1 ;;; proto-stream.el --- negotiating TLS, STARTTLS and other connections
2 ;; Copyright (C) 2010 Free Software Foundation, Inc.
4 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
7 ;; This file is part of GNU Emacs.
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 3, or (at your option)
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.
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., 51 Franklin Street, Fifth Floor,
22 ;; Boston, MA 02110-1301, USA.
26 ;; This library is meant to provide the glue between modules that want
27 ;; to establish a network connection to a server for protocols such as
28 ;; IMAP, NNTP, SMTP and POP3.
30 ;; The main problem is that there's more than a couple of interfaces
31 ;; towards doing this. You have normal, plain connections, which are
32 ;; no trouble at all, but you also have TLS/SSL connections, and you
33 ;; have STARTTLS. Negotiating this for each protocol can be rather
34 ;; tedious, so this library provides a single entry point, and hides
35 ;; much of the ugliness.
39 ;; (open-protocol-stream
40 ;; "*nnimap*" buffer address port
42 ;; :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.
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', `tls', `shell' or `starttls'. If
79 omitted, the default is `network'.
81 :end-of-command -- a regexp saying what the end of a command is.
82 This defaults to \"\\n\".
84 :capability-command -- a string representing the command used to
85 query server for capabilities. For instance, for IMAP this is
86 \"1 CAPABILITY\\r\\n\".
88 :starttls-function -- a function that takes one parameter, which
89 is the response to the capaibility command. It should return nil
90 if it turns out that the server doesn't support STARTTLS, or the
91 command to switch on STARTTLS otherwise."
92 (let ((type (or (cadr (memq :type parameters)) 'network)))
93 (when (and (eq type 'starttls)
94 (fboundp 'open-gnutls-stream))
98 (destructuring-bind (stream greeting capabilities)
99 (funcall (intern (format "proto-stream-open-%s" type) obarray)
100 name buffer host service parameters)
102 (memq (process-status stream)
105 greeting capabilities))))
107 (defun proto-stream-open-network (name buffer host service parameters)
108 (let* ((start (with-current-buffer buffer (point)))
109 (stream (open-network-stream name buffer host service))
110 (capability-command (cadr (memq :capability-command parameters)))
111 (eoc (proto-stream-eoc parameters))
112 (type (cadr (memq :type parameters)))
113 (greeting (proto-stream-get-response stream start eoc)))
114 (if (not capability-command)
115 (list stream greeting nil)
117 (proto-stream-command stream capability-command eoc))
119 (funcall (cadr (memq :starttls-function parameters))
122 ((or (not starttls-command)
123 (and (not (eq type 'starttls))
124 (not proto-stream-always-use-starttls)))
125 ;; If this server doesn't support STARTTLS, but we have
126 ;; requested it explicitly, then close the connection and
128 (if (eq type 'starttls)
130 (delete-process stream)
132 ;; Otherwise, just return this plain network connection.
133 (list stream greeting capabilities)))
134 ((or (fboundp 'open-gnutls-stream)
135 (executable-find "gnutls-cli"))
136 (unless (fboundp 'open-gnutls-stream)
137 (delete-process stream)
138 (let* ((starttls-use-gnutls t)
139 (starttls-extra-arguments
140 (if (eq type 'starttls)
141 ;; When doing opportunistic TLS upgrades we
142 ;; don't really care about the identity of the
144 (cons "--insecure" starttls-extra-arguments)
145 starttls-extra-arguments)))
146 (setq stream (starttls-open-stream name buffer host service)))
147 (proto-stream-get-response stream start eoc))
148 (proto-stream-command stream starttls-command eoc)
149 (if (fboundp 'open-gnutls-stream)
150 (gnutls-negotiate stream nil)
151 (starttls-negotiate stream))
152 ;; Re-get the capabilities, since they may have changed
153 ;; after switching to TLS.
154 (list stream greeting
155 (proto-stream-command stream capability-command eoc)))
156 ((eq (cadr (memq :type parameters)) 'starttls)
157 (delete-process stream)
160 (list stream greeting capabilities)))))))
162 (defun proto-stream-command (stream command eoc)
163 (let ((start (with-current-buffer (process-buffer stream) (point-max))))
164 (process-send-string stream command)
165 (proto-stream-get-response stream start eoc)))
167 (defun proto-stream-get-response (stream start end-of-command)
168 (with-current-buffer (process-buffer stream)
171 (while (and (memq (process-status stream)
173 (not (re-search-forward end-of-command nil t)))
174 (accept-process-output stream 0 50)
176 (if (= start (point))
177 ;; The process died; return nil.
179 ;; Return the data we got back.
180 (buffer-substring start (point))))))
182 (defun proto-stream-open-tls (name buffer host service parameters)
183 (with-current-buffer buffer
184 (let ((start (point-max))
186 (funcall (if (fboundp 'open-gnutls-stream)
189 name buffer host service)))
190 ;; If we're using tls.el, we have to delete the output from
191 ;; openssl/gnutls-cli.
192 (unless (fboundp 'open-gnutls-stream)
193 (proto-stream-get-response
194 stream start (proto-stream-eoc parameters))
195 (goto-char (point-min))
196 (when (re-search-forward (proto-stream-eoc parameters) nil t)
197 (goto-char (match-beginning 0))
198 (delete-region (point-min) (line-beginning-position))))
199 (proto-stream-capability-open start stream parameters))))
201 (defun proto-stream-open-shell (name buffer host service parameters)
202 (proto-stream-capability-open
203 (with-current-buffer buffer (point))
204 (let ((process-connection-type nil))
205 (start-process name buffer shell-file-name
208 (cadr (memq :shell-command parameters))
214 (defun proto-stream-capability-open (start stream parameters)
215 (let ((capability-command (cadr (memq :capability-command parameters)))
216 (greeting (proto-stream-get-response
217 stream start (proto-stream-eoc parameters))))
218 (list stream greeting
219 (and capability-command
220 (proto-stream-command
221 stream capability-command (proto-stream-eoc parameters))))))
223 (defun proto-stream-eoc (parameters)
224 (or (cadr (memq :end-of-command parameters))
227 (provide 'proto-stream)
229 ;;; proto-stream.el ends here