1;;; gnus-nocem.el --- NoCeM pseudo-cancellation treatment
2
3;; Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 Free Software Foundation, Inc.
5
6;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
7;; Keywords: news
8
9;; This file is part of GNU Emacs.
10
11;; GNU Emacs is free software; you can redistribute it and/or modify
12;; it under the terms of the GNU General Public License as published by
13;; the Free Software Foundation; either version 2, or (at your option)
14;; any later version.
15
16;; GNU Emacs is distributed in the hope that it will be useful,
17;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19;; GNU General Public License for more details.
20
21;; You should have received a copy of the GNU General Public License
22;; along with GNU Emacs; see the file COPYING.  If not, write to the
23;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24;; Boston, MA 02110-1301, USA.
25
26;;; Commentary:
27
28;;; Code:
29
30(eval-when-compile (require 'cl))
31
32(require 'gnus)
33(require 'nnmail)
34(require 'gnus-art)
35(require 'gnus-sum)
36(require 'gnus-range)
37
38(defgroup gnus-nocem nil
39  "NoCeM pseudo-cancellation treatment."
40  :group 'gnus-score)
41
42(defcustom gnus-nocem-groups
43  '("news.lists.filters" "news.admin.net-abuse.bulletins"
44    "alt.nocem.misc" "news.admin.net-abuse.announce")
45  "*List of groups that will be searched for NoCeM messages."
46  :group 'gnus-nocem
47  :type '(repeat (string :tag "Group")))
48
49(defcustom gnus-nocem-issuers
50  '("AutoMoose-1"			; CancelMoose[tm]
51    "clewis@ferret.ocunix"		; Chris Lewis
52    "cosmo.roadkill"
53    "SpamHippo"
54    "hweede@snafu.de")
55  "*List of NoCeM issuers to pay attention to.
56
57This can also be a list of `(ISSUER CONDITION ...)' elements.
58
59See <URL:http://www.xs4all.nl/~rosalind/nocemreg/nocemreg.html> for an
60issuer registry."
61  :group 'gnus-nocem
62  :link '(url-link "http://www.xs4all.nl/~rosalind/nocemreg/nocemreg.html")
63  :type '(repeat (choice string sexp)))
64
65(defcustom gnus-nocem-directory
66  (nnheader-concat gnus-article-save-directory "NoCeM/")
67  "*Directory where NoCeM files will be stored."
68  :group 'gnus-nocem
69  :type 'directory)
70
71(defcustom gnus-nocem-expiry-wait 15
72  "*Number of days to keep NoCeM headers in the cache."
73  :group 'gnus-nocem
74  :type 'integer)
75
76(defcustom gnus-nocem-verifyer 'pgg-verify
77  "*Function called to verify that the NoCeM message is valid.
78One likely value is `pgg-verify'.  If the function in this variable
79isn't bound, the message will be used unconditionally."
80  :group 'gnus-nocem
81  :type '(radio (function-item pgg-verify)
82		(function-item mc-verify)
83		(function :tag "other")))
84
85(defcustom gnus-nocem-liberal-fetch nil
86  "*If t try to fetch all messages which have @@NCM in the subject.
87Otherwise don't fetch messages which have references or whose message-id
88matches a previously scanned and verified nocem message."
89  :group 'gnus-nocem
90  :type 'boolean)
91
92(defcustom gnus-nocem-check-article-limit 500
93  "*If non-nil, the maximum number of articles to check in any NoCeM group."
94  :group 'gnus-nocem
95  :version "21.1"
96  :type '(choice (const :tag "unlimited" nil)
97		 (integer 1000)))
98
99(defcustom gnus-nocem-check-from t
100  "Non-nil means check for valid issuers in message bodies.
101Otherwise don't bother fetching articles unless their author matches a
102valid issuer, which is much faster if you are selective about the issuers."
103  :group 'gnus-nocem
104  :version "21.1"
105  :type 'boolean)
106
107;;; Internal variables
108
109(defvar gnus-nocem-active nil)
110(defvar gnus-nocem-alist nil)
111(defvar gnus-nocem-touched-alist nil)
112(defvar gnus-nocem-hashtb nil)
113(defvar gnus-nocem-seen-message-ids nil)
114
115;;; Functions
116
117(defun gnus-nocem-active-file ()
118  (concat (file-name-as-directory gnus-nocem-directory) "active"))
119
120(defun gnus-nocem-cache-file ()
121  (concat (file-name-as-directory gnus-nocem-directory) "cache"))
122
123;;
124;; faster lookups for group names:
125;;
126
127(defvar gnus-nocem-real-group-hashtb nil
128  "Real-name mappings of subscribed groups.")
129
130(defun gnus-fill-real-hashtb ()
131  "Fill up a hash table with the real-name mappings from the user's active file."
132  (setq gnus-nocem-real-group-hashtb (gnus-make-hashtable
133				      (length gnus-newsrc-alist)))
134  (mapcar (lambda (group)
135	    (setq group (gnus-group-real-name (car group)))
136	    (gnus-sethash group t gnus-nocem-real-group-hashtb))
137	  gnus-newsrc-alist))
138
139;;;###autoload
140(defun gnus-nocem-scan-groups ()
141  "Scan all NoCeM groups for new NoCeM messages."
142  (interactive)
143  (let ((groups gnus-nocem-groups)
144	(gnus-inhibit-demon t)
145	group active gactive articles check-headers)
146    (gnus-make-directory gnus-nocem-directory)
147    ;; Load any previous NoCeM headers.
148    (gnus-nocem-load-cache)
149    ;; Get the group name mappings:
150    (gnus-fill-real-hashtb)
151    ;; Read the active file if it hasn't been read yet.
152    (and (file-exists-p (gnus-nocem-active-file))
153	 (not gnus-nocem-active)
154	 (ignore-errors
155	   (load (gnus-nocem-active-file) t t t)))
156    ;; Go through all groups and see whether new articles have
157    ;; arrived.
158    (while (setq group (pop groups))
159      (if (not (setq gactive (gnus-activate-group group)))
160	  ()				; This group doesn't exist.
161	(setq active (nth 1 (assoc group gnus-nocem-active)))
162	(when (and (not (< (cdr gactive) (car gactive))) ; Empty group.
163		   (or (not active)
164		       (< (cdr active) (cdr gactive))))
165	  ;; Ok, there are new articles in this group, se we fetch the
166	  ;; headers.
167	  (save-excursion
168	    (let ((dependencies (make-vector 10 nil))
169		  headers header)
170	      (with-temp-buffer
171		(setq headers
172		      (if (eq 'nov
173			      (gnus-retrieve-headers
174			       (setq articles
175				     (gnus-uncompress-range
176				      (cons
177				       (if active (1+ (cdr active))
178					 (car gactive))
179				       (cdr gactive))))
180			       group))
181			  (gnus-get-newsgroup-headers-xover
182			   articles nil dependencies)
183			(gnus-get-newsgroup-headers dependencies)))
184		(while (setq header (pop headers))
185		  ;; We take a closer look on all articles that have
186		  ;; "@@NCM" in the subject.  Unless we already read
187		  ;; this cross posted message.  Nocem messages
188		  ;; are not allowed to have references, so we can
189		  ;; ignore scanning followups.
190		  (and (string-match "@@NCM" (mail-header-subject header))
191		       (and gnus-nocem-check-from
192			    (let ((case-fold-search t))
193			      (catch 'ok
194				(mapcar
195				 (lambda (author)
196				   (if (consp author)
197				       (setq author (car author)))
198				   (if (string-match
199					author (mail-header-from header))
200				       (throw 'ok t)))
201				 gnus-nocem-issuers)
202				nil)))
203		       (or gnus-nocem-liberal-fetch
204			   (and (or (string= "" (mail-header-references
205						 header))
206				    (null (mail-header-references header)))
207				(not (member (mail-header-message-id header)
208					     gnus-nocem-seen-message-ids))))
209		       (push header check-headers)))
210		(setq check-headers (last (nreverse check-headers)
211					  gnus-nocem-check-article-limit))
212		(let ((i 0)
213		      (len (length check-headers)))
214		  (dolist (h check-headers)
215		    (gnus-message
216		     7 "Checking article %d in %s for NoCeM (%d of %d)..."
217		     (mail-header-number h) group (incf i) len)
218		    (gnus-nocem-check-article group h)))))))
219	(setq gnus-nocem-active
220	      (cons (list group gactive)
221		    (delq (assoc group gnus-nocem-active)
222			  gnus-nocem-active)))))
223    ;; Save the results, if any.
224    (gnus-nocem-save-cache)
225    (gnus-nocem-save-active)))
226
227(defun gnus-nocem-check-article (group header)
228  "Check whether the current article is an NCM article and that we want it."
229  ;; Get the article.
230  (let ((date (mail-header-date header))
231	(gnus-newsgroup-name group)
232	issuer b e type)
233    (when (or (not date)
234	      (time-less-p
235	       (time-since (date-to-time date))
236	       (days-to-time gnus-nocem-expiry-wait)))
237      (gnus-request-article-this-buffer (mail-header-number header) group)
238      (goto-char (point-min))
239      (when (re-search-forward
240	     "-----BEGIN PGP\\( SIGNED\\)? MESSAGE-----"
241	     nil t)
242	(delete-region (point-min) (match-beginning 0)))
243      (when (re-search-forward
244	     "-----END PGP \\(MESSAGE\\|SIGNATURE\\)-----\n?"
245	     nil t)
246	(delete-region (match-end 0) (point-max)))
247      (goto-char (point-min))
248      ;; The article has to have proper NoCeM headers.
249      (when (and (setq b (search-forward "\n@@BEGIN NCM HEADERS\n" nil t))
250		 (setq e (search-forward "\n@@BEGIN NCM BODY\n" nil t)))
251	;; We get the name of the issuer.
252	(narrow-to-region b e)
253	(setq issuer (mail-fetch-field "issuer")
254	      type (mail-fetch-field "type"))
255	(widen)
256	(if (not (gnus-nocem-message-wanted-p issuer type))
257	    (message "invalid NoCeM issuer: %s" issuer)
258	  (and (gnus-nocem-verify-issuer issuer) ; She is who she says she is.
259	       (gnus-nocem-enter-article) ; We gobble the message.
260	       (push (mail-header-message-id header) ; But don't come back for
261		     gnus-nocem-seen-message-ids))))))) ; second helpings.
262
263(defun gnus-nocem-message-wanted-p (issuer type)
264  (let ((issuers gnus-nocem-issuers)
265	wanted conditions condition)
266    (cond
267     ;; Do the quick check first.
268     ((member issuer issuers)
269      t)
270     ((setq conditions (cdr (assoc issuer issuers)))
271      ;; Check whether we want this type.
272      (while (setq condition (pop conditions))
273	(cond
274	 ((stringp condition)
275	  (when (string-match condition type)
276	    (setq wanted t)))
277	 ((and (consp condition)
278	       (eq (car condition) 'not)
279	       (stringp (cadr condition)))
280	  (when (string-match (cadr condition) type)
281	    (setq wanted nil)))
282	 (t
283	  (error "Invalid NoCeM condition: %S" condition))))
284      wanted))))
285
286(defun gnus-nocem-verify-issuer (person)
287  "Verify using PGP that the canceler is who she says she is."
288  (if (functionp gnus-nocem-verifyer)
289      (ignore-errors
290	(funcall gnus-nocem-verifyer))
291    ;; If we don't have Mailcrypt, then we use the message anyway.
292    t))
293
294(defun gnus-nocem-enter-article ()
295  "Enter the current article into the NoCeM cache."
296  (goto-char (point-min))
297  (let ((b (search-forward "\n@@BEGIN NCM BODY\n" nil t))
298	(e (search-forward "\n@@END NCM BODY\n" nil t))
299	(buf (current-buffer))
300	ncm id group)
301    (when (and b e)
302      (narrow-to-region b (1+ (match-beginning 0)))
303      (goto-char (point-min))
304      (while (search-forward "\t" nil t)
305	(cond
306	 ((not (ignore-errors
307		 (setq group (let ((obarray gnus-nocem-real-group-hashtb))
308			       (read buf)))))
309	  ;; An error.
310	  )
311	 ((not (symbolp group))
312	  ;; Ignore invalid entries.
313	  )
314	 ((not (boundp group))
315	  ;; Make sure all entries in the hashtb are bound.
316	  (set group nil))
317	 (t
318	  (when (gnus-gethash (gnus-group-real-name (symbol-name group))
319			      gnus-nocem-real-group-hashtb)
320	    ;; Valid group.
321	    (beginning-of-line)
322	    (while (eq (char-after) ?\t)
323	      (forward-line -1))
324	    (setq id (buffer-substring (point) (1- (search-forward "\t"))))
325	    (unless (if gnus-nocem-hashtb
326			(gnus-gethash id gnus-nocem-hashtb)
327		      (setq gnus-nocem-hashtb (gnus-make-hashtable))
328		      nil)
329	      ;; only store if not already present
330	      (gnus-sethash id t gnus-nocem-hashtb)
331	      (push id ncm))
332	    (forward-line 1)
333	    (while (eq (char-after) ?\t)
334	      (forward-line 1))))))
335      (when ncm
336	(setq gnus-nocem-touched-alist t)
337	(push (cons (let ((time (current-time))) (setcdr (cdr time) nil) time)
338		    ncm)
339	      gnus-nocem-alist))
340      t)))
341
342;;;###autoload
343(defun gnus-nocem-load-cache ()
344  "Load the NoCeM cache."
345  (interactive)
346  (unless gnus-nocem-alist
347    ;; The buffer doesn't exist, so we create it and load the NoCeM
348    ;; cache.
349    (when (file-exists-p (gnus-nocem-cache-file))
350      (load (gnus-nocem-cache-file) t t t)
351      (gnus-nocem-alist-to-hashtb))))
352
353(defun gnus-nocem-save-cache ()
354  "Save the NoCeM cache."
355  (when (and gnus-nocem-alist
356	     gnus-nocem-touched-alist)
357    (with-temp-file (gnus-nocem-cache-file)
358      (gnus-prin1 `(setq gnus-nocem-alist ',gnus-nocem-alist)))
359    (setq gnus-nocem-touched-alist nil)))
360
361(defun gnus-nocem-save-active ()
362  "Save the NoCeM active file."
363  (with-temp-file (gnus-nocem-active-file)
364    (gnus-prin1 `(setq gnus-nocem-active ',gnus-nocem-active))))
365
366(defun gnus-nocem-alist-to-hashtb ()
367  "Create a hashtable from the Message-IDs we have."
368  (let* ((alist gnus-nocem-alist)
369	 (pprev (cons nil alist))
370	 (prev pprev)
371	 (expiry (days-to-time gnus-nocem-expiry-wait))
372	 entry)
373    (setq gnus-nocem-hashtb (gnus-make-hashtable (* (length alist) 51)))
374    (while (setq entry (car alist))
375      (if (not (time-less-p (time-since (car entry)) expiry))
376	  ;; This entry has expired, so we remove it.
377	  (setcdr prev (cdr alist))
378	(setq prev alist)
379	;; This is ok, so we enter it into the hashtable.
380	(setq entry (cdr entry))
381	(while entry
382	  (gnus-sethash (car entry) t gnus-nocem-hashtb)
383	  (setq entry (cdr entry))))
384      (setq alist (cdr alist)))))
385
386(gnus-add-shutdown 'gnus-nocem-close 'gnus)
387
388(defun gnus-nocem-close ()
389  "Clear internal NoCeM variables."
390  (setq gnus-nocem-alist nil
391	gnus-nocem-hashtb nil
392	gnus-nocem-active nil
393	gnus-nocem-touched-alist nil
394	gnus-nocem-seen-message-ids nil
395	gnus-nocem-real-group-hashtb nil))
396
397(defun gnus-nocem-unwanted-article-p (id)
398  "Say whether article ID in the current group is wanted."
399  (and gnus-nocem-hashtb
400       (gnus-gethash id gnus-nocem-hashtb)))
401
402(provide 'gnus-nocem)
403
404;;; arch-tag: 0e0c74ea-2f8e-4f3e-8fff-09f767c1adef
405;;; gnus-nocem.el ends here
406