Question

Here we go again, I need some help with this.
the preg_match is not working as I want it, it is not validating any of site links. I need a 2nd pair of eyes to help me see what is wrong with my code.

if (!empty($_POST["url"]))
      {
          if (filter_var($_POST["url"], FILTER_VALIDATE_URL))
          {
              if (!preg_match('/^http(s)?:\/\/(?:[a-z\d-]+\.)*mysite.com(?:(?=\/)|$)/i', $url))
              {
                echo "<strong>Error</strong>: Not a valid Mysite.com link or could shorten link";
              } else {
                  $result = $sql->query("SELECT `id` FROM `shortcuts` WHERE `url`='{$_POST["url"]}'");
                  $id = $result[0]["id"];
                  if (empty($id))
                  {
                      $result = $sql->query("INSERT INTO `shortcuts` (`url`) VALUES ('{$_POST["url"]}')");
                      if ($result)
                      {
                          $id = $sql->get_increment();
                          if (empty($id))
                          {
                              echo "FAILED ENCODE";
                              exit(1);
                          }
                      }
                      $shorturl = "http://mysite.com/".encode($id);
                  }
              }
          }
      }

Answer 1

Make yourself the code less complicated, so it is easier to debug. You are concerned about a specific problem here if I understood you right:

if (matches_shorturl_pattern($url) {
    // go on ...
}

Create yourself a function. Good thing about is, you can test it isolated without submitting something or hitting the database.

/**
 * is URL a valid shorturl by syntax?
 *
 * @param string $url
 * @return bool
 */
function matches_shorturl_pattern($url) {
    $pattern = '/^http(s)?:\/\/(?:[a-z\d-]+\.)*mysite.com(?:(?=\/)|$)/i';
    $result = preg_match($pattern, $url);
    if ($result === FALSE) {
        throw new Exception('The regex did a poop.');
    }
    return (bool) $result;
}

It’s much easier to test this function alone with the inputs you want to test it again. Also you’re properly checking for error conditions then. Good luck.