lisp/url/url-http.el

   1 ;;; url-http.el --- HTTP retrieval routines
   2
   3 ;; Copyright (c) 1999, 2001, 2004  Free Software Foundation, Inc.
   4
   5 ;; Author: Bill Perry <wmperry@gnu.org>
   6 ;; Keywords: comm, data, processes
   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 2, 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 ;;; Code:
  28
  29 (eval-when-compile
  30   (require 'cl)
  31   (defvar url-http-extra-headers))
  32 (require 'url-gw)
  33 (require 'url-util)
  34 (require 'url-parse)
  35 (require 'url-cookie)
  36 (require 'mail-parse)
  37 (require 'url-auth)
  38 (autoload 'url-retrieve-synchronously "url")
  39 (autoload 'url-retrieve "url")
  40 (autoload 'url-cache-create-filename "url-cache")
  41 (autoload 'url-mark-buffer-as-dead "url")
  42
  43 (defconst url-http-default-port 80 "Default HTTP port.")
  44 (defconst url-http-asynchronous-p t "HTTP retrievals are asynchronous.")
  45 (defalias 'url-http-expand-file-name 'url-default-expander)
  46
  47 (defvar url-http-real-basic-auth-storage nil)
  48 (defvar url-http-proxy-basic-auth-storage nil)
  49
  50 (defvar url-http-open-connections (make-hash-table :test 'equal
  51                                                    :size 17)
  52   "A hash table of all open network connections.")
  53
  54 (defvar url-http-version "1.1"
  55   "What version of HTTP we advertise, as a string.
  56 Valid values are 1.1 and 1.0.
  57 This is only useful when debugging the HTTP subsystem.
  58
  59 Setting this to 1.0 will tell servers not to send chunked encoding,
  60 and other HTTP/1.1 specific features.
  61 ")
  62
  63 (defvar url-http-attempt-keepalives t
  64   "Whether to use a single TCP connection multiple times in HTTP.
  65 This is only useful when debugging the HTTP subsystem.  Setting to
  66 `nil' will explicitly close the connection to the server after every
  67 request.
  68 ")
  69
  70 ;(eval-when-compile
  71 ;; These are all macros so that they are hidden from external sight
  72 ;; when the file is byte-compiled.
  73 ;;
  74 ;; This allows us to expose just the entry points we want.
  75
  76 ;; These routines will allow us to implement persistent HTTP
  77 ;; connections.
  78 (defsubst url-http-debug (&rest args)
  79   (if quit-flag
  80       (let ((proc (get-buffer-process (current-buffer))))
  81         ;; The user hit C-g, honor it!  Some things can get in an
  82         ;; incredibly tight loop (chunked encoding)
  83         (if proc
  84             (progn
  85               (set-process-sentinel proc nil)
  86               (set-process-filter proc nil)))
  87         (error "Transfer interrupted!")))
  88   (apply 'url-debug 'http args))
  89
  90 (defun url-http-mark-connection-as-busy (host port proc)
  91   (url-http-debug "Marking connection as busy: %s:%d %S" host port proc)
  92   (puthash (cons host port)
  93               (delq proc (gethash (cons host port) url-http-open-connections))
  94               url-http-open-connections)
  95   proc)
  96
  97 (defun url-http-mark-connection-as-free (host port proc)
  98   (url-http-debug "Marking connection as free: %s:%d %S" host port proc)
  99   (set-process-buffer proc nil)
 100   (set-process-sentinel proc 'url-http-idle-sentinel)
 101   (puthash (cons host port)
 102               (cons proc (gethash (cons host port) url-http-open-connections))
 103               url-http-open-connections)
 104   nil)
 105
 106 (defun url-http-find-free-connection (host port)
 107   (let ((conns (gethash (cons host port) url-http-open-connections))
 108         (found nil))
 109     (while (and conns (not found))
 110       (if (not (memq (process-status (car conns)) '(run open)))
 111           (progn
 112             (url-http-debug "Cleaning up dead process: %s:%d %S"
 113                             host port (car conns))
 114             (url-http-idle-sentinel (car conns) nil))
 115         (setq found (car conns))
 116         (url-http-debug "Found existing connection: %s:%d %S" host port found))
 117       (pop conns))
 118     (if found
 119         (url-http-debug "Reusing existing connection: %s:%d" host port)
 120       (url-http-debug "Contacting host: %s:%d" host port))
 121     (url-lazy-message "Contacting host: %s:%d" host port)
 122     (url-http-mark-connection-as-busy host port
 123                                       (or found
 124                                           (url-open-stream host nil host
 125                                                            port)))))
 126
 127 ;; Building an HTTP request
 128 (defun url-http-user-agent-string ()
 129   (if (or (eq url-privacy-level 'paranoid)
 130           (and (listp url-privacy-level)
 131                (memq 'agent url-privacy-level)))
 132       ""
 133     (format "User-Agent: %sURL/%s%s\r\n"
 134             (if url-package-name
 135                 (concat url-package-name "/" url-package-version " ")
 136               "")
 137             url-version
 138             (cond
 139              ((and url-os-type url-system-type)
 140               (concat " (" url-os-type "; " url-system-type ")"))
 141              ((or url-os-type url-system-type)
 142               (concat " (" (or url-system-type url-os-type) ")"))
 143              (t "")))))
 144
 145 (defun url-http-create-request (url &optional ref-url)
 146   "Create an HTTP request for URL, referred to by REF-URL."
 147   (declare (special proxy-object proxy-info))
 148   (let* ((extra-headers)
 149          (request nil)
 150          (no-cache (cdr-safe (assoc "Pragma" url-request-extra-headers)))
 151          (proxy-obj (and (boundp 'proxy-object) proxy-object))
 152          (proxy-auth (if (or (cdr-safe (assoc "Proxy-Authorization"
 153                                               url-request-extra-headers))
 154                              (not proxy-obj))
 155                          nil
 156                        (let ((url-basic-auth-storage
 157                               'url-http-proxy-basic-auth-storage))
 158                          (url-get-authentication url nil 'any nil))))
 159          (real-fname (url-filename (or proxy-obj url)))
 160          (host (url-host (or proxy-obj url)))
 161          (auth (if (cdr-safe (assoc "Authorization" url-request-extra-headers))
 162                    nil
 163                  (url-get-authentication (or
 164                                           (and (boundp 'proxy-info)
 165                                                proxy-info)
 166                                           url) nil 'any nil))))
 167     (if (equal "" real-fname)
 168         (setq real-fname "/"))
 169     (setq no-cache (and no-cache (string-match "no-cache" no-cache)))
 170     (if auth
 171         (setq auth (concat "Authorization: " auth "\r\n")))
 172     (if proxy-auth
 173         (setq proxy-auth (concat "Proxy-Authorization: " proxy-auth "\r\n")))
 174
 175     ;; Protection against stupid values in the referer
 176     (if (and ref-url (stringp ref-url) (or (string= ref-url "file:nil")
 177                                            (string= ref-url "")))
 178         (setq ref-url nil))
 179
 180     ;; We do not want to expose the referer if the user is paranoid.
 181     (if (or (memq url-privacy-level '(low high paranoid))
 182             (and (listp url-privacy-level)
 183                  (memq 'lastloc url-privacy-level)))
 184         (setq ref-url nil))
 185
 186     ;; url-request-extra-headers contains an assoc-list of
 187     ;; header/value pairs that we need to put into the request.
 188     (setq extra-headers (mapconcat
 189                          (lambda (x)
 190                            (concat (car x) ": " (cdr x)))
 191                          url-request-extra-headers "\r\n"))
 192     (if (not (equal extra-headers ""))
 193         (setq extra-headers (concat extra-headers "\r\n")))
 194
 195     ;; This was done with a call to `format'.  Concatting parts has
 196     ;; the advantage of keeping the parts of each header togther and
 197     ;; allows us to elide null lines directly, at the cost of making
 198     ;; the layout less clear.
 199     (setq request
 200           (concat
 201            ;; The request
 202            (or url-request-method "GET") " "
 203            (if proxy-obj (url-recreate-url proxy-obj) real-fname)
 204            " HTTP/" url-http-version "\r\n"
 205            ;; Version of MIME we speak
 206            "MIME-Version: 1.0\r\n"
 207            ;; (maybe) Try to keep the connection open
 208            "Connection: " (if (or proxy-obj
 209                                   (not url-http-attempt-keepalives))
 210                               "close" "keep-alive") "\r\n"
 211            ;; HTTP extensions we support
 212            (if url-extensions-header
 213                (format
 214                 "Extension: %s\r\n" url-extensions-header))
 215            ;; Who we want to talk to
 216            (if (/= (url-port (or proxy-obj url))
 217                    (url-scheme-get-property
 218                     (url-type (or proxy-obj url)) 'default-port))
 219                (format
 220                 "Host: %s:%d\r\n" host (url-port (or proxy-obj url)))
 221              (format "Host: %s\r\n" host))
 222            ;; Who its from
 223            (if url-personal-mail-address
 224                (concat
 225                 "From: " url-personal-mail-address "\r\n"))
 226            ;; Encodings we understand
 227            (if url-mime-encoding-string
 228                (concat
 229                 "Accept-encoding: " url-mime-encoding-string "\r\n"))
 230            (if url-mime-charset-string
 231                (concat
 232                 "Accept-charset: " url-mime-charset-string "\r\n"))
 233            ;; Languages we understand
 234            (if url-mime-language-string
 235                (concat
 236                 "Accept-language: " url-mime-language-string "\r\n"))
 237            ;; Types we understand
 238            "Accept: " (or url-mime-accept-string "*/*") "\r\n"
 239            ;; User agent
 240            (url-http-user-agent-string)
 241            ;; Proxy Authorization
 242            proxy-auth
 243            ;; Authorization
 244            auth
 245            ;; Cookies
 246            (url-cookie-generate-header-lines host real-fname
 247                                              (equal "https" (url-type url)))
 248            ;; If-modified-since
 249            (if (and (not no-cache)
 250                     (member url-request-method '("GET" nil)))
 251                (let ((tm (url-is-cached (or proxy-obj url))))
 252                  (if tm
 253                      (concat "If-modified-since: "
 254                              (url-get-normalized-date tm) "\r\n"))))
 255            ;; Whence we came
 256            (if ref-url (concat
 257                         "Referer: " ref-url "\r\n"))
 258            extra-headers
 259            ;; Length of data
 260            (if url-request-data
 261                (concat
 262                 "Content-length: " (number-to-string
 263                                     (length url-request-data))
 264                 "\r\n"))
 265            ;; End request
 266            "\r\n"
 267            ;; Any data
 268            url-request-data))
 269     (url-http-debug "Request is: \n%s" request)
 270     request))
 271
 272 ;; Parsing routines
 273 (defun url-http-clean-headers ()
 274   "Remove trailing \r from header lines.
 275 This allows us to use `mail-fetch-field', etc."
 276   (declare (special url-http-end-of-headers))
 277   (goto-char (point-min))
 278   (while (re-search-forward "\r$" url-http-end-of-headers t)
 279     (replace-match "")))
 280
 281 (defun url-http-handle-authentication (proxy)
 282   (declare (special status success url-http-method url-http-data
 283                     url-callback-function url-callback-arguments))
 284   (url-http-debug "Handling %s authentication" (if proxy "proxy" "normal"))
 285   (let ((auth (or (mail-fetch-field (if proxy "proxy-authenticate" "www-authenticate"))
 286                   "basic"))
 287         (type nil)
 288         (url (url-recreate-url url-current-object))
 289         (url-basic-auth-storage 'url-http-real-basic-auth-storage)
 290         )
 291
 292     ;; Cheating, but who cares? :)
 293     (if proxy
 294         (setq url-basic-auth-storage 'url-http-proxy-basic-auth-storage))
 295
 296     (setq auth (url-eat-trailing-space (url-strip-leading-spaces auth)))
 297     (if (string-match "[ \t]" auth)
 298         (setq type (downcase (substring auth 0 (match-beginning 0))))
 299       (setq type (downcase auth)))
 300
 301     (if (not (url-auth-registered type))
 302         (progn
 303           (widen)
 304           (goto-char (point-max))
 305           (insert "<hr>Sorry, but I do not know how to handle " type
 306                   " authentication.  If you'd like to write it,"
 307                   " send it to " url-bug-address ".<hr>")
 308           (setq status t))
 309       (let* ((args auth)
 310              (ctr (1- (length args)))
 311              auth)
 312         (while (/= 0 ctr)
 313           (if (char-equal ?, (aref args ctr))
 314               (aset args ctr ?\;))
 315           (setq ctr (1- ctr)))
 316         (setq args (url-parse-args args)
 317               auth (url-get-authentication url (cdr-safe (assoc "realm" args))
 318                                            type t args))
 319         (if (not auth)
 320             (setq success t)
 321           (push (cons (if proxy "Proxy-Authorization" "Authorization") auth)
 322                 url-http-extra-headers)
 323           (let ((url-request-method url-http-method)
 324                 (url-request-data url-http-data)
 325                 (url-request-extra-headers url-http-extra-headers))
 326             (url-retrieve url url-callback-function
 327                           url-callback-arguments)))))))
 328
 329 (defun url-http-parse-response ()
 330   "Parse just the response code."
 331   (declare (special url-http-end-of-headers url-http-response-status))
 332   (if (not url-http-end-of-headers)
 333       (error "Trying to parse HTTP response code in odd buffer: %s" (buffer-name)))
 334   (url-http-debug "url-http-parse-response called in (%s)" (buffer-name))
 335   (goto-char (point-min))
 336   (skip-chars-forward " \t\n")          ; Skip any blank crap
 337   (skip-chars-forward "HTTP/")          ; Skip HTTP Version
 338   (read (current-buffer))
 339   (setq url-http-response-status (read (current-buffer))))
 340
 341 (defun url-http-handle-cookies ()
 342   "Handle all set-cookie / set-cookie2 headers in an HTTP response.
 343 The buffer must already be narrowed to the headers, so mail-fetch-field will
 344 work correctly."
 345   (let ((cookies (mail-fetch-field "Set-Cookie" nil nil t))
 346         (cookies2 (mail-fetch-field "Set-Cookie2" nil nil t))
 347         (url-current-object url-http-cookies-sources))
 348     (and cookies (url-http-debug "Found %d Set-Cookie headers" (length cookies)))
 349     (and cookies2 (url-http-debug "Found %d Set-Cookie2 headers" (length cookies2)))
 350     (while cookies
 351       (url-cookie-handle-set-cookie (pop cookies)))
 352 ;;;     (while cookies2
 353 ;;;       (url-cookie-handle-set-cookie2 (pop cookies)))
 354     )
 355   )
 356
 357 (defun url-http-parse-headers ()
 358  "Parse and handle HTTP specific headers.
 359 Return t if and only if the current buffer is still active and
 360 should be shown to the user."
 361   ;; The comments after each status code handled are taken from RFC
 362   ;; 2616 (HTTP/1.1)
 363   (declare (special url-http-end-of-headers url-http-response-status
 364                     url-http-method url-http-data url-http-process
 365                     url-callback-function url-callback-arguments))
 366
 367   (url-http-mark-connection-as-free (url-host url-current-object)
 368                                     (url-port url-current-object)
 369                                     url-http-process)
 370
 371   (if (or (not (boundp 'url-http-end-of-headers))
 372           (not url-http-end-of-headers))
 373       (error "Trying to parse headers in odd buffer: %s" (buffer-name)))
 374   (goto-char (point-min))
 375   (url-http-debug "url-http-parse-headers called in (%s)" (buffer-name))
 376   (url-http-parse-response)
 377   (mail-narrow-to-head)
 378   ;;(narrow-to-region (point-min) url-http-end-of-headers)
 379   (let ((class nil)
 380         (success nil))
 381     (setq class (/ url-http-response-status 100))
 382     (url-http-debug "Parsed HTTP headers: class=%d status=%d" class url-http-response-status)
 383     (url-http-handle-cookies)
 384
 385     (case class
 386       ;; Classes of response codes
 387       ;;
 388       ;; 5xx = Server Error
 389       ;; 4xx = Client Error
 390       ;; 3xx = Redirection
 391       ;; 2xx = Successful
 392       ;; 1xx = Informational
 393       (1                                ; Information messages
 394        ;; 100 = Continue with request
 395        ;; 101 = Switching protocols
 396        ;; 102 = Processing (Added by DAV)
 397        (url-mark-buffer-as-dead (current-buffer))
 398        (error "HTTP responses in class 1xx not supported (%d)" url-http-response-status))
 399       (2                                ; Success
 400        ;; 200 Ok
 401        ;; 201 Created
 402        ;; 202 Accepted
 403        ;; 203 Non-authoritative information
 404        ;; 204 No content
 405        ;; 205 Reset content
 406        ;; 206 Partial content
 407        ;; 207 Multi-status (Added by DAV)
 408        (case url-http-response-status
 409          ((204 205)
 410           ;; No new data, just stay at the same document
 411           (url-mark-buffer-as-dead (current-buffer))
 412           (setq success t))
 413          (otherwise
 414           ;; Generic success for all others.  Store in the cache, and
 415           ;; mark it as successful.
 416           (widen)
 417           (if (and url-automatic-caching (equal url-http-method "GET"))
 418               (url-store-in-cache (current-buffer)))
 419           (setq success t))))
 420       (3                                ; Redirection
 421        ;; 300 Multiple choices
 422        ;; 301 Moved permanently
 423        ;; 302 Found
 424        ;; 303 See other
 425        ;; 304 Not modified
 426        ;; 305 Use proxy
 427        ;; 307 Temporary redirect
 428        (let ((redirect-uri (or (mail-fetch-field "Location")
 429                                (mail-fetch-field "URI"))))
 430          (case url-http-response-status
 431            (300
 432             ;; Quoth the spec (section 10.3.1)
 433             ;; -------------------------------
 434             ;; The requested resource corresponds to any one of a set of
 435             ;; representations, each with its own specific location and
 436             ;; agent-driven negotiation information is being provided so
 437             ;; that the user can select a preferred representation and
 438             ;; redirect its request to that location.
 439             ;; [...]
 440             ;; If the server has a preferred choice of representation, it
 441             ;; SHOULD include the specific URI for that representation in
 442             ;; the Location field; user agents MAY use the Location field
 443             ;; value for automatic redirection.
 444             ;; -------------------------------
 445             ;; We do not support agent-driven negotiation, so we just
 446             ;; redirect to the preferred URI if one is provided.
 447             nil)
 448            ((301 302 307)
 449             ;; If the 301|302 status code is received in response to a
 450             ;; request other than GET or HEAD, the user agent MUST NOT
 451             ;; automatically redirect the request unless it can be
 452             ;; confirmed by the user, since this might change the
 453             ;; conditions under which the request was issued.
 454             (if (member url-http-method '("HEAD" "GET"))
 455                 ;; Automatic redirection is ok
 456                 nil
 457               ;; It is just too big of a pain in the ass to get this
 458               ;; prompt all the time.  We will just silently lose our
 459               ;; data and convert to a GET method.
 460               (url-http-debug "Converting `%s' request to `GET' because of REDIRECT(%d)"
 461                               url-http-method url-http-response-status)
 462               (setq url-http-method "GET"
 463                     url-http-data nil)))
 464            (303
 465             ;; The response to the request can be found under a different
 466             ;; URI and SHOULD be retrieved using a GET method on that
 467             ;; resource.
 468             (setq url-http-method "GET"
 469                   url-http-data nil))
 470            (304
 471             ;; The 304 response MUST NOT contain a message-body.
 472             (url-http-debug "Extracting document from cache... (%s)"
 473                             (url-cache-create-filename (url-view-url t)))
 474             (url-cache-extract (url-cache-create-filename (url-view-url t)))
 475             (setq redirect-uri nil
 476                   success t))
 477            (305
 478             ;; The requested resource MUST be accessed through the
 479             ;; proxy given by the Location field.  The Location field
 480             ;; gives the URI of the proxy.  The recipient is expected
 481             ;; to repeat this single request via the proxy.  305
 482             ;; responses MUST only be generated by origin servers.
 483             (error "Redirection thru a proxy server not supported: %s"
 484                    redirect-uri))
 485            (otherwise
 486             ;; Treat everything like '300'
 487             nil))
 488          (when redirect-uri
 489            ;; Clean off any whitespace and/or <...> cruft.
 490            (if (string-match "\\([^ \t]+\\)[ \t]" redirect-uri)
 491                (setq redirect-uri (match-string 1 redirect-uri)))
 492            (if (string-match "^<\\(.*\\)>$" redirect-uri)
 493                (setq redirect-uri (match-string 1 redirect-uri)))
 494
 495            ;; Some stupid sites (like sourceforge) send a
 496            ;; non-fully-qualified URL (ie: /), which royally confuses
 497            ;; the URL library.
 498            (if (not (string-match url-nonrelative-link redirect-uri))
 499                (setq redirect-uri (url-expand-file-name redirect-uri)))
 500            (let ((url-request-method url-http-method)
 501                  (url-request-data url-http-data)
 502                  (url-request-extra-headers url-http-extra-headers))
 503              (url-retrieve redirect-uri url-callback-function
 504                            (cons redirect-uri
 505                                  (cdr url-callback-arguments)))
 506              (url-mark-buffer-as-dead (current-buffer))))))
 507       (4                                ; Client error
 508        ;; 400 Bad Request
 509        ;; 401 Unauthorized
 510        ;; 402 Payment required
 511        ;; 403 Forbidden
 512        ;; 404 Not found
 513        ;; 405 Method not allowed
 514        ;; 406 Not acceptable
 515        ;; 407 Proxy authentication required
 516        ;; 408 Request time-out
 517        ;; 409 Conflict
 518        ;; 410 Gone
 519        ;; 411 Length required
 520        ;; 412 Precondition failed
 521        ;; 413 Request entity too large
 522        ;; 414 Request-URI too large
 523        ;; 415 Unsupported media type
 524        ;; 416 Requested range not satisfiable
 525        ;; 417 Expectation failed
 526        ;; 422 Unprocessable Entity (Added by DAV)
 527        ;; 423 Locked
 528        ;; 424 Failed Dependency
 529        (case url-http-response-status
 530          (401
 531           ;; The request requires user authentication.  The response
 532           ;; MUST include a WWW-Authenticate header field containing a
 533           ;; challenge applicable to the requested resource.  The
 534           ;; client MAY repeat the request with a suitable
 535           ;; Authorization header field.
 536           (url-http-handle-authentication nil))
 537          (402
 538           ;; This code is reserved for future use
 539           (url-mark-buffer-as-dead (current-buffer))
 540           (error "Somebody wants you to give them money"))
 541          (403
 542           ;; The server understood the request, but is refusing to
 543           ;; fulfill it.  Authorization will not help and the request
 544           ;; SHOULD NOT be repeated.
 545           (setq success t))
 546          (404
 547           ;; Not found
 548           (setq success t))
 549          (405
 550           ;; The method specified in the Request-Line is not allowed
 551           ;; for the resource identified by the Request-URI.  The
 552           ;; response MUST include an Allow header containing a list of
 553           ;; valid methods for the requested resource.
 554           (setq success t))
 555          (406
 556           ;; The resource identified by the request is only capable of
 557           ;; generating response entities which have content
 558           ;; characteristics nota cceptable according to the accept
 559           ;; headers sent in the request.
 560           (setq success t))
 561          (407
 562           ;; This code is similar to 401 (Unauthorized), but indicates
 563           ;; that the client must first authenticate itself with the
 564           ;; proxy.  The proxy MUST return a Proxy-Authenticate header
 565           ;; field containing a challenge applicable to the proxy for
 566           ;; the requested resource.
 567           (url-http-handle-authentication t))
 568          (408
 569           ;; The client did not produce a request within the time that
 570           ;; the server was prepared to wait.  The client MAY repeat
 571           ;; the request without modifications at any later time.
 572           (setq success t))
 573          (409
 574           ;; The request could not be completed due to a conflict with
 575           ;; the current state of the resource.  This code is only
 576           ;; allowed in situations where it is expected that the user
 577           ;; mioght be able to resolve the conflict and resubmit the
 578           ;; request.  The response body SHOULD include enough
 579           ;; information for the user to recognize the source of the
 580           ;; conflict.
 581           (setq success t))
 582          (410
 583           ;; The requested resource is no longer available at the
 584           ;; server and no forwarding address is known.
 585           (setq success t))
 586          (411
 587           ;; The server refuses to accept the request without a defined
 588           ;; Content-Length.  The client MAY repeat the request if it
 589           ;; adds a valid Content-Length header field containing the
 590           ;; length of the message-body in the request message.
 591           ;;
 592           ;; NOTE - this will never happen because
 593           ;; `url-http-create-request' automatically calculates the
 594           ;; content-length.
 595           (setq success t))
 596          (412
 597           ;; The precondition given in one or more of the
 598           ;; request-header fields evaluated to false when it was
 599           ;; tested on the server.
 600           (setq success t))
 601          ((413 414)
 602           ;; The server is refusing to process a request because the
 603           ;; request entity|URI is larger than the server is willing or
 604           ;; able to process.
 605           (setq success t))
 606          (415
 607           ;; The server is refusing to service the request because the
 608           ;; entity of the request is in a format not supported by the
 609           ;; requested resource for the requested method.
 610           (setq success t))
 611          (416
 612           ;; A server SHOULD return a response with this status code if
 613           ;; a request included a Range request-header field, and none
 614           ;; of the range-specifier values in this field overlap the
 615           ;; current extent of the selected resource, and the request
 616           ;; did not include an If-Range request-header field.
 617           (setq success t))
 618          (417
 619           ;; The expectation given in an Expect request-header field
 620           ;; could not be met by this server, or, if the server is a
 621           ;; proxy, the server has unambiguous evidence that the
 622           ;; request could not be met by the next-hop server.
 623           (setq success t))
 624          (otherwise
 625           ;; The request could not be understood by the server due to
 626           ;; malformed syntax.  The client SHOULD NOT repeat the
 627           ;; request without modifications.
 628           (setq success t))))
 629       (5
 630        ;; 500 Internal server error
 631        ;; 501 Not implemented
 632        ;; 502 Bad gateway
 633        ;; 503 Service unavailable
 634        ;; 504 Gateway time-out
 635        ;; 505 HTTP version not supported
 636        ;; 507 Insufficient storage
 637        (setq success t)
 638        (case url-http-response-status
 639          (501
 640           ;; The server does not support the functionality required to
 641           ;; fulfill the request.
 642           nil)
 643          (502
 644           ;; The server, while acting as a gateway or proxy, received
 645           ;; an invalid response from the upstream server it accessed
 646           ;; in attempting to fulfill the request.
 647           nil)
 648          (503
 649           ;; The server is currently unable to handle the request due
 650           ;; to a temporary overloading or maintenance of the server.
 651           ;; The implication is that this is a temporary condition
 652           ;; which will be alleviated after some delay.  If known, the
 653           ;; length of the delay MAY be indicated in a Retry-After
 654           ;; header.  If no Retry-After is given, the client SHOULD
 655           ;; handle the response as it would for a 500 response.
 656           nil)
 657          (504
 658           ;; The server, while acting as a gateway or proxy, did not
 659           ;; receive a timely response from the upstream server
 660           ;; specified by the URI (e.g. HTTP, FTP, LDAP) or some other
 661           ;; auxiliary server (e.g. DNS) it needed to access in
 662           ;; attempting to complete the request.
 663           nil)
 664          (505
 665           ;; The server does not support, or refuses to support, the
 666           ;; HTTP protocol version that was used in the request
 667           ;; message.
 668           nil)
 669          (507                           ; DAV
 670           ;; The method could not be performed on the resource
 671           ;; because the server is unable to store the representation
 672           ;; needed to successfully complete the request.  This
 673           ;; condition is considered to be temporary.  If the request
 674           ;; which received this status code was the result of a user
 675           ;; action, the request MUST NOT be repeated until it is
 676           ;; requested by a separate user action.
 677           nil)))
 678       (otherwise
 679        (error "Unknown class of HTTP response code: %d (%d)"
 680               class url-http-response-status)))
 681     (if (not success)
 682         (url-mark-buffer-as-dead (current-buffer)))
 683     (url-http-debug "Finished parsing HTTP headers: %S" success)
 684     (widen)
 685     success))
 686
 687 ;; Miscellaneous
 688 (defun url-http-activate-callback ()
 689   "Activate callback specified when this buffer was created."
 690   (declare (special url-http-process
 691                     url-callback-function
 692                     url-callback-arguments))
 693   (url-http-mark-connection-as-free (url-host url-current-object)
 694                                     (url-port url-current-object)
 695                                     url-http-process)
 696   (url-http-debug "Activating callback in buffer (%s)" (buffer-name))
 697   (apply url-callback-function url-callback-arguments))
 698
 699 ;; )
 700
 701 ;; These unfortunately cannot be macros... please ignore them!
 702 (defun url-http-idle-sentinel (proc why)
 703   "Remove this (now defunct) process PROC from the list of open connections."
 704   (maphash (lambda (key val)
 705                 (if (memq proc val)
 706                     (puthash key (delq proc val) url-http-open-connections)))
 707               url-http-open-connections))
 708
 709 (defun url-http-end-of-document-sentinel (proc why)
 710   ;; Sentinel used for old HTTP/0.9 or connections we know are going
 711   ;; to die as the 'end of document' notifier.
 712   (url-http-debug "url-http-end-of-document-sentinel in buffer (%s)"
 713                   (process-buffer proc))
 714   (url-http-idle-sentinel proc why)
 715   (save-excursion
 716     (set-buffer (process-buffer proc))
 717     (goto-char (point-min))
 718     (if (not (looking-at "HTTP/"))
 719         ;; HTTP/0.9 just gets passed back no matter what
 720         (url-http-activate-callback)
 721       (if (url-http-parse-headers)
 722           (url-http-activate-callback)))))
 723
 724 (defun url-http-simple-after-change-function (st nd length)
 725   ;; Function used when we do NOT know how long the document is going to be
 726   ;; Just _very_ simple 'downloaded %d' type of info.
 727   (declare (special url-http-end-of-headers))
 728   (url-lazy-message "Reading %s..." (url-pretty-length nd)))
 729
 730 (defun url-http-content-length-after-change-function (st nd length)
 731   "Function used when we DO know how long the document is going to be.
 732 More sophisticated percentage downloaded, etc.
 733 Also does minimal parsing of HTTP headers and will actually cause
 734 the callback to be triggered."
 735   (declare (special url-current-object
 736                     url-http-end-of-headers
 737                     url-http-content-length
 738                     url-http-content-type
 739                     url-http-process))
 740   (if url-http-content-type
 741       (url-display-percentage
 742        "Reading [%s]... %s of %s (%d%%)"
 743        (url-percentage (- nd url-http-end-of-headers)
 744                        url-http-content-length)
 745        url-http-content-type
 746        (url-pretty-length (- nd url-http-end-of-headers))
 747        (url-pretty-length url-http-content-length)
 748        (url-percentage (- nd url-http-end-of-headers)
 749                        url-http-content-length))
 750     (url-display-percentage
 751      "Reading... %s of %s (%d%%)"
 752      (url-percentage (- nd url-http-end-of-headers)
 753                      url-http-content-length)
 754      (url-pretty-length (- nd url-http-end-of-headers))
 755      (url-pretty-length url-http-content-length)
 756      (url-percentage (- nd url-http-end-of-headers)
 757                      url-http-content-length)))
 758
 759   (if (> (- nd url-http-end-of-headers) url-http-content-length)
 760       (progn
 761         ;; Found the end of the document!  Wheee!
 762         (url-display-percentage nil nil)
 763         (message "Reading... done.")
 764         (if (url-http-parse-headers)
 765             (url-http-activate-callback)))))
 766
 767 (defun url-http-chunked-encoding-after-change-function (st nd length)
 768   "Function used when dealing with 'chunked' encoding.
 769 Cannot give a sophisticated percentage, but we need a different
 770 function to look for the special 0-length chunk that signifies
 771 the end of the document."
 772   (declare (special url-current-object
 773                     url-http-end-of-headers
 774                     url-http-content-type
 775                     url-http-chunked-length
 776                     url-http-chunked-counter
 777                     url-http-process url-http-chunked-start))
 778   (save-excursion
 779     (goto-char st)
 780     (let ((read-next-chunk t)
 781           (case-fold-search t)
 782           (regexp nil)
 783           (no-initial-crlf nil))
 784       ;; We need to loop thru looking for more chunks even within
 785       ;; one after-change-function call.
 786       (while read-next-chunk
 787         (setq no-initial-crlf (= 0 url-http-chunked-counter))
 788         (if url-http-content-type
 789             (url-display-percentage nil
 790              "Reading [%s]... chunk #%d"
 791              url-http-content-type url-http-chunked-counter)
 792           (url-display-percentage nil
 793            "Reading... chunk #%d"
 794            url-http-chunked-counter))
 795         (url-http-debug "Reading chunk %d (%d %d %d)"
 796                         url-http-chunked-counter st nd length)
 797         (setq regexp (if no-initial-crlf
 798                          "\\([0-9a-z]+\\).*\r?\n"
 799                        "\r?\n\\([0-9a-z]+\\).*\r?\n"))
 800
 801         (if url-http-chunked-start
 802             ;; We know how long the chunk is supposed to be, skip over
 803             ;; leading crap if possible.
 804             (if (> nd (+ url-http-chunked-start url-http-chunked-length))
 805                 (progn
 806                   (url-http-debug "Got to the end of chunk #%d!"
 807                                   url-http-chunked-counter)
 808                   (goto-char (+ url-http-chunked-start
 809                                 url-http-chunked-length)))
 810               (url-http-debug "Still need %d bytes to hit end of chunk"
 811                               (- (+ url-http-chunked-start
 812                                     url-http-chunked-length)
 813                                  nd))
 814               (setq read-next-chunk nil)))
 815         (if (not read-next-chunk)
 816             (url-http-debug "Still spinning for next chunk...")
 817           (if no-initial-crlf (skip-chars-forward "\r\n"))
 818           (if (not (looking-at regexp))
 819               (progn
 820            ;; Must not have received the entirety of the chunk header,
 821                 ;; need to spin some more.
 822                 (url-http-debug "Did not see start of chunk @ %d!" (point))
 823                 (setq read-next-chunk nil))
 824             (add-text-properties (match-beginning 0) (match-end 0)
 825                                  (list 'start-open t
 826                                        'end-open t
 827                                        'chunked-encoding t
 828                                        'face (if (featurep 'xemacs)
 829                                                  'text-cursor
 830                                                'cursor)
 831                                        'invisible t))
 832             (setq url-http-chunked-length (string-to-number (buffer-substring
 833                                                              (match-beginning 1)
 834                                                              (match-end 1))
 835                                                             16)
 836                   url-http-chunked-counter (1+ url-http-chunked-counter)
 837                   url-http-chunked-start (set-marker
 838                                           (or url-http-chunked-start
 839                                               (make-marker))
 840                                           (match-end 0)))
 841 ;           (if (not url-http-debug)
 842                 (delete-region (match-beginning 0) (match-end 0));)
 843             (url-http-debug "Saw start of chunk %d (length=%d, start=%d"
 844                             url-http-chunked-counter url-http-chunked-length
 845                             (marker-position url-http-chunked-start))
 846             (if (= 0 url-http-chunked-length)
 847                 (progn
 848                   ;; Found the end of the document!  Wheee!
 849                   (url-http-debug "Saw end of stream chunk!")
 850                   (setq read-next-chunk nil)
 851                   (url-display-percentage nil nil)
 852                   (goto-char (match-end 1))
 853                   (if (re-search-forward "^\r*$" nil t)
 854                       (url-http-debug "Saw end of trailers..."))
 855                   (if (url-http-parse-headers)
 856                       (url-http-activate-callback))))))))))
 857
 858 (defun url-http-wait-for-headers-change-function (st nd length)
 859   ;; This will wait for the headers to arrive and then splice in the
 860   ;; next appropriate after-change-function, etc.
 861   (declare (special url-current-object
 862                     url-http-end-of-headers
 863                     url-http-content-type
 864                     url-http-content-length
 865                     url-http-transfer-encoding
 866                     url-callback-function
 867                     url-callback-arguments
 868                     url-http-process
 869                     url-http-method
 870                     url-http-after-change-function
 871                     url-http-response-status))
 872   (url-http-debug "url-http-wait-for-headers-change-function (%s)"
 873                   (buffer-name))
 874   (if (not (bobp))
 875       (let ((end-of-headers nil)
 876             (old-http nil)
 877             (content-length nil))
 878         (goto-char (point-min))
 879         (if (not (looking-at "^HTTP/[1-9]\\.[0-9]"))
 880             ;; Not HTTP/x.y data, must be 0.9
 881             ;; God, I wish this could die.
 882             (setq end-of-headers t
 883                   url-http-end-of-headers 0
 884                   old-http t)
 885           (if (re-search-forward "^\r*$" nil t)
 886               ;; Saw the end of the headers
 887               (progn
 888                 (url-http-debug "Saw end of headers... (%s)" (buffer-name))
 889                 (setq url-http-end-of-headers (set-marker (make-marker)
 890                                                           (point))
 891                       end-of-headers t)
 892                 (url-http-clean-headers))))
 893
 894         (if (not end-of-headers)
 895             ;; Haven't seen the end of the headers yet, need to wait
 896             ;; for more data to arrive.
 897             nil
 898           (if old-http
 899               (message "HTTP/0.9 How I hate thee!")
 900             (progn
 901               (url-http-parse-response)
 902               (mail-narrow-to-head)
 903               ;;(narrow-to-region (point-min) url-http-end-of-headers)
 904               (setq url-http-transfer-encoding (mail-fetch-field
 905                                                 "transfer-encoding")
 906                     url-http-content-type (mail-fetch-field "content-type"))
 907               (if (mail-fetch-field "content-length")
 908                   (setq url-http-content-length
 909                         (string-to-number (mail-fetch-field "content-length"))))
 910               (widen)))
 911           (if url-http-transfer-encoding
 912               (setq url-http-transfer-encoding
 913                     (downcase url-http-transfer-encoding)))
 914
 915           (cond
 916            ((or (= url-http-response-status 204)
 917                 (= url-http-response-status 205))
 918             (url-http-debug "%d response must have headers only (%s)."
 919                             url-http-response-status (buffer-name))
 920             (if (url-http-parse-headers)
 921                 (url-http-activate-callback)))
 922            ((string= "HEAD" url-http-method)
 923             ;; A HEAD request is _ALWAYS_ terminated by the header
 924             ;; information, regardless of any entity headers,
 925             ;; according to section 4.4 of the HTTP/1.1 draft.
 926             (url-http-debug "HEAD request must have headers only (%s)."
 927                             (buffer-name))
 928             (if (url-http-parse-headers)
 929                 (url-http-activate-callback)))
 930            ((string= "CONNECT" url-http-method)
 931             ;; A CONNECT request is finished, but we cannot stick this
 932             ;; back on the free connectin list
 933             (url-http-debug "CONNECT request must have headers only.")
 934             (if (url-http-parse-headers)
 935                 (url-http-activate-callback)))
 936            ((equal url-http-response-status 304)
 937             ;; Only allowed to have a header section.  We have to handle
 938             ;; this here instead of in url-http-parse-headers because if
 939             ;; you have a cached copy of something without a known
 940             ;; content-length, and try to retrieve it from the cache, we'd
 941             ;; fall into the 'being dumb' section and wait for the
 942             ;; connection to terminate, which means we'd wait for 10
 943             ;; seconds for the keep-alives to time out on some servers.
 944             (if (url-http-parse-headers)
 945                 (url-http-activate-callback)))
 946            (old-http
 947             ;; HTTP/0.9 always signaled end-of-connection by closing the
 948             ;; connection.
 949             (url-http-debug
 950              "Saw HTTP/0.9 response, connection closed means end of document.")
 951             (setq url-http-after-change-function
 952                   'url-http-simple-after-change-function))
 953            ((equal url-http-transfer-encoding "chunked")
 954             (url-http-debug "Saw chunked encoding.")
 955             (setq url-http-after-change-function
 956                   'url-http-chunked-encoding-after-change-function)
 957             (if (> nd url-http-end-of-headers)
 958                 (progn
 959                   (url-http-debug
 960                    "Calling initial chunked-encoding for extra data at end of headers")
 961                   (url-http-chunked-encoding-after-change-function
 962                    (marker-position url-http-end-of-headers) nd
 963                    (- nd url-http-end-of-headers)))))
 964            ((integerp url-http-content-length)
 965             (url-http-debug
 966              "Got a content-length, being smart about document end.")
 967             (setq url-http-after-change-function
 968                   'url-http-content-length-after-change-function)
 969             (cond
 970              ((= 0 url-http-content-length)
 971               ;; We got a NULL body!  Activate the callback
 972               ;; immediately!
 973               (url-http-debug
 974                "Got 0-length content-length, activating callback immediately.")
 975               (if (url-http-parse-headers)
 976                   (url-http-activate-callback)))
 977              ((> nd url-http-end-of-headers)
 978               ;; Have some leftover data
 979               (url-http-debug "Calling initial content-length for extra data at end of headers")
 980               (url-http-content-length-after-change-function
 981                (marker-position url-http-end-of-headers)
 982                nd
 983                (- nd url-http-end-of-headers)))
 984              (t
 985               nil)))
 986            (t
 987             (url-http-debug "No content-length, being dumb.")
 988             (setq url-http-after-change-function
 989                   'url-http-simple-after-change-function)))))
 990     ;; We are still at the beginning of the buffer... must just be
 991     ;; waiting for a response.
 992     (url-http-debug "Spinning waiting for headers..."))
 993   (goto-char (point-max)))
 994
 995 ;;;###autoload
 996 (defun url-http (url callback cbargs)
 997   "Retrieve URL via HTTP asynchronously.
 998 URL must be a parsed URL.  See `url-generic-parse-url' for details.
 999 When retrieval is completed, the function CALLBACK is executed with
1000 CBARGS as the arguments."
1001   (check-type url vector "Need a pre-parsed URL.")
1002   (declare (special url-current-object
1003                     url-http-end-of-headers
1004                     url-http-content-type
1005                     url-http-content-length
1006                     url-http-transfer-encoding
1007                     url-http-after-change-function
1008                     url-callback-function
1009                     url-callback-arguments
1010                     url-http-method
1011                     url-http-extra-headers
1012                     url-http-data
1013                     url-http-chunked-length
1014                     url-http-chunked-start
1015                     url-http-chunked-counter
1016                     url-http-process))
1017   (let ((connection (url-http-find-free-connection (url-host url)
1018                                                    (url-port url)))
1019         (buffer (generate-new-buffer (format " *http %s:%d*"
1020                                              (url-host url)
1021                                              (url-port url)))))
1022     (if (not connection)
1023         ;; Failed to open the connection for some reason
1024         (progn
1025           (kill-buffer buffer)
1026           (setq buffer nil)
1027           (error "Could not create connection to %s:%d" (url-host url)
1028                  (url-port url)))
1029       (save-excursion
1030         (set-buffer buffer)
1031         (mm-disable-multibyte)
1032         (setq url-current-object url
1033               mode-line-format "%b [%s]")
1034
1035         (dolist (var '(url-http-end-of-headers
1036                        url-http-content-type
1037                        url-http-content-length
1038                        url-http-transfer-encoding
1039                        url-http-after-change-function
1040                        url-http-response-status
1041                        url-http-chunked-length
1042                        url-http-chunked-counter
1043                        url-http-chunked-start
1044                        url-callback-function
1045                        url-callback-arguments
1046                        url-http-process
1047                        url-http-method
1048                        url-http-extra-headers
1049                        url-http-data
1050                        url-http-cookies-sources))
1051           (set (make-local-variable var) nil))
1052
1053         (setq url-http-method (or url-request-method "GET")
1054               url-http-extra-headers url-request-extra-headers
1055               url-http-data url-request-data
1056               url-http-process connection
1057               url-http-chunked-length nil
1058               url-http-chunked-start nil
1059               url-http-chunked-counter 0
1060               url-callback-function callback
1061               url-callback-arguments cbargs
1062               url-http-after-change-function 'url-http-wait-for-headers-change-function
1063               url-http-cookies-sources (if (boundp 'proxy-object)
1064                                            proxy-object
1065                                          url-current-object))
1066
1067         (set-process-buffer connection buffer)
1068         (set-process-sentinel connection 'url-http-end-of-document-sentinel)
1069         (set-process-filter connection 'url-http-generic-filter)
1070         (process-send-string connection (url-http-create-request url))))
1071     buffer))
1072
1073 ;; Since Emacs 19/20 does not allow you to change the
1074 ;; `after-change-functions' hook in the midst of running them, we fake
1075 ;; an after change by hooking into the process filter and inserting
1076 ;; the data ourselves.  This is slightly less efficient, but there
1077 ;; were tons of weird ways the after-change code was biting us in the
1078 ;; shorts.
1079 (defun url-http-generic-filter (proc data)
1080   ;; Sometimes we get a zero-length data chunk after the process has
1081   ;; been changed to 'free', which means it has no buffer associated
1082   ;; with it.  Do nothing if there is no buffer, or 0 length data.
1083   (declare (special url-http-after-change-function))
1084   (and (process-buffer proc)
1085        (/= (length data) 0)
1086        (save-excursion
1087          (set-buffer (process-buffer proc))
1088          (url-http-debug "Calling after change function `%s' for `%S'" url-http-after-change-function proc)
1089          (funcall url-http-after-change-function
1090                   (point-max)
1091                   (progn
1092                     (goto-char (point-max))
1093                     (insert data)
1094                     (point-max))
1095                   (length data)))))
1096
1097 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
1098 ;;; file-name-handler stuff from here on out
1099 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
1100 (if (not (fboundp 'symbol-value-in-buffer))
1101     (defun url-http-symbol-value-in-buffer (symbol buffer
1102                                                    &optional unbound-value)
1103       "Return the value of SYMBOL in BUFFER, or UNBOUND-VALUE if it is unbound."
1104       (save-excursion
1105         (set-buffer buffer)
1106         (if (not (boundp symbol))
1107             unbound-value
1108           (symbol-value symbol))))
1109   (defalias 'url-http-symbol-value-in-buffer 'symbol-value-in-buffer))
1110
1111 (defun url-http-head (url)
1112   (let ((url-request-method "HEAD")
1113         (url-request-data nil))
1114     (url-retrieve-synchronously url)))
1115
1116 ;;;###autoload
1117 (defun url-http-file-exists-p (url)
1118   (let ((status nil)
1119         (exists nil)
1120         (buffer (url-http-head url)))
1121     (if (not buffer)
1122         (setq exists nil)
1123       (setq status (url-http-symbol-value-in-buffer 'url-http-response-status
1124                                                     buffer 500)
1125             exists (and (>= status 200) (< status 300)))
1126       (kill-buffer buffer))
1127     exists))
1128
1129 ;;;###autoload
1130 (defalias 'url-http-file-readable-p 'url-http-file-exists-p)
1131
1132 (defun url-http-head-file-attributes (url &optional id-format)
1133   (let ((buffer (url-http-head url))
1134         (attributes nil))
1135     (when buffer
1136       (setq attributes (make-list 11 nil))
1137       (setf (nth 1 attributes) 1)       ; Number of links to file
1138       (setf (nth 2 attributes) 0)       ; file uid
1139       (setf (nth 3 attributes) 0)       ; file gid
1140       (setf (nth 7 attributes)          ; file size
1141             (url-http-symbol-value-in-buffer 'url-http-content-length
1142                                              buffer -1))
1143       (setf (nth 8 attributes) (eval-when-compile (make-string 10 ?-)))
1144       (kill-buffer buffer))
1145     attributes))
1146
1147 ;;;###autoload
1148 (defun url-http-file-attributes (url &optional id-format)
1149   (if (url-dav-supported-p url)
1150       (url-dav-file-attributes url id-format)
1151     (url-http-head-file-attributes url id-format)))
1152
1153 ;;;###autoload
1154 (defun url-http-options (url)
1155   "Returns a property list describing options available for URL.
1156 This list is retrieved using the `OPTIONS' HTTP method.
1157
1158 Property list members:
1159
1160 methods
1161   A list of symbols specifying what HTTP methods the resource
1162   supports.
1163
1164 dav
1165   A list of numbers specifying what DAV protocol/schema versions are
1166   supported.
1167
1168 dasl
1169   A list of supported DASL search types supported (string form)
1170
1171 ranges
1172   A list of the units available for use in partial document fetches.
1173
1174 p3p
1175   The `Platform For Privacy Protection' description for the resource.
1176   Currently this is just the raw header contents.  This is likely to
1177   change once P3P is formally supported by the URL package or
1178   Emacs/W3.
1179 "
1180   (let* ((url-request-method "OPTIONS")
1181          (url-request-data nil)
1182          (buffer (url-retrieve-synchronously url))
1183          (header nil)
1184          (options nil))
1185     (when (and buffer (= 2 (/ (url-http-symbol-value-in-buffer
1186                                'url-http-response-status buffer 0) 100)))
1187       ;; Only parse the options if we got a 2xx response code!
1188       (save-excursion
1189         (save-restriction
1190           (save-match-data
1191             (set-buffer buffer)
1192             (mail-narrow-to-head)
1193
1194             ;; Figure out what methods are supported.
1195             (when (setq header (mail-fetch-field "allow"))
1196               (setq options (plist-put
1197                              options 'methods
1198                              (mapcar 'intern (split-string header "[ ,]+")))))
1199
1200             ;; Check for DAV
1201             (when (setq header (mail-fetch-field "dav"))
1202               (setq options (plist-put
1203                              options 'dav
1204                              (delq 0
1205                                    (mapcar 'string-to-number
1206                                            (split-string header "[, ]+"))))))
1207
1208             ;; Now for DASL
1209             (when (setq header (mail-fetch-field "dasl"))
1210               (setq options (plist-put
1211                              options 'dasl
1212                              (split-string header "[, ]+"))))
1213
1214             ;; P3P - should get more detailed here.  FIXME
1215             (when (setq header (mail-fetch-field "p3p"))
1216               (setq options (plist-put options 'p3p header)))
1217
1218             ;; Check for whether they accept byte-range requests.
1219             (when (setq header (mail-fetch-field "accept-ranges"))
1220               (setq options (plist-put
1221                              options 'ranges
1222                              (delq 'none
1223                                    (mapcar 'intern
1224                                            (split-string header "[, ]+"))))))
1225             ))))
1226     (if buffer (kill-buffer buffer))
1227     options))
1228
1229 (provide 'url-http)
1230
1231 ;; arch-tag: ba7c59ae-c0f4-4a31-9617-d85f221732ee
1232 ;;; url-http.el ends here