链接预览脚本出错

我有一个链接预览脚本的下面的代码，像facebook一样工作，但问题是，当我输入url https://www.facebook.com而不是显示我的fb标志它显示我的谷歌chrome标志，它显示更新你的浏览器

    <?php
    $url = $_POST['url'];
    $url = url_clean($url);
    //clean url
    function url_clean($ini_url)
    {
        $uri = trim($ini_url);
        if (get_magic_quotes_gpc()) 
        {
            $uri = stripslashes($uri);
        }
        $uri = strtr($uri, array_flip(get_html_translation_table(HTML_ENTITIES)));
        $uri = strip_tags($uri);
        $uri = htmlspecialchars($uri);
        return $uri;
    }
    //strip the url
    function domain_strip($url)
    {
        if(filter_var($url, FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED) === FALSE)
        {
            return false;
        }
        /*** get the url parts ***/
        $parts = parse_url($url);
        /*** return the host domain ***/
        return $parts['host'];
    }   
    //get the information
    function get_dat($clean_url)
    {
        $web_site = fopen($clean_url, "r"); 
        if (!$web_site)
        {
            exit("Error");
        } 
        $info = '';
        while (!feof($web_site))
        {
            $info .= fgets($web_site, 1024);
        }
        return $info;
    }
    $string = get_dat($url);

    /// get title
    $title_regex = "/<title>(.+)<'/title>/i";
    preg_match_all($title_regex, $string, $title, PREG_PATTERN_ORDER);
    $url_title = $title[1];
    /// get decription
    $tags = get_meta_tags($url);
    // fetch images
    $image_regex = '/<img[^>]*'.'src=['"|''](.*)['"|'']/Ui';
    preg_match_all($image_regex, $string, $img, PREG_PATTERN_ORDER);
    $images_array = $img[1];
    ?>
    <div class="link_prev_container">
    <!----image_cont----->
    <?php
    if(!$images_array)
    {
        echo '';
    }
    else
    {
      echo '<div class="image_holder">';
      $k=1;
      for ($i=0;$i<=sizeof($images_array);$i++)
      {
          if(@$images_array[$i])
          {
              if(@getimagesize(@$images_array[$i]))
              {
                  list($width, $height, $type, $attr) = getimagesize(@$images_array[$i]);
                  if($width >= 50 && $height >= 50 ){
                  echo "<img src='".@$images_array[$i]."' width='100' id='".$k."' >";
                  $k++;
                  }
              }
          }
      }
      echo '</div>';
    }
    ?>
    <!----text inf----->
    <div class="text_inf_holder">
      <div class="title_container"><?php  echo substr(@$url_title[0],0,40) ?></div>
      <div class="brief_container"><?php  echo @$tags['description']; ?></div>
      <div class="link_container"><a class="link" href="<?php echo $url; ?>"><?php echo domain_strip($url) ?></a></div>
    </div>
    </div>

我的问题:什么是facebook的链接预览脚本搜索，上面的脚本不是吗?