WP stripping out code

Hi

I am using some php in my functions.php with a form on another page which creates posts on my wordpress site, when using this php form on a non-wordpress site without the post creation feature, it functions perfectly however when using on my wordpress site it appears to strip out the site name in the [tab:sitename] and just leaves [tab:].

Any ideas?

This is the code for functions.php:

$formatted = "";
$groups = array();
$first = true;

if(isset($_POST["input"]))
{
  $iframes = split("\n", $_POST["input"]);
  foreach($iframes as $iframe)
  {
    $iframe = trim($iframe);

    if($iframe == "")
    {
      continue;
    }

    if(stripos($iframe, "iframe") === false)
    {
      if(!$first)
      {
        $formatted .= "[tab:END]\n";
        array_push($groups, $formatted);
        $formatted = "";
      }

      $formatted .= $iframe . "\n";
      $first = false;

      continue;
    }

    preg_match_all('/src="([^"]*)"/i', $iframe, $matches);
    $site_name = $matches[1][0];
    $site_name = parse_url($site_name);
    $site_name = $site_name["host"];
    $site_name = split("\.", $site_name);
    $site_name = $site_name[0] == "www" ? $site_name[1] : $site_name[0];

    $formatted .= "[tab:" . $site_name . "]";
    $formatted .= $iframe;
    $formatted .= "\n";
  }
  $formatted .= "[tab:END]\n";
  array_push($groups, $formatted);

  foreach($groups as $group)
  {
    $title = split("\n", $group);
    $title = $title[0];
    $title = split("/", $title);
    $title = ucwords(str_replace("-", " ", $title[3]));

    $post = array(
      "post_content" => $group,
      "post_title" => $title,
      "post_status" => "publish",
      "filter" => true
    );

    wp_insert_post($post, $wp_error);
  }
}