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[emacs.git] / lisp / mail / rfc822.el

;;; rfc822.el --- hairy rfc822 parser for mail and news and suchlike

;; Copyright (C) 1986-1987, 1990, 2001-2014 Free Software Foundation,
;; Inc.

;; Author: Richard Mlynarik <mly@eddie.mit.edu>
;; Maintainer: FSF
;; Keywords: mail

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; Support functions for parsing RFC-822 headers, used by mail and news
;; modes.

;;; Code:

(defvar rfc822-address-start)

;; uses rfc822-address-start free, throws to address
(defun rfc822-bad-address (reason)
  (save-restriction
    (insert "_^_")
    (narrow-to-region rfc822-address-start
                      (if (re-search-forward "[,;]" nil t)
                          (max (point-min) (1- (point)))
                        (point-max)))
    ;; make the error string be suitable for inclusion in (...)
    (let ((losers '("\\" "(" ")" "\n")))
      (while losers
        (goto-char (point-min))
        (while (search-forward (car losers) nil t)
          (backward-char 1)
          (insert ?\\)
          (forward-char 1))
        (setq losers (cdr losers))))
    (goto-char (point-min)) (insert "(Unparsable address -- "
                                    reason
                                    ": \"")
    (goto-char (point-max)) (insert "\")"))
  (rfc822-nuke-whitespace)
  (throw 'address (buffer-substring rfc822-address-start (point))))

(defun rfc822-nuke-whitespace (&optional leave-space)
  (let (ch)
    (while (cond ((eobp)
                  nil)
                 ((= (setq ch (following-char)) ?\()
                  (forward-char 1)
                  (while (if (eobp)
                             (rfc822-bad-address "Unbalanced comment (...)")
                           (/= (setq ch (following-char)) ?\)))
                    (cond ((looking-at "[^()\\]+")
                           (replace-match ""))
                          ((= ch ?\()
                           (rfc822-nuke-whitespace))
                          ((< (point) (1- (point-max)))
                           (delete-char 2))
                          (t
                           (rfc822-bad-address "orphaned backslash"))))
                  ;; delete remaining "()"
                  (forward-char -1)
                  (delete-char 2)
                  t)
                 ((memq ch '(?\  ?\t ?\n))
                  (delete-region (point)
                                 (progn (skip-chars-forward " \t\n") (point)))
                  t)
                 (t
                  nil)))
    (or (not leave-space)
        (eobp)
        (bobp)
        (= (preceding-char) ?\ )
        (insert ?\ ))))

(defun rfc822-looking-at (regex &optional leave-space)
  (if (cond ((stringp regex)
             (if (looking-at regex)
                 (progn (goto-char (match-end 0))
                        t)))
            (t
             (if (and (not (eobp))
                      (= (following-char) regex))
                 (progn (forward-char 1)
                        t))))
      (let ((tem (match-data)))
        (rfc822-nuke-whitespace leave-space)
        (set-match-data tem)
        t)))

(defun rfc822-snarf-word ()
  ;; word is atom | quoted-string
  (cond ((= (following-char) ?\")
         ;; quoted-string
         (or (rfc822-looking-at "\"\\([^\"\\\n]\\|\\\\.\\|\\\\\n\\)*\"")
             (rfc822-bad-address "Unterminated quoted string")))
        ((rfc822-looking-at "[^][\000-\037 ()<>@,;:\\\".]+")
         ;; atom
         )
        (t
         (rfc822-bad-address "Rubbish in address"))))

(defun rfc822-snarf-words ()
  (rfc822-snarf-word)
  (while (rfc822-looking-at ?.)
    (rfc822-snarf-word)))

(defun rfc822-snarf-subdomain ()
  ;; sub-domain is domain-ref | domain-literal
  (cond ((= (following-char) ?\[)
         ;; domain-ref
         (or (rfc822-looking-at "\\[\\([^][\\\n]\\|\\\\.\\|\\\\\n\\)*\\]")
             (rfc822-bad-address "Unterminated domain literal [...]")))
        ((rfc822-looking-at "[^][\000-\037 ()<>@,;:\\\".]+")
         ;; domain-literal = atom
         )
        (t
         (rfc822-bad-address "Rubbish in host/domain specification"))))

(defun rfc822-snarf-domain ()
  (rfc822-snarf-subdomain)
  (while (rfc822-looking-at ?.)
    (rfc822-snarf-subdomain)))

(defun rfc822-snarf-frob-list (name separator terminator snarfer
                                    &optional return)
  (let ((first t)
        (list ())
        tem)
    (while (cond ((eobp)
                  (rfc822-bad-address
                    (format "End of addresses in middle of %s" name)))
                 ((rfc822-looking-at terminator)
                  nil)
                 ((rfc822-looking-at separator)
                  ;; multiple separators are allowed and do nothing.
                  (while (rfc822-looking-at separator))
                  t)
                 (first
                  t)
                 (t
                  (rfc822-bad-address
                    (format "Gubbish in middle of %s" name))))
      (setq tem (funcall snarfer)
            first nil)
      (and return tem
           (setq list (if (listp tem)
                          (nconc (reverse tem) list)
                          (cons tem list)))))
    (nreverse list)))

;; return either an address (a string) or a list of addresses
(defun rfc822-addresses-1 (&optional allow-groups)
  ;; Looking for an rfc822 `address'
  ;; Either a group (1*word ":" [#mailbox] ";")
  ;; or a mailbox (addr-spec | 1*word route-addr)
  ;;  addr-spec is (local-part "@" domain)
  ;;  route-addr is ("<" [1#("@" domain) ":"] addr-spec ">")
  ;;  local-part is (word *("." word))
  ;;  word is (atom | quoted-string)
  ;;  quoted-string is ("\([^\"\\n]\|\\.\|\\\n\)")
  ;;  atom is [^\000-\037\177 ()<>@,;:\".[]]+
  ;;  domain is sub-domain *("." sub-domain)
  ;;  sub-domain is domain-ref | domain-literal
  ;;  domain-literal is  "[" *(dtext | quoted-pair) "]"
  ;;  dtext is "[^][\\n"
  ;;  domain-ref is atom
  (let ((rfc822-address-start (point))
        (n 0))
    (catch 'address
      ;; optimize common cases:
      ;;  foo
      ;;  foo.bar@bar.zap
      ;; followed by "\\'\\|,\\|([^()\\]*)\\'"
      ;; other common cases are:
      ;;  foo bar <foo.bar@baz.zap>
      ;;  "foo bar" <foo.bar@baz.zap>
      ;;  those aren't hacked yet.
      (if (and (rfc822-looking-at "[^][\000-\037 ()<>@,;:\\\"]+\\(\\|@[^][\000-\037 ()<>@,;:\\\"]+\\)" t)
               (progn (or (eobp)
                          (rfc822-looking-at ?,))))
          (progn
            ;; rfc822-looking-at may have inserted a space
            (or (bobp) (/= (preceding-char) ?\ ) (delete-char -1))
            ;; relying on the fact that rfc822-looking-at <char>
            ;;  doesn't mung match-data
            (throw 'address (buffer-substring rfc822-address-start (match-end 0)))))
      (goto-char rfc822-address-start)
      (while t
        (cond ((and (= n 1) (rfc822-looking-at ?@))
               ;; local-part@domain
               (rfc822-snarf-domain)
               (throw 'address
                 (buffer-substring rfc822-address-start (point))))
              ((rfc822-looking-at ?:)
               (cond ((not allow-groups)
                      (rfc822-bad-address "A group name may not appear here"))
                     ((= n 0)
                      (rfc822-bad-address "No name for :...; group")))
               ;; group
               (throw 'address
                 ;; return a list of addresses
                 (rfc822-snarf-frob-list ":...; group" ?\, ?\;
                                         'rfc822-addresses-1 t)))
              ((rfc822-looking-at ?<)
               (let ((start (point))
                     (strip t))
                 (cond ((rfc822-looking-at ?>)
                        ;; empty path
                        ())
                       ((and (not (eobp)) (= (following-char) ?\@))
                        ;; <@foo.bar,@baz:quux@abcd.efg>
                        (rfc822-snarf-frob-list "<...> address" ?\, ?\:
                          (function (lambda ()
                                      (if (rfc822-looking-at ?\@)
                                          (rfc822-snarf-domain)
                                        (rfc822-bad-address
                                          "Gubbish in route-addr")))))
                        (rfc822-snarf-words)
                        (or (rfc822-looking-at ?@)
                            (rfc822-bad-address "Malformed <..@..> address"))
                        (rfc822-snarf-domain)
                        (setq strip nil))
                       ((progn (rfc822-snarf-words) (rfc822-looking-at ?@))
                        ; allow <foo> (losing unix seems to do this)
                        (rfc822-snarf-domain)))
                 (let ((end (point)))
                   (if (rfc822-looking-at ?\>)
                       (throw 'address
                         (buffer-substring (if strip start (1- start))
                                           (if strip end (1+ end))))
                     (rfc822-bad-address "Unterminated <...> address")))))
              ((looking-at "[^][\000-\037 ()<>@,;:\\.]")
               ;; this allows "." to be part of the words preceding
               ;; an addr-spec, since many broken mailers output
               ;; "Hern K. Herklemeyer III
               ;;   <yank@megadeath.dod.gods-own-country>"
               (let ((again t))
                 (while again
                   (or (= n 0) (bobp) (= (preceding-char) ?\ )
                       (insert ?\ ))
                   (rfc822-snarf-words)
                   (setq n (1+ n))
                   (setq again (or (rfc822-looking-at ?.)
                                   (looking-at "[^][\000-\037 ()<>@,;:\\.]"))))))
              ((= n 0)
               (throw 'address nil))
              ((= n 1) ; allow "foo" (losing unix seems to do this)
               (throw 'address
                 (buffer-substring rfc822-address-start (point))))
              ((> n 1)
               (rfc822-bad-address "Missing comma between addresses or badly-formatted address"))
              ((or (eobp) (= (following-char) ?,))
               (rfc822-bad-address "Missing comma or route-spec"))
              (t
               (rfc822-bad-address "Strange character or missing comma")))))))


(defun rfc822-addresses (header-text)
  (if (string-match "\\`[ \t]*\\([^][\000-\037 ()<>@,;:\\\".]+\\)[ \t]*\\'"
                    header-text)
      ;; Make very simple case moderately fast.
      (list (substring header-text (match-beginning 1) (match-end 1)))
    (let ((buf (generate-new-buffer " rfc822")))
      (unwind-protect
          (with-current-buffer buf
            (make-local-variable 'case-fold-search)
            (setq case-fold-search nil) ;For speed(?)
            (insert header-text)
            ;; unfold continuation lines
            (goto-char (point-min))

            (while (re-search-forward "\\([^\\]\\(\\\\\\\\\\)*\\)\n[ \t]"
                                      nil t)
              (replace-match "\\1 " t))

            (goto-char (point-min))
            ;; Give `rfc822-address-start' a non-nil initial value to
            ;; prevent `rfc822-bad-address' from raising a
            ;; `wrong-type-argument' error.
            (let* ((rfc822-address-start (point))
                   list tem
                   (err
                    (catch 'address
                      ;; Note that `rfc822-nuke-whitespace' and
                      ;; `rfc822-looking-at' can throw.
                      (rfc822-nuke-whitespace)
                      (while (not (eobp))
                        (setq rfc822-address-start (point))
                        (setq tem
                              (cond ((rfc822-looking-at ?\,)
                                     nil)
                                    ((looking-at "[][\000-\037@;:\\.>)]")
                                     (forward-char)
                                     (catch 'address ; For rfc822-bad-address
                                       (rfc822-bad-address
                                        (format "Strange character \\%c found"
                                                (preceding-char)))))
                                    (t
                                     (rfc822-addresses-1 t))))
                        (cond ((null tem))
                              ((stringp tem)
                               (setq list (cons tem list)))
                              (t
                               (setq list (nconc (nreverse tem) list)))))
                      nil)))
              (nreverse (append (if err (list err)) list))))
        (and buf (kill-buffer buf))))))

(provide 'rfc822)

;;; rfc822.el ends here