php 域名处理函数

下面这款个一个是判断输入的域名是不是合法的，然后再把http,https,ftp进行处理，分析再发送

function _scan_url()
   {
       $req = $this->_url;
      
       $pos = strpos($req, '://');
       $this->_protocol = strtolower(substr($req, 0, $pos));
      
       $req = substr($req, $pos+3);
       $pos = strpos($req, '/');
       if($pos === false)
           $pos = strlen($req);
       $host = substr($req, 0, $pos);
      
       if(strpos($host, ':') !== false)
       {
           list($this->_host, $this->_port) = explode(':', $host);
       }
       else
       {
           $this->_host = $host;
           $this->_port = ($this->_protocol == 'https') ? 443 : 80;
       }
      
       $this->_uri = substr($req, $pos);
       if($this->_uri == '')
           $this->_uri = '/';
   }

function cleanDomain($q,$w=0){ //整理域名 $w=1过滤www.前缀 $w=0不过滤
 $q = htmlspecialchars(strtolower(trim($q)));
 if(substr($q,0,7) == "http://" || substr($q,0,8) == "https://" || substr($q,0,6) == "ftp://"){
  $q = str_replace("http:/","",$q);
  $q = str_replace("https:/","",$q);
  $q = str_replace("ftp:/","",$q);
 }
 if(substr($q,0,4) == "www." && $w==1) {
  $q = str_replace("www.","",$q);
 }
 $q = trim($q,"/");
 return $q;
}