1 ;;; proto-stream.el --- negotiating TLS, STARTTLS and other connections
3 ;; Copyright (C) 2010-2011 Free Software Foundation, Inc.
5 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software: you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation, either version 3 of the License, or
13 ;; (at your option) any later version.
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
25 ;; This library is meant to provide the glue between modules that want
26 ;; to establish a network connection to a server for protocols such as
27 ;; IMAP, NNTP, SMTP and POP3.
29 ;; The main problem is that there's more than a couple of interfaces
30 ;; towards doing this. You have normal, plain connections, which are
31 ;; no trouble at all, but you also have TLS/SSL connections, and you
32 ;; have STARTTLS. Negotiating this for each protocol can be rather
33 ;; tedious, so this library provides a single entry point, and hides
34 ;; much of the ugliness.
38 ;; (open-protocol-stream
39 ;; "*nnimap*" buffer address port
41 ;; :capability-command "1 CAPABILITY\r\n"
44 ;; (lambda (capabilities)
45 ;; (if (not (string-match "STARTTLS" capabilities))
47 ;; "1 STARTTLS\r\n")))
55 (require 'format-spec)
57 (defcustom proto-stream-always-use-starttls (fboundp 'open-gnutls-stream)
58 "If non-nil, always try to upgrade network connections with STARTTLS."
63 (declare-function gnutls-negotiate "gnutls"
64 (proc type &optional priority-string trustfiles keyfiles))
67 (defun open-protocol-stream (name buffer host service &rest parameters)
68 "Open a network stream to HOST, upgrading to STARTTLS if possible.
69 The first four parameters have the same meaning as in
70 `open-network-stream'. The function returns a list where the
71 first element is the stream, the second element is the greeting
72 the server replied with after connecting, and the third element
73 is a string representing the capabilities of the server (if any).
75 The PARAMETERS is a keyword list that can have the following
78 :type -- either `network', `network-only, `tls', `shell' or
79 `starttls'. If omitted, the default is `network'. `network'
80 will be opportunistically upgraded to STARTTLS if both the server
81 and Emacs supports it. If you don't want STARTTLS upgrades, use
84 :end-of-command -- a regexp saying what the end of a command is.
85 This defaults to \"\\n\".
87 :success -- a regexp saying whether the STARTTLS command was
88 successful or not. For instance, for NNTP this is \"^3\".
90 :capability-command -- a string representing the command used to
91 query server for capabilities. For instance, for IMAP this is
92 \"1 CAPABILITY\\r\\n\".
94 :starttls-function -- a function that takes one parameter, which
95 is the response to the capaibility command. It should return nil
96 if it turns out that the server doesn't support STARTTLS, or the
97 command to switch on STARTTLS otherwise."
98 (let ((type (or (cadr (memq :type parameters)) 'network)))
101 (setq type 'network))
105 (funcall (intern (format "proto-stream-open-%s" type) obarray)
106 name buffer host service parameters)))
107 (if (null open-result)
108 (list nil nil nil type)
109 (let ((stream (car open-result)))
111 (memq (process-status stream)
116 (nth 3 open-result)))))))
118 (defun proto-stream-open-network-only (name buffer host service parameters)
119 (let ((start (with-current-buffer buffer (point)))
120 (stream (open-network-stream name buffer host service)))
122 (proto-stream-get-response
123 stream start (proto-stream-eoc parameters))
127 (defun proto-stream-open-network (name buffer host service parameters)
128 (let* ((start (with-current-buffer buffer (point)))
129 (stream (open-network-stream name buffer host service))
130 (capability-command (cadr (memq :capability-command parameters)))
131 (eoc (proto-stream-eoc parameters))
132 (type (cadr (memq :type parameters)))
133 (greeting (proto-stream-get-response stream start eoc))
135 (if (not capability-command)
136 (list stream greeting nil 'network)
138 (proto-stream-command stream capability-command eoc))
140 (funcall (cadr (memq :starttls-function parameters))
143 ;; If this server doesn't support STARTTLS, but we have
144 ;; requested it explicitly, then close the connection and
146 ((or (not starttls-command)
147 (and (not (eq type 'starttls))
148 (not proto-stream-always-use-starttls)))
149 (if (eq type 'starttls)
151 (delete-process stream)
153 ;; Otherwise, just return this plain network connection.
154 (list stream greeting capabilities 'network)))
155 ;; We have some kind of STARTTLS support, so we try to
156 ;; upgrade the connection opportunistically.
157 ((or (fboundp 'open-gnutls-stream)
158 (executable-find "gnutls-cli"))
159 (unless (fboundp 'open-gnutls-stream)
160 (delete-process stream)
161 (setq start (with-current-buffer buffer (point-max)))
162 (let* ((starttls-use-gnutls t)
163 (starttls-extra-arguments
164 (if (not (eq type 'starttls))
165 ;; When doing opportunistic TLS upgrades we
166 ;; don't really care about the identity of the
168 (cons "--insecure" starttls-extra-arguments)
169 starttls-extra-arguments)))
170 (setq stream (starttls-open-stream name buffer host service)))
171 (proto-stream-get-response stream start eoc))
174 (cadr (memq :success parameters))
175 (proto-stream-command stream starttls-command eoc)))
176 ;; We got an error back from the STARTTLS command.
178 (if (eq type 'starttls)
180 (delete-process stream)
182 (list stream greeting capabilities 'network)))
183 ;; The server said it was OK to start doing STARTTLS negotiations.
184 (if (fboundp 'open-gnutls-stream)
185 (gnutls-negotiate stream nil)
186 (unless (starttls-negotiate stream)
187 (delete-process stream)
189 (when (or (null stream)
190 (not (memq (process-status stream)
192 ;; It didn't successfully negotiate STARTTLS, so we reopen
194 (setq stream (open-network-stream name buffer host service))
195 (proto-stream-get-response stream start eoc))
196 ;; Re-get the capabilities, since they may have changed
197 ;; after switching to TLS.
198 (list stream greeting
199 (proto-stream-command stream capability-command eoc) 'tls)))
200 ;; We don't have STARTTLS support available, but the caller
201 ;; requested a STARTTLS connection, so we give up.
202 ((eq (cadr (memq :type parameters)) 'starttls)
203 (delete-process stream)
205 ;; Fall back on using a plain network stream.
207 (list stream greeting capabilities 'network)))))))
209 (defun proto-stream-command (stream command eoc)
210 (let ((start (with-current-buffer (process-buffer stream) (point-max))))
211 (process-send-string stream command)
212 (proto-stream-get-response stream start eoc)))
214 (defun proto-stream-get-response (stream start end-of-command)
215 (with-current-buffer (process-buffer stream)
218 (while (and (memq (process-status stream)
220 (not (re-search-forward end-of-command nil t)))
221 (accept-process-output stream 0 50)
223 (if (= start (point))
224 ;; The process died; return nil.
226 ;; Return the data we got back.
227 (buffer-substring start (point))))))
229 (defun proto-stream-open-tls (name buffer host service parameters)
230 (with-current-buffer buffer
231 (let ((start (point-max))
233 (funcall (if (fboundp 'open-gnutls-stream)
236 name buffer host service)))
239 ;; If we're using tls.el, we have to delete the output from
240 ;; openssl/gnutls-cli.
241 (unless (fboundp 'open-gnutls-stream)
242 (proto-stream-get-response
243 stream start (proto-stream-eoc parameters))
244 (goto-char (point-min))
245 (when (re-search-forward (proto-stream-eoc parameters) nil t)
246 (goto-char (match-beginning 0))
247 (delete-region (point-min) (line-beginning-position))))
248 (proto-stream-capability-open start stream parameters 'tls)))))
250 (defun proto-stream-open-shell (name buffer host service parameters)
251 (proto-stream-capability-open
252 (with-current-buffer buffer (point))
253 (let ((process-connection-type nil))
254 (start-process name buffer shell-file-name
257 (cadr (memq :shell-command parameters))
261 parameters 'network))
263 (defun proto-stream-capability-open (start stream parameters stream-type)
264 (let ((capability-command (cadr (memq :capability-command parameters)))
265 (greeting (proto-stream-get-response
266 stream start (proto-stream-eoc parameters))))
267 (list stream greeting
268 (and capability-command
269 (proto-stream-command
270 stream capability-command (proto-stream-eoc parameters)))
273 (defun proto-stream-eoc (parameters)
274 (or (cadr (memq :end-of-command parameters))
277 (provide 'proto-stream)
279 ;;; proto-stream.el ends here