1 ;;; url-http-ntlm.el --- NTLM authentication for the url library
3 ;; Copyright (C) 2008, 2015 Free Software Foundation, Inc.
5 ;; Author: Tom Schutzer-Weissmann <tom@schutzer-weissmann.net>
6 ;; Maintainer: Thomas Fitzsimmons <fitzsim@fitzsim.org>
7 ;; Keywords: comm, data, processes, hypermedia
9 ;; This program is free software; you can redistribute it and/or modify
10 ;; it under the terms of the GNU General Public License as published by
11 ;; the Free Software Foundation, either version 3 of the License, or
12 ;; (at your option) any later version.
14 ;; This program is distributed in the hope that it will be useful,
15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 ;; GNU General Public License for more details.
19 ;; You should have received a copy of the GNU General Public License
20 ;; along with this program. If not, see <http://www.gnu.org/licenses/>.
24 ;; This package provides a NTLM handler for the URL package.
25 ;; It supports one username and password per server.
29 ;; Add the directory containing this file to the load path and then
30 ;; load the url-http-ntlm package. One way would be to add something
31 ;; like the lines below to your .emacs file:
33 ;; (add-to-list 'load-path ".emacs.d/url-http-ntlm")
34 ;; (require 'url-http-ntlm)
38 ;; Taro Kawagishi <tarok@transpulse.org> wrote ntlm.el and md4.el,
39 ;; which are parts of FLIM (Faithful Library about Internet Message).
41 ;; http://stuff.mit.edu/afs/sipb/contrib/emacs/packages/flim-1.14.7/ntlm.el
42 ;; http://stuff.mit.edu/afs/sipb/contrib/emacs/packages/flim-1.14.7/md4.el
51 (defvar url-http-ntlm-auth-storage nil
52 "Authentication storage.
53 An alist that maps a server name to a pair of \(<username> <ntlm
56 The hashes are built using `ntlm-get-password-hashes'.
57 The username can contain the domain name, in the form \"user@domain\".
59 Note that for any server, only one user and password is ever stored.")
61 (defun url-ntlm-auth (url &optional prompt overwrite realm args)
62 "Return an NTLM HTTP authorization header.
63 Get the contents of the Authorization header for a HTTP response
64 using NTLM authentication, to access URL. Because NTLM is a
65 two-step process, this function expects to be called twice, first
66 to generate the NTLM type 1 message (request), then to respond to
67 the server's type 2 message (challenge) with a suitable response.
69 PROMPT, OVERWRITE, and REALM are ignored.
71 ARGS is expected to contain the WWW-Authentication header from
72 the server's last response. These are used by
73 `url-http-get-stage' to determine what stage we are at."
74 (url-ntlm-ensure-keepalive)
75 (let ((stage (url-ntlm-get-stage args)))
77 ;; NTLM Type 1 message: the request
79 (destructuring-bind (&optional server user hash)
80 (url-http-ntlm-authorisation url)
83 (ntlm-build-auth-request user server)))))
84 ;; NTLM Type 3 message: the response
86 (let ((challenge (url-http-ntlm-get-challenge)))
87 (destructuring-bind (server user hash)
88 (url-http-ntlm-authorisation url)
90 (ntlm-build-auth-response challenge
94 (url-http-ntlm-authorisation url :clear)))))
96 (defun url-ntlm-ensure-keepalive ()
97 "Report an error if `url-http-attempt-keepalives' is not set."
98 (assert url-http-attempt-keepalives
100 (concat "NTLM authentication won't work unless"
101 " `url-http-attempt-keepalives' is set!")))
103 (defun url-ntlm-clean-headers ()
104 "Remove Authorization element from `url-http-extra-headers' alist."
105 (setq url-http-extra-headers
106 (url-http-ntlm-rmssoc "Authorization" url-http-extra-headers)))
108 (defvar url-ntlm-last-args nil
109 "Stores the last ARGS argument to `url-ntlm-get-stage' and the return value.
110 This is used to detect multiple calls.")
111 (make-variable-buffer-local 'url-ntlm-last-args)
113 (defun url-ntlm-get-stage (args)
114 "Determine what stage of the NTLM handshake we are at.
115 PROMPT and ARGS come from `url-ntlm-auth''s caller,
116 `url-get-authentication'. Their meaning depends on the current
117 implementation - this function is well and truly coupled.
119 url-get-authentication' calls `url-ntlm-auth' once when checking
120 what authentication schemes are supported (PROMPT and ARGS are
121 nil), and then twice for every stage of the handshake: the first
122 time PROMPT is nil, the second, t; ARGS contains the server
123 response's \"WWW-Authenticate\" header, munged by
125 (let* ((response-rxp "^NTLM TlRMTVNTUAADAAA")
126 (challenge-rxp "^TLRMTVNTUAACAAA")
127 (auth-header (assoc "Authorization" url-http-extra-headers))
130 (if (eq args (car url-ntlm-last-args))
131 ;; multiple calls, return the same argument we returned last time
132 (cdr url-ntlm-last-args)
134 (cond ((and auth-header (string-match response-rxp
137 ((and (= (length args) 2)
138 (destructuring-bind (challenge ntlm) args
139 (and (string-equal "ntlm" (car ntlm))
140 (string-match challenge-rxp
145 (url-ntlm-clean-headers)
146 (setq url-ntlm-last-args (cons args stage))
149 (defun url-http-ntlm-authorisation (url &optional clear)
150 "Get or clear NTLM authentication details for URL.
151 If CLEAR is non-nil, clear any saved credentials for server.
152 Otherwise, return the credentials, prompting the user if
155 If URL contains a username and a password, they are used and
156 stored credentials are not affected.
158 Note that for any server, only one user and password is ever
160 (let* ((href (if (stringp url)
161 (url-generic-parse-url url)
163 (server (url-host href))
164 (user (url-user href))
165 (pass (url-password href))
166 (stored (assoc server url-http-ntlm-auth-storage))
167 (both (and user pass)))
171 (setq url-http-ntlm-auth-storage
172 (url-http-ntlm-rmssoc server url-http-ntlm-auth-storage))
176 (and stored user (not (equal user (second stored))))
178 (let* ((user* (if both
180 (read-string (url-auth-user-prompt url realm)
181 (or user (user-real-login-name)))))
184 (read-passwd "Password: ")))
185 (entry `(,server . (,user*
186 ,(ntlm-get-password-hashes pass*)))))
188 (setq url-http-ntlm-auth-storage
190 (url-http-ntlm-rmssoc server
191 url-http-ntlm-auth-storage))))
195 (defun url-http-ntlm-get-challenge ()
196 "Return the NTLM Type-2 message in the WWW-Authenticate header, if present."
198 (mail-narrow-to-head)
199 (let ((www-authenticate (mail-fetch-field "www-authenticate")))
200 (when (string-match "NTLM\\s-+\\(\\S-+\\)"
202 (base64-decode-string (match-string 1 www-authenticate))))))
204 (defun url-http-ntlm-rmssoc (key alist)
205 "Remove all elements whose `car' match KEY from ALIST."
206 (remove* key alist :key 'car :test 'equal))
208 (defun url-http-ntlm-string (data)
209 "Return DATA encoded as an NTLM string."
210 (concat "NTLM " (base64-encode-string data :nobreak)))
212 (url-register-auth-scheme "ntlm" nil 8)
214 (provide 'url-http-ntlm)
216 ;;; url-http-ntlm.el ends here