<?php

/**
 * functions/imap_utf7_local.php - utf7-imap functions
 *
 * This implements all functions that do imap UTF7 conversions.
 * Before 1.3.2 functions were stored in imap_utf7_decode_local.php and
 * imap_utf7_encode_local.php files.
 *
 * @copyright 1999-2026 The SquirrelMail Project Team
 * @license http://opensource.org/licenses/gpl-license.php GNU Public License
 * @version $Id: imap_utf7_local.php 15046 2026-01-15 10:59:16Z pdontthink $
 * @package squirrelmail
 * @subpackage imap
 * @since 1.3.2
 */

/**
 * Function that uses php mbstring functions to convert from and to utf7-imap charset
 *
 * Since 1.5.1 list of supported charsets depends sq_mb_list_encoding function.
 * Before that it was hardcoded to iso-8859-x, utf-8 and iso-2022-jp.
 * @param string $str folder name
 * @param string $to_encoding name of resulting charset
 * @param string $from_encoding name of original charset
 * @param string $default_charset default charset used by translation.
 * @return string encoded folder name or ''
 * @since 1.4.2
 */
function sqimap_mb_convert_encoding($str, $to_encoding, $from_encoding, $default_charset) {
    $supported_encodings=sq_mb_list_encodings();
    if ( in_array(strtolower($default_charset),$supported_encodings) &&
         function_exists('mb_convert_encoding')) {
        return mb_convert_encoding($str, $to_encoding, $from_encoding);
    }
    return '';
}

/**
 * encode folder name to utf7-imap
 *
 * If mbstring functions do not support charset used by translation, falls back to iso-8859-1
 * @param string $s folder name
 * @return string utf7-imap encoded folder name
 * @since 1.2.7
 */
function imap_utf7_encode_local($s) {
    global $languages, $squirrelmail_language;

    if (isset($languages[$squirrelmail_language]['XTRA_CODE']) &&
            function_exists($languages[$squirrelmail_language]['XTRA_CODE'].'_utf7_imap_encode')) {
        return call_user_func($languages[$squirrelmail_language]['XTRA_CODE'] . '_utf7_imap_encode', $s);
    }

    if ($s == '')    //If empty, don't bother
        return '';

    global $default_charset;
    set_my_charset();    //must be called before using $default_charset
    if ((strtolower($default_charset) != 'iso-8859-1') && ($default_charset != '')) {
        $utf7_s = sqimap_mb_convert_encoding($s, 'UTF7-IMAP', $default_charset, $default_charset);
        if ($utf7_s != '')
            return $utf7_s;
    }

    // Later code works only for ISO-8859-1

    $b64_s = '';     // buffer for substring to be base64-encoded
    $utf7_s = '';    // imap-utf7-encoded string
    for ($i = 0; $i < strlen($s); $i++) {
        $c = $s[$i];
        $ord_c = ord($c);
        if ((($ord_c >= 0x20) and ($ord_c <= 0x25)) or
                (($ord_c >= 0x27) and ($ord_c <= 0x7e))) {
            if ($b64_s) {
                $utf7_s = $utf7_s . '&' . encodeBASE64($b64_s) .'-';
                $b64_s = '';
            }
            $utf7_s = $utf7_s . $c;
        } elseif ($ord_c == 0x26) {
            if ($b64_s) {
                $utf7_s = $utf7_s . '&' . encodeBASE64($b64_s) . '-';
                $b64_s = '';
            }
            $utf7_s = $utf7_s . '&-';
        } else {
            $b64_s = $b64_s . chr(0) . $c;
        }
    }
    //
    // flush buffer
    //
    if ($b64_s) {
        $utf7_s = $utf7_s . '&' . encodeBASE64($b64_s) . '-';
        $b64_s = '';
    }
    return $utf7_s;
}

/**
 * converts folder name from utf7-imap to charset used by translation
 *
 * If mbstring functions do not support charset used by translation, falls back to iso-8859-1
 * @param string $s folder name in utf7-imap
 * @return string folder name in charset used by translation
 * @since 1.2.7
 */
function imap_utf7_decode_local($s) {
    global $languages, $squirrelmail_language;

    if (isset($languages[$squirrelmail_language]['XTRA_CODE']) &&
            function_exists($languages[$squirrelmail_language]['XTRA_CODE'] . '_utf7_imap_decode')) {
        return call_user_func($languages[$squirrelmail_language]['XTRA_CODE'] . '_utf7_imap_decode', $s);
    }

    if ($s == '')    //If empty, don't bother
        return '';

    global $default_charset;
    set_my_charset();    //must be called before using $default_charset
    if ((strtolower($default_charset) != 'iso-8859-1') && ($default_charset != '')) {
        $utf7_s = sqimap_mb_convert_encoding($s, $default_charset, 'UTF7-IMAP', $default_charset);
        if ($utf7_s != '')
            return $utf7_s;
    }

    // Later code works only for ISO-8859-1

    $b64_s = '';
    $iso_8859_1_s = '';
    for ($i = 0, $len = strlen($s); $i < $len; $i++) {
        $c = $s[$i];
        if (strlen($b64_s) > 0) {
            if ($c == '-') {
                if ($b64_s == '&') {
                    $iso_8859_1_s = $iso_8859_1_s . '&';
                } else {
                    $iso_8859_1_s = $iso_8859_1_s .
                        decodeBASE64(substr($b64_s, 1));
                }
                $b64_s = '';
            } else {
                $b64_s = $b64_s . $c;
            }
        } else {
            if ($c == '&') {
                $b64_s = '&';
            } else {
                $iso_8859_1_s = $iso_8859_1_s . $c;
            }
        }
    }
    return $iso_8859_1_s;
}
/**
 * Converts string to base64
 * @param string $s string
 * @return string base64 encoded string
 * @since 1.2.7
 */
function encodeBASE64($s) {
    $B64Chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,';
    $p = 0;     // phase: 1 / 2 / 3 / 1 / 2 / 3...
    $e = '';    // base64-encoded string
    //foreach($s as $c) {
    for ($i = 0; $i < strlen($s); $i++) {
        $c = $s[$i];
        if ($p == 0) {
            $e = $e . substr($B64Chars, ((ord($c) & 252) >> 2), 1);
            $t = (ord($c) & 3);
            $p = 1;
        } elseif ($p == 1) {
            $e = $e . $B64Chars[($t << 4) + ((ord($c) & 240) >> 4)];
            $t = (ord($c) & 15);
            $p = 2;
        } elseif ($p == 2) {
            $e = $e . $B64Chars[($t << 2) + ((ord($c) & 192) >> 6)];
            $e = $e . $B64Chars[ord($c) & 63];
            $p = 0;
        }
    }
    //
    // flush buffer
    //
    if ($p == 1) {
        $e = $e . $B64Chars[$t << 4];
    } elseif ($p == 2) {
        $e = $e . $B64Chars[$t << 2];
    }
    return $e;
}

/**
 * Converts string from base64
 * @param string $s base64 encoded string
 * @return string decoded string
 * @since 1.2.7
 */
function decodeBASE64($s) {
    $B64Values = array(
            'A' =>  0, 'B' =>  1, 'C' =>  2, 'D' =>  3, 'E' =>  4, 'F' =>  5,
            'G' =>  6, 'H' =>  7, 'I' =>  8, 'J' =>  9, 'K' => 10, 'L' => 11,
            'M' => 12, 'N' => 13, 'O' => 14, 'P' => 15, 'Q' => 16, 'R' => 17,
            'S' => 18, 'T' => 19, 'U' => 20, 'V' => 21, 'W' => 22, 'X' => 23,
            'Y' => 24, 'Z' => 25,
            'a' => 26, 'b' => 27, 'c' => 28, 'd' => 29, 'e' => 30, 'f' => 31,
            'g' => 32, 'h' => 33, 'i' => 34, 'j' => 35, 'k' => 36, 'l' => 37,
            'm' => 38, 'n' => 39, 'o' => 40, 'p' => 41, 'q' => 42, 'r' => 43,
            's' => 44, 't' => 45, 'u' => 46, 'v' => 47, 'w' => 48, 'x' => 49,
            'y' => 50, 'z' => 51,
            '0' => 52, '1' => 53, '2' => 54, '3' => 55, '4' => 56, '5' => 57,
            '6' => 58, '7' => 59, '8' => 60, '9' => 61, '+' => 62, ',' => 63
            );
    $p = 0;
    $d = '';
    $unicodeNullByteToggle = 0;
    for ($i = 0, $len = strlen($s); $i < $len; $i++) {
        $c = $s[$i];
        if ($p == 0) {
            $t = $B64Values[$c];
            $p = 1;
        } elseif ($p == 1) {
            if ($unicodeNullByteToggle) {
                $d = $d . chr(($t << 2) + (($B64Values[$c] & 48) >> 4));
                $unicodeNullByteToggle = 0;
            } else {
                $unicodeNullByteToggle = 1;
            }
            $t = ($B64Values[$c] & 15);
            $p = 2;
        } elseif ($p == 2) {
            if ($unicodeNullByteToggle) {
                $d = $d . chr(($t << 4) + (($B64Values[$c] & 60) >> 2));
                $unicodeNullByteToggle = 0;
            } else {
                $unicodeNullByteToggle = 1;
            }
            $t = ($B64Values[$c] & 3);
            $p = 3;
        } elseif ($p == 3) {
            if ($unicodeNullByteToggle) {
                $d = $d . chr(($t << 6) + $B64Values[$c]);
                $unicodeNullByteToggle = 0;
            } else {
                $unicodeNullByteToggle = 1;
            }
            $t = ($B64Values[$c] & 3);
            $p = 0;
        }
    }
    return $d;
}
