lisp/gnus-nocem.el

   1 ;;; gnus-nocem.el --- NoCeM pseudo-cancellation treatment
   2 ;; Copyright (C) 1995,96 Free Software Foundation, Inc.
   3
   4 ;; Author: Lars Magne Ingebrigtsen <larsi@ifi.uio.no>
   5 ;; Keywords: news
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software; you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation; either version 2, or (at your option)
  12 ;; any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22 ;; Boston, MA 02111-1307, USA.
  23
  24 ;;; Commentary:
  25
  26 ;;; Code:
  27
  28 (require 'gnus)
  29 (require 'nnmail)
  30 (eval-when-compile (require 'cl))
  31
  32 (defvar gnus-nocem-groups
  33   '("alt.nocem.misc" "news.admin.net-abuse.announce")
  34   "*List of groups that will be searched for NoCeM messages.")
  35
  36 (defvar gnus-nocem-issuers
  37   '("Automoose-1" ; The CancelMoose[tm] on autopilot.
  38     "clewis@ferret.ocunix.on.ca;" ; Chris Lewis -- Canadian angel & despammer.
  39     "jem@xpat.com;"  ; John Milburn -- despammer in Korea.
  40     "red@redpoll.mrfs.oh.us (Richard E. Depew)" ; Spew/bincancel guy.
  41     )
  42   "*List of NoCeM issuers to pay attention to.")
  43
  44 (defvar gnus-nocem-directory
  45   (concat (file-name-as-directory gnus-article-save-directory) "NoCeM/")
  46   "*Directory where NoCeM files will be stored.")
  47
  48 (defvar gnus-nocem-expiry-wait 15
  49   "*Number of days to keep NoCeM headers in the cache.")
  50
  51 (defvar gnus-nocem-verifyer nil
  52   "*Function called to verify that the NoCeM message is valid.
  53 One likely value is `mc-verify'.  If the function in this variable
  54 isn't bound, the message will be used unconditionally.")
  55
  56 ;;; Internal variables
  57
  58 (defvar gnus-nocem-active nil)
  59 (defvar gnus-nocem-alist nil)
  60 (defvar gnus-nocem-touched-alist nil)
  61 (defvar gnus-nocem-hashtb nil)
  62
  63 ;;; Functions
  64
  65 (defun gnus-nocem-active-file ()
  66   (concat (file-name-as-directory gnus-nocem-directory) "active"))
  67
  68 (defun gnus-nocem-cache-file ()
  69   (concat (file-name-as-directory gnus-nocem-directory) "cache"))
  70
  71 (defun gnus-nocem-scan-groups ()
  72   "Scan all NoCeM groups for new NoCeM messages."
  73   (interactive)
  74   (let ((groups gnus-nocem-groups)
  75         group active gactive articles)
  76     (or (file-exists-p gnus-nocem-directory)
  77         (make-directory gnus-nocem-directory t))
  78     ;; Load any previous NoCeM headers.
  79     (gnus-nocem-load-cache)
  80     ;; Read the active file if it hasn't been read yet.
  81     (and (file-exists-p (gnus-nocem-active-file))
  82          (not gnus-nocem-active)
  83          (condition-case ()
  84              (load (gnus-nocem-active-file) t t t)
  85            (error nil)))
  86     ;; Go through all groups and see whether new articles have
  87     ;; arrived.
  88     (while (setq group (pop groups))
  89       (if (not (setq gactive (gnus-activate-group group)))
  90           () ; This group doesn't exist.
  91         (setq active (nth 1 (assoc group gnus-nocem-active)))
  92         (when (and (not (< (cdr gactive) (car gactive))) ; Empty group.
  93                    (or (not active)
  94                        (< (cdr active) (cdr gactive))))
  95           ;; Ok, there are new articles in this group, se we fetch the
  96           ;; headers.
  97           (save-excursion
  98             (let ((dependencies (make-vector 10 nil))
  99                   (buffer (nnheader-set-temp-buffer " *Gnus NoCeM*"))
 100                   headers)
 101               (setq headers
 102                     (if (eq 'nov
 103                             (gnus-retrieve-headers
 104                              (setq articles
 105                                    (gnus-uncompress-range
 106                                     (cons
 107                                      (if active (1+ (cdr active))
 108                                        (car gactive))
 109                                      (cdr gactive))))
 110                              group))
 111                         (gnus-get-newsgroup-headers-xover
 112                          articles nil dependencies)
 113                       (gnus-get-newsgroup-headers dependencies)))
 114               (while headers
 115                 ;; We take a closer look on all articles that have
 116                 ;; "@@NCM" in the subject.
 117                 (when (string-match "@@NCM"
 118                                     (mail-header-subject (car headers)))
 119                   (gnus-nocem-check-article group (car headers)))
 120                 (setq headers (cdr headers)))
 121               (kill-buffer (current-buffer)))))
 122         (setq gnus-nocem-active
 123               (cons (list group gactive)
 124                     (delq (assoc group gnus-nocem-active)
 125                           gnus-nocem-active)))))
 126     ;; Save the results, if any.
 127     (gnus-nocem-save-cache)
 128     (gnus-nocem-save-active)))
 129
 130 (defun gnus-nocem-check-article (group header)
 131   "Check whether the current article is an NCM article and that we want it."
 132   ;; Get the article.
 133   (gnus-message 7 "Checking article %d in %s for NoCeM..."
 134                 (mail-header-number header) group)
 135   (let ((date (mail-header-date header))
 136         issuer b e)
 137     (when (or (not date)
 138               (nnmail-time-less
 139                (nnmail-time-since (nnmail-date-to-time date))
 140                (nnmail-days-to-time gnus-nocem-expiry-wait)))
 141       (gnus-request-article-this-buffer (mail-header-number header) group)
 142       (goto-char (point-min))
 143       ;; The article has to have proper NoCeM headers.
 144       (when (and (setq b (search-forward "\n@@BEGIN NCM HEADERS\n" nil t))
 145                  (setq e (search-forward "\n@@BEGIN NCM BODY\n" nil t)))
 146         ;; We get the name of the issuer.
 147         (narrow-to-region b e)
 148         (setq issuer (mail-fetch-field "issuer"))
 149         (and (member issuer gnus-nocem-issuers) ; We like her...
 150              (gnus-nocem-verify-issuer issuer) ; She is who she says she is..
 151              (gnus-nocem-enter-article)))))) ; We gobble the message.
 152
 153 (defun gnus-nocem-verify-issuer (person)
 154   "Verify using PGP that the canceler is who she says she is."
 155   (widen)
 156   (if (fboundp gnus-nocem-verifyer)
 157       (funcall gnus-nocem-verifyer)
 158     ;; If we don't have MailCrypt, then we use the message anyway.
 159     t))
 160
 161 (defun gnus-nocem-enter-article ()
 162   "Enter the current article into the NoCeM cache."
 163   (goto-char (point-min))
 164   (let ((b (search-forward "\n@@BEGIN NCM BODY\n" nil t))
 165         (e (search-forward "\n@@END NCM BODY\n" nil t))
 166         (buf (current-buffer))
 167         ncm id)
 168     (when (and b e)
 169       (narrow-to-region b (1+ (match-beginning 0)))
 170       (goto-char (point-min))
 171       (while (search-forward "\t" nil t)
 172         (when (condition-case nil
 173                   (boundp (let ((obarray gnus-active-hashtb)) (read buf)))
 174                 (error nil))
 175           (beginning-of-line)
 176           (while (= (following-char) ?\t)
 177             (forward-line -1))
 178           (setq id (buffer-substring (point) (1- (search-forward "\t"))))
 179           (push id ncm)
 180           (gnus-sethash id t gnus-nocem-hashtb)
 181           (forward-line 1)
 182           (while (= (following-char) ?\t)
 183             (forward-line 1))))
 184       (when ncm
 185         (setq gnus-nocem-touched-alist t)
 186         (push (cons (let ((time (current-time))) (setcdr (cdr time) nil) time)
 187                     ncm)
 188               gnus-nocem-alist)))))
 189
 190 (defun gnus-nocem-load-cache ()
 191   "Load the NoCeM cache."
 192   (unless gnus-nocem-alist
 193     ;; The buffer doesn't exist, so we create it and load the NoCeM
 194     ;; cache.
 195     (when (file-exists-p (gnus-nocem-cache-file))
 196       (load (gnus-nocem-cache-file) t t t)
 197       (gnus-nocem-alist-to-hashtb))))
 198
 199 (defun gnus-nocem-save-cache ()
 200   "Save the NoCeM cache."
 201   (when (and gnus-nocem-alist
 202              gnus-nocem-touched-alist)
 203     (nnheader-temp-write (gnus-nocem-cache-file)
 204       (prin1 `(setq gnus-nocem-alist ',gnus-nocem-alist) (current-buffer)))
 205     (setq gnus-nocem-touched-alist nil)))
 206
 207 (defun gnus-nocem-save-active ()
 208   "Save the NoCeM active file."
 209   (nnheader-temp-write (gnus-nocem-active-file)
 210     (prin1 `(setq gnus-nocem-active ',gnus-nocem-active) (current-buffer))))
 211
 212 (defun gnus-nocem-alist-to-hashtb ()
 213   "Create a hashtable from the Message-IDs we have."
 214   (let* ((alist gnus-nocem-alist)
 215          (pprev (cons nil alist))
 216          (prev pprev)
 217          (expiry (nnmail-days-to-time gnus-nocem-expiry-wait))
 218          entry)
 219     (setq gnus-nocem-hashtb (gnus-make-hashtable (* (length alist) 51)))
 220     (while (setq entry (car alist))
 221       (if (not (nnmail-time-less (nnmail-time-since (car entry)) expiry))
 222           ;; This entry has expired, so we remove it.
 223           (setcdr prev (cdr alist))
 224         (setq prev alist)
 225         ;; This is ok, so we enter it into the hashtable.
 226         (setq entry (cdr entry))
 227         (while entry
 228           (gnus-sethash (car entry) t gnus-nocem-hashtb)
 229           (setq entry (cdr entry))))
 230       (setq alist (cdr alist)))))
 231
 232 (gnus-add-shutdown 'gnus-nocem-close 'gnus)
 233
 234 (defun gnus-nocem-close ()
 235   "Clear internal NoCeM variables."
 236   (setq gnus-nocem-alist nil
 237         gnus-nocem-hashtb nil
 238         gnus-nocem-active nil
 239         gnus-nocem-touched-alist nil))
 240
 241 (defun gnus-nocem-unwanted-article-p (id)
 242   "Say whether article ID in the current group is wanted."
 243   (gnus-gethash id gnus-nocem-hashtb))
 244
 245 (provide 'gnus-nocem)
 246
 247 ;;; gnus-nocem.el ends here