lisp/gnus/starttls.el

   1 ;;; starttls.el --- STARTTLS functions
   2
   3 ;; Copyright (C) 1999, 2000, 2003, 2004 Free Software Foundation, Inc.
   4
   5 ;; Author: Daiki Ueno <ueno@unixuser.org>
   6 ;; Author: Simon Josefsson <simon@josefsson.org>
   7 ;; Created: 1999/11/20
   8 ;; Keywords: TLS, SSL, OpenSSL, GNUTLS, mail, news
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 2, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  25 ;; Boston, MA 02111-1307, USA.
  26
  27 ;;; Commentary:
  28
  29 ;; This module defines some utility functions for STARTTLS profiles.
  30
  31 ;; [RFC 2595] "Using TLS with IMAP, POP3 and ACAP"
  32 ;;      by Chris Newman <chris.newman@innosoft.com> (1999/06)
  33
  34 ;; This file now contain a combination of the two previous
  35 ;; implementations both called "starttls.el".  The first one is Daiki
  36 ;; Ueno's starttls.el which uses his own "starttls" command line tool,
  37 ;; and the second one is Simon Josefsson's starttls.el which uses
  38 ;; "gnutls-cli" from GNUTLS.
  39 ;;
  40 ;; If "starttls" is available, it is prefered by the code over
  41 ;; "gnutls-cli", for backwards compatibility.  Use
  42 ;; `starttls-use-gnutls' to toggle between implementations if you have
  43 ;; both tools installed.  It is recommended to use GNUTLS, though, as
  44 ;; it performs more verification of the certificates.
  45
  46 ;; The GNUTLS support require GNUTLS 0.9.90 (released 2003-10-08) or
  47 ;; later, from <http://www.gnu.org/software/gnutls/>, or "starttls"
  48 ;; from <ftp://ftp.opaopa.org/pub/elisp/>.
  49
  50 ;; Usage is similar to `open-network-stream'.  For example:
  51 ;;
  52 ;; (when (setq tmp (starttls-open-stream
  53 ;;                      "test" (current-buffer) "yxa.extundo.com" 25))
  54 ;;   (accept-process-output tmp 15)
  55 ;;   (process-send-string tmp "STARTTLS\n")
  56 ;;   (accept-process-output tmp 15)
  57 ;;   (message "STARTTLS output:\n%s" (starttls-negotiate tmp))
  58 ;;   (process-send-string tmp "EHLO foo\n"))
  59
  60 ;; An example run yield the following output:
  61 ;;
  62 ;; 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]
  63 ;; 220 2.0.0 Ready to start TLS
  64 ;; 250-yxa.extundo.com Hello c494102a.s-bi.bostream.se [217.215.27.65], pleased to meet you
  65 ;; 250-ENHANCEDSTATUSCODES
  66 ;; 250-PIPELINING
  67 ;; 250-EXPN
  68 ;; 250-VERB
  69 ;; 250-8BITMIME
  70 ;; 250-SIZE
  71 ;; 250-DSN
  72 ;; 250-ETRN
  73 ;; 250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN
  74 ;; 250-DELIVERBY
  75 ;; 250 HELP
  76 ;; nil
  77 ;;
  78 ;; With the message buffer containing:
  79 ;;
  80 ;; STARTTLS output:
  81 ;; *** Starting TLS handshake
  82 ;; - Server's trusted authorities:
  83 ;;    [0]: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=CA,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
  84 ;; - Certificate type: X.509
  85 ;;  - Got a certificate list of 2 certificates.
  86 ;;
  87 ;;  - Certificate[0] info:
  88 ;;  # The hostname in the certificate matches 'yxa.extundo.com'.
  89 ;;  # valid since: Wed May 26 12:16:00 CEST 2004
  90 ;;  # expires at: Wed Jul 26 12:16:00 CEST 2023
  91 ;;  # serial number: 04
  92 ;;  # fingerprint: 7c 04 4b c1 fa 26 9b 5d 90 22 52 3c 65 3d 85 3a
  93 ;;  # version: #1
  94 ;;  # public key algorithm: RSA
  95 ;;  #   Modulus: 1024 bits
  96 ;;  # Subject's DN: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=Mail server,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
  97 ;;  # Issuer's DN: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=CA,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
  98 ;;
  99 ;;  - Certificate[1] info:
 100 ;;  # valid since: Sun May 23 11:35:00 CEST 2004
 101 ;;  # expires at: Sun Jul 23 11:35:00 CEST 2023
 102 ;;  # serial number: 00
 103 ;;  # fingerprint: fc 76 d8 63 1a c9 0b 3b fa 40 fe ed 47 7a 58 ae
 104 ;;  # version: #3
 105 ;;  # public key algorithm: RSA
 106 ;;  #   Modulus: 1024 bits
 107 ;;  # Subject's DN: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=CA,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
 108 ;;  # Issuer's DN: C=SE,ST=Stockholm,L=Stockholm,O=YXA,OU=CA,CN=yxa.extundo.com,EMAIL=staff@yxa.extundo.com
 109 ;;
 110 ;; - Peer's certificate issuer is unknown
 111 ;; - Peer's certificate is NOT trusted
 112 ;; - Version: TLS 1.0
 113 ;; - Key Exchange: RSA
 114 ;; - Cipher: ARCFOUR 128
 115 ;; - MAC: SHA
 116 ;; - Compression: NULL
 117
 118 ;;; Code:
 119
 120 (defgroup starttls nil
 121   "Support for `Transport Layer Security' protocol."
 122   :version "21.1"
 123   :group 'mail)
 124
 125 (defcustom starttls-gnutls-program "gnutls-cli"
 126   "Name of GNUTLS command line tool.
 127 This program is used when GNUTLS is used, i.e. when
 128 `starttls-use-gnutls' is non-nil."
 129   :version "22.1"
 130   :type 'string
 131   :group 'starttls)
 132
 133 (defcustom starttls-program "starttls"
 134   "The program to run in a subprocess to open an TLSv1 connection.
 135 This program is used when the `starttls' command is used,
 136 i.e. when `starttls-use-gnutls' is nil."
 137   :type 'string
 138   :group 'starttls)
 139
 140 (defcustom starttls-use-gnutls (not (executable-find starttls-program))
 141   "*Whether to use GNUTLS instead of the `starttls' command."
 142   :version "22.1"
 143   :type 'boolean
 144   :group 'starttls)
 145
 146 (defcustom starttls-extra-args nil
 147   "Extra arguments to `starttls-program'.
 148 This program is used when the `starttls' command is used,
 149 i.e. when `starttls-use-gnutls' is nil."
 150   :type '(repeat string)
 151   :group 'starttls)
 152
 153 (defcustom starttls-extra-arguments nil
 154   "Extra arguments to `starttls-program'.
 155 This program is used when GNUTLS is used, i.e. when
 156 `starttls-use-gnutls' is non-nil.
 157
 158 For example, non-TLS compliant servers may require
 159 '(\"--protocols\" \"ssl3\").  Invoke \"gnutls-cli --help\" to
 160 find out which parameters are available."
 161   :version "22.1"
 162   :type '(repeat string)
 163   :group 'starttls)
 164
 165 (defcustom starttls-process-connection-type nil
 166   "*Value for `process-connection-type' to use when starting STARTTLS process."
 167   :version "22.1"
 168   :type 'boolean
 169   :group 'starttls)
 170
 171 (defcustom starttls-connect "- Simple Client Mode:\n\n"
 172   "*Regular expression indicating successful connection.
 173 The default is what GNUTLS's \"gnutls-cli\" outputs."
 174   ;; GNUTLS cli.c:main() print this string when it is starting to run
 175   ;; in the application read/write phase.  If the logic, or the string
 176   ;; itself, is modified, this must be updated.
 177   :version "22.1"
 178   :type 'regexp
 179   :group 'starttls)
 180
 181 (defcustom starttls-failure "\\*\\*\\* Handshake has failed"
 182   "*Regular expression indicating failed TLS handshake.
 183 The default is what GNUTLS's \"gnutls-cli\" outputs."
 184   ;; GNUTLS cli.c:do_handshake() print this string on failure.  If the
 185   ;; logic, or the string itself, is modified, this must be updated.
 186   :version "22.1"
 187   :type 'regexp
 188   :group 'starttls)
 189
 190 (defcustom starttls-success "- Compression: "
 191   "*Regular expression indicating completed TLS handshakes.
 192 The default is what GNUTLS's \"gnutls-cli\" outputs."
 193   ;; GNUTLS cli.c:do_handshake() calls, on success,
 194   ;; common.c:print_info(), that unconditionally print this string
 195   ;; last.  If that logic, or the string itself, is modified, this
 196   ;; must be updated.
 197   :version "22.1"
 198   :type 'regexp
 199   :group 'starttls)
 200
 201 (defun starttls-negotiate-gnutls (process)
 202   "Negotiate TLS on process opened by `open-starttls-stream'.
 203 This should typically only be done once.  It typically return a
 204 multi-line informational message with information about the
 205 handshake, or NIL on failure."
 206   (let (buffer info old-max done-ok done-bad)
 207     (if (null (setq buffer (process-buffer process)))
 208         ;; XXX How to remove/extract the TLS negotiation junk?
 209         (signal-process (process-id process) 'SIGALRM)
 210       (with-current-buffer buffer
 211         (save-excursion
 212           (setq old-max (goto-char (point-max)))
 213           (signal-process (process-id process) 'SIGALRM)
 214           (while (and (processp process)
 215                       (eq (process-status process) 'run)
 216                       (save-excursion
 217                         (goto-char old-max)
 218                         (not (or (setq done-ok (re-search-forward
 219                                                 starttls-success nil t))
 220                                  (setq done-bad (re-search-forward
 221                                                  starttls-failure nil t))))))
 222             (accept-process-output process 1 100)
 223             (sit-for 0.1))
 224           (setq info (buffer-substring-no-properties old-max (point-max)))
 225           (delete-region old-max (point-max))
 226           (if (or (and done-ok (not done-bad))
 227                   ;; Prevent mitm that fake success msg after failure msg.
 228                   (and done-ok done-bad (< done-ok done-bad)))
 229               info
 230             (message "STARTTLS negotiation failed: %s" info)
 231             nil))))))
 232
 233 (defun starttls-negotiate (process)
 234   (if starttls-use-gnutls
 235       (starttls-negotiate-gnutls process)
 236     (signal-process (process-id process) 'SIGALRM)))
 237
 238 (defun starttls-open-stream-gnutls (name buffer host service)
 239   (message "Opening STARTTLS connection to `%s'..." host)
 240   (let* (done
 241          (old-max (with-current-buffer buffer (point-max)))
 242          (process-connection-type starttls-process-connection-type)
 243          (process (apply #'start-process name buffer
 244                          starttls-gnutls-program "-s" host
 245                          "-p" (if (integerp service)
 246                                   (int-to-string service)
 247                                 service)
 248                          starttls-extra-arguments)))
 249     (process-kill-without-query process)
 250     (while (and (processp process)
 251                 (eq (process-status process) 'run)
 252                 (save-excursion
 253                   (set-buffer buffer)
 254                   (goto-char old-max)
 255                   (not (setq done (re-search-forward
 256                                    starttls-connect nil t)))))
 257       (accept-process-output process 0 100)
 258       (sit-for 0.1))
 259     (if done
 260         (with-current-buffer buffer
 261           (delete-region old-max done))
 262       (delete-process process)
 263       (setq process nil))
 264     (message "Opening STARTTLS connection to `%s'...%s"
 265              host (if done "done" "failed"))
 266     process))
 267
 268 (defun starttls-open-stream (name buffer host service)
 269   "Open a TLS connection for a service to a host.
 270 Returns a subprocess-object to represent the connection.
 271 Input and output work as for subprocesses; `delete-process' closes it.
 272 Args are NAME BUFFER HOST SERVICE.
 273 NAME is name for process.  It is modified if necessary to make it unique.
 274 BUFFER is the buffer (or `buffer-name') to associate with the process.
 275  Process output goes at end of that buffer, unless you specify
 276  an output stream or filter function to handle the output.
 277  BUFFER may be also nil, meaning that this process is not associated
 278  with any buffer
 279 Third arg is name of the host to connect to, or its IP address.
 280 Fourth arg SERVICE is name of the service desired, or an integer
 281 specifying a port number to connect to."
 282   (if starttls-use-gnutls
 283       (starttls-open-stream-gnutls name buffer host service)
 284     (let* ((process-connection-type starttls-process-connection-type)
 285            (process (apply #'start-process
 286                            name buffer starttls-program
 287                            host (format "%s" service)
 288                            starttls-extra-args)))
 289       (process-kill-without-query process)
 290       process)))
 291
 292 (provide 'starttls)
 293
 294 ;;; arch-tag: 648b3bd8-63bd-47f5-904c-7c819aea2297
 295 ;;; starttls.el ends here