lisp/rfc2231.el

   1 ;;; rfc2231.el --- Functions for decoding rfc2231 headers
   2
   3 ;; Copyright (C) 1998-2013 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 (mm-replace-in-string string "\\\\\"" "\"")
  67                     mod t))
  68             (when (and (string-match "\\\\(" string)
  69                        (string-match "\\\\)" string)
  70                        (not (string-match "\\`(\\|[^\\][()]" string)))
  71               (setq string (mm-replace-in-string string "\\\\\\([()]\\)" "\\1")
  72                     mod t))
  73             (or (and mod
  74                      (ignore-errors
  75                        (mail-header-remove-whitespace
  76                         (mail-header-remove-comments string))))
  77                 ;; Finally, attempt to extract only type.
  78                 (if (string-match
  79                      (concat "\\`[\t\n ]*\\([^" ietf-drums-tspecials "\t\n ]+"
  80                              "\\(?:/[^" ietf-drums-tspecials
  81                              "\t\n ]+\\)?\\)\\(?:[\t\n ;]\\|\\'\\)")
  82                      string)
  83                     (match-string 1 string)
  84                   ""))))))
  85       (let ((table (copy-syntax-table ietf-drums-syntax-table)))
  86         (modify-syntax-entry ?\' "w" table)
  87         (modify-syntax-entry ?* " " table)
  88         (modify-syntax-entry ?\; " " table)
  89         (modify-syntax-entry ?= " " table)
  90         ;; The following isn't valid, but one should be liberal
  91         ;; in what one receives.
  92         (modify-syntax-entry ?\: "w" table)
  93         (set-syntax-table table))
  94       (setq c (char-after))
  95       (when (and (memq c ttoken)
  96                  (not (memq c stoken))
  97                  (setq type (ignore-errors
  98                               (downcase
  99                                (buffer-substring (point) (progn
 100                                                            (forward-sexp 1)
 101                                                            (point)))))))
 102         ;; Do the params
 103         (condition-case err
 104             (progn
 105               (while (not (eobp))
 106                 (setq c (char-after))
 107                 (unless (eq c ?\;)
 108                   (error "Invalid header: %s" string))
 109                 (forward-char 1)
 110                 ;; If c in nil, then this is an invalid header, but
 111                 ;; since elm generates invalid headers on this form,
 112                 ;; we allow it.
 113                 (when (setq c (char-after))
 114                   (if (and (memq c ttoken)
 115                            (not (memq c stoken)))
 116                       (setq attribute
 117                             (intern
 118                              (downcase
 119                               (buffer-substring
 120                                (point) (progn (forward-sexp 1) (point))))))
 121                     (error "Invalid header: %s" string))
 122                   (setq c (char-after))
 123                   (if (eq c ?*)
 124                       (progn
 125                         (forward-char 1)
 126                         (setq c (char-after))
 127                         (if (not (memq c ntoken))
 128                             (setq encoded t
 129                                   number nil)
 130                           (setq number
 131                                 (string-to-number
 132                                  (buffer-substring
 133                                   (point) (progn (forward-sexp 1) (point)))))
 134                           (setq c (char-after))
 135                           (when (eq c ?*)
 136                             (setq encoded t)
 137                             (forward-char 1)
 138                             (setq c (char-after)))))
 139                     (setq number nil
 140                           encoded nil))
 141                   (unless (eq c ?=)
 142                     (error "Invalid header: %s" string))
 143                   (forward-char 1)
 144                   (setq c (char-after))
 145                   (cond
 146                    ((eq c ?\")
 147                     (setq value (buffer-substring (1+ (point))
 148                                                   (progn
 149                                                     (forward-sexp 1)
 150                                                     (1- (point)))))
 151                     (when encoded
 152                       (setq value (mapconcat (lambda (c) (format "%%%02x" c))
 153                                              value ""))))
 154                    ((and (or (memq c ttoken)
 155                              ;; EXTENSION: Support non-ascii chars.
 156                              (> c ?\177))
 157                          (not (memq c stoken)))
 158                     (setq value
 159                           (buffer-substring
 160                            (point)
 161                            (progn
 162                              ;; Jump over asterisk, non-ASCII
 163                              ;; and non-boundary characters.
 164                              (while (and c
 165                                          (or (eq c ?*)
 166                                              (> c ?\177)
 167                                              (not (eq (char-syntax c) ? ))))
 168                                (forward-char 1)
 169                                (setq c (char-after)))
 170                              (point)))))
 171                    (t
 172                     (error "Invalid header: %s" string)))
 173                   (push (list attribute value number encoded)
 174                         parameters))))
 175           (error
 176            (setq parameters nil)
 177            (when signal-error
 178              (signal (car err) (cdr err)))))
 179
 180         ;; Now collect and concatenate continuation parameters.
 181         (let ((cparams nil)
 182               elem)
 183           (loop for (attribute value part encoded)
 184                 in (sort parameters (lambda (e1 e2)
 185                                       (< (or (caddr e1) 0)
 186                                          (or (caddr e2) 0))))
 187                 do (cond
 188                     ;; First part.
 189                     ((or (not (setq elem (assq attribute cparams)))
 190                          (and (numberp part)
 191                               (zerop part)))
 192                      (push (list attribute value encoded) cparams))
 193                     ;; Repetition of a part; do nothing.
 194                     ((and elem
 195                           (null number))
 196                      )
 197                     ;; Concatenate continuation parts.
 198                     (t
 199                      (setcar (cdr elem) (concat (cadr elem) value)))))
 200           ;; Finally decode encoded values.
 201           (cons type (mapcar
 202                       (lambda (elem)
 203                         (cons (car elem)
 204                               (if (nth 2 elem)
 205                                   (rfc2231-decode-encoded-string (nth 1 elem))
 206                                 (nth 1 elem))))
 207                       (nreverse cparams))))))))
 208
 209 (defun rfc2231-decode-encoded-string (string)
 210   "Decode an RFC2231-encoded string.
 211 These look like:
 212  \"us-ascii'en-us'This%20is%20%2A%2A%2Afun%2A%2A%2A\",
 213  \"us-ascii''This%20is%20%2A%2A%2Afun%2A%2A%2A\",
 214  \"'en-us'This%20is%20%2A%2A%2Afun%2A%2A%2A\",
 215  \"''This%20is%20%2A%2A%2Afun%2A%2A%2A\", or
 216  \"This is ***fun***\"."
 217   (string-match "\\`\\(?:\\([^']+\\)?'\\([^']+\\)?'\\)?\\(.+\\)" string)
 218   (let ((coding-system (mm-charset-to-coding-system (match-string 1 string)))
 219         ;;(language (match-string 2 string))
 220         (value (match-string 3 string)))
 221     (mm-with-unibyte-buffer
 222       (insert value)
 223       (goto-char (point-min))
 224       (while (re-search-forward "%\\([0-9A-Fa-f][0-9A-Fa-f]\\)" nil t)
 225         (insert
 226          (prog1
 227              (string-to-number (match-string 1) 16)
 228            (delete-region (match-beginning 0) (match-end 0)))))
 229       ;; Decode using the charset, if any.
 230       (if (memq coding-system '(nil ascii))
 231           (buffer-string)
 232         (mm-decode-coding-string (buffer-string) coding-system)))))
 233
 234 (defun rfc2231-encode-string (param value)
 235   "Return and PARAM=VALUE string encoded according to RFC2231.
 236 Use `mml-insert-parameter' or `mml-insert-parameter-string' to insert
 237 the result of this function."
 238   (let ((control (ietf-drums-token-to-list ietf-drums-no-ws-ctl-token))
 239         (tspecial (ietf-drums-token-to-list ietf-drums-tspecials))
 240         (special (ietf-drums-token-to-list "*'%\n\t"))
 241         (ascii (ietf-drums-token-to-list ietf-drums-text-token))
 242         (num -1)
 243         ;; Don't make lines exceeding 76 column.
 244         (limit (- 74 (length param)))
 245         spacep encodep charsetp charset broken)
 246     (mm-with-multibyte-buffer
 247       (insert value)
 248       (goto-char (point-min))
 249       (while (not (eobp))
 250         (cond
 251          ((or (memq (following-char) control)
 252               (memq (following-char) tspecial)
 253               (memq (following-char) special))
 254           (setq encodep t))
 255          ((eq (following-char) ? )
 256           (setq spacep t))
 257          ((not (memq (following-char) ascii))
 258           (setq charsetp t)))
 259         (forward-char 1))
 260       (when charsetp
 261         (setq charset (mm-encode-body)))
 262       (mm-disable-multibyte)
 263       (cond
 264        ((or encodep charsetp
 265             (progn
 266               (end-of-line)
 267               (> (current-column) (if spacep (- limit 2) limit))))
 268         (setq limit (- limit 6))
 269         (goto-char (point-min))
 270         (insert (symbol-name (or charset 'us-ascii)) "''")
 271         (while (not (eobp))
 272           (if (or (not (memq (following-char) ascii))
 273                   (memq (following-char) control)
 274                   (memq (following-char) tspecial)
 275                   (memq (following-char) special)
 276                   (eq (following-char) ? ))
 277               (progn
 278                 (when (>= (current-column) (1- limit))
 279                   (insert ";\n")
 280                   (setq broken t))
 281                 (insert "%" (format "%02x" (following-char)))
 282                 (delete-char 1))
 283             (when (> (current-column) limit)
 284               (insert ";\n")
 285               (setq broken t))
 286             (forward-char 1)))
 287         (goto-char (point-min))
 288         (if (not broken)
 289             (insert param "*=")
 290           (while (not (eobp))
 291             (insert (if (>= num 0) " " "")
 292                     param "*" (format "%d" (incf num)) "*=")
 293             (forward-line 1))))
 294        (spacep
 295         (goto-char (point-min))
 296         (insert param "=\"")
 297         (goto-char (point-max))
 298         (insert "\""))
 299        (t
 300         (goto-char (point-min))
 301         (insert param "=")))
 302       (buffer-string))))
 303
 304 (provide 'rfc2231)
 305
 306 ;;; rfc2231.el ends here