1 ;;; rfc2047.el --- functions for encoding and decoding rfc2047 messages
3 ;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007 Free Software Foundation, Inc.
6 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
7 ;; MORIOKA Tomohiko <morioka@jaist.ac.jp>
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software; you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation; either version 3, or (at your option)
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs; see the file COPYING. If not, write to the
22 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
23 ;; Boston, MA 02110-1301, USA.
27 ;; RFC 2047 is "MIME (Multipurpose Internet Mail Extensions) Part
28 ;; Three: Message Header Extensions for Non-ASCII Text".
34 (defvar message-posting-charset)
39 ;; Fixme: Avoid this (used for mail-parse-charset) mm dependence on gnus.
41 (require 'rfc2045) ;; rfc2045-encode-string
42 (autoload 'mm-body-7-or-8 "mm-bodies")
44 (defvar rfc2047-header-encoding-alist
45 '(("Newsgroups" . nil)
48 ("\\(Resent-\\)?\\(From\\|Cc\\|To\\|Bcc\\|\\(In-\\)?Reply-To\\|Sender\
49 \\|Mail-Followup-To\\|Mail-Copies-To\\|Approved\\)" . address-mime)
51 "*Header/encoding method alist.
52 The list is traversed sequentially. The keys can either be
57 1) nil, in which case no encoding is done;
58 2) `mime', in which case the header will be encoded according to RFC2047;
59 3) `address-mime', like `mime', but takes account of the rules for address
60 fields (where quoted strings and comments must be treated separately);
61 4) a charset, in which case it will be encoded as that charset;
62 5) `default', in which case the field will be encoded as the rest
65 (defvar rfc2047-charset-encoding-alist
89 "Alist of MIME charsets to RFC2047 encodings.
90 Valid encodings are nil, `Q' and `B'. These indicate binary (no) encoding,
91 quoted-printable and base64 respectively.")
93 (defvar rfc2047-encode-function-alist
94 '((Q . rfc2047-q-encode-string)
95 (B . rfc2047-b-encode-string)
97 "Alist of RFC2047 encodings to encoding functions.")
99 (defvar rfc2047-encode-encoded-words t
100 "Whether encoded words should be encoded again.")
102 (defvar rfc2047-allow-irregular-q-encoded-words t
103 "*Whether to decode irregular Q-encoded words.")
105 (eval-and-compile ;; Necessary to hard code them in `rfc2047-decode-region'.
106 (defconst rfc2047-encoded-word-regexp
107 "=\\?\\([^][\000-\040()<>@,\;:*\\\"/?.=]+\\)\\(?:\\*[^?]+\\)?\\?\
108 \\(B\\?[+/0-9A-Za-z]*=*\
111 "Regexp that matches encoded word."
112 ;; The patterns for the B encoding and the Q encoding, i.e. the ones
113 ;; beginning with "B" and "Q" respectively, are restricted into only
114 ;; the characters that those encodings may generally use.
116 (defconst rfc2047-encoded-word-regexp-loose
117 "=\\?\\([^][\000-\040()<>@,\;:*\\\"/?.=]+\\)\\(?:\\*[^?]+\\)?\\?\
118 \\(B\\?[+/0-9A-Za-z]*=*\
119 \\|Q\\?\\(?:\\?+[ -<>@-~]\\)?\\(?:[ ->@-~]+\\?+[ -<>@-~]\\)*[ ->@-~]*\\?*\
121 "Regexp that matches encoded word allowing loose Q encoding."
122 ;; The pattern for the Q encoding, i.e. the one beginning with "Q",
124 ;; "Q\\?\\(\\?+[^\n=?]\\)?\\([^\n?]+\\?+[^\n=?]\\)*[^\n?]*\\?*"
125 ;; <--------1-------><----------2,3----------><--4--><-5->
127 ;; 1. After "Q?", allow "?"s that follow a character other than "=".
128 ;; 2. Allow "=" after "Q?"; it isn't regarded as the terminator.
129 ;; 3. In the middle of an encoded word, allow "?"s that follow a
130 ;; character other than "=".
131 ;; 4. Allow any characters other than "?" in the middle of an
133 ;; 5. At the end, allow "?"s.
137 ;;; Functions for encoding RFC2047 messages
140 (defun rfc2047-qp-or-base64 ()
141 "Return the type with which to encode the buffer.
142 This is either `base64' or `quoted-printable'."
144 (let ((limit (min (point-max) (+ 2000 (point-min))))
146 (goto-char (point-min))
147 (skip-chars-forward "\x20-\x7f\r\n\t" limit)
148 (while (< (point) limit)
151 (skip-chars-forward "\x20-\x7f\r\n\t" limit))
152 (if (or (< (* 6 n8bit) (- limit (point-min)))
153 ;; Don't base64, say, a short line with a single
154 ;; non-ASCII char when splitting parts by charset.
159 (defun rfc2047-narrow-to-field ()
160 "Narrow the buffer to the header on the current line."
166 (if (re-search-forward "^[^ \n\t]" nil t)
169 (goto-char (point-min)))
171 (defun rfc2047-field-value ()
172 "Return the value of the field at point."
175 (rfc2047-narrow-to-field)
176 (re-search-forward ":[ \t\n]*" nil t)
177 (buffer-substring-no-properties (point) (point-max)))))
179 (defun rfc2047-quote-special-characters-in-quoted-strings (&optional
181 "Quote special characters with `\\'s in quoted strings.
182 Quoting will not be done in a quoted string if it contains characters
183 matching ENCODABLE-REGEXP or it is within parentheses."
184 (goto-char (point-min))
185 (let ((tspecials (concat "[" ietf-drums-tspecials "]"))
188 (with-syntax-table (standard-syntax-table)
192 (eq (char-before) ?\)))
194 (goto-char (point-max)))
196 (narrow-to-region start (point))
198 (while (search-forward "\"" nil t)
199 (setq beg (match-beginning 0))
200 (unless (eq (char-before beg) ?\\)
206 (setq end (1- (point)))
208 (if (and encodable-regexp
209 (re-search-forward encodable-regexp end t))
212 (narrow-to-region beg end)
213 (while (re-search-forward tspecials nil 'move)
214 (if (eq (char-before) ?\\)
215 (if (looking-at tspecials) ;; Already quoted.
218 (goto-char (match-beginning 0))
224 (goto-char (point-max)))
226 (setq start (point))))))
228 (defvar rfc2047-encoding-type 'address-mime
229 "The type of encoding done by `rfc2047-encode-region'.
230 This should be dynamically bound around calls to
231 `rfc2047-encode-region' to either `mime' or `address-mime'. See
232 `rfc2047-header-encoding-alist', for definitions.")
234 (defun rfc2047-encode-message-header ()
235 "Encode the message header according to `rfc2047-header-encoding-alist'.
236 Should be called narrowed to the head of the message."
239 (goto-char (point-min))
240 (let (alist elem method)
243 (rfc2047-narrow-to-field)
245 alist rfc2047-header-encoding-alist)
246 (while (setq elem (pop alist))
247 (when (or (and (stringp (car elem))
248 (looking-at (car elem)))
252 (if (not (rfc2047-encodable-p))
254 (when (eq method 'address-mime)
255 (rfc2047-quote-special-characters-in-quoted-strings))
256 (if (and (eq (mm-body-7-or-8) '8bit)
259 (car message-posting-charset)))
260 ;; 8 bit must be decoded.
261 (mm-encode-coding-region
262 (point-min) (point-max)
263 (mm-charset-to-coding-system
264 (car message-posting-charset))))
265 ;; No encoding necessary, but folding is nice
269 (goto-char (point-min))
270 (skip-chars-forward "^:")
271 (when (looking-at ": ")
275 ;; We found something that may perhaps be encoded.
276 (re-search-forward "^[^:]+: *" nil t)
278 ((eq method 'address-mime)
279 (rfc2047-encode-region (point) (point-max)))
281 (let ((rfc2047-encoding-type 'mime))
282 (rfc2047-encode-region (point) (point-max))))
283 ((eq method 'default)
284 (if (and (featurep 'mule)
285 (if (boundp 'default-enable-multibyte-characters)
286 default-enable-multibyte-characters)
288 (mm-encode-coding-region (point) (point-max)
289 mail-parse-charset)))
290 ;; We get this when CC'ing messsages to newsgroups with
291 ;; 8-bit names. The group name mail copy just got
292 ;; unconditionally encoded. Previously, it would ask
293 ;; whether to encode, which was quite confusing for the
294 ;; user. If the new behaviour is wrong, tell me. I have
295 ;; left the old code commented out below.
296 ;; -- Per Abrahamsen <abraham@dina.kvl.dk> Date: 2001-10-07.
297 ;; Modified by Dave Love, with the commented-out code changed
298 ;; in accordance with changes elsewhere.
300 (rfc2047-encode-region (point) (point-max)))
302 ;;; (if (or (message-options-get
303 ;;; 'rfc2047-encode-message-header-encode-any)
304 ;;; (message-options-set
305 ;;; 'rfc2047-encode-message-header-encode-any
307 ;;; "Some texts are not encoded. Encode anyway?")))
308 ;;; (rfc2047-encode-region (point-min) (point-max))
309 ;;; (error "Cannot send unencoded text")))
310 ((mm-coding-system-p method)
311 (if (or (and (featurep 'mule)
312 (if (boundp 'default-enable-multibyte-characters)
313 default-enable-multibyte-characters))
314 (featurep 'file-coding))
315 (mm-encode-coding-region (point) (point-max) method)))
318 (goto-char (point-max)))))))
320 ;; Fixme: This, and the require below may not be the Right Thing, but
321 ;; should be safe just before release. -- fx 2001-02-08
323 (defun rfc2047-encodable-p ()
324 "Return non-nil if any characters in current buffer need encoding in headers.
325 The buffer may be narrowed."
326 (require 'message) ; for message-posting-charset
328 (mm-find-mime-charset-region (point-min) (point-max))))
329 (goto-char (point-min))
330 (or (and rfc2047-encode-encoded-words
332 (re-search-forward rfc2047-encoded-word-regexp nil t)
333 (goto-char (point-min))))
335 (not (equal charsets (list (car message-posting-charset))))))))
337 ;; Use this syntax table when parsing into regions that may need
338 ;; encoding. Double quotes are string delimiters, backslash is
339 ;; character quoting, and all other RFC 2822 special characters are
340 ;; treated as punctuation so we can use forward-sexp/forward-word to
341 ;; skip to the end of regions appropriately. Nb. ietf-drums does
342 ;; things differently.
343 (defconst rfc2047-syntax-table
344 ;; (make-char-table 'syntax-table '(2)) only works in Emacs.
345 (let ((table (make-syntax-table)))
346 ;; The following is done to work for setting all elements of the table
347 ;; in Emacs 21 and 22 and XEmacs; it appears to be the cleanest way.
348 ;; Play safe and don't assume the form of the word syntax entry --
350 (if (fboundp 'set-char-table-range) ; Emacs
351 (funcall (intern "set-char-table-range")
352 table t (aref (standard-syntax-table) ?a))
353 (if (fboundp 'put-char-table)
354 (if (fboundp 'get-char-table) ; warning avoidance
355 (put-char-table t (get-char-table ?a (standard-syntax-table))
357 (modify-syntax-entry ?\\ "\\" table)
358 (modify-syntax-entry ?\" "\"" table)
359 (modify-syntax-entry ?\( "(" table)
360 (modify-syntax-entry ?\) ")" table)
361 (modify-syntax-entry ?\< "." table)
362 (modify-syntax-entry ?\> "." table)
363 (modify-syntax-entry ?\[ "." table)
364 (modify-syntax-entry ?\] "." table)
365 (modify-syntax-entry ?: "." table)
366 (modify-syntax-entry ?\; "." table)
367 (modify-syntax-entry ?, "." table)
368 (modify-syntax-entry ?@ "." table)
371 (defun rfc2047-encode-region (b e)
372 "Encode words in region B to E that need encoding.
373 By default, the region is treated as containing RFC2822 addresses.
374 Dynamically bind `rfc2047-encoding-type' to change that."
376 (narrow-to-region b e)
377 (let ((encodable-regexp (if rfc2047-encode-encoded-words
378 "[^\000-\177]+\\|=\\?"
380 start ; start of current token
382 ;; Whether there's an encoded word before the current token,
383 ;; either immediately or separated by space.
385 (orig-text (buffer-substring-no-properties b e)))
386 (if (eq 'mime rfc2047-encoding-type)
387 ;; Simple case. Continuous words in which all those contain
388 ;; non-ASCII characters are encoded collectively. Encoding
389 ;; ASCII words, including `Re:' used in Subject headers, is
390 ;; avoided for interoperability with non-MIME clients and
391 ;; for making it easy to find keywords.
393 (goto-char (point-min))
394 (while (progn (skip-chars-forward " \t\n")
397 (while (and (looking-at "[ \t\n]*\\([^ \t\n]+\\)")
399 (setq end (match-end 0))
400 (re-search-forward encodable-regexp end t)))
402 (if (> (point) start)
403 (rfc2047-encode start (point))
405 ;; `address-mime' case -- take care of quoted words, comments.
406 (rfc2047-quote-special-characters-in-quoted-strings encodable-regexp)
407 (with-syntax-table rfc2047-syntax-table
408 (goto-char (point-min))
409 (condition-case err ; in case of unbalanced quotes
410 ;; Look for rfc2822-style: sequences of atoms, quoted
411 ;; strings, specials, whitespace. (Specials mustn't be
415 (skip-chars-forward " \t\n")
418 ((not (char-after))) ; eob
420 ((eq ?\" (setq csyntax (char-syntax (char-after))))
424 ;; Does it need encoding?
426 (if (re-search-forward encodable-regexp end 'move)
427 ;; It needs encoding. Strip the quotes first,
428 ;; since encoded words can't occur in quotes.
431 (delete-backward-char 1)
435 ;; There was a preceding quoted word. We need
436 ;; to include any separating whitespace in this
437 ;; word to avoid it getting lost.
438 (skip-chars-backward " \t")
439 ;; A space is needed between the encoded words.
443 ;; Adjust the end position for the deleted quotes.
444 (rfc2047-encode start (- end 2))
445 (setq last-encoded t)) ; record that it was encoded
446 (setq last-encoded nil)))
448 ;; Skip other delimiters, but record that they've
449 ;; potentially separated quoted words.
451 (setq last-encoded nil))
453 (error "Unbalanced parentheses"))
455 ;; Look for the end of parentheses.
457 ;; Encode text as an unstructured field.
458 (let ((rfc2047-encoding-type 'mime))
459 (rfc2047-encode-region (1+ start) (1- (point))))
460 (skip-chars-forward ")"))
461 (t ; normal token/whitespace sequence
463 ;; Skip one ASCII word, or encode continuous words
464 ;; in which all those contain non-ASCII characters.
466 (while (not (or end (eobp)))
467 (when (looking-at "[\000-\177]+")
471 (while (and (or (re-search-forward
472 "[ \t\n]\\|\\Sw" end 'move)
474 (eq ?\\ (char-syntax (char-before))))
475 ;; Skip backslash-quoted characters.
478 (setq end (match-beginning 0))
479 (if rfc2047-encode-encoded-words
482 (when (search-forward "=?" end 'move)
483 (goto-char (match-beginning 0))
486 ;; Where the value nil of `end' means there may be
487 ;; text to have to be encoded following the point.
488 ;; Otherwise, the point reached to the end of ASCII
489 ;; words separated by whitespace or a special char.
491 (when (looking-at encodable-regexp)
492 (goto-char (setq begin (match-end 0)))
493 (while (and (looking-at "[ \t\n]+\\([^ \t\n]+\\)")
494 (setq end (match-end 0))
496 (while (re-search-forward
497 encodable-regexp end t))
500 (or (not (re-search-forward "\\Sw" end t))
502 (goto-char (match-beginning 0))
505 (when (looking-at "[^ \t\n]+")
506 (setq end (match-end 0))
507 (if (re-search-forward "\\Sw+" end t)
508 ;; There are special characters better
509 ;; to be encoded so that MTAs may parse
511 (cond ((= end (point)))
512 ((looking-at (concat "\\sw*\\("
517 (goto-char (1- (match-end 0)))
518 (unless (= (point) (match-beginning 0))
519 ;; Separate encodable text and
523 (skip-chars-forward " \t\n")
524 (if (and (looking-at "[^ \t\n]+")
525 (string-match encodable-regexp
528 (goto-char end)))))))
529 (skip-chars-backward " \t\n")
532 (if (re-search-forward encodable-regexp end 'move)
534 (unless (memq (char-before start) '(nil ?\t ? ))
537 (skip-chars-backward "^ \t\n")
538 (and (looking-at "\\Sw+")
539 (= (match-end 0) start)))
540 ;; Also encode bogus delimiters.
542 ;; Separate encodable text and delimiter.
545 (setq start (1+ start)
547 (rfc2047-encode start end)
548 (setq last-encoded t))
549 (setq last-encoded nil)))))
551 (if (or debug-on-quit debug-on-error)
552 (signal (car err) (cdr err))
553 (error "Invalid data for rfc2047 encoding: %s"
554 (mm-replace-in-string orig-text "[ \t\n]+" " "))))))))
555 (rfc2047-fold-region b (point))
556 (goto-char (point-max))))
558 (defun rfc2047-encode-string (string)
559 "Encode words in STRING.
560 By default, the string is treated as containing addresses (see
561 `rfc2047-encoding-type')."
562 (mm-with-multibyte-buffer
564 (rfc2047-encode-region (point-min) (point-max))
568 ;; 2. Syntax of encoded-words
570 ;; While there is no limit to the length of a multiple-line header
571 ;; field, each line of a header field that contains one or more
572 ;; 'encoded-word's is limited to 76 characters.
574 ;; In `rfc2047-encode-parameter' it is bound to nil, so don't defconst it.
575 (defvar rfc2047-encode-max-chars 76
576 "Maximum characters of each header line that contain encoded-words.
577 According to RFC 2047, it is 76. If it is nil, encoded-words
578 will not be folded. Too small value may cause an error. You
579 should not change this value.")
581 (defun rfc2047-encode-1 (column string cs encoder start crest tail
583 "Subroutine used by `rfc2047-encode'."
584 (cond ((string-equal string "")
586 ((not rfc2047-encode-max-chars)
588 (funcall encoder (if cs
589 (mm-encode-coding-string string cs)
592 ((>= column rfc2047-encode-max-chars)
594 (cond ((string-match "\n[ \t]+\\'" eword)
595 ;; Reomove a superfluous empty line.
596 (setq eword (substring eword 0 (match-beginning 0))))
597 ((string-match "(+\\'" eword)
598 ;; Break the line before the open parenthesis.
599 (setq crest (concat crest (match-string 0 eword))
600 eword (substring eword 0 (match-beginning 0))))))
601 (rfc2047-encode-1 (length crest) string cs encoder start " " tail
602 (concat eword "\n" crest)))
605 (limit (1- (length string)))
610 (setq next (concat start
613 (mm-encode-coding-string
614 (substring string 0 (1+ index))
616 (substring string 0 (1+ index))))
618 len (+ column (length next)))
619 (if (> len rfc2047-encode-max-chars)
622 (if (or (< index limit)
623 (<= (+ len (or (string-match "\n" tail)
625 rfc2047-encode-max-chars))
628 (if (string-match "\\`)+" tail)
629 ;; Break the line after the close parenthesis.
630 (setq tail (concat (substring tail 0 (match-end 0))
632 (substring tail (match-end 0)))
638 (concat eword next tail)
641 (string-match "(+\\'" eword))
642 (setq crest (concat crest (match-string 0 eword))
643 eword (substring eword 0 (match-beginning 0)))
644 (setq eword (concat eword next)))
646 eword (concat eword next)))
647 (when (string-match "\n[ \t]+\\'" eword)
648 ;; Reomove a superfluous empty line.
649 (setq eword (substring eword 0 (match-beginning 0))))
650 (rfc2047-encode-1 (length crest) (substring string index)
651 cs encoder start " " tail
652 (concat eword "\n" crest)))))))
654 (defun rfc2047-encode (b e)
655 "Encode the word(s) in the region B to E.
656 Point moves to the end of the region."
657 (let ((mime-charset (or (mm-find-mime-charset-region b e) (list 'us-ascii)))
658 cs encoding tail crest eword)
659 (cond ((> (length mime-charset) 1)
660 (error "Can't rfc2047-encode `%s'"
661 (buffer-substring-no-properties b e)))
662 ((= (length mime-charset) 1)
663 (setq mime-charset (car mime-charset)
664 cs (mm-charset-to-coding-system mime-charset))
665 (unless (and (mm-multibyte-p)
666 (mm-coding-system-p cs))
669 (narrow-to-region b e)
671 (or (cdr (assq mime-charset
672 rfc2047-charset-encoding-alist))
673 ;; For the charsets that don't have a preferred
674 ;; encoding, choose the one that's shorter.
675 (if (eq (rfc2047-qp-or-base64) 'base64)
680 (skip-chars-forward "^ \t\n")
681 ;; `tail' may contain a close parenthesis.
682 (setq tail (buffer-substring-no-properties e (point)))
684 (setq b (point-marker)
685 e (set-marker (make-marker) e))
686 (rfc2047-fold-region (point-at-bol) b)
688 (skip-chars-backward "^ \t\n")
689 (unless (= 0 (skip-chars-backward " \t"))
690 ;; `crest' may contain whitespace and an open parenthesis.
691 (setq crest (buffer-substring-no-properties (point) b)))
692 (setq eword (rfc2047-encode-1
694 (mm-replace-in-string
695 (buffer-substring-no-properties b e)
696 "\n\\([ \t]?\\)" "\\1")
698 (or (cdr (assq encoding
699 rfc2047-encode-function-alist))
701 (concat "=?" (downcase (symbol-name mime-charset))
702 "?" (upcase (symbol-name encoding)) "?")
705 (delete-region (if (eq (aref eword 0) ?\n)
707 ;; The line was folded before encoding.
712 ;; `eword' contains `crest' and `tail'.
716 (unless (or (/= 0 (length tail))
718 (looking-at "[ \t\n)]"))
723 (defun rfc2047-fold-field ()
724 "Fold the current header field."
727 (rfc2047-narrow-to-field)
728 (rfc2047-fold-region (point-min) (point-max)))))
730 (defun rfc2047-fold-region (b e)
731 "Fold long lines in region B to E."
733 (narrow-to-region b e)
734 (goto-char (point-min))
738 (bol (save-restriction
742 (when (and (or break qword-break)
743 (> (- (point) bol) 76))
744 (goto-char (or break qword-break))
747 (skip-chars-backward " \t")
748 (if (looking-at "[ \t]")
751 (setq bol (1- (point)))
752 ;; Don't break before the first non-LWSP characters.
753 (skip-chars-forward " \t")
757 ((eq (char-after) ?\n)
762 (skip-chars-forward " \t")
763 (unless (or (eobp) (eq (char-after) ?\n))
765 ((eq (char-after) ?\r)
767 ((memq (char-after) '(? ?\t))
768 (skip-chars-forward " \t")
769 (unless first ;; Don't break just after the header name.
770 (setq break (point))))
772 (if (not (looking-at "=\\?[^=]"))
773 (if (eq (char-after) ?=)
775 (skip-chars-forward "^ \t\n\r="))
776 ;; Don't break at the start of the field.
777 (unless (= (point) b)
778 (setq qword-break (point)))
779 (skip-chars-forward "^ \t\n\r")))
781 (skip-chars-forward "^ \t\n\r")))
783 (when (and (or break qword-break)
784 (> (- (point) bol) 76))
785 (goto-char (or break qword-break))
788 (if (or (> 0 (skip-chars-backward " \t"))
789 (looking-at "[ \t]"))
792 (setq bol (1- (point)))
793 ;; Don't break before the first non-LWSP characters.
794 (skip-chars-forward " \t")
796 (forward-char 1))))))
798 (defun rfc2047-unfold-field ()
799 "Fold the current line."
802 (rfc2047-narrow-to-field)
803 (rfc2047-unfold-region (point-min) (point-max)))))
805 (defun rfc2047-unfold-region (b e)
806 "Unfold lines in region B to E."
808 (narrow-to-region b e)
809 (goto-char (point-min))
810 (let ((bol (save-restriction
813 (eol (point-at-eol)))
816 (if (and (looking-at "[ \t]")
817 (< (- (point-at-eol) bol) 76))
818 (delete-region eol (progn
820 (skip-chars-forward "\r\n")
822 (setq bol (point-at-bol)))
823 (setq eol (point-at-eol))
826 (defun rfc2047-b-encode-string (string)
827 "Base64-encode the header contained in STRING."
828 (base64-encode-string string t))
830 (defun rfc2047-q-encode-string (string)
831 "Quoted-printable-encode the header in STRING."
832 (mm-with-unibyte-buffer
834 (quoted-printable-encode-region
835 (point-min) (point-max) nil
836 ;; = (\075), _ (\137), ? (\077) are used in the encoded word.
837 ;; Avoid using 8bit characters.
838 ;; This list excludes `especials' (see the RFC2047 syntax),
839 ;; meaning that some characters in non-structured fields will
840 ;; get encoded when they con't need to be. The following is
841 ;; what it used to be.
842 ;;; ;; Equivalent to "^\000-\007\011\013\015-\037\200-\377=_?"
843 ;;; "\010\012\014\040-\074\076\100-\136\140-\177")
844 "-\b\n\f !#-'*+0-9A-Z\\^`-~\d")
845 (subst-char-in-region (point-min) (point-max) ? ?_)
848 (defun rfc2047-encode-parameter (param value)
849 "Return and PARAM=VALUE string encoded in the RFC2047-like style.
850 This is a replacement for the `rfc2231-encode-string' function.
852 When attaching files as MIME parts, we should use the RFC2231 encoding
853 to specify the file names containing non-ASCII characters. However,
854 many mail softwares don't support it in practice and recipients won't
855 be able to extract files with correct names. Instead, the RFC2047-like
856 encoding is acceptable generally. This function provides the very
857 RFC2047-like encoding, resigning to such a regrettable trend. To use
858 it, put the following line in your ~/.gnus.el file:
860 \(defalias 'mail-header-encode-parameter 'rfc2047-encode-parameter)
862 (let ((rfc2047-encoding-type 'mime)
863 (rfc2047-encode-max-chars nil))
864 (rfc2045-encode-string param (rfc2047-encode-string value))))
867 ;;; Functions for decoding RFC2047 messages
870 (defvar rfc2047-quote-decoded-words-containing-tspecials nil
871 "If non-nil, quote decoded words containing special characters.")
873 (defvar rfc2047-allow-incomplete-encoded-text t
874 "*Non-nil means allow incomplete encoded-text in successive encoded-words.
875 Dividing of encoded-text in the place other than character boundaries
876 violates RFC2047 section 5, while we have a capability to decode it.
877 If it is non-nil, the decoder will decode B- or Q-encoding in each
878 encoded-word, concatenate them, and decode it by charset. Otherwise,
879 the decoder will fully decode each encoded-word before concatenating
882 (defun rfc2047-strip-backslashes-in-quoted-strings ()
883 "Strip backslashes in quoted strings. `\\\"' remains."
884 (goto-char (point-min))
886 (with-syntax-table (standard-syntax-table)
887 (while (search-forward "\"" nil t)
888 (unless (eq (char-before) ?\\)
889 (setq beg (match-end 0))
890 (goto-char (match-beginning 0))
895 (narrow-to-region beg (1- (point)))
897 (while (search-forward "\\" nil 'move)
898 (unless (memq (char-after) '(?\"))
899 (delete-backward-char 1))
903 (goto-char beg))))))))
905 (defun rfc2047-charset-to-coding-system (charset)
906 "Return coding-system corresponding to MIME CHARSET.
907 If your Emacs implementation can't decode CHARSET, return nil."
908 (when (stringp charset)
909 (setq charset (intern (downcase charset))))
910 (when (or (not charset)
911 (eq 'gnus-all mail-parse-ignored-charsets)
912 (memq 'gnus-all mail-parse-ignored-charsets)
913 (memq charset mail-parse-ignored-charsets))
914 (setq charset mail-parse-charset))
915 (let ((cs (mm-charset-to-coding-system charset)))
916 (cond ((eq cs 'ascii)
917 (setq cs (or (mm-charset-to-coding-system mail-parse-charset)
919 ((mm-coding-system-p cs))
921 (listp mail-parse-ignored-charsets)
922 (memq 'gnus-unknown mail-parse-ignored-charsets))
923 (setq cs (mm-charset-to-coding-system mail-parse-charset))))
928 (defun rfc2047-decode-encoded-words (words)
929 "Decode successive encoded-words in WORDS and return a decoded string.
930 Each element of WORDS looks like (CHARSET ENCODING ENCODED-TEXT
932 (let (word charset cs encoding text rest)
934 (setq word (pop words))
935 (if (and (setq cs (rfc2047-charset-to-coding-system
936 (setq charset (car word))))
938 (cond ((char-equal ?B (nth 1 word))
939 (setq text (base64-decode-string
940 (rfc2047-pad-base64 (nth 2 word)))))
941 ((char-equal ?Q (nth 1 word))
942 (setq text (quoted-printable-decode-string
943 (mm-subst-char-in-string
944 ?_ ? (nth 2 word) t)))))
946 (message "%s" (error-message-string code))
948 (if (and rfc2047-allow-incomplete-encoded-text
950 ;; Concatenate text of which the charset is the same.
951 (setcdr (car rest) (concat (cdar rest) text))
952 (push (cons cs text) rest))
953 ;; Don't decode encoded-word.
954 (push (cons nil (nth 3 word)) rest)))
957 (or (and (setq cs (caar rest))
959 (mm-decode-coding-string (cdar rest) cs)
961 (message "%s" (error-message-string code))
963 (concat (when (cdr rest) " ")
966 (not (eq (string-to-char words) ? )))
972 ;; Fixme: This should decode in place, not cons intermediate strings.
973 ;; Also check whether it needs to worry about delimiting fields like
976 ;; In fact it's reported that (invalid) encoding of mailboxes in
977 ;; addr-specs is in use, so delimiting fields might help. Probably
978 ;; not decoding a word which isn't properly delimited is good enough
979 ;; and worthwhile (is it more correct or not?), e.g. something like
980 ;; `=?iso-8859-1?q?foo?=@'.
982 (defun rfc2047-decode-region (start end &optional address-mime)
983 "Decode MIME-encoded words in region between START and END.
984 If ADDRESS-MIME is non-nil, strip backslashes which precede characters
985 other than `\"' and `\\' in quoted strings."
987 (let ((case-fold-search t)
989 (if rfc2047-allow-irregular-q-encoded-words
991 (concat "[\n\t ]*\\(" rfc2047-encoded-word-regexp-loose "\\)"))
993 (concat "[\n\t ]*\\(" rfc2047-encoded-word-regexp "\\)"))))
997 (narrow-to-region start end)
999 (rfc2047-strip-backslashes-in-quoted-strings))
1000 (goto-char (setq b start))
1001 ;; Look for the encoded-words.
1002 (while (setq match (re-search-forward eword-regexp nil t))
1003 (setq e (match-beginning 1)
1007 (push (list (match-string 2) ;; charset
1008 (char-after (match-beginning 3)) ;; encoding
1009 (substring (match-string 3) 2) ;; encoded-text
1010 (match-string 1)) ;; encoded-word
1012 ;; Look for the subsequent encoded-words.
1013 (when (setq match (looking-at eword-regexp))
1014 (goto-char (setq end (match-end 0)))))
1015 ;; Replace the encoded-words with the decoded one.
1016 (delete-region e end)
1017 (insert (rfc2047-decode-encoded-words (nreverse words)))
1019 (narrow-to-region e (point))
1021 ;; Remove newlines between decoded words, though such
1022 ;; things essentially must not be there.
1023 (while (re-search-forward "[\n\r]+" nil t)
1024 (replace-match " "))
1025 ;; Quote decoded words if there are special characters
1026 ;; which might violate RFC2822.
1027 (when (and rfc2047-quote-decoded-words-containing-tspecials
1028 (let ((regexp (car (rassq
1030 rfc2047-header-encoding-alist))))
1035 (while (and (memq (char-after) '(? ?\t))
1036 (zerop (forward-line -1))))
1037 (looking-at regexp)))))
1040 (skip-chars-forward " \t")
1041 (setq start (point))
1042 (setq quoted (eq (char-after) ?\"))
1043 (goto-char (point-max))
1044 (skip-chars-backward " \t")
1045 (if (setq quoted (and quoted
1046 (> (point) (1+ start))
1047 (eq (char-before) ?\")))
1050 (setq start (1+ start)
1051 end (point-marker)))
1052 (setq end (point-marker)))
1054 (while (search-forward "\"" end t)
1057 (zerop (% (skip-chars-backward "\\\\") 2))
1058 (goto-char (match-beginning 0)))
1061 (when (and (not quoted)
1065 (concat "[" ietf-drums-tspecials "]")
1071 (set-marker end nil)))
1072 (goto-char (point-max)))
1073 (when (and (mm-multibyte-p)
1075 (not (eq mail-parse-charset 'us-ascii))
1076 (not (eq mail-parse-charset 'gnus-decoded)))
1077 (mm-decode-coding-region b e mail-parse-charset))
1079 (when (and (mm-multibyte-p)
1081 (not (eq mail-parse-charset 'us-ascii))
1082 (not (eq mail-parse-charset 'gnus-decoded)))
1083 (mm-decode-coding-region b (point-max) mail-parse-charset))))))
1085 (defun rfc2047-decode-address-region (start end)
1086 "Decode MIME-encoded words in region between START and END.
1087 Backslashes which precede characters other than `\"' and `\\' in quoted
1088 strings are stripped."
1089 (rfc2047-decode-region start end t))
1091 (defun rfc2047-decode-string (string &optional address-mime)
1092 "Decode MIME-encoded STRING and return the result.
1093 If ADDRESS-MIME is non-nil, strip backslashes which precede characters
1094 other than `\"' and `\\' in quoted strings."
1095 (let ((m (mm-multibyte-p)))
1096 (if (string-match "=\\?" string)
1098 ;; Fixme: This logic is wrong, but seems to be required by
1099 ;; Gnus summary buffer generation. The value of `m' depends
1100 ;; on the current buffer, not global multibyteness or that
1101 ;; of the string. Also the string returned should always be
1102 ;; multibyte in a multibyte session, i.e. the buffer should
1103 ;; be multibyte before `buffer-string' is called.
1105 (mm-enable-multibyte))
1108 (rfc2047-decode-region (point-min) (point-max) address-mime))
1113 (when (mm-multibyte-string-p string)
1114 (mm-enable-multibyte))
1116 (rfc2047-strip-backslashes-in-quoted-strings)
1118 ;; Fixme: As above, `m' here is inappropriate.
1121 (not (eq mail-parse-charset 'us-ascii))
1122 (not (eq mail-parse-charset 'gnus-decoded)))
1123 ;; `decode-coding-string' in Emacs offers a third optional
1124 ;; arg NOCOPY to avoid consing a new string if the decoding
1125 ;; is "trivial". Unfortunately it currently doesn't
1126 ;; consider anything else than a `nil' coding system
1128 ;; `rfc2047-decode-string' is called multiple times for each
1129 ;; article during summary buffer generation, and we really
1130 ;; want to avoid unnecessary consing. So we bypass
1131 ;; `decode-coding-string' if the string is purely ASCII.
1132 (if (and (fboundp 'detect-coding-string)
1133 ;; string is purely ASCII
1134 (eq (detect-coding-string string t) 'undecided))
1136 (mm-decode-coding-string string mail-parse-charset))
1137 (mm-string-as-multibyte string)))))
1139 (defun rfc2047-decode-address-string (string)
1140 "Decode MIME-encoded STRING and return the result.
1141 Backslashes which precede characters other than `\"' and `\\' in quoted
1142 strings are stripped."
1143 (rfc2047-decode-string string t))
1145 (defun rfc2047-pad-base64 (string)
1146 "Pad STRING to quartets."
1147 ;; Be more liberal to accept buggy base64 strings. If
1148 ;; base64-decode-string accepts buggy strings, this function could
1149 ;; be aliased to identity.
1150 (if (= 0 (mod (length string) 4))
1152 (when (string-match "=+$" string)
1153 (setq string (substring string 0 (match-beginning 0))))
1154 (case (mod (length string) 4)
1156 (1 string) ;; Error, don't pad it.
1157 (2 (concat string "=="))
1158 (3 (concat string "=")))))
1162 ;;; arch-tag: a07fe3d4-22b5-4c4a-bd89-b1f82d5d36f6
1163 ;;; rfc2047.el ends here