Revision: miles@gnu.org--gnu-2004/emacs--cvs-trunk--0--patch-523

Merge from emacs--gnus--5.10, gnus--rel--5.10

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 * miles@gnu.org--gnu-2004/emacs--gnus--5.10--base-0
   tag of miles@gnu.org--gnu-2004/emacs--cvs-trunk--0--patch-464

 * miles@gnu.org--gnu-2004/emacs--gnus--5.10--patch-1
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 * miles@gnu.org--gnu-2004/emacs--gnus--5.10--patch-2
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 * miles@gnu.org--gnu-2004/emacs--gnus--5.10--patch-3
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 * miles@gnu.org--gnu-2004/emacs--gnus--5.10--patch-4
   Merge from gnus--rel--5.10

 * miles@gnu.org--gnu-2004/gnus--rel--5.10--patch-18
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1 files changed, 251 insertions, 0 deletions

diff --git a/lisp/gnus/canlock.el b/lisp/gnus/canlock.el
new file mode 100644
index 00000000000..99d6500001a
--- /dev/null
+++ b/lisp/gnus/canlock.el
@@ -0,0 +1,251 @@
+;;; canlock.el --- functions for Cancel-Lock feature
+
+;; Copyright (C) 1998, 1999, 2001, 2002, 2003, 2004
+;;        Free Software Foundation, Inc.
+
+;; Author: Katsumi Yamaoka <yamaoka@jpl.org>
+;; Keywords: news, cancel-lock, hmac, sha1, rfc2104
+
+;; This program 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 2, or (at your option)
+;; any later version.
+
+;; This program 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 this program; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;; Canlock is a library for generating and verifying Cancel-Lock and/or
+;; Cancel-Key header in news articles.  This is used to protect articles
+;; from rogue cancel, supersede or replace attacks.  The method is based
+;; on draft-ietf-usefor-cancel-lock-01.txt which was released on November
+;; 3rd 1998.  For instance, you can add Cancel-Lock (and possibly Cancel-
+;; Key) header in a news article by using a hook which will be evaluated
+;; just before sending an article as follows:
+;;
+;; (add-hook '*e**a*e-header-hook 'canlock-insert-header t)
+;;
+;; Verifying Cancel-Lock is mainly a function of news servers, however,
+;; you can verify your own article using the command `canlock-verify' in
+;; the (raw) article buffer.  You will be prompted for the password for
+;; each time if the option `canlock-password' or `canlock-password-for-
+;; verify' is nil.  Note that setting these options is a bit unsafe.
+
+;;; Code:
+
+(eval-when-compile
+  (require 'cl))
+
+(require 'sha1)
+
+(defvar mail-header-separator)
+
+(defgroup canlock nil
+  "The Cancel-Lock feature."
+  :group 'applications)
+
+(defcustom canlock-password nil
+  "Password to use when signing a Cancel-Lock or a Cancel-Key header."
+  :type '(radio (const :format "Not specified " nil)
+		(string :tag "Password" :size 0))
+  :group 'canlock)
+
+(defcustom canlock-password-for-verify canlock-password
+  "Password to use when verifying a Cancel-Lock or a Cancel-Key header."
+  :type '(radio (const :format "Not specified " nil)
+		(string :tag "Password" :size 0))
+  :group 'canlock)
+
+(defcustom canlock-force-insert-header nil
+  "If non-nil, insert a Cancel-Lock or a Cancel-Key header even if the
+buffer does not look like a news message."
+  :type 'boolean
+  :group 'canlock)
+
+(eval-when-compile
+  (defmacro canlock-string-as-unibyte (string)
+    "Return a unibyte string with the same individual bytes as STRING."
+    (if (fboundp 'string-as-unibyte)
+	(list 'string-as-unibyte string)
+      string)))
+
+(defun canlock-sha1 (message)
+  "Make a SHA-1 digest of MESSAGE as a unibyte string of length 20 bytes."
+  (let (sha1-maximum-internal-length)
+    (sha1 message nil nil 'binary)))
+
+(defun canlock-make-cancel-key (message-id password)
+  "Make a Cancel-Key header."
+  (when (> (length password) 20)
+    (setq password (canlock-sha1 password)))
+  (setq password (concat password (make-string (- 64 (length password)) 0)))
+  (let ((ipad (mapconcat (lambda (byte)
+			   (char-to-string (logxor 54 byte)))
+			 password ""))
+	(opad (mapconcat (lambda (byte)
+			   (char-to-string (logxor 92 byte)))
+			 password "")))
+    (base64-encode-string
+     (canlock-sha1
+      (concat opad
+	      (canlock-sha1
+	       (concat ipad (canlock-string-as-unibyte message-id))))))))
+
+(defun canlock-narrow-to-header ()
+  "Narrow the buffer to the head of the message."
+  (let (case-fold-search)
+    (narrow-to-region
+     (goto-char (point-min))
+     (goto-char (if (re-search-forward
+		     (format "^$\\|^%s$"
+			     (regexp-quote mail-header-separator))
+		     nil t)
+		    (match-beginning 0)
+		  (point-max))))))
+
+(defun canlock-delete-headers ()
+  "Delete Cancel-Key or Cancel-Lock headers in the narrowed buffer."
+  (let ((case-fold-search t))
+    (goto-char (point-min))
+    (while (re-search-forward "^Cancel-\\(Key\\|Lock\\):" nil t)
+      (delete-region (match-beginning 0)
+		     (if (re-search-forward "^[^\t ]" nil t)
+			 (goto-char (match-beginning 0))
+		       (point-max))))))
+
+(defun canlock-fetch-fields (&optional key)
+  "Return a list of the values of Cancel-Lock header.
+If KEY is non-nil, look for a Cancel-Key header instead.  The buffer
+is expected to be narrowed to just the headers of the message."
+  (let ((field (mail-fetch-field (if key "Cancel-Key" "Cancel-Lock")))
+	fields rest
+	(case-fold-search t))
+    (when field
+      (setq fields (split-string field "[\t\n\r ,]+"))
+      (while fields
+	(when (string-match "^sha1:" (setq field (pop fields)))
+	  (push (substring field 5) rest)))
+      (nreverse rest))))
+
+(defun canlock-fetch-id-for-key ()
+  "Return a Message-ID in Cancel, Supersedes or Replaces header.
+The buffer is expected to be narrowed to just the headers of the
+message."
+  (or (let ((cancel (mail-fetch-field "Control")))
+	(and cancel
+	     (string-match "^cancel[\t ]+\\(<[^\t\n @<>]+@[^\t\n @<>]+>\\)"
+			   cancel)
+	     (match-string 1 cancel)))
+      (mail-fetch-field "Supersedes")
+      (mail-fetch-field "Replaces")))
+
+;;;###autoload
+(defun canlock-insert-header (&optional id-for-key id-for-lock password)
+  "Insert a Cancel-Key and/or a Cancel-Lock header if possible."
+  (let (news control key-for-key key-for-lock)
+    (save-excursion
+      (save-restriction
+	(canlock-narrow-to-header)
+	(when (setq news (or canlock-force-insert-header
+			     (mail-fetch-field "Newsgroups")))
+	  (unless id-for-key
+	    (setq id-for-key (canlock-fetch-id-for-key)))
+	  (if (and (setq control (mail-fetch-field "Control"))
+		   (string-match "^cancel[\t ]+<[^\t\n @<>]+@[^\t\n @<>]+>"
+				 control))
+	      (setq id-for-lock nil)
+	    (unless id-for-lock
+	      (setq id-for-lock (mail-fetch-field "Message-ID"))))
+	  (canlock-delete-headers)
+	  (goto-char (point-max))))
+      (when news
+	(if (not (or id-for-key id-for-lock))
+	    (message "There are no Message-ID(s)")
+	  (unless password
+	    (setq password (or canlock-password
+			       (read-passwd
+				"Password for Canlock: "))))
+	  (if (or (not (stringp password)) (zerop (length password)))
+	      (message "Password for Canlock is bad")
+	    (setq key-for-key (when id-for-key
+				(canlock-make-cancel-key
+				 id-for-key password))
+		  key-for-lock (when id-for-lock
+				 (canlock-make-cancel-key
+				  id-for-lock password)))
+	    (if (not (or key-for-key key-for-lock))
+		(message "Couldn't insert Canlock header")
+	      (when key-for-key
+		(insert "Cancel-Key: sha1:" key-for-key "\n"))
+	      (when key-for-lock
+		(insert "Cancel-Lock: sha1:"
+			(base64-encode-string (canlock-sha1 key-for-lock))
+			"\n")))))))))
+
+;;;###autoload
+(defun canlock-verify (&optional buffer)
+  "Verify Cancel-Lock or Cancel-Key in BUFFER.
+If BUFFER is nil, the current buffer is assumed.  Signal an error if
+it fails."
+  (interactive)
+  (let (keys locks errmsg id-for-key id-for-lock password
+	     key-for-key key-for-lock match)
+    (save-excursion
+      (when buffer
+	(set-buffer buffer))
+      (save-restriction
+	(widen)
+	(canlock-narrow-to-header)
+	(setq keys (canlock-fetch-fields 'key)
+	      locks (canlock-fetch-fields))
+	(if (not (or keys locks))
+	    (setq errmsg
+		  "There are neither Cancel-Lock nor Cancel-Key headers")
+	  (setq id-for-key (canlock-fetch-id-for-key)
+		id-for-lock (mail-fetch-field "Message-ID"))
+	  (or id-for-key id-for-lock
+	      (setq errmsg "There are no Message-ID(s)")))))
+    (if errmsg
+	(error "%s" errmsg)
+      (setq password (or canlock-password-for-verify
+			 (read-passwd "Password for Canlock: ")))
+      (if (or (not (stringp password)) (zerop (length password)))
+	  (error "Password for Canlock is bad")
+	(when keys
+	  (when id-for-key
+	    (setq key-for-key (canlock-make-cancel-key id-for-key password))
+	    (while (and keys (not match))
+	      (setq match (string-equal key-for-key (pop keys)))))
+	  (setq keys (if match "good" "bad")))
+	(setq match nil)
+	(when locks
+	  (when id-for-lock
+	    (setq key-for-lock
+		  (base64-encode-string
+		   (canlock-sha1 (canlock-make-cancel-key id-for-lock
+							  password))))
+	    (when (and locks (not match))
+	      (setq match (string-equal key-for-lock (pop locks)))))
+	  (setq locks (if match "good" "bad")))
+	(prog1
+	    (when (member "bad" (list keys locks))
+	      "bad")
+	  (cond ((and keys locks)
+		 (message "Cancel-Key is %s, Cancel-Lock is %s" keys locks))
+		(locks
+		 (message "Cancel-Lock is %s" locks))
+		(keys
+		 (message "Cancel-Key is %s" keys))))))))
+
+(provide 'canlock)
+
+;;; arch-tag: 033c4f09-b9f1-459d-bd0d-254430283f78
+;;; canlock.el ends here