code.delx.au - gnu-emacs/blob - lisp/mail/rfc2231.el

   1 ;;; rfc2231.el --- Functions for decoding rfc2231 headers
   2
   3 ;; Copyright (C) 1998-2016 Free Software Foundation, Inc.
   4
   5 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
   6 ;; This file is part of GNU Emacs.
   7
   8 ;; GNU Emacs is free software: you can redistribute it and/or modify
   9 ;; it under the terms of the GNU General Public License as published by
  10 ;; the Free Software Foundation, either version 3 of the License, or
  11 ;; (at your option) any later version.
  12
  13 ;; GNU Emacs is distributed in the hope that it will be useful,
  14 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 ;; GNU General Public License for more details.
  17
  18 ;; You should have received a copy of the GNU General Public License
  19 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 ;;; Commentary:
  22
  23 ;;; Code:
  24
  25 (eval-when-compile (require 'cl))
  26 (require 'ietf-drums)
  27 (require 'rfc2047)
  28 (autoload 'mm-encode-body "mm-bodies")
  29 (autoload 'mail-header-remove-whitespace "mail-parse")
  30 (autoload 'mail-header-remove-comments "mail-parse")
  31
  32 (defun rfc2231-get-value (ct attribute)
  33   "Return the value of ATTRIBUTE from CT."
  34   (cdr (assq attribute (cdr ct))))
  35
  36 (defun rfc2231-parse-qp-string (string)
  37   "Parse QP-encoded string using `rfc2231-parse-string'.
  38 N.B.  This is in violation with RFC2047, but it seem to be in common use."
  39   (rfc2231-parse-string (rfc2047-decode-string string)))
  40
  41 (defun rfc2231-parse-string (string &optional signal-error)
  42   "Parse STRING and return a list.
  43 The list will be on the form
  44  `(name (attribute . value) (attribute . value)...)'.
  45
  46 If the optional SIGNAL-ERROR is non-nil, signal an error when this
  47 function fails in parsing of parameters.  Otherwise, this function
  48 must never cause a Lisp error."
  49   (with-temp-buffer
  50     (let ((ttoken (ietf-drums-token-to-list ietf-drums-text-token))
  51           (stoken (ietf-drums-token-to-list ietf-drums-tspecials))
  52           (ntoken (ietf-drums-token-to-list "0-9"))
  53           c type attribute encoded number parameters value)
  54       (ietf-drums-init
  55        (condition-case nil
  56            (mail-header-remove-whitespace
  57             (mail-header-remove-comments string))
  58          ;; The most likely cause of an error is unbalanced parentheses
  59          ;; or double-quotes.  If all parentheses and double-quotes are
  60          ;; quoted meaninglessly with backslashes, removing them might
  61          ;; make it parsable.  Let's try...
  62          (error
  63           (let (mod)
  64             (when (and (string-match "\\\\\"" string)
  65                        (not (string-match "\\`\"\\|[^\\]\"" string)))
  66               (setq string (replace-regexp-in-string "\\\\\"" "\"" string)
  67                     mod t))
  68             (when (and (string-match "\\\\(" string)
  69                        (string-match "\\\\)" string)
  70                        (not (string-match "\\`(\\|[^\\][()]" string)))
  71               (setq string (replace-regexp-in-string
  72                             "\\\\\\([()]\\)" "\\1" string)
  73                     mod t))
  74             (or (and mod
  75                      (ignore-errors
  76                        (mail-header-remove-whitespace
  77                         (mail-header-remove-comments string))))
  78                 ;; Finally, attempt to extract only type.
  79                 (if (string-match
  80                      (concat "\\`[\t\n ]*\\([^" ietf-drums-tspecials "\t\n ]+"
  81                              "\\(?:/[^" ietf-drums-tspecials
  82                              "\t\n ]+\\)?\\)\\(?:[\t\n ;]\\|\\'\\)")
  83                      string)
  84                     (match-string 1 string)
  85                   ""))))))
  86       (let ((table (copy-syntax-table ietf-drums-syntax-table)))
  87         (modify-syntax-entry ?\' "w" table)
  88         (modify-syntax-entry ?* " " table)
  89         (modify-syntax-entry ?\; " " table)
  90         (modify-syntax-entry ?= " " table)
  91         ;; The following isn't valid, but one should be liberal
  92         ;; in what one receives.
  93         (modify-syntax-entry ?\: "w" table)
  94         (set-syntax-table table))
  95       (setq c (char-after))
  96       (when (and (memq c ttoken)
  97                  (not (memq c stoken))
  98                  (setq type (ignore-errors
  99                               (downcase
 100                                (buffer-substring (point) (progn
 101                                                            (forward-sexp 1)
 102                                                            (point)))))))
 103         ;; Do the params
 104         (condition-case err
 105             (progn
 106               (while (not (eobp))
 107                 (setq c (char-after))
 108                 (unless (eq c ?\;)
 109                   (error "Invalid header: %s" string))
 110                 (forward-char 1)
 111                 ;; If c in nil, then this is an invalid header, but
 112                 ;; since elm generates invalid headers on this form,
 113                 ;; we allow it.
 114                 (when (setq c (char-after))
 115                   (if (and (memq c ttoken)
 116                            (not (memq c stoken)))
 117                       (setq attribute
 118                             (intern
 119                              (downcase
 120                               (buffer-substring
 121                                (point) (progn (forward-sexp 1) (point))))))
 122                     (error "Invalid header: %s" string))
 123                   (setq c (char-after))
 124                   (if (eq c ?*)
 125                       (progn
 126                         (forward-char 1)
 127                         (setq c (char-after))
 128                         (if (not (memq c ntoken))
 129                             (setq encoded t
 130                                   number nil)
 131                           (setq number
 132                                 (string-to-number
 133                                  (buffer-substring
 134                                   (point) (progn (forward-sexp 1) (point)))))
 135                           (setq c (char-after))
 136                           (when (eq c ?*)
 137                             (setq encoded t)
 138                             (forward-char 1)
 139                             (setq c (char-after)))))
 140                     (setq number nil
 141                           encoded nil))
 142                   (unless (eq c ?=)
 143                     (error "Invalid header: %s" string))
 144                   (forward-char 1)
 145                   (setq c (char-after))
 146                   (cond
 147                    ((eq c ?\")
 148                     (setq value (buffer-substring (1+ (point))
 149                                                   (progn
 150                                                     (forward-sexp 1)
 151                                                     (1- (point)))))
 152                     (when encoded
 153                       (setq value (mapconcat (lambda (c) (format "%%%02x" c))
 154                                              value ""))))
 155                    ((and (or (memq c ttoken)
 156                              ;; EXTENSION: Support non-ascii chars.
 157                              (> c ?\177))
 158                          (not (memq c stoken)))
 159                     (setq value
 160                           (buffer-substring
 161                            (point)
 162                            (progn
 163                              ;; Jump over asterisk, non-ASCII
 164                              ;; and non-boundary characters.
 165                              (while (and c
 166                                          (or (eq c ?*)
 167                                              (> c ?\177)
 168                                              (not (eq (char-syntax c) ? ))))
 169                                (forward-char 1)
 170                                (setq c (char-after)))
 171                              (point)))))
 172                    (t
 173                     (error "Invalid header: %s" string)))
 174                   (push (list attribute value number encoded)
 175                         parameters))))
 176           (error
 177            (setq parameters nil)
 178            (when signal-error
 179              (signal (car err) (cdr err)))))
 180
 181         ;; Now collect and concatenate continuation parameters.
 182         (let ((cparams nil)
 183               elem)
 184           (loop for (attribute value part encoded)
 185                 in (sort parameters (lambda (e1 e2)
 186                                       (< (or (caddr e1) 0)
 187                                          (or (caddr e2) 0))))
 188                 do (cond
 189                     ;; First part.
 190                     ((or (not (setq elem (assq attribute cparams)))
 191                          (and (numberp part)
 192                               (zerop part)))
 193                      (push (list attribute value encoded) cparams))
 194                     ;; Repetition of a part; do nothing.
 195                     ((and elem
 196                           (null number))
 197                      )
 198                     ;; Concatenate continuation parts.
 199                     (t
 200                      (setcar (cdr elem) (concat (cadr elem) value)))))
 201           ;; Finally decode encoded values.
 202           (cons type (mapcar
 203                       (lambda (elem)
 204                         (cons (car elem)
 205                               (if (nth 2 elem)
 206                                   (rfc2231-decode-encoded-string (nth 1 elem))
 207                                 (nth 1 elem))))
 208                       (nreverse cparams))))))))
 209
 210 (defun rfc2231-decode-encoded-string (string)
 211   "Decode an RFC2231-encoded string.
 212 These look like:
 213  \"us-ascii\\='en-us\\='This%20is%20%2A%2A%2Afun%2A%2A%2A\",
 214  \"us-ascii\\='\\='This%20is%20%2A%2A%2Afun%2A%2A%2A\",
 215  \"\\='en-us\\='This%20is%20%2A%2A%2Afun%2A%2A%2A\",
 216  \"\\='\\='This%20is%20%2A%2A%2Afun%2A%2A%2A\", or
 217  \"This is ***fun***\"."
 218   (string-match "\\`\\(?:\\([^']+\\)?'\\([^']+\\)?'\\)?\\(.+\\)" string)
 219   (let ((coding-system (mm-charset-to-coding-system
 220                         (match-string 1 string) nil t))
 221         ;;(language (match-string 2 string))
 222         (value (match-string 3 string)))
 223     (mm-with-unibyte-buffer
 224       (insert value)
 225       (goto-char (point-min))
 226       (while (re-search-forward "%\\([0-9A-Fa-f][0-9A-Fa-f]\\)" nil t)
 227         (insert
 228          (prog1
 229              (string-to-number (match-string 1) 16)
 230            (delete-region (match-beginning 0) (match-end 0)))))
 231       ;; Decode using the charset, if any.
 232       (if (memq coding-system '(nil ascii))
 233           (buffer-string)
 234         (decode-coding-string (buffer-string) coding-system)))))
 235
 236 (defun rfc2231-encode-string (param value)
 237   "Return and PARAM=VALUE string encoded according to RFC2231.
 238 Use `mml-insert-parameter' or `mml-insert-parameter-string' to insert
 239 the result of this function."
 240   (let ((control (ietf-drums-token-to-list ietf-drums-no-ws-ctl-token))
 241         (tspecial (ietf-drums-token-to-list ietf-drums-tspecials))
 242         (special (ietf-drums-token-to-list "*'%\n\t"))
 243         (ascii (ietf-drums-token-to-list ietf-drums-text-token))
 244         (num -1)
 245         ;; Don't make lines exceeding 76 column.
 246         (limit (- 74 (length param)))
 247         spacep encodep charsetp charset broken)
 248     (mm-with-multibyte-buffer
 249       (insert value)
 250       (goto-char (point-min))
 251       (while (not (eobp))
 252         (cond
 253          ((or (memq (following-char) control)
 254               (memq (following-char) tspecial)
 255               (memq (following-char) special))
 256           (setq encodep t))
 257          ((eq (following-char) ? )
 258           (setq spacep t))
 259          ((not (memq (following-char) ascii))
 260           (setq charsetp t)))
 261         (forward-char 1))
 262       (when charsetp
 263         (setq charset (mm-encode-body)))
 264       (mm-disable-multibyte)
 265       (cond
 266        ((or encodep charsetp
 267             (progn
 268               (end-of-line)
 269               (> (current-column) (if spacep (- limit 2) limit))))
 270         (setq limit (- limit 6))
 271         (goto-char (point-min))
 272         (insert (symbol-name (or charset 'us-ascii)) "''")
 273         (while (not (eobp))
 274           (if (or (not (memq (following-char) ascii))
 275                   (memq (following-char) control)
 276                   (memq (following-char) tspecial)
 277                   (memq (following-char) special)
 278                   (eq (following-char) ? ))
 279               (progn
 280                 (when (>= (current-column) (1- limit))
 281                   (insert ";\n")
 282                   (setq broken t))
 283                 (insert "%" (format "%02x" (following-char)))
 284                 (delete-char 1))
 285             (when (> (current-column) limit)
 286               (insert ";\n")
 287               (setq broken t))
 288             (forward-char 1)))
 289         (goto-char (point-min))
 290         (if (not broken)
 291             (insert param "*=")
 292           (while (not (eobp))
 293             (insert (if (>= num 0) " " "")
 294                     param "*" (format "%d" (incf num)) "*=")
 295             (forward-line 1))))
 296        (spacep
 297         (goto-char (point-min))
 298         (insert param "=\"")
 299         (goto-char (point-max))
 300         (insert "\""))
 301        (t
 302         (goto-char (point-min))
 303         (insert param "=")))
 304       (buffer-string))))
 305
 306 (provide 'rfc2231)
 307
 308 ;;; rfc2231.el ends here