code.delx.au - gnu-emacs-elpa/blob - packages/url-http-ntlm/url-http-ntlm.el

   1 ;;; url-http-ntlm.el --- NTLM authentication for the url library
   2
   3 ;; Copyright (C) 2008  Tom Schutzer-Weissmann
   4
   5 ;; Author: Tom Schutzer-Weissmann <tom@schutzer-weissmann.net>
   6 ;; Keywords: comm, data, processes, hypermedia
   7
   8 ;; This program is free software; you can redistribute it and/or modify
   9 ;; it under the terms of the GNU General Public License as published by
  10 ;; the Free Software Foundation, either version 3 of the License, or
  11 ;; (at your option) any later version.
  12
  13 ;; This program is distributed in the hope that it will be useful,
  14 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 ;; GNU General Public License for more details.
  17
  18 ;; You should have received a copy of the GNU General Public License
  19 ;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 ;;; Commentary:
  22 ;;
  23 ;; This package provides a NTLM handler for the URL package.
  24 ;; It supports one username and password per server.
  25 ;;
  26 ;; Installation:
  27 ;;
  28 ;; Add the directory containing this file to the load path and then
  29 ;; load the url-http-ntlm package.  One way would be to add something
  30 ;; like the lines below to your .emacs file:
  31 ;;
  32 ;; (add-to-list 'load-path ".emacs.d/url-http-ntlm")
  33 ;; (require 'url-http-ntlm)
  34 ;;
  35 ;; Acknowledgements:
  36 ;;
  37 ;; Taro Kawagishi <tarok@transpulse.org> wrote ntlm.el and md4.el,
  38 ;; which are parts of FLIM (Faithful Library about Internet Message).
  39 ;;
  40 ;; http://stuff.mit.edu/afs/sipb/contrib/emacs/packages/flim-1.14.7/ntlm.el
  41 ;; http://stuff.mit.edu/afs/sipb/contrib/emacs/packages/flim-1.14.7/md4.el
  42
  43 ;;; Code:
  44 (require 'url-auth)
  45 (require 'url-http)
  46 (require 'mail-parse)
  47 (require 'cl)
  48 (require 'ntlm)
  49
  50 (defvar url-http-ntlm-auth-storage nil
  51   "Authentication storage. An alist that maps a server name
  52 to a pair of \(<username> <ntlm hashes>\).
  53
  54 The hashes are built using `ntlm-get-password-hashes'.
  55 The username can contain the domain name, in the form \"user@domain\".
  56
  57 Note that for any server, only one user and password is ever stored.")
  58
  59 (defun url-ntlm-auth (url &optional prompt overwrite realm args)
  60   "Get the contents of the Authorization header for a HTTP
  61   response using NTLM authentication, to access URL.  Because
  62   NTLM is a two-step process, this function expects to be called
  63   twice, first to generate the NTLM type 1 message (request),
  64   then to respond to the server's type 2 message (challenge) with
  65   a suitable response.
  66
  67   PROMPT, OVERWRITE, and REALM are ignored.
  68
  69   ARGS is expected to contain the WWW-Authentication header from
  70   the server's last response. These are used by
  71   `url-http-get-stage' to determine what stage we are at."
  72   (url-ntlm-ensure-keepalive)
  73   (let ((stage (url-ntlm-get-stage args)))
  74     (case stage
  75       ;;
  76       ;; NTLM Type 1 message: the request
  77       (:request
  78        (destructuring-bind (&optional server user hash)
  79            (url-http-ntlm-authorisation url)
  80          (when server
  81            (url-http-ntlm-string (ntlm-build-auth-request user server)))))
  82       ;;
  83       ;; NTLM Type 3 message: the response
  84       (:response
  85        (let ((challenge (url-http-ntlm-get-challenge)))
  86          (destructuring-bind (server user hash)
  87              (url-http-ntlm-authorisation url)
  88            (url-http-ntlm-string (ntlm-build-auth-response challenge
  89                                                            user
  90                                                            hash)))))
  91       (:error
  92        (url-http-ntlm-authorisation url :clear)))))
  93
  94 (defun url-ntlm-ensure-keepalive ()
  95   (assert url-http-attempt-keepalives
  96           nil
  97           (concat "NTLM authentication won't work unless"
  98                   " `url-http-attempt-keepalives' is set!")))
  99
 100 (defun url-ntlm-clean-headers ()
 101   (setq url-http-extra-headers
 102         (url-http-ntlm-rmssoc "Authorization" url-http-extra-headers)))
 103
 104 (defvar url-ntlm-last-args nil
 105   "Stores the last ARGS argument to `url-ntlm-get-stage' and the return value.
 106 This is used to detect multiple calls.")
 107 (make-variable-buffer-local 'url-ntlm-last-args)
 108
 109 (defun url-ntlm-get-stage (args)
 110   "Determine what stage of the NTLM handshake we are at.
 111 PROMPT and ARGS come from `url-ntlm-auth''s caller,
 112 `url-get-authentication'. Their meaning depends on the current
 113 implementation - this function is well and truly coupled.
 114
 115 url-get-authentication' calls `url-ntlm-auth' once when checking
 116 what authentication schemes are supported (PROMPT and ARGS are
 117 nil), and then twice for every stage of the handshake: the first
 118 time PROMPT is nil, the second, t; ARGS contains the server
 119 response's \"WWW-Authenticate\" header, munged by
 120 `url-parse-args'."
 121   (let* ((response-rxp     "^NTLM TlRMTVNTUAADAAA")
 122          (challenge-rxp    "^TLRMTVNTUAACAAA")
 123          (auth-header      (assoc "Authorization" url-http-extra-headers))
 124          (case-fold-search t)
 125          stage)
 126     (if (eq args (car url-ntlm-last-args))
 127         ;; multiple calls, return the same argument we returned last time
 128         (cdr url-ntlm-last-args)
 129         ;;
 130         (let ((stage
 131                (cond ((and auth-header (string-match response-rxp
 132                                                      (cdr auth-header)))
 133                       :error)
 134                      ((and (= (length args) 2)
 135                            (destructuring-bind (challenge ntlm) args
 136                              (and (string-equal "ntlm" (car ntlm))
 137                                   (string-match challenge-rxp
 138                                                 (car challenge)))))
 139                       :response)
 140                      (t
 141                       :request))))
 142           (url-ntlm-clean-headers)
 143           (setq url-ntlm-last-args (cons args stage))
 144           stage))))
 145
 146 (defun url-http-ntlm-authorisation (url &optional clear)
 147   "Get or clear NTLM authentication details for URL. If CLEAR is
 148   non-nil, clear any saved credentials for server. Otherwise,
 149   return the credentials, prompting the user if necessary.
 150
 151 If URL contains a username and a password, they are used and
 152 stored credentials are not affected.
 153
 154 Note that for any server, only one user and password is ever
 155 stored."
 156   (let* ((href   (if (stringp url)
 157                      (url-generic-parse-url url)
 158                      url))
 159          (server (url-host href))
 160          (user   (url-user href))
 161          (pass   (url-password href))
 162          (stored (assoc server url-http-ntlm-auth-storage))
 163          (both   (and user pass)))
 164     (if clear
 165         ;; clear
 166         (unless both
 167           (setq url-http-ntlm-auth-storage
 168                 (url-http-ntlm-rmssoc server url-http-ntlm-auth-storage))
 169           nil)
 170         ;; get
 171         (if (or both
 172                 (and stored user (not (equal user (second stored))))
 173                 (not stored))
 174             (let* ((user*  (if both
 175                                user
 176                                (read-string (url-auth-user-prompt url realm)
 177                                             (or user (user-real-login-name)))))
 178                    (pass*  (if both
 179                                pass
 180                                (read-passwd "Password: ")))
 181                    (entry `(,server . (,user*
 182                                        ,(ntlm-get-password-hashes pass*)))))
 183               (unless both
 184                 (setq url-http-ntlm-auth-storage
 185                       (cons entry
 186                             (url-http-ntlm-rmssoc server
 187                                                   url-http-ntlm-auth-storage))))
 188               entry)
 189             ;;
 190             stored))))
 191
 192 (defun url-http-ntlm-get-challenge ()
 193   "Return the NTLM Type-2 message in the WWW-Authenticate header,
 194 if it is there."
 195   (save-restriction
 196     (mail-narrow-to-head)
 197     (let ((www-authenticate (mail-fetch-field "www-authenticate")))
 198       (when (string-match "NTLM\\s-+\\(\\S-+\\)"
 199                           www-authenticate)
 200         (base64-decode-string (match-string 1 www-authenticate))))))
 201
 202 (defun url-http-ntlm-rmssoc (key alist)
 203   (remove* key alist :key 'car :test 'equal))
 204
 205 (defun url-http-ntlm-string (data)
 206   (concat "NTLM " (base64-encode-string data :nobreak)))
 207
 208 (url-register-auth-scheme "ntlm" nil 8)
 209
 210 (provide 'url-http-ntlm)
 211
 212 ;;; url-http-ntlm.el ends here