Use hash_equals in password.php (and move it to funcs.php)

Signed-off-by: Mcat12 <newtoncat12@yahoo.com>

scripts/pi-hole/php/func.php

@@ -25,4 +25,24 @@ function checkfile($filename) {
     }
 }
 
+// Credit: http://php.net/manual/en/function.hash-equals.php#119576
+if(!function_exists('hash_equals')) {
+    function hash_equals($known_string, $user_string) {
+        $ret = 0;
+
+        if (strlen($known_string) !== strlen($user_string)) {
+         $user_string = $known_string;
+         $ret = 1;
+        }
+
+        $res = $known_string ^ $user_string;
+
+        for ($i = strlen($res) - 1; $i >= 0; --$i) {
+         $ret |= ord($res[$i]);
+        }
+
+        return !$ret;
+   }
+}
+
 ?>