lisp/gnus/starttls.el

   1 ;;; starttls.el --- STARTTLS functions
   2
   3 ;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
   5
   6 ;; Author: Daiki Ueno <ueno@unixuser.org>
   7 ;; Author: Simon Josefsson <simon@josefsson.org>
   8 ;; Created: 1999/11/20
   9 ;; Keywords: TLS, SSL, OpenSSL, GNUTLS, mail, news
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; This module defines some utility functions for STARTTLS profiles.
  29
  30 ;; [RFC 2595] "Using TLS with IMAP, POP3 and ACAP"
  31 ;;      by Chris Newman <chris.newman@innosoft.com> (1999/06)
  32
  33 ;; This file now contains a combination of the two previous
  34 ;; implementations both called "starttls.el".  The first one is Daiki
  35 ;; Ueno's starttls.el which uses his own "starttls" command line tool,
  36 ;; and the second one is Simon Josefsson's starttls.el which uses
  37 ;; "gnutls-cli" from GNUTLS.
  38 ;;
  39 ;; If "starttls" is available, it is prefered by the code over
  40 ;; "gnutls-cli", for backwards compatibility.  Use
  41 ;; `starttls-use-gnutls' to toggle between implementations if you have
  42 ;; both tools installed.  It is recommended to use GNUTLS, though, as
  43 ;; it performs more verification of the certificates.
  44
  45 ;; The GNUTLS support requires GNUTLS 0.9.90 (released 2003-10-08) or
  46 ;; later, from <http://www.gnu.org/software/gnutls/>, or "starttls"
  47 ;; from <ftp://ftp.opaopa.org/pub/elisp/>.
  48
  49 ;; Usage is similar to `open-network-stream'.  For example:
  50 ;;
  51 ;; (when (setq tmp (starttls-open-stream
  52 ;;                      "test" (current-buffer) "yxa.extundo.com" 25))
  53 ;;   (accept-process-output tmp 15)
  54 ;;   (process-send-string tmp "STARTTLS\n")
  55 ;;   (accept-process-output tmp 15)
  56 ;;   (message "STARTTLS output:\n%s" (starttls-negotiate tmp))
  57 ;;   (process-send-string tmp "EHLO foo\n"))
  58
  59 ;; An example run yields the following output:
  60 ;;
  61 ;; 220 yxa.extundo.com ESMTP Sendmail 8.12.11/8.12.11/Debian-3; Wed, 26 May 2004 19:12:29 +0200; (No UCE/UBE) logging access from: c494102a.s-bi.bostream.se(OK)-c494102a.s-bi.bostream.se [217.215.27.65]
  62 ;; 220 2.0.0 Ready to start TLS
  63 ;; 250-yxa.extundo.com Hello c494102a.s-bi.bostream.se [217.215.27.65], pleased to meet you
  64 ;; 250-ENHANCEDSTATUSCODES
  65 ;; 250-PIPELINING
  66 ;; 250-EXPN
  67 ;; 250-VERB
  68 ;; 250-8BITMIME
  69 ;; 250-SIZE
  70 ;; 250-DSN
  71 ;; 250-ETRN
  72 ;; 250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN
  73 ;; 250-DELIVERBY
  74 ;; 250 HELP
  75 ;; nil
  76 ;;
  77 ;; With the message buffer containing:
  78 ;;
  79 ;; STARTTLS output:
  80 ;; *** Starting TLS handshake
  81 ;; - Server's trusted authorities:
  82 ;;    [0]: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=CA,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
  83 ;; - Certificate type: X.509
  84 ;;  - Got a certificate list of 2 certificates.
  85 ;;
  86 ;;  - Certificate[0] info:
  87 ;;  # The hostname in the certificate matches 'yxa.extundo.com'.
  88 ;;  # valid since: Wed May 26 12:16:00 CEST 2004
  89 ;;  # expires at: Wed Jul 26 12:16:00 CEST 2023
  90 ;;  # serial number: 04
  91 ;;  # fingerprint: 7c 04 4b c1 fa 26 9b 5d 90 22 52 3c 65 3d 85 3a
  92 ;;  # version: #1
  93 ;;  # public key algorithm: RSA
  94 ;;  #   Modulus: 1024 bits
  95 ;;  # Subject's DN: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=Mail server,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
  96 ;;  # Issuer's DN: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=CA,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
  97 ;;
  98 ;;  - Certificate[1] info:
  99 ;;  # valid since: Sun May 23 11:35:00 CEST 2004
 100 ;;  # expires at: Sun Jul 23 11:35:00 CEST 2023
 101 ;;  # serial number: 00
 102 ;;  # fingerprint: fc 76 d8 63 1a c9 0b 3b fa 40 fe ed 47 7a 58 ae
 103 ;;  # version: #3
 104 ;;  # public key algorithm: RSA
 105 ;;  #   Modulus: 1024 bits
 106 ;;  # Subject's DN: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=CA,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
 107 ;;  # Issuer's DN: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=CA,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
 108 ;;
 109 ;; - Peer's certificate issuer is unknown
 110 ;; - Peer's certificate is NOT trusted
 111 ;; - Version: TLS 1.0
 112 ;; - Key Exchange: RSA
 113 ;; - Cipher: ARCFOUR 128
 114 ;; - MAC: SHA
 115 ;; - Compression: NULL
 116
 117 ;;; Code:
 118
 119 (defgroup starttls nil
 120   "Support for `Transport Layer Security' protocol."
 121   :version "21.1"
 122   :group 'mail)
 123
 124 (defcustom starttls-gnutls-program "gnutls-cli"
 125   "Name of GNUTLS command line tool.
 126 This program is used when GNUTLS is used, i.e. when
 127 `starttls-use-gnutls' is non-nil."
 128   :version "22.1"
 129   :type 'string
 130   :group 'starttls)
 131
 132 (defcustom starttls-program "starttls"
 133   "The program to run in a subprocess to open an TLSv1 connection.
 134 This program is used when the `starttls' command is used,
 135 i.e. when `starttls-use-gnutls' is nil."
 136   :type 'string
 137   :group 'starttls)
 138
 139 (defcustom starttls-use-gnutls (not (executable-find starttls-program))
 140   "*Whether to use GNUTLS instead of the `starttls' command."
 141   :version "22.1"
 142   :type 'boolean
 143   :group 'starttls)
 144
 145 (defcustom starttls-extra-args nil
 146   "Extra arguments to `starttls-program'.
 147 These apply when the `starttls' command is used, i.e. when
 148 `starttls-use-gnutls' is nil."
 149   :type '(repeat string)
 150   :group 'starttls)
 151
 152 (defcustom starttls-extra-arguments nil
 153   "Extra arguments to `starttls-program'.
 154 These apply when GNUTLS is used, i.e. when `starttls-use-gnutls' is non-nil.
 155
 156 For example, non-TLS compliant servers may require
 157 '(\"--protocols\" \"ssl3\").  Invoke \"gnutls-cli --help\" to
 158 find out which parameters are available."
 159   :version "22.1"
 160   :type '(repeat string)
 161   :group 'starttls)
 162
 163 (defcustom starttls-process-connection-type nil
 164   "*Value for `process-connection-type' to use when starting STARTTLS process."
 165   :version "22.1"
 166   :type 'boolean
 167   :group 'starttls)
 168
 169 (defcustom starttls-connect "- Simple Client Mode:\n\n"
 170   "*Regular expression indicating successful connection.
 171 The default is what GNUTLS's \"gnutls-cli\" outputs."
 172   ;; GNUTLS cli.c:main() prints this string when it is starting to run
 173   ;; in the application read/write phase.  If the logic, or the string
 174   ;; itself, is modified, this must be updated.
 175   :version "22.1"
 176   :type 'regexp
 177   :group 'starttls)
 178
 179 (defcustom starttls-failure "\\*\\*\\* Handshake has failed"
 180   "*Regular expression indicating failed TLS handshake.
 181 The default is what GNUTLS's \"gnutls-cli\" outputs."
 182   ;; GNUTLS cli.c:do_handshake() prints this string on failure.  If the
 183   ;; logic, or the string itself, is modified, this must be updated.
 184   :version "22.1"
 185   :type 'regexp
 186   :group 'starttls)
 187
 188 (defcustom starttls-success "- Compression: "
 189   "*Regular expression indicating completed TLS handshakes.
 190 The default is what GNUTLS's \"gnutls-cli\" outputs."
 191   ;; GNUTLS cli.c:do_handshake() calls, on success,
 192   ;; common.c:print_info(), that unconditionally print this string
 193   ;; last.  If that logic, or the string itself, is modified, this
 194   ;; must be updated.
 195   :version "22.1"
 196   :type 'regexp
 197   :group 'starttls)
 198
 199 (defun starttls-negotiate-gnutls (process)
 200   "Negotiate TLS on PROCESS opened by `open-starttls-stream'.
 201 This should typically only be done once.  It typically returns a
 202 multi-line informational message with information about the
 203 handshake, or nil on failure."
 204   (let (buffer info old-max done-ok done-bad)
 205     (if (null (setq buffer (process-buffer process)))
 206         ;; XXX How to remove/extract the TLS negotiation junk?
 207         (signal-process (process-id process) 'SIGALRM)
 208       (with-current-buffer buffer
 209         (save-excursion
 210           (setq old-max (goto-char (point-max)))
 211           (signal-process (process-id process) 'SIGALRM)
 212           (while (and (processp process)
 213                       (eq (process-status process) 'run)
 214                       (save-excursion
 215                         (goto-char old-max)
 216                         (not (or (setq done-ok (re-search-forward
 217                                                 starttls-success nil t))
 218                                  (setq done-bad (re-search-forward
 219                                                  starttls-failure nil t))))))
 220             (accept-process-output process 1 100)
 221             (sit-for 0.1))
 222           (setq info (buffer-substring-no-properties old-max (point-max)))
 223           (delete-region old-max (point-max))
 224           (if (or (and done-ok (not done-bad))
 225                   ;; Prevent mitm that fake success msg after failure msg.
 226                   (and done-ok done-bad (< done-ok done-bad)))
 227               info
 228             (message "STARTTLS negotiation failed: %s" info)
 229             nil))))))
 230
 231 (defun starttls-negotiate (process)
 232   (if starttls-use-gnutls
 233       (starttls-negotiate-gnutls process)
 234     (signal-process (process-id process) 'SIGALRM)))
 235
 236 (eval-and-compile
 237   (if (fboundp 'set-process-query-on-exit-flag)
 238       (defalias 'starttls-set-process-query-on-exit-flag
 239         'set-process-query-on-exit-flag)
 240     (defalias 'starttls-set-process-query-on-exit-flag
 241       'process-kill-without-query)))
 242
 243 (defun starttls-open-stream-gnutls (name buffer host port)
 244   (message "Opening STARTTLS connection to `%s:%s'..." host port)
 245   (let* (done
 246          (old-max (with-current-buffer buffer (point-max)))
 247          (process-connection-type starttls-process-connection-type)
 248          (process (apply #'start-process name buffer
 249                          starttls-gnutls-program "-s" host
 250                          "-p" (if (integerp port)
 251                                   (int-to-string port)
 252                                 port)
 253                          starttls-extra-arguments)))
 254     (starttls-set-process-query-on-exit-flag process nil)
 255     (while (and (processp process)
 256                 (eq (process-status process) 'run)
 257                 (save-excursion
 258                   (set-buffer buffer)
 259                   (goto-char old-max)
 260                   (not (setq done (re-search-forward
 261                                    starttls-connect nil t)))))
 262       (accept-process-output process 0 100)
 263       (sit-for 0.1))
 264     (if done
 265         (with-current-buffer buffer
 266           (delete-region old-max done))
 267       (delete-process process)
 268       (setq process nil))
 269     (message "Opening STARTTLS connection to `%s:%s'...%s"
 270              host port (if done "done" "failed"))
 271     process))
 272
 273 (defun starttls-open-stream (name buffer host port)
 274   "Open a TLS connection for a port to a host.
 275 Returns a subprocess object to represent the connection.
 276 Input and output work as for subprocesses; `delete-process' closes it.
 277 Args are NAME BUFFER HOST PORT.
 278 NAME is name for process.  It is modified if necessary to make it unique.
 279 BUFFER is the buffer (or `buffer-name') to associate with the process.
 280  Process output goes at end of that buffer, unless you specify
 281  an output stream or filter function to handle the output.
 282  BUFFER may be also nil, meaning that this process is not associated
 283  with any buffer
 284 Third arg is name of the host to connect to, or its IP address.
 285 Fourth arg PORT is an integer specifying a port to connect to.
 286 If `starttls-use-gnutls' is nil, this may also be a service name, but
 287 GNUTLS requires a port number."
 288   (if starttls-use-gnutls
 289       (starttls-open-stream-gnutls name buffer host port)
 290     (message "Opening STARTTLS connection to `%s:%s'" host (format "%s" port))
 291     (let* ((process-connection-type starttls-process-connection-type)
 292            (process (apply #'start-process
 293                            name buffer starttls-program
 294                            host (format "%s" port)
 295                            starttls-extra-args)))
 296       (starttls-set-process-query-on-exit-flag process nil)
 297       process)))
 298
 299 (defun starttls-any-program-available ()
 300   (let ((program (if starttls-use-gnutls
 301                      starttls-gnutls-program
 302                    starttls-program)))
 303     (condition-case ()
 304         (progn
 305           (call-process program)
 306           program)
 307       (error (progn
 308                (message "No STARTTLS program was available (tried '%s')"
 309                         program)
 310                nil)))))
 311
 312 (provide 'starttls)
 313
 314 ;; arch-tag: 648b3bd8-63bd-47f5-904c-7c819aea2297
 315 ;;; starttls.el ends here