Issue barbushin#339 Custom utf7 decoder - returns original string as …

…described in description

src/PhpImap/Mailbox.php

@@ -510,13 +510,90 @@ public function encodeStringToUtf7Imap(string $str): string
  */
  public function decodeStringFromUtf7ImapToUtf8(string $str): string
  {
- $out = imap_utf7_decode($str);
+ $index_64 = array(
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, 63, -1, -1, -1,
+ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
+ -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
+ 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
+ -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
+ 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1
+ );
+
+ $u7len = strlen($str);
+ $p = '';
+ $err = $str;
+
+ for ($i = 0; $u7len > 0; $i++, $u7len--) {
+ $u7 = $str[$i];
+ if ($u7 === '&') {
+ $i++;
+ $u7len--;
+ $u7 = $str[$i] ?? '';
+
+ if ($u7len && $u7 === '-') {
+ $p .= '&';
+ continue;
+ }
+
+ $ch = 0;
+ $k = 10;
+ for (; $u7len > 0; $i++, $u7len--) {
+ $u7 = $str[$i];
+
+ if ((ord($u7) & 0x80) || ($b = $index_64[ord($u7)]) === -1) {
+ break;
+ }
+
+ if ($k > 0) {
+ $ch |= $b << $k;
+ $k -= 6;
+ } else {
+ $ch |= $b >> (-$k);
+ if ($ch < 0x80) {
+ /* Printable US-ASCII */
+ if (0x20 <= $ch && $ch < 0x7f) {
+ return $err;
+ }
+ $p .= chr($ch);
+ } else if ($ch < 0x800) {
+ $p .= chr(0xc0 | ($ch >> 6));
+ $p .= chr(0x80 | ($ch & 0x3f));
+ } else {
+ $p .= chr(0xe0 | ($ch >> 12));
+ $p .= chr(0x80 | (($ch >> 6) & 0x3f));
+ $p .= chr(0x80 | ($ch & 0x3f));
+ }
+
+ $ch = ($b << (16 + $k)) & 0xffff;
+ $k += 10;
+ }
+ }
+
+ /* Non-zero or too many extra bits */
+ if ($ch || $k < 6) {
+ return $err;
+ }
+
+ /* BASE64 not properly terminated */
+ if (!$u7len || $u7 !== '-') {
+ return $err;
+ }
 
- if (!\is_string($out)) {
- throw new UnexpectedValueException('mb_convert_encoding($str, \'UTF-8\', \'UTF7-IMAP\') could not convert $str');
+ /* Adjacent BASE64 sections */
+ if ($u7len > 2 && $str[$i + 1] === '&' && $str[$i + 2] !== '-') {
+ return $err;
+ }
+ } else if (ord($u7) < 0x20 || ord($u7) >= 0x7f) {
+ /* Not printable US-ASCII */
+ return $err;
+ } else {
+ $p .= $u7;
+ }
  }
 
- return $out;
+ return str_replace(array('\\\\', '\"'), array('\\', '"'), $p);
  }
 
  /**