PHP防止SQL注入攻击和XSS攻击

代码如下：

/**
 * 防sql注入和xss攻击
 * @param $arr
 */
function safefilter (&$arr)
{

   $ra=array('/([\x00-\x08,\x0b-\x0c,\x0e-\x19])/','/script/','/javascript/','/vbscript/','/expression/','/applet/','/meta/','/xml/','/blink/','/link/','/style/','/embed/','/object/','/frame/','/layer/','/title/','/bgsound/','/base/','/onload/','/onunload/','/onchange/','/onsubmit/','/onreset/','/onselect/','/onblur/','/onfocus/','/onabort/','/onkeydown/','/onkeypress/','/onkeyup/','/onclick/','/ondblclick/','/onmousedown/','/onmousemove/','/onmouseout/','/onmouseover/','/onmouseup/','/onunload/');

   if (is_array($arr))
   {
     foreach ($arr as $key => $value)
     {
        if (!is_array($value))
        {
          if (!get_magic_quotes_gpc())             //不对magic_quotes_gpc转义过的字符使用addslashes(),避免双重转义。
          {
             $value  = addslashes($value);           //给单引号（'）、双引号（"）、反斜线（\）与 nul（null 字符）加上反斜线转义
          }
          $value       = preg_replace($ra,'',$value);     //删除非打印字符，粗暴式过滤xss可疑字符串
          $arr[$key]     = htmlentities(strip_tags($value)); //去除 html 和 php 标记并转换为 html 实体
        }
        else
        {
          safefilter($arr[$key]);
        }
     }
   }
}