charset: Normalize charset

This pull request adds a cleanup util for bogus and invalid charsets, mostly
added by a nameless company out of Redmond, WA.

include/class.charset.php

+<?php
+/*********************************************************************
+    class.charset.php
+
+    Charset util class
+
+    Copyright (c) 2015 osTicket
+    http://www.osticket.com
+
+    Released under the GNU General Public License WITHOUT ANY WARRANTY.
+    See LICENSE.TXT for details.
+
+    vim: expandtab sw=4 ts=4 sts=4:
+**********************************************************************/
+
+class Charset {
+
+    // Cleanup invalid charsets
+    // Thanks in part to https://github.com/mikel/mail/commit/88457e
+    function normalize($charset) {
+
+        $match = array();
+        switch (true) {
+        // Windows charsets - force correct format
+        case preg_match('`^Windows-?(\d+)$`', $charset, $match):
+            return 'Windows-'.$match[1];
+        // ks_c_5601-1987: Korean alias for cp949
+        case preg_match('`^ks_c_5601-1987`', $charset):
+            return 'cp949';
+        // Incorrect, bogus, ambiguous or empty charsets
+        // ISO-8859-1 is assumed
+        case preg_match('`^(default|x-user-defined|iso|us-ascii)`', $charset):
+        case preg_match('`^\s*$`', $charset):
+            return 'ISO-8859-1';
+        }
+
+        // Hmmmm
+        return $charset;
+    }
+}
+?>

include/class.format.php

@@ -14,6 +14,7 @@
     vim: expandtab sw=4 ts=4 sts=4:
 **********************************************************************/
 
+include_once INCLUDE_DIR.'class.charset.php';
 
 class Format {
 
@@ -47,12 +48,8 @@ class Format {
         if (!$charset && function_exists('mb_detect_encoding'))
             $charset = mb_detect_encoding($text);
 
-        // Cleanup - incorrect, bogus, or ambiguous charsets
-        // ISO-8859-1 is assumed for empty charset.
-        if (!$charset || in_array(strtolower(trim($charset)),
-                array('default','x-user-defined','iso','us-ascii')))
-            $charset = 'ISO-8859-1';
-
+        // Normalize bogus or ambiguous charsets
+        $charset = Charset::normalize(trim($charset));
         $original = $text;
         if (function_exists('iconv'))
             $text = iconv($charset, $encoding.'//IGNORE', $text);