lisp/gnus/sasl.el

   1 ;;; sasl.el --- SASL client framework
   2
   3 ;; Copyright (C) 2000, 2007  Free Software Foundation, Inc.
   4
   5 ;; Author: Daiki Ueno <ueno@unixuser.org>
   6 ;; Keywords: SASL
   7
   8 ;; This file is part of GNU Emacs.
   9
  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, or (at your option)
  13 ;; any later version.
  14
  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.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23 ;; Boston, MA 02110-1301, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; This module provides common interface functions to share several
  28 ;; SASL mechanism drivers.  The toplevel is designed to be mostly
  29 ;; compatible with [Java-SASL].
  30 ;;
  31 ;; [SASL] J. Myers, "Simple Authentication and Security Layer (SASL)",
  32 ;;      RFC 2222, October 1997.
  33 ;;
  34 ;; [Java-SASL] R. Weltman & R. Lee, "The Java SASL Application Program
  35 ;;      Interface", draft-weltman-java-sasl-03.txt, March 2000.
  36
  37 ;;; Code:
  38
  39 (defvar sasl-mechanisms
  40   '("CRAM-MD5" "DIGEST-MD5" "PLAIN" "LOGIN" "ANONYMOUS"
  41     "NTLM" "SCRAM-MD5"))
  42
  43 (defvar sasl-mechanism-alist
  44   '(("CRAM-MD5" sasl-cram)
  45     ("DIGEST-MD5" sasl-digest)
  46     ("PLAIN" sasl-plain)
  47     ("LOGIN" sasl-login)
  48     ("ANONYMOUS" sasl-anonymous)
  49     ("NTLM" sasl-ntlm)
  50     ("SCRAM-MD5" sasl-scram)))
  51
  52 (defvar sasl-unique-id-function #'sasl-unique-id-function)
  53
  54 (put 'sasl-error 'error-message "SASL error")
  55 (put 'sasl-error 'error-conditions '(sasl-error error))
  56
  57 (defun sasl-error (datum)
  58   (signal 'sasl-error (list datum)))
  59
  60 ;;; @ SASL client
  61 ;;;
  62
  63 (defun sasl-make-client (mechanism name service server)
  64   "Return a newly allocated SASL client.
  65 NAME is name of the authorization.  SERVICE is name of the service desired.
  66 SERVER is the fully qualified host name of the server to authenticate to."
  67   (vector mechanism name service server (make-symbol "sasl-client-properties")))
  68
  69 (defun sasl-client-mechanism (client)
  70   "Return the authentication mechanism driver of CLIENT."
  71   (aref client 0))
  72
  73 (defun sasl-client-name (client)
  74   "Return the authorization name of CLIENT, a string."
  75   (aref client 1))
  76
  77 (defun sasl-client-service (client)
  78   "Return the service name of CLIENT, a string."
  79   (aref client 2))
  80
  81 (defun sasl-client-server (client)
  82   "Return the server name of CLIENT, a string."
  83   (aref client 3))
  84
  85 (defun sasl-client-set-properties (client plist)
  86   "Destructively set the properties of CLIENT.
  87 The second argument PLIST is the new property list."
  88   (setplist (aref client 4) plist))
  89
  90 (defun sasl-client-set-property (client property value)
  91   "Add the given property/value to CLIENT."
  92   (put (aref client 4) property value))
  93
  94 (defun sasl-client-property (client property)
  95   "Return the value of the PROPERTY of CLIENT."
  96   (get (aref client 4) property))
  97
  98 (defun sasl-client-properties (client)
  99   "Return the properties of CLIENT."
 100   (symbol-plist (aref client 4)))
 101
 102 ;;; @ SASL mechanism
 103 ;;;
 104
 105 (defun sasl-make-mechanism (name steps)
 106   "Make an authentication mechanism.
 107 NAME is a IANA registered SASL mechanism name.
 108 STEPS is list of continuation function."
 109   (vector name
 110           (mapcar
 111            (lambda (step)
 112              (let ((symbol (make-symbol (symbol-name step))))
 113                (fset symbol (symbol-function step))
 114                symbol))
 115            steps)))
 116
 117 (defun sasl-mechanism-name (mechanism)
 118   "Return name of MECHANISM, a string."
 119   (aref mechanism 0))
 120
 121 (defun sasl-mechanism-steps (mechanism)
 122   "Return the authentication steps of MECHANISM, a list of functions."
 123   (aref mechanism 1))
 124
 125 (defun sasl-find-mechanism (mechanisms)
 126   "Retrieve an apropriate mechanism object from MECHANISMS hints."
 127   (let* ((sasl-mechanisms sasl-mechanisms)
 128          (mechanism
 129           (catch 'done
 130             (while sasl-mechanisms
 131               (if (member (car sasl-mechanisms) mechanisms)
 132                   (throw 'done (nth 1 (assoc (car sasl-mechanisms)
 133                                              sasl-mechanism-alist))))
 134               (setq sasl-mechanisms (cdr sasl-mechanisms))))))
 135     (if mechanism
 136         (require mechanism))
 137     (get mechanism 'sasl-mechanism)))
 138
 139 ;;; @ SASL authentication step
 140 ;;;
 141
 142 (defun sasl-step-data (step)
 143   "Return the data which STEP holds, a string."
 144   (aref step 1))
 145
 146 (defun sasl-step-set-data (step data)
 147   "Store DATA string to STEP."
 148   (aset step 1 data))
 149
 150 (defun sasl-next-step (client step)
 151   "Evaluate the challenge and prepare an appropriate next response.
 152 The data type of the value and optional 2nd argument STEP is nil or
 153 opaque authentication step which holds the reference to the next action
 154 and the current challenge.  At the first time STEP should be set to nil."
 155   (let* ((steps
 156           (sasl-mechanism-steps
 157            (sasl-client-mechanism client)))
 158          (function
 159           (if (vectorp step)
 160               (nth 1 (memq (aref step 0) steps))
 161             (car steps))))
 162     (if function
 163         (vector function (funcall function client step)))))
 164
 165 (defvar sasl-read-passphrase nil)
 166 (defun sasl-read-passphrase (prompt)
 167   (if (not sasl-read-passphrase)
 168       (if (functionp 'read-passwd)
 169           (setq sasl-read-passphrase 'read-passwd)
 170         (if (load "passwd" t)
 171             (setq sasl-read-passphrase 'read-passwd)
 172           (autoload 'ange-ftp-read-passwd "ange-ftp")
 173           (setq sasl-read-passphrase 'ange-ftp-read-passwd))))
 174   (funcall sasl-read-passphrase prompt))
 175
 176 (defun sasl-unique-id ()
 177   "Compute a data string which must be different each time.
 178 It contain at least 64 bits of entropy."
 179   (concat (funcall sasl-unique-id-function)(funcall sasl-unique-id-function)))
 180
 181 (defvar sasl-unique-id-char nil)
 182
 183 ;; stolen (and renamed) from message.el
 184 (defun sasl-unique-id-function ()
 185   ;; Don't use microseconds from (current-time), they may be unsupported.
 186   ;; Instead we use this randomly inited counter.
 187   (setq sasl-unique-id-char
 188         (% (1+ (or sasl-unique-id-char (logand (random t) (1- (lsh 1 20)))))
 189            ;; (current-time) returns 16-bit ints,
 190            ;; and 2^16*25 just fits into 4 digits i base 36.
 191            (* 25 25)))
 192   (let ((tm (current-time)))
 193     (concat
 194      (sasl-unique-id-number-base36
 195       (+ (car   tm)
 196          (lsh (% sasl-unique-id-char 25) 16)) 4)
 197      (sasl-unique-id-number-base36
 198       (+ (nth 1 tm)
 199          (lsh (/ sasl-unique-id-char 25) 16)) 4))))
 200
 201 (defun sasl-unique-id-number-base36 (num len)
 202   (if (if (< len 0)
 203           (<= num 0)
 204         (= len 0))
 205       ""
 206     (concat (sasl-unique-id-number-base36 (/ num 36) (1- len))
 207             (char-to-string (aref "zyxwvutsrqponmlkjihgfedcba9876543210"
 208                                   (% num 36))))))
 209
 210 ;;; PLAIN (RFC2595 Section 6)
 211 (defconst sasl-plain-steps
 212   '(sasl-plain-response))
 213
 214 (defun sasl-plain-response (client step)
 215   (let ((passphrase
 216          (sasl-read-passphrase
 217           (format "PLAIN passphrase for %s: " (sasl-client-name client))))
 218         (authenticator-name
 219          (sasl-client-property
 220           client 'authenticator-name))
 221         (name (sasl-client-name client)))
 222     (unwind-protect
 223         (if (and authenticator-name
 224                  (not (string= authenticator-name name)))
 225             (concat authenticator-name "\0" name "\0" passphrase)
 226           (concat "\0" name "\0" passphrase))
 227       (fillarray passphrase 0))))
 228
 229 (put 'sasl-plain 'sasl-mechanism
 230      (sasl-make-mechanism "PLAIN" sasl-plain-steps))
 231
 232 (provide 'sasl-plain)
 233
 234 ;;; LOGIN (No specification exists)
 235 (defconst sasl-login-steps
 236   '(ignore                              ;no initial response
 237     sasl-login-response-1
 238     sasl-login-response-2))
 239
 240 (defun sasl-login-response-1 (client step)
 241 ;;;  (unless (string-match "^Username:" (sasl-step-data step))
 242 ;;;    (sasl-error (format "Unexpected response: %s" (sasl-step-data step))))
 243   (sasl-client-name client))
 244
 245 (defun sasl-login-response-2 (client step)
 246 ;;;  (unless (string-match "^Password:" (sasl-step-data step))
 247 ;;;    (sasl-error (format "Unexpected response: %s" (sasl-step-data step))))
 248   (sasl-read-passphrase
 249    (format "LOGIN passphrase for %s: " (sasl-client-name client))))
 250
 251 (put 'sasl-login 'sasl-mechanism
 252      (sasl-make-mechanism "LOGIN" sasl-login-steps))
 253
 254 (provide 'sasl-login)
 255
 256 ;;; ANONYMOUS (RFC2245)
 257 (defconst sasl-anonymous-steps
 258   '(ignore                              ;no initial response
 259     sasl-anonymous-response))
 260
 261 (defun sasl-anonymous-response (client step)
 262   (or (sasl-client-property client 'trace)
 263       (sasl-client-name client)))
 264
 265 (put 'sasl-anonymous 'sasl-mechanism
 266      (sasl-make-mechanism "ANONYMOUS" sasl-anonymous-steps))
 267
 268 (provide 'sasl-anonymous)
 269
 270 (provide 'sasl)
 271
 272 ;;; arch-tag: 8b3326fa-4978-4fda-93e2-cb2c6255f887
 273 ;;; sasl.el ends here