ECF Admin Panel Finder V1.2

<?php
echo '<title>ECF Admin Panel Finder</title>';
echo '<h1><center>ECF Admin Panel Finder</center></h1><br/>';
echo '<center>Enter Site Name<br/>Ex : http://sitename</center><br/><br/>';
function Search(){
    echo '<center><form action="" method="post"><input type="text" name="domain" value="">&nbsp&nbsp<input type="submit" name="search" value="Search">';
}
if(isset($_POST['search'])){
    $domain = $_POST['domain'];
    Search();
    if(!empty($domain)){
        $file = fopen("admin.txt", "r");
        echo '<br/><br/>';
        while(! feof($file)){
            $part = fgets($file);
            $link = $domain.$part;
            $res = get_headers($link);
            strtok($res[0]," ");
            $res = strtok(" ");
            if($res==200) echo '<a href="'.$link.'" target="_blank">'.$link.'</a><br/>';
        }
        fclose($file);
    }

}
else Search();
?>