lisp/url/url-auth.el

   1 ;;; url-auth.el --- Uniform Resource Locator authorization modules
   2
   3 ;; Copyright (C) 1996-1999, 2004-2012  Free Software Foundation, Inc.
   4
   5 ;; Keywords: comm, data, processes, hypermedia
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs 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.
  13
  14 ;; GNU Emacs 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.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  21
  22 ;;; Code:
  23
  24 (require 'url-vars)
  25 (require 'url-parse)
  26 (autoload 'url-warn "url")
  27 (autoload 'auth-source-search "auth-source")
  28
  29 (defsubst url-auth-user-prompt (url realm)
  30   "String to usefully prompt for a username."
  31   (concat "Username [for "
  32           (or realm (url-truncate-url-for-viewing
  33                      (url-recreate-url url)
  34                      (- (window-width) 10 20)))
  35           "]: "))
  36
  37 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  38 ;;; Basic authorization code
  39 ;;; ------------------------
  40 ;;; This implements the BASIC authorization type.  See the online
  41 ;;; documentation at
  42 ;;; http://www.w3.org/hypertext/WWW/AccessAuthorization/Basic.html
  43 ;;; for the complete documentation on this type.
  44 ;;;
  45 ;;; This is very insecure, but it works as a proof-of-concept
  46 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  47 (defvar url-basic-auth-storage 'url-http-real-basic-auth-storage
  48   "Where usernames and passwords are stored.
  49
  50 Must be a symbol pointing to another variable that will actually store
  51 the information.  The value of this variable is an assoc list of assoc
  52 lists.  The first assoc list is keyed by the server name.  The cdr of
  53 this is an assoc list based on the 'directory' specified by the URL we
  54 are looking up.")
  55
  56 (defun url-basic-auth (url &optional prompt overwrite realm args)
  57   "Get the username/password for the specified URL.
  58 If optional argument PROMPT is non-nil, ask for the username/password
  59 to use for the url and its descendants.  If optional third argument
  60 OVERWRITE is non-nil, overwrite the old username/password pair if it
  61 is found in the assoc list.  If REALM is specified, use that as the realm
  62 instead of the filename inheritance method."
  63   (let* ((href (if (stringp url)
  64                    (url-generic-parse-url url)
  65                  url))
  66          (server (url-host href))
  67          (type (url-type href))
  68          (port (url-port href))
  69          (file (url-filename href))
  70          (user (url-user href))
  71          (pass (url-password href))
  72          (enable-recursive-minibuffers t) ; for url-handler-mode (bug#10298)
  73          byserv retval data)
  74     (setq server (format "%s:%d" server port)
  75           file (cond
  76                 (realm realm)
  77                 ((string= "" file) "/")
  78                 ((string-match "/$" file) file)
  79                 (t (url-file-directory file)))
  80           byserv (cdr-safe (assoc server
  81                                   (symbol-value url-basic-auth-storage))))
  82     (cond
  83      ((and prompt (not byserv))
  84       (setq user (or
  85                   (url-do-auth-source-search server type :user)
  86                   (read-string (url-auth-user-prompt url realm)
  87                                (or user (user-real-login-name))))
  88             pass (or
  89                   (url-do-auth-source-search server type :secret)
  90                   (read-passwd "Password: " nil (or pass ""))))
  91       (set url-basic-auth-storage
  92            (cons (list server
  93                        (cons file
  94                              (setq retval
  95                                    (base64-encode-string
  96                                     (format "%s:%s" user
  97                                             (encode-coding-string pass 'utf-8))))))
  98                  (symbol-value url-basic-auth-storage))))
  99      (byserv
 100       (setq retval (cdr-safe (assoc file byserv)))
 101       (if (and (not retval)
 102                (string-match "/" file))
 103           (while (and byserv (not retval))
 104             (setq data (car (car byserv)))
 105             (if (or (not (string-match "/" data)) ; It's a realm - take it!
 106                     (and
 107                      (>= (length file) (length data))
 108                      (string= data (substring file 0 (length data)))))
 109                 (setq retval (cdr (car byserv))))
 110             (setq byserv (cdr byserv))))
 111       (if (or (and (not retval) prompt) overwrite)
 112           (progn
 113             (setq user (or
 114                         (url-do-auth-source-search server type :user)
 115                         (read-string (url-auth-user-prompt url realm)
 116                                      (user-real-login-name)))
 117                   pass (or
 118                         (url-do-auth-source-search server type :secret)
 119                         (read-passwd "Password: "))
 120                   retval (base64-encode-string (format "%s:%s" user pass))
 121                   byserv (assoc server (symbol-value url-basic-auth-storage)))
 122             (setcdr byserv
 123                     (cons (cons file retval) (cdr byserv))))))
 124      (t (setq retval nil)))
 125     (if retval (setq retval (concat "Basic " retval)))
 126     retval))
 127
 128 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 129 ;;; Digest authorization code
 130 ;;; ------------------------
 131 ;;; This implements the DIGEST authorization type.  See the internet draft
 132 ;;; ftp://ds.internic.net/internet-drafts/draft-ietf-http-digest-aa-01.txt
 133 ;;; for the complete documentation on this type.
 134 ;;;
 135 ;;; This is very secure
 136 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 137 (defvar url-digest-auth-storage nil
 138   "Where usernames and passwords are stored.
 139 Its value is an assoc list of assoc lists.  The first assoc list is
 140 keyed by the server name.  The cdr of this is an assoc list based
 141 on the 'directory' specified by the url we are looking up.")
 142
 143 (defun url-digest-auth-create-key (username password realm method uri)
 144   "Create a key for digest authentication method"
 145   (let* ((info (if (stringp uri)
 146                    (url-generic-parse-url uri)
 147                  uri))
 148          (a1 (md5 (concat username ":" realm ":" password)))
 149          (a2 (md5 (concat method ":" (url-filename info)))))
 150     (list a1 a2)))
 151
 152 (defun url-digest-auth (url &optional prompt overwrite realm args)
 153   "Get the username/password for the specified URL.
 154 If optional argument PROMPT is non-nil, ask for the username/password
 155 to use for the URL and its descendants.  If optional third argument
 156 OVERWRITE is non-nil, overwrite the old username/password pair if it
 157 is found in the assoc list.  If REALM is specified, use that as the realm
 158 instead of hostname:portnum."
 159   (if args
 160       (let* ((href (if (stringp url)
 161                        (url-generic-parse-url url)
 162                      url))
 163              (server (url-host href))
 164              (type (url-type href))
 165              (port (url-port href))
 166              (file (url-filename href))
 167              (enable-recursive-minibuffers t)
 168              user pass byserv retval data)
 169         (setq file (cond
 170                     (realm realm)
 171                     ((string-match "/$" file) file)
 172                     (t (url-file-directory file)))
 173               server (format "%s:%d" server port)
 174               byserv (cdr-safe (assoc server url-digest-auth-storage)))
 175         (cond
 176          ((and prompt (not byserv))
 177           (setq user (or
 178                       (url-do-auth-source-search server type :user)
 179                       (read-string (url-auth-user-prompt url realm)
 180                                    (user-real-login-name)))
 181                 pass (or
 182                       (url-do-auth-source-search server type :secret)
 183                       (read-passwd "Password: "))
 184                 url-digest-auth-storage
 185                 (cons (list server
 186                             (cons file
 187                                   (setq retval
 188                                         (cons user
 189                                               (url-digest-auth-create-key
 190                                                user pass realm
 191                                                (or url-request-method "GET")
 192                                                url)))))
 193                       url-digest-auth-storage)))
 194          (byserv
 195           (setq retval (cdr-safe (assoc file byserv)))
 196           (if (and (not retval)         ; no exact match, check directories
 197                    (string-match "/" file)) ; not looking for a realm
 198               (while (and byserv (not retval))
 199                 (setq data (car (car byserv)))
 200                 (if (or (not (string-match "/" data))
 201                         (and
 202                          (>= (length file) (length data))
 203                          (string= data (substring file 0 (length data)))))
 204                     (setq retval (cdr (car byserv))))
 205                 (setq byserv (cdr byserv))))
 206           (if overwrite
 207               (if (and (not retval) prompt)
 208                   (setq user (or
 209                               (url-do-auth-source-search server type :user)
 210                               (read-string (url-auth-user-prompt url realm)
 211                                            (user-real-login-name)))
 212                         pass (or
 213                               (url-do-auth-source-search server type :secret)
 214                               (read-passwd "Password: "))
 215                         retval (setq retval
 216                                      (cons user
 217                                            (url-digest-auth-create-key
 218                                             user pass realm
 219                                             (or url-request-method "GET")
 220                                             url)))
 221                         byserv (assoc server url-digest-auth-storage))
 222                 (setcdr byserv
 223                         (cons (cons file retval) (cdr byserv))))))
 224          (t (setq retval nil)))
 225         (if retval
 226             (if (cdr-safe (assoc "opaque" args))
 227                 (let ((nonce (or (cdr-safe (assoc "nonce" args)) "nonegiven"))
 228                       (opaque (cdr-safe (assoc "opaque" args))))
 229                   (format
 230                    (concat "Digest username=\"%s\", realm=\"%s\","
 231                            "nonce=\"%s\", uri=\"%s\","
 232                            "response=\"%s\", opaque=\"%s\"")
 233                    (nth 0 retval) realm nonce (url-filename href)
 234                    (md5 (concat (nth 1 retval) ":" nonce ":"
 235                                 (nth 2 retval))) opaque))
 236               (let ((nonce (or (cdr-safe (assoc "nonce" args)) "nonegiven")))
 237                 (format
 238                  (concat "Digest username=\"%s\", realm=\"%s\","
 239                          "nonce=\"%s\", uri=\"%s\","
 240                          "response=\"%s\"")
 241                  (nth 0 retval) realm nonce (url-filename href)
 242                  (md5 (concat (nth 1 retval) ":" nonce ":"
 243                               (nth 2 retval))))))))))
 244
 245 (defvar url-registered-auth-schemes nil
 246   "A list of the registered authorization schemes and various and sundry
 247 information associated with them.")
 248
 249 (defun url-do-auth-source-search (server type parameter)
 250   (let* ((auth-info (auth-source-search :max 1 :host server :port type))
 251          (auth-info (nth 0 auth-info))
 252          (token (plist-get auth-info parameter))
 253          (token (if (functionp token) (funcall token) token)))
 254     token))
 255
 256 ;;;###autoload
 257 (defun url-get-authentication (url realm type prompt &optional args)
 258   "Return an authorization string suitable for use in the WWW-Authenticate
 259 header in an HTTP/1.0 request.
 260
 261 URL    is the url you are requesting authorization to.  This can be either a
 262        string representing the URL, or the parsed representation returned by
 263        `url-generic-parse-url'
 264 REALM  is the realm at a specific site we are looking for.  This should be a
 265        string specifying the exact realm, or nil or the symbol 'any' to
 266        specify that the filename portion of the URL should be used as the
 267        realm
 268 TYPE   is the type of authentication to be returned.  This is either a string
 269        representing the type (basic, digest, etc), or nil or the symbol 'any'
 270        to specify that any authentication is acceptable.  If requesting 'any'
 271        the strongest matching authentication will be returned.  If this is
 272        wrong, it's no big deal, the error from the server will specify exactly
 273        what type of auth to use
 274 PROMPT is boolean - specifies whether to ask the user for a username/password
 275        if one cannot be found in the cache"
 276   (if (not realm)
 277       (setq realm (cdr-safe (assoc "realm" args))))
 278   (if (stringp url)
 279       (setq url (url-generic-parse-url url)))
 280   (if (or (null type) (eq type 'any))
 281       ;; Whooo doogies!
 282       ;; Go through and get _all_ the authorization strings that could apply
 283       ;; to this URL, store them along with the 'rating' we have in the list
 284       ;; of schemes, then sort them so that the 'best' is at the front of the
 285       ;; list, then get the car, then get the cdr.
 286       ;; Zooom zooom zoooooom
 287       (cdr-safe
 288        (car-safe
 289         (sort
 290          (mapcar
 291           (function
 292            (lambda (scheme)
 293              (if (fboundp (car (cdr scheme)))
 294                  (cons (cdr (cdr scheme))
 295                        (funcall (car (cdr scheme)) url nil nil realm))
 296                (cons 0 nil))))
 297           url-registered-auth-schemes)
 298          (function
 299           (lambda (x y)
 300             (cond
 301              ((null (cdr x)) nil)
 302              ((and (cdr x) (null (cdr y))) t)
 303              ((and (cdr x) (cdr y))
 304               (>= (car x) (car y)))
 305              (t nil)))))))
 306     (if (symbolp type) (setq type (symbol-name type)))
 307     (let* ((scheme (car-safe
 308                     (cdr-safe (assoc (downcase type)
 309                                      url-registered-auth-schemes)))))
 310       (if (and scheme (fboundp scheme))
 311           (funcall scheme url prompt
 312                    (and prompt
 313                         (funcall scheme url nil nil realm args))
 314                    realm args)))))
 315
 316 ;;;###autoload
 317 (defun url-register-auth-scheme (type &optional function rating)
 318   "Register an HTTP authentication method.
 319
 320 TYPE     is a string or symbol specifying the name of the method.
 321          This should be the same thing you expect to get returned in
 322          an Authenticate header in HTTP/1.0 - it will be downcased.
 323 FUNCTION is the function to call to get the authorization information.
 324          This defaults to `url-?-auth', where ? is TYPE.
 325 RATING   a rating between 1 and 10 of the strength of the authentication.
 326          This is used when asking for the best authentication for a specific
 327          URL.  The item with the highest rating is returned."
 328   (let* ((type (cond
 329                 ((stringp type) (downcase type))
 330                 ((symbolp type) (downcase (symbol-name type)))
 331                 (t (error "Bad call to `url-register-auth-scheme'"))))
 332          (function (or function (intern (concat "url-" type "-auth"))))
 333          (rating (cond
 334                   ((null rating) 2)
 335                   ((stringp rating) (string-to-number rating))
 336                   (t rating)))
 337          (node (assoc type url-registered-auth-schemes)))
 338     (if (not (fboundp function))
 339         (url-warn 'security
 340                   (format (concat
 341                            "Tried to register `%s' as an auth scheme"
 342                            ", but it is not a function!") function)))
 343
 344     (if node
 345         (setcdr node (cons function rating))
 346       (setq url-registered-auth-schemes
 347             (cons (cons type (cons function rating))
 348                   url-registered-auth-schemes)))))
 349
 350 (defun url-auth-registered (scheme)
 351   "Return non-nil if SCHEME is registered as an auth type."
 352   (assoc scheme url-registered-auth-schemes))
 353
 354 (provide 'url-auth)
 355
 356 ;;; url-auth.el ends here