Remove use of unreliable charset detection (#8344)

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Update to jQuery-UI 1.13.1 (#8455)
 - Use navigator.pdfViewerEnabled for PDF viewer detection
+- Remove use of unreliable charset detection (#8344)
 - Password: Add support for ssha256 algorithm (#8459)
 - Fix slow loading of long HTML content into the HTML editor (#8108)
 - Fix bug where SMTP password didn't work if it contained '%p' (#8435)

program/lib/Roundcube/rcube_charset.php

@@ -348,6 +348,46 @@ class rcube_charset
         return $str;
     }
 
+    /**
+     * Check if the specified input string matches one of the provided charsets.
+     * This includes UTF-32, UTF-16, RCUBE_CHARSET and default_charset.
+     *
+     * @param string $str  Input string
+     * @param array  $from Suspected charsets of the input string
+     *
+     * @return string|null First matching charset
+     */
+    public static function check($str, $charsets = [])
+    {
+        $chunk = strlen($str) > 100 * 1024 ? substr($str, 0, 100 * 1024) : $str;
+
+        // Add dehault charset, system charset and easily detectable charset to the list
+        if (substr($chunk, 0, 4) == "\0\0\xFE\xFF") $charsets[] = 'UTF-32BE';
+        if (substr($chunk, 0, 4) == "\xFF\xFE\0\0") $charsets[] = 'UTF-32LE';
+        if (substr($chunk, 0, 2) == "\xFE\xFF")     $charsets[] = 'UTF-16BE';
+        if (substr($chunk, 0, 2) == "\xFF\xFE")     $charsets[] = 'UTF-16LE';
+
+        // heuristics
+        if (preg_match('/\x00\x00\x00[^\x00]/', $chunk))    $charsets[] = 'UTF-32BE';
+        if (preg_match('/[^\x00]\x00\x00\x00/', $chunk))    $charsets[] = 'UTF-32LE';
+        if (preg_match('/\x00[^\x00]\x00[^\x00]/', $chunk)) $charsets[] = 'UTF-16BE';
+        if (preg_match('/[^\x00]\x00[^\x00]\x00/', $chunk)) $charsets[] = 'UTF-16LE';
+
+        $charsets[] = RCUBE_CHARSET;
+        $charsets[] = (string) rcube::get_instance()->config->get('default_charset');
+
+        $charsets = array_map(['rcube_charset', 'parse_charset'], $charsets);
+        $charsets = array_unique(array_filter($charsets));
+
+        foreach ($charsets as $charset) {
+            $ret = self::convert($chunk, $charset);
+
+            if ($ret === rcube_charset::clean($ret)) {
+                return $charset;
+            }
+        }
+    }
+
     /**
      * Converts string from standard UTF-7 (RFC 2152) to UTF-8.
      *
@@ -415,6 +455,7 @@ class rcube_charset
      * @param string $language User language
      *
      * @return string Charset name
+     * @deprecated
      */
     public static function detect($string, $failover = null, $language = null)
     {

program/lib/Roundcube/rcube_csv2vcard.php

@@ -420,12 +420,12 @@ class rcube_csv2vcard
      */
     public function import($csv, $dry_run = false, $skip_head = true)
     {
-        // convert to UTF-8
-        $head      = substr($csv, 0, 4096);
-        $charset   = rcube_charset::detect($head, RCUBE_CHARSET);
-        $csv       = rcube_charset::convert($csv, $charset);
-        $csv       = preg_replace(['/^[\xFE\xFF]{2}/', '/^\xEF\xBB\xBF/', '/^\x00+/'], '', $csv); // also remove BOM
-        $head      = '';
+        // convert to UTF-8 (supports default_charset and RCUBE_CHARSET as input)
+        // TODO: If the input charset is invalid we should probably just abort here
+        if ($charset = rcube_charset::check($csv)) {
+            $csv = rcube_charset::convert($csv, $charset);
+        }
+        $csv = preg_replace(['/^[\xFE\xFF]{2}/', '/^\xEF\xBB\xBF/', '/^\x00+/'], '', $csv); // also remove BOM
 
         // Split CSV file into lines
         $lines = rcube_utils::explode_quoted_string('[\r\n]+', $csv);

program/lib/Roundcube/rcube_imap.php

@@ -2362,7 +2362,7 @@ class rcube_imap extends rcube_storage
                 $charset = $this->struct_charset;
             }
             else {
-                $charset = rcube_charset::detect($filename_mime, $this->default_charset);
+                $charset = $this->default_charset;
             }
 
             $part->filename = rcube_mime::decode_mime_string($filename_mime, $charset);

program/lib/Roundcube/rcube_message.php

@@ -1223,21 +1223,9 @@ class rcube_message
             $charsets[] = $this->headers->charset;
         }
 
-        if (empty($charsets)) {
-            $rcube      = rcube::get_instance();
-            $charsets[] = rcube_charset::detect($name, $rcube->config->get('default_charset', RCUBE_CHARSET));
-        }
-
-        foreach (array_unique($charsets) as $charset) {
-            $_name = rcube_charset::convert($name, $charset);
-
-            if ($_name == rcube_charset::clean($_name)) {
-                if (!$part->charset) {
-                    $part->charset = $charset;
-                }
-
-                return $_name;
-            }
+        if ($charset = rcube_charset::check($name, $charsets)) {
+            $name = rcube_charset::convert($name, $charset);
+            $part->charset = $charset;
         }
 
         return $name;

program/lib/Roundcube/rcube_vcard.php

@@ -994,21 +994,6 @@ class rcube_vcard
      */
     private static function detect_encoding($string)
     {
-        // Detect common encodings
-        if (substr($string, 0, 4) == "\0\0\xFE\xFF") return 'UTF-32BE';  // Big Endian
-        if (substr($string, 0, 4) == "\xFF\xFE\0\0") return 'UTF-32LE';  // Little Endian
-        if (substr($string, 0, 2) == "\xFE\xFF")     return 'UTF-16BE';  // Big Endian
-        if (substr($string, 0, 2) == "\xFF\xFE")     return 'UTF-16LE';  // Little Endian
-        if (substr($string, 0, 3) == "\xEF\xBB\xBF") return 'UTF-8';
-
-        // heuristics
-        if (strlen($string) >= 4) {
-            if ($string[0] == "\0" && $string[1] == "\0" && $string[2] == "\0" && $string[3] != "\0") return 'UTF-32BE';
-            if ($string[0] != "\0" && $string[1] == "\0" && $string[2] == "\0" && $string[3] == "\0") return 'UTF-32LE';
-            if ($string[0] == "\0" && $string[1] != "\0" && $string[2] == "\0" && $string[3] != "\0") return 'UTF-16BE';
-            if ($string[0] != "\0" && $string[1] == "\0" && $string[2] != "\0" && $string[3] == "\0") return 'UTF-16LE';
-        }
-
         // Extract the plain text from the vCard, so the detection is more accurate
         // This will for example exclude photos
 
@@ -1024,6 +1009,9 @@ class rcube_vcard
 
             $prefix = substr($lines[$i], 0, $pos);
 
+            // We remove \0 as so it works with UTF-16/UTF-32 encodings
+            $prefix = str_replace("\0", '', $prefix);
+
             // Take only properties that are known to contain human-readable text
             if (!preg_match('/^(item\d+\.)?(N|FN|ORG|ADR|NOTE|TITLE|CATEGORIES)(;|$)/', $prefix)) {
                 continue;
@@ -1060,10 +1048,13 @@ class rcube_vcard
             }
 
             $string .= $data . ' ';
-        }
 
-        $fallback = rcube::get_instance()->config->get('default_charset', 'ISO-8859-1'); // fallback to Latin-1
+            // 100 KB should be enough for charset check
+            if (strlen($string) > 100 * 1024) {
+                break;
+            }
+        }
 
-        return rcube_charset::detect($string, $fallback);
+        return rcube_charset::check($string) ?: RCUBE_CHARSET;
     }
 }