Creating Rss Page for our site using our Content

Creating Rss Page for our site using our Content:

function rssfeed() {
  global $base_url;
  $sp_name = arg(2); //(your content node id)
  $node_names = node_get_types('names'); //(your content type name)
  $title_name = $node_names[$sp_name] != '' ? $node_names[$sp_name] : $sp_name; 
  $query = "SELECT n.nid, n.type, n.title, nr.body, n.changed
    FROM {node} n
    JOIN {node_revisions} nr ON nr.nid = n.nid
    WHERE n.type = '%s'"; //(contents for the rss)
  $result = db_query($query, $sp_name);
//[ Creating Structure for rss Page ]
  header("Content-Type: application/rss+xml; charset=iso-8859-1");
  $rssfeed = '<rss version="2.0"> 
    <channel>
      <title>' . $title_name . '</title>';
  while($row = db_fetch_array($result)) {
    $nid = $row['nid'];
    $src = 'node/'.$nid;
    $url_alias = drupal_get_path_alias($src);
    extract($row);
    //encode description
    //$contenttitle = utf8_decode($title);
    //$contenttitle = str_replace('', '&trade;', $contenttitle);
    $contenttitle = html_entity_decode($title, ENT_QUOTES, "UTF-8");
    //$contenttitle = str_replace(array('&' , '®'), array('&amp;' , '&reg;'), $contenttitle);
    //encode description
    $contentdesc = html_entity_decode(strip_tags($body), ENT_QUOTES, "UTF-8");
   // $contentdesc = str_replace('&', '&amp;', $contentdesc);
    //Designing Each Rss
    $url = $base_url . '/'.$url_alias;
    $rssfeed .= '
      <item>
        <title>' .($contenttitle) . '</title>
        <description>' . check_plain($contentdesc)  . '</description>
        <link>' . $url . '</link>
        <pubDate>' . date("D, d M Y H:i:s O", $changed) . '</pubDate>
      </item>';
  }
  $rssfeed .= '
    </channel>
  </rss>';
  echo $rssfeed; //[Returning the rss structure]
}