lisp/net/sasl.el

   1 ;;; sasl.el --- SASL client framework
   2
   3 ;; Copyright (C) 2000, 2007-2013 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 of the License, or
  13 ;; (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.
  22
  23 ;;; Commentary:
  24
  25 ;; This module provides common interface functions to share several
  26 ;; SASL mechanism drivers.  The toplevel is designed to be mostly
  27 ;; compatible with [Java-SASL].
  28 ;;
  29 ;; [SASL] J. Myers, "Simple Authentication and Security Layer (SASL)",
  30 ;;      RFC 2222, October 1997.
  31 ;;
  32 ;; [Java-SASL] R. Weltman & R. Lee, "The Java SASL Application Program
  33 ;;      Interface", draft-weltman-java-sasl-03.txt, March 2000.
  34
  35 ;;; Code:
  36
  37 (defvar sasl-mechanisms
  38   '("CRAM-MD5" "DIGEST-MD5" "PLAIN" "LOGIN" "ANONYMOUS"
  39     "NTLM" "SCRAM-MD5"))
  40
  41 (defvar sasl-mechanism-alist
  42   '(("CRAM-MD5" sasl-cram)
  43     ("DIGEST-MD5" sasl-digest)
  44     ("PLAIN" sasl-plain)
  45     ("LOGIN" sasl-login)
  46     ("ANONYMOUS" sasl-anonymous)
  47     ("NTLM" sasl-ntlm)
  48     ("SCRAM-MD5" sasl-scram)))
  49
  50 (defvar sasl-unique-id-function #'sasl-unique-id-function)
  51
  52 (put 'sasl-error 'error-message "SASL error")
  53 (put 'sasl-error 'error-conditions '(sasl-error error))
  54
  55 (defun sasl-error (datum)
  56   (signal 'sasl-error (list datum)))
  57
  58 ;;; @ SASL client
  59 ;;;
  60
  61 (defun sasl-make-client (mechanism name service server)
  62   "Return a newly allocated SASL client.
  63 NAME is name of the authorization.  SERVICE is name of the service desired.
  64 SERVER is the fully qualified host name of the server to authenticate to."
  65   (vector mechanism name service server (make-symbol "sasl-client-properties")))
  66
  67 (defun sasl-client-mechanism (client)
  68   "Return the authentication mechanism driver of CLIENT."
  69   (aref client 0))
  70
  71 (defun sasl-client-name (client)
  72   "Return the authorization name of CLIENT, a string."
  73   (aref client 1))
  74
  75 (defun sasl-client-service (client)
  76   "Return the service name of CLIENT, a string."
  77   (aref client 2))
  78
  79 (defun sasl-client-server (client)
  80   "Return the server name of CLIENT, a string."
  81   (aref client 3))
  82
  83 (defun sasl-client-set-properties (client plist)
  84   "Destructively set the properties of CLIENT.
  85 The second argument PLIST is the new property list."
  86   (setplist (aref client 4) plist))
  87
  88 (defun sasl-client-set-property (client property value)
  89   "Add the given PROPERTY/VALUE to CLIENT."
  90   (put (aref client 4) property value))
  91
  92 (defun sasl-client-property (client property)
  93   "Return the value of the PROPERTY of CLIENT."
  94   (get (aref client 4) property))
  95
  96 (defun sasl-client-properties (client)
  97   "Return the properties of CLIENT."
  98   (symbol-plist (aref client 4)))
  99
 100 ;;; @ SASL mechanism
 101 ;;;
 102
 103 (defun sasl-make-mechanism (name steps)
 104   "Make an authentication mechanism.
 105 NAME is a IANA registered SASL mechanism name.
 106 STEPS is list of continuation functions."
 107   (vector name
 108           (mapcar
 109            (lambda (step)
 110              (let ((symbol (make-symbol (symbol-name step))))
 111                (fset symbol (symbol-function step))
 112                symbol))
 113            steps)))
 114
 115 (defun sasl-mechanism-name (mechanism)
 116   "Return name of MECHANISM, a string."
 117   (aref mechanism 0))
 118
 119 (defun sasl-mechanism-steps (mechanism)
 120   "Return the authentication steps of MECHANISM, a list of functions."
 121   (aref mechanism 1))
 122
 123 (defun sasl-find-mechanism (mechanisms)
 124   "Retrieve an appropriate mechanism object from MECHANISMS hints."
 125   (let* ((sasl-mechanisms sasl-mechanisms)
 126          (mechanism
 127           (catch 'done
 128             (while sasl-mechanisms
 129               (if (member (car sasl-mechanisms) mechanisms)
 130                   (throw 'done (nth 1 (assoc (car sasl-mechanisms)
 131                                              sasl-mechanism-alist))))
 132               (setq sasl-mechanisms (cdr sasl-mechanisms))))))
 133     (if mechanism
 134         (require mechanism))
 135     (get mechanism 'sasl-mechanism)))
 136
 137 ;;; @ SASL authentication step
 138 ;;;
 139
 140 (defun sasl-step-data (step)
 141   "Return the data which STEP holds, a string."
 142   (aref step 1))
 143
 144 (defun sasl-step-set-data (step data)
 145   "Store DATA string to STEP."
 146   (aset step 1 data))
 147
 148 (defun sasl-next-step (client step)
 149   "Evaluate the challenge and prepare an appropriate next response.
 150 The data type of the value and 2nd argument STEP is nil or opaque
 151 authentication step which holds the reference to the next action and
 152 the current challenge.  At the first time STEP should be set to nil."
 153   (let* ((steps
 154           (sasl-mechanism-steps
 155            (sasl-client-mechanism client)))
 156          (function
 157           (if (vectorp step)
 158               (nth 1 (memq (aref step 0) steps))
 159             (car steps))))
 160     (if function
 161         (vector function (funcall function client step)))))
 162
 163 (defvar sasl-read-passphrase nil)
 164 (defun sasl-read-passphrase (prompt)
 165   (if (not sasl-read-passphrase)
 166       (if (functionp 'read-passwd)
 167           (setq sasl-read-passphrase 'read-passwd)
 168         (if (load "passwd" t)
 169             (setq sasl-read-passphrase 'read-passwd)
 170           (autoload 'ange-ftp-read-passwd "ange-ftp")
 171           (setq sasl-read-passphrase 'ange-ftp-read-passwd))))
 172   (funcall sasl-read-passphrase prompt))
 173
 174 (defun sasl-unique-id ()
 175   "Compute a data string which must be different each time.
 176 It contain at least 64 bits of entropy."
 177   (concat (funcall sasl-unique-id-function)(funcall sasl-unique-id-function)))
 178
 179 (defvar sasl-unique-id-char nil)
 180
 181 ;; stolen (and renamed) from message.el
 182 (defun sasl-unique-id-function ()
 183   ;; Don't use microseconds from (current-time), they may be unsupported.
 184   ;; Instead we use this randomly inited counter.
 185   (setq sasl-unique-id-char
 186         (% (1+ (or sasl-unique-id-char (logand (random) (1- (lsh 1 20)))))
 187            ;; (current-time) returns 16-bit ints,
 188            ;; and 2^16*25 just fits into 4 digits i base 36.
 189            (* 25 25)))
 190   (let ((tm (current-time)))
 191     (concat
 192      (sasl-unique-id-number-base36
 193       (+ (car   tm)
 194          (lsh (% sasl-unique-id-char 25) 16)) 4)
 195      (sasl-unique-id-number-base36
 196       (+ (nth 1 tm)
 197          (lsh (/ sasl-unique-id-char 25) 16)) 4))))
 198
 199 (defun sasl-unique-id-number-base36 (num len)
 200   (if (if (< len 0)
 201           (<= num 0)
 202         (= len 0))
 203       ""
 204     (concat (sasl-unique-id-number-base36 (/ num 36) (1- len))
 205             (char-to-string (aref "zyxwvutsrqponmlkjihgfedcba9876543210"
 206                                   (% num 36))))))
 207
 208 ;;; PLAIN (RFC2595 Section 6)
 209 (defconst sasl-plain-steps
 210   '(sasl-plain-response))
 211
 212 (defun sasl-plain-response (client step)
 213   (let ((passphrase
 214          (sasl-read-passphrase
 215           (format "PLAIN passphrase for %s: " (sasl-client-name client))))
 216         (authenticator-name
 217          (sasl-client-property
 218           client 'authenticator-name))
 219         (name (sasl-client-name client)))
 220     (unwind-protect
 221         (if (and authenticator-name
 222                  (not (string= authenticator-name name)))
 223             (concat authenticator-name "\0" name "\0" passphrase)
 224           (concat "\0" name "\0" passphrase))
 225       (fillarray passphrase 0))))
 226
 227 (put 'sasl-plain 'sasl-mechanism
 228      (sasl-make-mechanism "PLAIN" sasl-plain-steps))
 229
 230 (provide 'sasl-plain)
 231
 232 ;;; LOGIN (No specification exists)
 233 (defconst sasl-login-steps
 234   '(ignore                              ;no initial response
 235     sasl-login-response-1
 236     sasl-login-response-2))
 237
 238 (defun sasl-login-response-1 (client step)
 239 ;;;  (unless (string-match "^Username:" (sasl-step-data step))
 240 ;;;    (sasl-error (format "Unexpected response: %s" (sasl-step-data step))))
 241   (sasl-client-name client))
 242
 243 (defun sasl-login-response-2 (client step)
 244 ;;;  (unless (string-match "^Password:" (sasl-step-data step))
 245 ;;;    (sasl-error (format "Unexpected response: %s" (sasl-step-data step))))
 246   (sasl-read-passphrase
 247    (format "LOGIN passphrase for %s: " (sasl-client-name client))))
 248
 249 (put 'sasl-login 'sasl-mechanism
 250      (sasl-make-mechanism "LOGIN" sasl-login-steps))
 251
 252 (provide 'sasl-login)
 253
 254 ;;; ANONYMOUS (RFC2245)
 255 (defconst sasl-anonymous-steps
 256   '(ignore                              ;no initial response
 257     sasl-anonymous-response))
 258
 259 (defun sasl-anonymous-response (client step)
 260   (or (sasl-client-property client 'trace)
 261       (sasl-client-name client)))
 262
 263 (put 'sasl-anonymous 'sasl-mechanism
 264      (sasl-make-mechanism "ANONYMOUS" sasl-anonymous-steps))
 265
 266 (provide 'sasl-anonymous)
 267
 268 (provide 'sasl)
 269
 270 ;;; sasl.el ends here