misc.lisp

   1 ;;; -*- Mode: LISP; Syntax: COMMON-LISP; Package: HUNCHENTOOT; Base: 10 -*-
   2
   3 ;;; Copyright (c) 2004-2010, Dr. Edmund Weitz. All rights reserved.
   4
   5 ;;; Redistribution and use in source and binary forms, with or without
   6 ;;; modification, are permitted provided that the following conditions
   7 ;;; are met:
   8
   9 ;;;   * Redistributions of source code must retain the above copyright
  10 ;;;     notice, this list of conditions and the following disclaimer.
  11
  12 ;;;   * Redistributions in binary form must reproduce the above
  13 ;;;     copyright notice, this list of conditions and the following
  14 ;;;     disclaimer in the documentation and/or other materials
  15 ;;;     provided with the distribution.
  16
  17 ;;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS' AND ANY EXPRESSED
  18 ;;; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19 ;;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20 ;;; ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  21 ;;; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22 ;;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  23 ;;; GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  24 ;;; INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  25 ;;; WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  26 ;;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  27 ;;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28
  29 (in-package :hunchentoot)
  30
  31 (let ((scanner-hash (make-hash-table :test #'equal)))
  32   (defun scanner-for-get-param (param-name)
  33     "Returns a CL-PPCRE scanner which matches a GET parameter in a
  34 URL.  Scanners are memoized in SCANNER-HASH once they are created."
  35     (or (gethash param-name scanner-hash)
  36         (setf (gethash param-name scanner-hash)
  37                 (create-scanner
  38                  `(:alternation
  39                    ;; session=value at end of URL
  40                    (:sequence
  41                     (:char-class #\? #\&)
  42                     ,param-name
  43                     #\=
  44                     (:greedy-repetition 0 nil (:inverted-char-class #\&))
  45                     :end-anchor)
  46                    ;; session=value with other parameters following
  47                    (:sequence
  48                     (:register (:char-class #\? #\&))
  49                     ,param-name
  50                     #\=
  51                     (:greedy-repetition 0 nil (:inverted-char-class #\&))
  52                     #\&))))))
  53   (defun add-cookie-value-to-url (url &key
  54                                       (cookie-name (session-cookie-name *acceptor*))
  55                                       (value (when-let (session (session *request*))
  56                                                (session-cookie-value session)))
  57                                       (replace-ampersands-p t))
  58     "Removes all GET parameters named COOKIE-NAME from URL and then
  59 adds a new GET parameter with the name COOKIE-NAME and the value
  60 VALUE.  If REPLACE-AMPERSANDS-P is true all literal ampersands in URL
  61 are replaced with '&amp;'. The resulting URL is returned."
  62     (unless url
  63       ;; see URL-REWRITE:*URL-REWRITE-FILL-TAGS*
  64       (setq url (request-uri *request*)))
  65     (setq url (regex-replace-all (scanner-for-get-param cookie-name) url "\\1"))
  66     (when value
  67       (setq url (format nil "~A~:[?~;&~]~A=~A"
  68                         url
  69                         (find #\? url)
  70                         cookie-name
  71                         (url-encode value))))
  72     (when replace-ampersands-p
  73       (setq url (regex-replace-all "&" url "&amp;")))
  74     url))
  75
  76 (defun maybe-rewrite-urls-for-session (html &key
  77                                             (cookie-name (session-cookie-name *acceptor*))
  78                                             (value (when-let (session (session *request*))
  79                                                      (session-cookie-value session))))
  80   "Rewrites the HTML page HTML such that the name/value pair
  81 COOKIE-NAME/COOKIE-VALUE is inserted if the client hasn't sent a
  82 cookie of the same name but only if *REWRITE-FOR-SESSION-URLS* is
  83 true.  See the docs for URL-REWRITE:REWRITE-URLS."
  84   (cond ((or (not *rewrite-for-session-urls*)
  85              (null value)
  86              (cookie-in cookie-name))
  87           html)
  88         (t
  89           (with-input-from-string (*standard-input* html)
  90             (with-output-to-string (*standard-output*)
  91               (url-rewrite:rewrite-urls
  92                (lambda (url)
  93                  (add-cookie-value-to-url url
  94                                           :cookie-name cookie-name
  95                                           :value value))))))))
  96
  97 (defun create-prefix-dispatcher (prefix handler)
  98   "Creates a request dispatch function which will dispatch to the
  99 function denoted by HANDLER if the file name of the current request
 100 starts with the string PREFIX."
 101   (lambda (request)
 102     (let ((mismatch (mismatch (script-name request) prefix
 103                               :test #'char=)))
 104       (and (or (null mismatch)
 105                (>= mismatch (length prefix)))
 106            handler))))
 107
 108 (defun create-regex-dispatcher (regex handler)
 109   "Creates a request dispatch function which will dispatch to the
 110 function denoted by HANDLER if the file name of the current request
 111 matches the CL-PPCRE regular expression REGEX."
 112   (let ((scanner (create-scanner regex)))
 113     (lambda (request)
 114       (and (scan scanner (script-name request))
 115            handler))))
 116
 117 (defun abort-request-handler (&optional result)
 118   "This function can be called by a request handler at any time to
 119 immediately abort handling the request.  This works as if the handler
 120 had returned RESULT.  See the source code of REDIRECT for an example."
 121   (throw 'handler-done result))
 122
 123 (defun maybe-handle-range-header (file)
 124   "Helper function for handle-static-file.  Determines whether the
 125   requests specifies a Range header.  If so, parses the header and
 126   position the already opened file to the location specified.  Returns
 127   the number of bytes to transfer from the file.  Invalid specified
 128   ranges are reported to the client with a HTTP 416 status code."
 129   (let ((bytes-to-send (file-length file)))
 130     (cl-ppcre:register-groups-bind
 131         (start end)
 132         ("^bytes=(\\d+)-(\\d*)$" (header-in* :range) :sharedp t)
 133       ;; body won't be executed if regular expression does not match
 134       (setf start (parse-integer start))
 135       (setf end (if (> (length end) 0)
 136                     (parse-integer end)
 137                     (1- (file-length file))))
 138       (when (or (< start 0)
 139                 (>= end (file-length file)))
 140         (setf (return-code*) +http-requested-range-not-satisfiable+
 141               (header-out :content-range) (format nil "bytes 0-~D/~D" (1- (file-length file)) (file-length file)))
 142         (throw 'handler-done
 143           (format nil "invalid request range (requested ~D-~D, accepted 0-~D)"
 144                   start end (1- (file-length file)))))
 145       (file-position file start)
 146       (setf (return-code*) +http-partial-content+
 147             bytes-to-send (1+ (- end start))
 148             (header-out :content-range) (format nil "bytes ~D-~D/~D" start end (file-length file))))
 149     bytes-to-send))
 150
 151 (defun handle-static-file (pathname &optional content-type)
 152   "A function which acts like a Hunchentoot handler for the file
 153 denoted by PATHNAME.  Sends a content type header corresponding to
 154 CONTENT-TYPE or \(if that is NIL) tries to determine the content type
 155 via the file's suffix."
 156   (when (or (wild-pathname-p pathname)
 157             (not (fad:file-exists-p pathname))
 158             (fad:directory-exists-p pathname))
 159     ;; file does not exist
 160     (setf (return-code*) +http-not-found+)
 161     (abort-request-handler))
 162   (unless content-type
 163     (setf content-type (mime-type pathname)))
 164   (let ((time (or (file-write-date pathname)
 165                   (get-universal-time)))
 166         bytes-to-send)
 167     (setf (content-type*) (or (and content-type
 168                                    (maybe-add-charset-to-content-type-header content-type (reply-external-format*)))
 169                               "application/octet-stream")
 170           (header-out :last-modified) (rfc-1123-date time)
 171           (header-out :accept-ranges) "bytes")
 172     (handle-if-modified-since time)
 173     (with-open-file (file pathname
 174                           :direction :input
 175                           :element-type 'octet)
 176       (setf bytes-to-send (maybe-handle-range-header file)
 177             (content-length*) bytes-to-send)
 178       (let ((out (send-headers))
 179             (buf (make-array +buffer-length+ :element-type 'octet)))
 180         (loop
 181            (when (zerop bytes-to-send)
 182              (return))
 183            (let* ((chunk-size (min +buffer-length+ bytes-to-send)))
 184              (unless (eql chunk-size (read-sequence buf file :end chunk-size))
 185                (error "can't read from input file"))
 186              (write-sequence buf out :end chunk-size)
 187              (decf bytes-to-send chunk-size)))
 188         (finish-output out)))))
 189
 190 (defun create-static-file-dispatcher-and-handler (uri path &optional content-type)
 191   "Creates and returns a request dispatch function which will dispatch
 192 to a handler function which emits the file denoted by the pathname
 193 designator PATH with content type CONTENT-TYPE if the SCRIPT-NAME of
 194 the request matches the string URI.  If CONTENT-TYPE is NIL, tries to
 195 determine the content type via the file's suffix."
 196   ;; the dispatcher
 197   (lambda (request)
 198     (when (equal (script-name request) uri)
 199       ;; the handler
 200       (lambda ()
 201         (handle-static-file path content-type)))))
 202
 203 (defun create-folder-dispatcher-and-handler (uri-prefix base-path &optional content-type)
 204   "Creates and returns a dispatch function which will dispatch to a
 205 handler function which emits the file relative to BASE-PATH that is
 206 denoted by the URI of the request relative to URI-PREFIX.  URI-PREFIX
 207 must be a string ending with a slash, BASE-PATH must be a pathname
 208 designator for an existing directory.  If CONTENT-TYPE is not NIL,
 209 it'll be the content type used for all files in the folder."
 210   (unless (and (stringp uri-prefix)
 211                (plusp (length uri-prefix))
 212                (char= (char uri-prefix (1- (length uri-prefix))) #\/))
 213     (parameter-error "~S must be string ending with a slash." uri-prefix))
 214   (unless (fad:directory-pathname-p base-path)
 215     (parameter-error "~S is supposed to denote a directory." base-path))
 216   (flet ((handler ()
 217            (let ((request-path (request-pathname *request* uri-prefix)))
 218              (when (null request-path)
 219                (setf (return-code*) +http-forbidden+)
 220                (abort-request-handler))
 221              (handle-static-file (merge-pathnames request-path base-path) content-type))))
 222     (create-prefix-dispatcher uri-prefix #'handler)))
 223
 224 (defun no-cache ()
 225   "Adds appropriate headers to completely prevent caching on most browsers."
 226   (setf (header-out :expires)
 227           "Mon, 26 Jul 1997 05:00:00 GMT"
 228         (header-out :cache-control)
 229           "no-store, no-cache, must-revalidate, post-check=0, pre-check=0"
 230         (header-out :pragma)
 231           "no-cache"
 232         (header-out :last-modified)
 233           (rfc-1123-date))
 234   (values))
 235
 236 (defun redirect (target &key (host (host *request*) host-provided-p)
 237                              port
 238                              (protocol (if (ssl-p) :https :http))
 239                              (add-session-id (not (or host-provided-p
 240                                                       (starts-with-scheme-p target)
 241                                                       (cookie-in (session-cookie-name *acceptor*)))))
 242                              (code +http-moved-temporarily+))
 243   "Redirects the browser to TARGET which should be a string.  If
 244 TARGET is a full URL starting with a scheme, HOST, PORT and PROTOCOL
 245 are ignored.  Otherwise, TARGET should denote the path part of a URL,
 246 PROTOCOL must be one of the keywords :HTTP or :HTTPS, and the URL to
 247 redirect to will be constructed from HOST, PORT, PROTOCOL, and TARGET.
 248 Adds a session ID if ADD-SESSION-ID is true.  If CODE is a 3xx
 249 redirection code, it will be sent as status code."
 250   (check-type code (integer 300 399))
 251   (let ((url (if (starts-with-scheme-p target)
 252                target
 253                (format nil "~A://~A~@[:~A~]~A"
 254                        (ecase protocol
 255                          ((:http) "http")
 256                          ((:https) "https"))
 257                        (if port
 258                          (first (ppcre:split ":" (or host "")))
 259                          host)
 260                        port target))))
 261     (when add-session-id
 262       (setq url (add-cookie-value-to-url url :replace-ampersands-p nil)))
 263     (setf (header-out :location) url
 264           (return-code*) code)
 265     (abort-request-handler)))
 266
 267 (defun require-authorization (&optional (realm "Hunchentoot"))
 268   "Sends back appropriate headers to require basic HTTP authentication
 269 \(see RFC 2617) for the realm REALM."
 270   (setf (header-out :www-authenticate)
 271           (format nil "Basic realm=\"~A\"" (quote-string realm))
 272         (return-code *reply*)
 273           +http-authorization-required+)
 274   (abort-request-handler))