title: $_SERVER['HTTP_HOST'] shows only domain name without www
body: <p>Even if in url i write "www.", $_SERVER['HTTP_HOST'] have only domain.com without "www."</p>
  
  <p>I can't redirect from non-www to www because of this. How to fix this issue?</p>
  
  <pre><code>      ["HTTP_HOST"]=&gt;
        string(8) "ca-fi.ru"
        ["HTTP_COOKIE"]=&gt;
        string(120) "d7b6b86aae18e551749a9da9d54f3daf=floar2lr37318dc76ask49bii5; 849c6485c12558d081c065b4d94a566b=d9iqj8s6oqo41kipg3qaefq497"
        ["HTTP_USER_AGENT"]=&gt;
        string(99) "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.52 Safari/536.5"
  
        ["PATH"]=&gt;
        string(28) "/usr/local/bin:/usr/bin:/bin"
        ["SERVER_SIGNATURE"]=&gt;
        string(69) "
      Apache/2.2.20 (Ubuntu) Server at ca-fi.ru Port 80
  
      "
        ["SERVER_SOFTWARE"]=&gt;
        string(22) "Apache/2.2.20 (Ubuntu)"
        ["SERVER_NAME"]=&gt;
        string(8) "ca-fi.ru"
        ["SERVER_ADDR"]=&gt;
        string(13) "192.168.10.12"
        ["SERVER_PORT"]=&gt;
        string(2) "80"
        ["REMOTE_ADDR"]=&gt;
        string(12) "192.168.10.1"
        ["DOCUMENT_ROOT"]=&gt;
        string(8) "/var/www"
  
        ["REQUEST_METHOD"]=&gt;
        string(3) "GET"
  
        ["REQUEST_URI"]=&gt;
        string(1) "/"
        ["SCRIPT_NAME"]=&gt;
        string(10) "/index.php"
        ["PHP_SELF"]=&gt;
        string(10) "/index.php"
        ["REQUEST_TIME"]=&gt;
        int(1338819407)
  </code></pre>