PHP uppercase to lowercase rewrite optimization?

Question

I am using this PHP code to redirect any form of UPPERCASE in URI's to lowercase. There are three exceptions: if the URI includes either "adminpanel" or "search" there is no redirect, also if it already is lowercase there is no redirect

Do you see any way to improve the function in PHP?

$trailed = $_SERVER['REQUEST_URI'];
$pos1 = strpos($trailed,"adminpanel");
$pos2 = strpos($trailed,"search");
if ($pos1 === false && $pos2 === false && strlen($trailed) !== strlen(preg_replace('/[A-Z]/', '',     $trailed))) {
    $trailed = strtolower($trailed);
    header('HTTP/1.1 301 Moved Permanently'); 
    header('Location: http://'. $_SERVER["SERVER_NAME"] . $trailed);
    exit;
}

Answer 1

I think this will fail to redirect in the case that a URI has mixed case. Is this intended? Also, might using string comparison of $trailed and strtolower($trailed) be less verbose than using a regular expression in the third clause of the if statement on line 4?

Answer 2

Instead of comparing the original string and the result of preg_replace() you could let preg_match() test, if there is an upper case letter in the string.

if ( preg_match('/[[:upper:]]/', $_SERVER['REQUEST_URI']) ) {
  if ( false===stripos($trailed, 'adminpanel') && false===stripos($trailed, 'search') {
    // strotolower
    // ...
  }
}

(This might not be relevant now but as a side note: pcre has some unicode support. Instead of [:upper:] you'd use \p{Lu} to test for unicode upper case letters, see http://www.pcre.org/pcre.txt)

Answer 3

$trailed = $_SERVER['REQUEST_URI'];
if (!strpos($trailed,"admin") && !strpos($trailed,"search") && preg_match('/[[:upper:]]/', $trailed)) {
  $trailed = strtolower($trailed);
  header('HTTP/1.1 301 Moved Permanently'); 
  header('Location: http://'. $_SERVER["SERVER_NAME"] . $trailed);
  exit;
}

Taking a combined approach this code is about 140% faster than the first one. Only one if statement with the strpos inside and a preg_match instead of string length comparison.

Sorry I don't have the reputation yet to vote up the answers that lead to the final version and thank you very much for your help :)