType=&#39;&#39;;

  public function \_\_construct($config=array()){
    foreach($config as $key=>$value){
      $this->$key=$value;
    }
  }
  
  public function getImg($imgUrl){
    $this->imgUrl=$imgUrl;
    /\*\* 处理url \*/
    if(substr($this->imgUrl,0,7)!==&#39;http://&#39; && substr($this->imgUrl,0,8)!==&#39;https://&#39;){
      $this->imgUrl=&#39;http://&#39;.$this->imgUrl;
    }
    /\*\* 解析url中的host \*/
    $url\_array=parse\_url($this->imgUrl);
    /\*\* 设置referer \*/
    $this->referer=$this->referer==""?&#39;http://&#39;.$url\_array\[&#39;host&#39;\]:$this->referer;
    /\*\*开始获取 \*/
    $this->urlOpen();
    $this->imgBody;
    /\*\*处理错误 \*/
    if($this->imgCode!=200){
      $this->error(1);
      exit();
    }
    
    /\*\*获取图片格式 \*/
    preg\_match("/Content-Type: image\\/(.+?)\\n/sim",$this->imgHeader,$result);
    /\*\*看看是不是图片 \*/
    if(!isset($result\[1\])){
      $this->error(2);
      exit();
    }else{
      $this->imgType=$result\[1\];
    }
    /\*\* 输出内容 \*/
    $this->out();    
  }
  private function out(){
    /\*\* gif 不处理，直接出图 \*/
    if($this->imgType==&#39;gif&#39;){
      header("Content-Type: image/gif");
      echo $this->imgBody;
      exit();
    }
    header("Content-Type: image/png");
    /\*\* 其他类型的，加水印 \*/
    $im=imagecreatefromstring($this->imgBody);
    $white = imagecolorallocate($im, 255, 255, 255);
    /\*加上水印\*/
    if($this->water){
      imagettftext($im, 12, 0, 20, 20, $white, "/fonts/hwxh.ttf", $this->water);      
    }
    imagepng($im);
    
  }
  private function error($err){
    header("Content-Type: image/jpeg");
    $im=imagecreatefromstring(file\_get\_contents(&#39;./default.jpg&#39;));
    imagejpeg($im);
  }

  private function urlOpen()
  {
    $ch = curl\_init();
    curl\_setopt($ch, CURLOPT\_URL, $this->imgUrl);
    curl\_setopt($ch, CURLOPT\_USERAGENT, $this->ua);
    curl\_setopt ($ch,CURLOPT\_REFERER,$this->referer);
    curl\_setopt($ch, CURLOPT\_RETURNTRANSFER, 1);
    curl\_setopt($ch, CURLOPT\_HEADER, 1);
    /\*\*跳转也要 \*/
    curl\_setopt($ch, CURLOPT\_FOLLOWLOCATION, true);
    /\*\* 支持https \*/
    $opt\[CURLOPT\_SSL\_VERIFYHOST\] = 2;
    $opt\[CURLOPT\_SSL\_VERIFYPEER\] = FALSE;
    curl\_setopt\_array($ch, $opt);
    $response = curl\_exec($ch);
    $this->imgCode=curl\_getinfo($ch, CURLINFO\_HTTP\_CODE) ;
    if ($this->imgCode == &#39;200&#39;) {
      $headerSize = curl\_getinfo($ch, CURLINFO\_HEADER\_SIZE);
      $this->imgHeader = substr($response, 0, $headerSize);
      $this->imgBody = substr($response, $headerSize);
      return ;
    }
    curl\_close($ch);
  }

 }
$img=new ImgBridge(array(&#39;water&#39;=>&#39;&#39;));
$img->getImg(strstr($\_SERVER\["QUERY\_STRING"\], "http"));