php域验证

Question

我在面对两个问题时需要帮助。

1. 不存在域扩展名的链接（.com，.net，ect）将存储在 数据库为单词

2. 脚本允许自我缩短较短的网址，这是一个主要的 问题。

我怎么能

1. 检查域扩展名，否则提交失败

   和

2. 检查用户是否正在尝试缩短我自己的链接并失败。

我的代码：

function remove_http($url) 
{
  $disallowed = array('http://', 'https://', 'http//', 'https//');
  foreach($disallowed as $d) {
    if(strpos($url, $d) === 0) {
     return str_replace($d, '', $url);
     }
  }
  return $url;
}

$url_to_shorten = get_magic_quotes_gpc() ? stripslashes(trim($_REQUEST['url'])) : trim($_REQUEST['url']);

if(!empty($url_to_shorten) || parse_url($url_to_shorten, PHP_URL_SCHEME) )
{
    require('framework/core/config.xml.php');

    // check if the URL has already been shortened
    $already_shortened = mysql_result(mysql_query('SELECT id FROM ' . DB_TABLE. ' WHERE long_url="' . mysql_real_escape_string(remove_http($url_to_shorten)) . '"'), 0);
    if(!empty($already_shortened))
    {
        // URL has already been shortened
        $shortened_url = getShortenedURLFromID($already_shortened);
    }
    else
    {
        // URL not in database, insert
        mysql_query('LOCK TABLES ' . DB_TABLE . ' WRITE;');
        mysql_query('INSERT INTO ' . DB_TABLE . ' (long_url, created, creator) VALUES ("' . mysql_real_escape_string(remove_http($url_to_shorten)) . '", "' . time() . '", "' . mysql_real_escape_string($_SERVER['REMOTE_ADDR']) . '")');
        $shortened_url = getShortenedURLFromID(mysql_insert_id());
        mysql_query('UNLOCK TABLES');
    }
    echo BASE_HREF . $shortened_url;
}


function getShortenedURLFromID ($integer, $base = ALLOWED_CHARS)
{
   $length = strlen($base);
   while($integer > $length - 1)
   {
    $out = $base[fmod($integer, $length)] . $out;
    $integer = floor( $integer / $length );
   }
   return $base[$integer] . $out;
}