1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2009-2014, VU University, Amsterdam
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35:- module(http_server_files,
   36          [ serve_files_in_directory/2  % +Alias, +HTTPRequest
   37          ]).   38:- use_module(library(http/http_path)).   39:- use_module(library(http/http_dispatch)).   40
   41/** <module> Serve files needed by modules from the server
   42
   43This module provides an infrastructure   for serving resource-files such
   44as icons, JavaScript, CSS files, etc.   The default configuration serves
   45the    HTTP    locations    =icons=,     =css=      and     =js=    (see
   46http_absolute_location/3)
   47
   48The location for these services  can  be   changed  by  adding rules for
   49http:location/3.  Directories  providing  additional    or   alternative
   50resources can be achieved by adding rules for user:file_search_path/2.
   51*/
   52
   53:- multifile
   54    http:location/3.                % Alias, Expansion, Options
   55:- dynamic
   56    http:location/3.                % Alias, Expansion, Options
   57
   58http:location(icons, root(icons), [ priority(-100) ]).
   59http:location(css,   root(css),   [ priority(-100) ]).
   60http:location(js,    root(js),    [ priority(-100) ]).
   61
   62:- multifile
   63    user:file_search_path/2.   64:- dynamic
   65    user:file_search_path/2.   66
   67user:file_search_path(icons, library('http/web/icons')).
   68user:file_search_path(css,   library('http/web/css')).
   69user:file_search_path(js,    library('http/web/js')).
   70
   71:- http_handler(icons(.), serve_files_in_directory(icons),
   72                [prefix, priority(-100)]).   73:- http_handler(css(.),   serve_files_in_directory(css),
   74                [prefix, priority(-100)]).   75:- http_handler(js(.),    serve_files_in_directory(js),
   76                [prefix, priority(-100)]).   77
   78%!  serve_files_in_directory(+Alias, +Request)
   79%
   80%   Serve files from the directory  Alias   from  the path-info from
   81%   Request.    This    predicate    is     used    together    with
   82%   file_search_path/2. Note that multiple  clauses   for  the  same
   83%   file_search_path alias can be used to merge files from different
   84%   physical locations onto the same HTTP   directory. Note that the
   85%   handler must be declared  as  =prefix=.   Below  is  an  example
   86%   serving images from  http://<host>/img/...   from  the directory
   87%   =http/web/icons=.
   88%
   89%       ==
   90%       http:location(img, root(img), []).
   91%       user:file_search_path(icons, library('http/web/icons')).
   92%
   93%       :- http_handler(img(.), serve_files_in_directory(icons), [prefix]).
   94%       ==
   95%
   96%   This predicate calls http_404/2 if the   physical file cannot be
   97%   located. If the requested  path-name   is  unsafe  (i.e., points
   98%   outside  the  hierarchy  defines    by   the  file_search_path/2
   99%   declaration), this handlers returns a _403 Forbidden_ page.
  100%
  101%   @see http_reply_file/3
  102
  103serve_files_in_directory(Alias, Request) :-
  104    memberchk(path_info(PathInfo), Request),
  105    !,
  106    Term =.. [Alias,PathInfo],
  107    (   catch(http_safe_file(Term, []),
  108              error(permission_error(read, file, _), _),
  109              fail)
  110    ->  (   absolute_file_name(Term, Path,
  111                               [ access(read),
  112                                 file_errors(fail)
  113                               ])
  114        ->  http_reply_file(Path,
  115                            [ unsafe(true),
  116                              static_gzip(true)
  117                            ], Request)
  118        ;   http_404([], Request)
  119        )
  120    ;   memberchk(path(Path), Request),
  121        throw(http_reply(forbidden(Path)))
  122    ).
  123serve_files_in_directory(_Alias, Request) :-
  124    memberchk(path(Path), Request),
  125    throw(http_reply(forbidden(Path)))