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)  2002-2020, University of Amsterdam
    7                              VU University Amsterdam
    8    All rights reserved.
    9
   10    Redistribution and use in source and binary forms, with or without
   11    modification, are permitted provided that the following conditions
   12    are met:
   13
   14    1. Redistributions of source code must retain the above copyright
   15       notice, this list of conditions and the following disclaimer.
   16
   17    2. Redistributions in binary form must reproduce the above copyright
   18       notice, this list of conditions and the following disclaimer in
   19       the documentation and/or other materials provided with the
   20       distribution.
   21
   22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   33    POSSIBILITY OF SUCH DAMAGE.
   34*/
   35
   36:- module(http_header,
   37          [ http_read_request/2,        % +Stream, -Request
   38            http_read_reply_header/2,   % +Stream, -Reply
   39            http_reply/2,               % +What, +Stream
   40            http_reply/3,               % +What, +Stream, +HdrExtra
   41            http_reply/4,               % +What, +Stream, +HdrExtra, -Code
   42            http_reply/5,               % +What, +Stream, +HdrExtra, +Context,
   43                                        % -Code
   44            http_reply/6,               % +What, +Stream, +HdrExtra, +Context,
   45                                        % +Request, -Code
   46            http_reply_header/3,        % +Stream, +What, +HdrExtra
   47            http_status_reply/4,        % +Status, +Out, +HdrExtra, -Code
   48            http_status_reply/5,        % +Status, +Out, +HdrExtra,
   49                                        % +Context, -Code
   50
   51            http_timestamp/2,           % +Time, -HTTP string
   52
   53            http_post_data/3,           % +Stream, +Data, +HdrExtra
   54
   55            http_read_header/2,         % +Fd, -Header
   56            http_parse_header/2,        % +Codes, -Header
   57            http_parse_header_value/3,  % +Header, +HeaderValue, -MediaTypes
   58            http_join_headers/3,        % +Default, +InHdr, -OutHdr
   59            http_update_encoding/3,     % +HeaderIn, -Encoding, -HeaderOut
   60            http_update_connection/4,   % +HeaderIn, +Request, -Connection, -HeaderOut
   61            http_update_transfer/4      % +HeaderIn, +Request, -Transfer, -HeaderOut
   62          ]).   63:- autoload(html_write,
   64	    [ print_html/2, print_html/1, page/4, html/3,
   65	      html_print_length/2
   66	    ]).   67:- autoload(http_exception,[map_exception_to_http_status/4]).   68:- autoload(mimepack,[mime_pack/3]).   69:- autoload(mimetype,[file_mime_type/2]).   70:- autoload(library(apply),[maplist/2]).   71:- autoload(library(base64),[base64/2]).   72:- autoload(library(debug),[debug/3,debugging/1]).   73:- autoload(library(error),[syntax_error/1,domain_error/2]).   74:- autoload(library(lists),[append/3,member/2,select/3,delete/3]).   75:- autoload(library(memfile),
   76	    [ new_memory_file/1, open_memory_file/3,
   77	      free_memory_file/1, open_memory_file/4,
   78	      size_memory_file/3
   79	    ]).   80:- autoload(library(option),[option/3,option/2]).   81:- autoload(library(pairs),[pairs_values/2]).   82:- autoload(library(readutil),
   83	    [read_line_to_codes/2,read_line_to_codes/3]).   84:- autoload(library(sgml_write),[xml_write/3]).   85:- autoload(library(socket),[gethostname/1]).   86:- autoload(library(uri),
   87	    [ uri_components/2, uri_data/3, uri_encoded/3, uri_query_components/2
   88	    ]).   89:- autoload(library(url),[parse_url_search/2]).   90:- autoload(library(dcg/basics),
   91	    [ integer/3, atom/3, whites/2, blanks_to_nl/2, string/3,
   92	      number/3, blanks/2, float/3, nonblanks/3, eos/2
   93	    ]).   94:- use_module(library(settings),[setting/4,setting/2]).   95
   96:- multifile
   97    http:status_page/3,             % +Status, +Context, -HTML
   98    http:status_reply/3,            % +Status, -Reply, +Options
   99    http:serialize_reply/2,         % +Reply, -Body
  100    http:post_data_hook/3,          % +Data, +Out, +HdrExtra
  101    http:mime_type_encoding/2.      % +MimeType, -Encoding
  102
  103% see http_update_transfer/4.
  104
  105:- setting(http:chunked_transfer, oneof([never,on_request,if_possible]),
  106           on_request, 'When to use Transfer-Encoding: Chunked').

  116:- discontiguous
  117    term_expansion/2.  118
  119
  120                 /*******************************
  121                 *          READ REQUEST        *
  122                 *******************************/

 http_read_request(+FdIn:stream, -Request) is det

Read an HTTP request-header from FdIn and return the broken-down request fields as +Name(+Value) pairs in a list. Request is unified to end_of_file if FdIn is at the end of input.

  130http_read_request(In, Request) :-
  131    catch(read_line_to_codes(In, Codes), E, true),
  132    (   var(E)
  133    ->  (   Codes == end_of_file
  134        ->  debug(http(header), 'end-of-file', []),
  135            Request = end_of_file
  136        ;   debug(http(header), 'First line: ~s', [Codes]),
  137            Request =  [input(In)|Request1],
  138            phrase(request(In, Request1), Codes),
  139            (   Request1 = [unknown(Text)|_]
  140            ->  string_codes(S, Text),
  141                syntax_error(http_request(S))
  142            ;   true
  143            )
  144        )
  145    ;   (   debugging(http(request))
  146        ->  message_to_string(E, Msg),
  147            debug(http(request), "Exception reading 1st line: ~s", [Msg])
  148        ;   true
  149        ),
  150        Request = end_of_file
  151    ).

 http_read_reply_header(+FdIn, -Reply)

Read the HTTP reply header. Throws an exception if the current input does not contain a valid reply header.

  159http_read_reply_header(In, [input(In)|Reply]) :-
  160    read_line_to_codes(In, Codes),
  161    (   Codes == end_of_file
  162    ->  debug(http(header), 'end-of-file', []),
  163        throw(error(syntax(http_reply_header, end_of_file), _))
  164    ;   debug(http(header), 'First line: ~s~n', [Codes]),
  165        (   phrase(reply(In, Reply), Codes)
  166        ->  true
  167        ;   atom_codes(Header, Codes),
  168            syntax_error(http_reply_header(Header))
  169        )
  170    ).
  171
  172
  173                 /*******************************
  174                 *        FORMULATE REPLY       *
  175                 *******************************/

 http_reply(+Data, +Out:stream) is det

 http_reply(+Data, +Out:stream, +HdrExtra) is det

 http_reply(+Data, +Out:stream, +HdrExtra, -Code) is det

 http_reply(+Data, +Out:stream, +HdrExtra, +Context, -Code) is det

 http_reply(+Data, +Out:stream, +HdrExtra, +Context, +Request, -Code) is det

Compose a complete HTTP reply from the term Data using additional headers from HdrExtra to the output stream Out. ExtraHeader is a list of Field(Value). Data is one of:

html(HTML)

HTML tokens as produced by html//1 from html_write.pl

file(+MimeType, +FileName)

Reply content of FileName using MimeType

file(+MimeType, +FileName, +Range)

Reply partial content of FileName with given MimeType

tmp_file(+MimeType, +FileName)

Same as file, but do not include modification time

bytes(+MimeType, +Bytes)

Send a sequence of Bytes with the indicated MimeType. Bytes is either a string of character codes 0..255 or list of integers in the range 0..255. Out-of-bound codes result in a representation error exception.

stream(+In, +Len)

Reply content of stream.

cgi_stream(+In, +Len)

Reply content of stream, which should start with an HTTP header, followed by a blank line. This is the typical output from a CGI script.

Status

HTTP status report as defined by http_status_reply/4.

Arguments:

HdrExtra	- provides additional reply-header fields, encoded as Name(Value). It can also contain a field content_length(-Len) to retrieve the value of the Content-length header that is replied.
Code	- is the numeric HTTP status code sent

To be done

- Complete documentation

  224http_reply(What, Out) :-
  225    http_reply(What, Out, [connection(close)], _).
  226
  227http_reply(Data, Out, HdrExtra) :-
  228    http_reply(Data, Out, HdrExtra, _Code).
  229
  230http_reply(Data, Out, HdrExtra, Code) :-
  231    http_reply(Data, Out, HdrExtra, [], Code).
  232
  233http_reply(Data, Out, HdrExtra, Context, Code) :-
  234    http_reply(Data, Out, HdrExtra, Context, [method(get)], Code).
  235
  236http_reply(Data, Out, HdrExtra, _Context, Request, Code) :-
  237    byte_count(Out, C0),
  238    memberchk(method(Method), Request),
  239    catch(http_reply_data(Data, Out, HdrExtra, Method, Code), E, true),
  240    !,
  241    (   var(E)
  242    ->  true
  243    ;   (   E = error(io_error(write,_), _)
  244        ;   E = error(socket_error(_,_), _)
  245        )
  246    ->  byte_count(Out, C1),
  247        Sent is C1 - C0,
  248        throw(error(http_write_short(Data, Sent), _))
  249    ;   E = error(timeout_error(write, _), _)
  250    ->  throw(E)
  251    ;   map_exception_to_http_status(E, Status, NewHdr, NewContext),
  252        http_status_reply(Status, Out, NewHdr, NewContext, Request, Code)
  253    ).
  254http_reply(Status, Out, HdrExtra, Context, Request, Code) :-
  255    http_status_reply(Status, Out, HdrExtra, Context, Request, Code).
  256
  257:- meta_predicate
  258    if_no_head(0, +).

 http_reply_data(+Data, +Out, +HdrExtra, +Method, -Code) is semidet

Fails if Data is not a defined reply-data format, but a status term. See http_reply/3 and http_status_reply/6.

Errors

- Various I/O errors.

  267http_reply_data(Data, Out, HdrExtra, Method, Code) :-
  268    http_reply_data_(Data, Out, HdrExtra, Method, Code),
  269    flush_output(Out).
  270
  271http_reply_data_(html(HTML), Out, HdrExtra, Method, Code) :-
  272    !,
  273    phrase(reply_header(html(HTML), HdrExtra, Code), Header),
  274    send_reply_header(Out, Header),
  275    if_no_head(print_html(Out, HTML), Method).
  276http_reply_data_(file(Type, File), Out, HdrExtra, Method, Code) :-
  277    !,
  278    phrase(reply_header(file(Type, File), HdrExtra, Code), Header),
  279    reply_file(Out, File, Header, Method).
  280http_reply_data_(gzip_file(Type, File), Out, HdrExtra, Method, Code) :-
  281    !,
  282    phrase(reply_header(gzip_file(Type, File), HdrExtra, Code), Header),
  283    reply_file(Out, File, Header, Method).
  284http_reply_data_(file(Type, File, Range), Out, HdrExtra, Method, Code) :-
  285    !,
  286    phrase(reply_header(file(Type, File, Range), HdrExtra, Code), Header),
  287    reply_file_range(Out, File, Header, Range, Method).
  288http_reply_data_(tmp_file(Type, File), Out, HdrExtra, Method, Code) :-
  289    !,
  290    phrase(reply_header(tmp_file(Type, File), HdrExtra, Code), Header),
  291    reply_file(Out, File, Header, Method).
  292http_reply_data_(bytes(Type, Bytes), Out, HdrExtra, Method, Code) :-
  293    !,
  294    phrase(reply_header(bytes(Type, Bytes), HdrExtra, Code), Header),
  295    send_reply_header(Out, Header),
  296    if_no_head(format(Out, '~s', [Bytes]), Method).
  297http_reply_data_(stream(In, Len), Out, HdrExtra, Method, Code) :-
  298    !,
  299    phrase(reply_header(cgi_data(Len), HdrExtra, Code), Header),
  300    copy_stream(Out, In, Header, Method, 0, end).
  301http_reply_data_(cgi_stream(In, Len), Out, HdrExtra, Method, Code) :-
  302    !,
  303    http_read_header(In, CgiHeader),
  304    seek(In, 0, current, Pos),
  305    Size is Len - Pos,
  306    http_join_headers(HdrExtra, CgiHeader, Hdr2),
  307    phrase(reply_header(cgi_data(Size), Hdr2, Code), Header),
  308    copy_stream(Out, In, Header, Method, 0, end).
  309
  310if_no_head(_, head) :-
  311    !.
  312if_no_head(Goal, _) :-
  313    call(Goal).
  314
  315reply_file(Out, _File, Header, head) :-
  316    !,
  317    send_reply_header(Out, Header).
  318reply_file(Out, File, Header, _) :-
  319    setup_call_cleanup(
  320        open(File, read, In, [type(binary)]),
  321        copy_stream(Out, In, Header, 0, end),
  322        close(In)).
  323
  324reply_file_range(Out, _File, Header, _Range, head) :-
  325    !,
  326    send_reply_header(Out, Header).
  327reply_file_range(Out, File, Header, bytes(From, To), _) :-
  328    setup_call_cleanup(
  329        open(File, read, In, [type(binary)]),
  330        copy_stream(Out, In, Header, From, To),
  331        close(In)).
  332
  333copy_stream(Out, _, Header, head, _, _) :-
  334    !,
  335    send_reply_header(Out, Header).
  336copy_stream(Out, In, Header, _, From, To) :-
  337    copy_stream(Out, In, Header, From, To).
  338
  339copy_stream(Out, In, Header, From, To) :-
  340    (   From == 0
  341    ->  true
  342    ;   seek(In, From, bof, _)
  343    ),
  344    peek_byte(In, _),
  345    send_reply_header(Out, Header),
  346    (   To == end
  347    ->  copy_stream_data(In, Out)
  348    ;   Len is To - From,
  349        copy_stream_data(In, Out, Len)
  350    ).

 http_status_reply(+Status, +Out, +HdrExtra, -Code) is det

 http_status_reply(+Status, +Out, +HdrExtra, +Context, -Code) is det

 http_status_reply(+Status, +Out, +HdrExtra, +Context, +Request, -Code) is det

Emit HTML non-200 status reports. Such requests are always sent as UTF-8 documents.

Status can be one of the following:

authorise(Method)

Challenge authorization. Method is one of

• basic(Realm)
• digest(Digest)

authorise(basic,Realm)

Same as authorise(basic(Realm)). Deprecated.

bad_request(ErrorTerm)

busy

created(Location)

forbidden(Url)

moved(To)

moved_temporary(To)

no_content

not_acceptable(WhyHtml)

not_found(Path)

method_not_allowed(Method, Path)

not_modified

resource_error(ErrorTerm)

see_other(To)

switching_protocols(Goal, Options)

server_error(ErrorTerm)

unavailable(WhyHtml)

  384http_status_reply(Status, Out, Options) :-
  385    _{header:HdrExtra, context:Context, code:Code, method:Method} :< Options,
  386    http_status_reply(Status, Out, HdrExtra, Context, [method(Method)], Code).
  387
  388http_status_reply(Status, Out, HdrExtra, Code) :-
  389    http_status_reply(Status, Out, HdrExtra, [], Code).
  390
  391http_status_reply(Status, Out, HdrExtra, Context, Code) :-
  392    http_status_reply(Status, Out, HdrExtra, Context, [method(get)], Code).
  393
  394http_status_reply(Status, Out, HdrExtra, Context, Request, Code) :-
  395    option(method(Method), Request, get),
  396    parsed_accept(Request, Accept),
  397    status_reply_flush(Status, Out,
  398                       _{ context: Context,
  399                          method:  Method,
  400                          code:    Code,
  401                          accept:  Accept,
  402                          header:  HdrExtra
  403                        }).
  404
  405parsed_accept(Request, Accept) :-
  406    memberchk(accept(Accept0), Request),
  407    http_parse_header_value(accept, Accept0, Accept1),
  408    !,
  409    Accept = Accept1.
  410parsed_accept(_, [ media(text/html, [], 0.1,  []),
  411                   media(_,         [], 0.01, [])
  412                 ]).
  413
  414status_reply_flush(Status, Out, Options) :-
  415    status_reply(Status, Out, Options),
  416    !,
  417    flush_output(Out).

 status_reply(+Status, +Out, +Options:dict)

Formulate a non-200 reply and send it to the stream Out. Options is a dict containing:

• header
• context
• method
• code
• accept

  430% Replies without content
  431status_reply(no_content, Out, Options) :-
  432    !,
  433    phrase(reply_header(status(no_content), Options), Header),
  434    send_reply_header(Out, Header).
  435status_reply(switching_protocols(_Goal,SwitchOptions), Out, Options) :-
  436    !,
  437    (   option(headers(Extra1), SwitchOptions)
  438    ->  true
  439    ;   option(header(Extra1), SwitchOptions, [])
  440    ),
  441    http_join_headers(Options.header, Extra1, HdrExtra),
  442    phrase(reply_header(status(switching_protocols),
  443                        Options.put(header,HdrExtra)), Header),
  444    send_reply_header(Out, Header).
  445status_reply(authorise(basic, ''), Out, Options) :-
  446    !,
  447    status_reply(authorise(basic), Out, Options).
  448status_reply(authorise(basic, Realm), Out, Options) :-
  449    !,
  450    status_reply(authorise(basic(Realm)), Out, Options).
  451status_reply(not_modified, Out, Options) :-
  452    !,
  453    phrase(reply_header(status(not_modified), Options), Header),
  454    send_reply_header(Out, Header).
  455% aliases (compatibility)
  456status_reply(busy, Out, Options) :-
  457    status_reply(service_unavailable(busy), Out, Options).
  458status_reply(unavailable(Why), Out, Options) :-
  459    status_reply(service_unavailable(Why), Out, Options).
  460status_reply(resource_error(Why), Out, Options) :-
  461    status_reply(service_unavailable(Why), Out, Options).
  462% replies with content
  463status_reply(Status, Out, Options) :-
  464    status_has_content(Status),
  465    status_page_hook(Status, Reply, Options),
  466    serialize_body(Reply, Body),
  467    Status =.. List,
  468    append(List, [Body], ExList),
  469    ExStatus =.. ExList,
  470    phrase(reply_header(ExStatus, Options), Header),
  471    send_reply_header(Out, Header),
  472    reply_status_body(Out, Body, Options).

 status_has_content(+StatusTerm, -HTTPCode)

True when StatusTerm is a status that usually comes with an expanatory content message.

  479status_has_content(created(_Location)).
  480status_has_content(moved(_To)).
  481status_has_content(moved_temporary(_To)).
  482status_has_content(gone(_URL)).
  483status_has_content(see_other(_To)).
  484status_has_content(bad_request(_ErrorTerm)).
  485status_has_content(authorise(_Method)).
  486status_has_content(forbidden(_URL)).
  487status_has_content(not_found(_URL)).
  488status_has_content(method_not_allowed(_Method, _URL)).
  489status_has_content(not_acceptable(_Why)).
  490status_has_content(server_error(_ErrorTerm)).
  491status_has_content(service_unavailable(_Why)).

 serialize_body(+Reply, -Body) is det

Serialize the reply as returned by status_page_hook/3 into a term:

body(Type, Encoding, Content)

In this term, Type is the media type, Encoding is the required wire encoding and Content a string representing the content.

  502serialize_body(Reply, Body) :-
  503    http:serialize_reply(Reply, Body),
  504    !.
  505serialize_body(html_tokens(Tokens), body(text/html, utf8, Content)) :-
  506    !,
  507    with_output_to(string(Content), print_html(Tokens)).
  508serialize_body(Reply, Reply) :-
  509    Reply = body(_,_,_),
  510    !.
  511serialize_body(Reply, _) :-
  512    domain_error(http_reply_body, Reply).
  513
  514reply_status_body(_, _, Options) :-
  515    Options.method == head,
  516    !.
  517reply_status_body(Out, body(_Type, Encoding, Content), _Options) :-
  518    (   Encoding == octet
  519    ->  format(Out, '~s', [Content])
  520    ;   setup_call_cleanup(
  521            set_stream(Out, encoding(Encoding)),
  522            format(Out, '~s', [Content]),
  523            set_stream(Out, encoding(octet)))
  524    ).

 http:serialize_reply(+Reply, -Body) is semidet

Multifile hook to serialize the result of status_reply/3 into a term

body(Type, Encoding, Content)

In this term, Type is the media type, Encoding is the required wire encoding and Content a string representing the content.

 status_page_hook(+Term, -Reply, +Options) is det

Calls the following two hooks to generate an HTML page from a status reply.

http:status_reply(+Term, -Reply, +Options)

Provide non-HTML description of the (non-200) reply. The term Reply is handed to serialize_body/2, calling the hook serialize_reply/2.

http:status_page(+Term, +Context, -HTML)

http:status_page(+Code, +Context, -HTML)

Arguments:

Term	- is the status term, e.g., not_found(URL)

See also

- status_page/3

  551status_page_hook(Term, Reply, Options) :-
  552    Context = Options.context,
  553    functor(Term, Name, _),
  554    status_number_fact(Name, Code),
  555    (   Options.code = Code,
  556        http:status_reply(Term, Reply, Options)
  557    ;   http:status_page(Term, Context, HTML),
  558        Reply = html_tokens(HTML)
  559    ;   http:status_page(Code, Context, HTML), % deprecated
  560        Reply = html_tokens(HTML)
  561    ),
  562    !.
  563status_page_hook(created(Location), html_tokens(HTML), _Options) :-
  564    phrase(page([ title('201 Created')
  565                ],
  566                [ h1('Created'),
  567                  p(['The document was created ',
  568                     a(href(Location), ' Here')
  569                    ]),
  570                  \address
  571                ]),
  572           HTML).
  573status_page_hook(moved(To), html_tokens(HTML), _Options) :-
  574    phrase(page([ title('301 Moved Permanently')
  575                ],
  576                [ h1('Moved Permanently'),
  577                  p(['The document has moved ',
  578                     a(href(To), ' Here')
  579                    ]),
  580                  \address
  581                ]),
  582           HTML).
  583status_page_hook(moved_temporary(To), html_tokens(HTML), _Options) :-
  584    phrase(page([ title('302 Moved Temporary')
  585                ],
  586                [ h1('Moved Temporary'),
  587                  p(['The document is currently ',
  588                     a(href(To), ' Here')
  589                    ]),
  590                  \address
  591                ]),
  592           HTML).
  593status_page_hook(gone(URL), html_tokens(HTML), _Options) :-
  594    phrase(page([ title('410 Resource Gone')
  595                ],
  596                [ h1('Resource Gone'),
  597                  p(['The document has been removed ',
  598                     a(href(URL), ' from here')
  599                    ]),
  600                  \address
  601                ]),
  602           HTML).
  603status_page_hook(see_other(To), html_tokens(HTML), _Options) :-
  604    phrase(page([ title('303 See Other')
  605                 ],
  606                 [ h1('See Other'),
  607                   p(['See other document ',
  608                      a(href(To), ' Here')
  609                     ]),
  610                   \address
  611                 ]),
  612            HTML).
  613status_page_hook(bad_request(ErrorTerm), html_tokens(HTML), _Options) :-
  614    '$messages':translate_message(ErrorTerm, Lines, []),
  615    phrase(page([ title('400 Bad Request')
  616                ],
  617                [ h1('Bad Request'),
  618                  p(\html_message_lines(Lines)),
  619                  \address
  620                ]),
  621           HTML).
  622status_page_hook(authorise(_Method), html_tokens(HTML), _Options):-
  623    phrase(page([ title('401 Authorization Required')
  624                ],
  625                [ h1('Authorization Required'),
  626                  p(['This server could not verify that you ',
  627                     'are authorized to access the document ',
  628                     'requested.  Either you supplied the wrong ',
  629                     'credentials (e.g., bad password), or your ',
  630                     'browser doesn\'t understand how to supply ',
  631                     'the credentials required.'
  632                    ]),
  633                  \address
  634                ]),
  635           HTML).
  636status_page_hook(forbidden(URL), html_tokens(HTML), _Options) :-
  637    phrase(page([ title('403 Forbidden')
  638                ],
  639                [ h1('Forbidden'),
  640                  p(['You don\'t have permission to access ', URL,
  641                     ' on this server'
  642                    ]),
  643                  \address
  644                ]),
  645           HTML).
  646status_page_hook(not_found(URL), html_tokens(HTML), _Options) :-
  647    phrase(page([ title('404 Not Found')
  648                ],
  649                [ h1('Not Found'),
  650                  p(['The requested URL ', tt(URL),
  651                     ' was not found on this server'
  652                    ]),
  653                  \address
  654                ]),
  655           HTML).
  656status_page_hook(method_not_allowed(Method,URL), html_tokens(HTML), _Options) :-
  657    upcase_atom(Method, UMethod),
  658    phrase(page([ title('405 Method not allowed')
  659                ],
  660                [ h1('Method not allowed'),
  661                  p(['The requested URL ', tt(URL),
  662                     ' does not support method ', tt(UMethod), '.'
  663                    ]),
  664                  \address
  665                ]),
  666           HTML).
  667status_page_hook(not_acceptable(WhyHTML), html_tokens(HTML), _Options) :-
  668    phrase(page([ title('406 Not Acceptable')
  669                ],
  670                [ h1('Not Acceptable'),
  671                  WhyHTML,
  672                  \address
  673                ]),
  674           HTML).
  675status_page_hook(server_error(ErrorTerm), html_tokens(HTML), _Options) :-
  676    '$messages':translate_message(ErrorTerm, Lines, []),
  677    phrase(page([ title('500 Internal server error')
  678                ],
  679                [ h1('Internal server error'),
  680                  p(\html_message_lines(Lines)),
  681                  \address
  682                ]),
  683           HTML).
  684status_page_hook(service_unavailable(Why), html_tokens(HTML), _Options) :-
  685    phrase(page([ title('503 Service Unavailable')
  686                ],
  687                [ h1('Service Unavailable'),
  688                  \unavailable(Why),
  689                  \address
  690                ]),
  691           HTML).
  692
  693unavailable(busy) -->
  694    html(p(['The server is temporarily out of resources, ',
  695            'please try again later'])).
  696unavailable(error(Formal,Context)) -->
  697    { '$messages':translate_message(error(Formal,Context), Lines, []) },
  698    html_message_lines(Lines).
  699unavailable(HTML) -->
  700    html(HTML).
  701
  702html_message_lines([]) -->
  703    [].
  704html_message_lines([nl|T]) -->
  705    !,
  706    html([br([])]),
  707    html_message_lines(T).
  708html_message_lines([flush]) -->
  709    [].
  710html_message_lines([ansi(_Style,Fmt,Args)|T]) -->
  711    !,
  712    { format(string(S), Fmt, Args)
  713    },
  714    html([S]),
  715    html_message_lines(T).
  716html_message_lines([url(Pos)|T]) -->
  717    !,
  718    msg_url(Pos),
  719    html_message_lines(T).
  720html_message_lines([url(URL, Label)|T]) -->
  721    !,
  722    html(a(href(URL), Label)),
  723    html_message_lines(T).
  724html_message_lines([Fmt-Args|T]) -->
  725    !,
  726    { format(string(S), Fmt, Args)
  727    },
  728    html([S]),
  729    html_message_lines(T).
  730html_message_lines([Fmt|T]) -->
  731    !,
  732    { format(string(S), Fmt, [])
  733    },
  734    html([S]),
  735    html_message_lines(T).
  736
  737msg_url(File:Line:Pos) -->
  738    !,
  739    html([File, :, Line, :, Pos]).
  740msg_url(File:Line) -->
  741    !,
  742    html([File, :, Line]).
  743msg_url(File) -->
  744    html([File]).

 http_join_headers(+Default, +Header, -Out)

Append headers from Default to Header if they are not already part of it.

  751http_join_headers([], H, H).
  752http_join_headers([H|T], Hdr0, Hdr) :-
  753    functor(H, N, A),
  754    functor(H2, N, A),
  755    member(H2, Hdr0),
  756    !,
  757    http_join_headers(T, Hdr0, Hdr).
  758http_join_headers([H|T], Hdr0, [H|Hdr]) :-
  759    http_join_headers(T, Hdr0, Hdr).

 http_update_encoding(+HeaderIn, -Encoding, -HeaderOut)

Allow for rewrite of the header, adjusting the encoding. We distinguish three options. If the user announces `text', we always use UTF-8 encoding. If the user announces charset=utf-8 we use UTF-8 and otherwise we use octet (raw) encoding. Alternatively we could dynamically choose for ASCII, ISO-Latin-1 or UTF-8.

  771http_update_encoding(Header0, utf8, [content_type(Type)|Header]) :-
  772    select(content_type(Type0), Header0, Header),
  773    sub_atom(Type0, 0, _, _, 'text/'),
  774    !,
  775    (   sub_atom(Type0, S, _, _, ';')
  776    ->  sub_atom(Type0, 0, S, _, B)
  777    ;   B = Type0
  778    ),
  779    atom_concat(B, '; charset=UTF-8', Type).
  780http_update_encoding(Header, Encoding, Header) :-
  781    memberchk(content_type(Type), Header),
  782    (   (   sub_atom(Type, _, _, _, 'UTF-8')
  783        ;   sub_atom(Type, _, _, _, 'utf-8')
  784        )
  785    ->  Encoding = utf8
  786    ;   http:mime_type_encoding(Type, Encoding)
  787    ->  true
  788    ;   mime_type_encoding(Type, Encoding)
  789    ).
  790http_update_encoding(Header, octet, Header).

 mime_type_encoding(+MimeType, -Encoding) is semidet

Encoding is the (default) character encoding for MimeType. Hooked by mime_type_encoding/2.

  797mime_type_encoding('application/json',         utf8).
  798mime_type_encoding('application/jsonrequest',  utf8).
  799mime_type_encoding('application/x-prolog',     utf8).
  800mime_type_encoding('application/n-quads',      utf8).
  801mime_type_encoding('application/n-triples',    utf8).
  802mime_type_encoding('application/sparql-query', utf8).
  803mime_type_encoding('application/trig',         utf8).

 http:mime_type_encoding(+MimeType, -Encoding) is semidet

Encoding is the (default) character encoding for MimeType. This is used for setting the encoding for HTTP replies after the user calls format('Content-type: <MIME type>~n'). This hook is called before mime_type_encoding/2. This default defines utf8 for JSON and Turtle derived application/ MIME types.

 http_update_connection(+CGIHeader, +Request, -Connection, -Header)

Merge keep-alive information from Request and CGIHeader into Header.

  819http_update_connection(CgiHeader, Request, Connect,
  820                       [connection(Connect)|Rest]) :-
  821    select(connection(CgiConn), CgiHeader, Rest),
  822    !,
  823    connection(Request, ReqConnection),
  824    join_connection(ReqConnection, CgiConn, Connect).
  825http_update_connection(CgiHeader, Request, Connect,
  826                       [connection(Connect)|CgiHeader]) :-
  827    connection(Request, Connect).
  828
  829join_connection(Keep1, Keep2, Connection) :-
  830    (   downcase_atom(Keep1, 'keep-alive'),
  831        downcase_atom(Keep2, 'keep-alive')
  832    ->  Connection = 'Keep-Alive'
  833    ;   Connection = close
  834    ).

 connection(+Header, -Connection)

Extract the desired connection from a header.

  841connection(Header, Close) :-
  842    (   memberchk(connection(Connection), Header)
  843    ->  Close = Connection
  844    ;   memberchk(http_version(1-X), Header),
  845        X >= 1
  846    ->  Close = 'Keep-Alive'
  847    ;   Close = close
  848    ).

 http_update_transfer(+Request, +CGIHeader, -Transfer, -Header)

Decide on the transfer encoding from the Request and the CGI header. The behaviour depends on the setting http:chunked_transfer. If never, even explitic requests are ignored. If on_request, chunked encoding is used if requested through the CGI header and allowed by the client. If if_possible, chunked encoding is used whenever the client allows for it, which is interpreted as the client supporting HTTP 1.1 or higher.

Chunked encoding is more space efficient and allows the client to start processing partial results. The drawback is that errors lead to incomplete pages instead of a nicely formatted complete page.

  867http_update_transfer(Request, CgiHeader, Transfer, Header) :-
  868    setting(http:chunked_transfer, When),
  869    http_update_transfer(When, Request, CgiHeader, Transfer, Header).
  870
  871http_update_transfer(never, _, CgiHeader, none, Header) :-
  872    !,
  873    delete(CgiHeader, transfer_encoding(_), Header).
  874http_update_transfer(_, _, CgiHeader, none, Header) :-
  875    memberchk(location(_), CgiHeader),
  876    !,
  877    delete(CgiHeader, transfer_encoding(_), Header).
  878http_update_transfer(_, Request, CgiHeader, Transfer, Header) :-
  879    select(transfer_encoding(CgiTransfer), CgiHeader, Rest),
  880    !,
  881    transfer(Request, ReqConnection),
  882    join_transfer(ReqConnection, CgiTransfer, Transfer),
  883    (   Transfer == none
  884    ->  Header = Rest
  885    ;   Header = [transfer_encoding(Transfer)|Rest]
  886    ).
  887http_update_transfer(if_possible, Request, CgiHeader, Transfer, Header) :-
  888    transfer(Request, Transfer),
  889    Transfer \== none,
  890    !,
  891    Header = [transfer_encoding(Transfer)|CgiHeader].
  892http_update_transfer(_, _, CgiHeader, none, CgiHeader).
  893
  894join_transfer(chunked, chunked, chunked) :- !.
  895join_transfer(_, _, none).

 transfer(+Header, -Connection)

Extract the desired connection from a header.

  902transfer(Header, Transfer) :-
  903    (   memberchk(transfer_encoding(Transfer0), Header)
  904    ->  Transfer = Transfer0
  905    ;   memberchk(http_version(1-X), Header),
  906        X >= 1
  907    ->  Transfer = chunked
  908    ;   Transfer = none
  909    ).

 content_length_in_encoding(+Encoding, +In, -Bytes)

Determine hom many bytes are required to represent the data from stream In using the given encoding. Fails if the data cannot be represented with the given encoding.

  918content_length_in_encoding(Enc, Stream, Bytes) :-
  919    stream_property(Stream, position(Here)),
  920    setup_call_cleanup(
  921        open_null_stream(Out),
  922        ( set_stream(Out, encoding(Enc)),
  923          catch(copy_stream_data(Stream, Out), _, fail),
  924          flush_output(Out),
  925          byte_count(Out, Bytes)
  926        ),
  927        ( close(Out, [force(true)]),
  928          set_stream_position(Stream, Here)
  929        )).
  930
  931
  932                 /*******************************
  933                 *          POST SUPPORT        *
  934                 *******************************/

 http_post_data(+Data, +Out:stream, +HdrExtra) is det

Send data on behalf on an HTTP POST request. This predicate is normally called by http_post/4 from http_client.pl to send the POST data to the server. Data is one of:

• html(+Tokens) Result of html//1 from html_write.pl
• xml(+Term) Post the result of xml_write/3 using the Mime-type text/xml
• xml(+Type, +Term) Post the result of xml_write/3 using the given Mime-type and an empty option list to xml_write/3.
• xml(+Type, +Term, +Options) Post the result of xml_write/3 using the given Mime-type and option list for xml_write/3.
• file(+File) Send contents of a file. Mime-type is determined by file_mime_type/2.
• file(+Type, +File) Send file with content of indicated mime-type.
• memory_file(+Type, +Handle) Similar to file(+Type, +File), but using a memory file instead of a real file. See new_memory_file/1.
• codes(+Codes) As codes(text/plain, Codes).
• codes(+Type, +Codes) Send Codes using the indicated MIME-type.
• bytes(+Type, +Bytes) Send Bytes using the indicated MIME-type. Bytes is either a string of character codes 0..255 or list of integers in the range 0..255. Out-of-bound codes result in a representation error exception.
• atom(+Atom) As atom(text/plain, Atom).
• atom(+Type, +Atom) Send Atom using the indicated MIME-type.
• cgi_stream(+Stream, +Len) Read the input from Stream which, like CGI data starts with a partial HTTP header. The fields of this header are merged with the provided HdrExtra fields. The first Len characters of Stream are used.
• form(+ListOfParameter) Send data of the MIME type application/x-www-form-urlencoded as produced by browsers issuing a POST request from an HTML form. ListOfParameter is a list of Name=Value or Name(Value).
• form_data(+ListOfData) Send data of the MIME type multipart/form-data as produced by browsers issuing a POST request from an HTML form using enctype multipart/form-data. ListOfData is the same as for the List alternative described below. Below is an example. Repository, etc. are atoms providing the value, while the last argument provides a value from a file.

  ...,
  http_post([ protocol(http),
              host(Host),
              port(Port),
              path(ActionPath)
            ],
            form_data([ repository = Repository,
                        dataFormat = DataFormat,
                        baseURI    = BaseURI,
                        verifyData = Verify,
                        data       = file(File)
                      ]),
            _Reply,
            []),
  ...,

• List If the argument is a plain list, it is sent using the MIME type multipart/mixed and packed using mime_pack/3. See mime_pack/3 for details on the argument format.

 1027http_post_data(Data, Out, HdrExtra) :-
 1028    http:post_data_hook(Data, Out, HdrExtra),
 1029    !.
 1030http_post_data(html(HTML), Out, HdrExtra) :-
 1031    !,
 1032    phrase(post_header(html(HTML), HdrExtra), Header),
 1033    send_request_header(Out, Header),
 1034    print_html(Out, HTML).
 1035http_post_data(xml(XML), Out, HdrExtra) :-
 1036    !,
 1037    http_post_data(xml(text/xml, XML, []), Out, HdrExtra).
 1038http_post_data(xml(Type, XML), Out, HdrExtra) :-
 1039    !,
 1040    http_post_data(xml(Type, XML, []), Out, HdrExtra).
 1041http_post_data(xml(Type, XML, Options), Out, HdrExtra) :-
 1042    !,
 1043    setup_call_cleanup(
 1044        new_memory_file(MemFile),
 1045        (   setup_call_cleanup(
 1046                open_memory_file(MemFile, write, MemOut),
 1047                xml_write(MemOut, XML, Options),
 1048                close(MemOut)),
 1049            http_post_data(memory_file(Type, MemFile), Out, HdrExtra)
 1050        ),
 1051        free_memory_file(MemFile)).
 1052http_post_data(file(File), Out, HdrExtra) :-
 1053    !,
 1054    (   file_mime_type(File, Type)
 1055    ->  true
 1056    ;   Type = text/plain
 1057    ),
 1058    http_post_data(file(Type, File), Out, HdrExtra).
 1059http_post_data(file(Type, File), Out, HdrExtra) :-
 1060    !,
 1061    phrase(post_header(file(Type, File), HdrExtra), Header),
 1062    send_request_header(Out, Header),
 1063    setup_call_cleanup(
 1064        open(File, read, In, [type(binary)]),
 1065        copy_stream_data(In, Out),
 1066        close(In)).
 1067http_post_data(memory_file(Type, Handle), Out, HdrExtra) :-
 1068    !,
 1069    phrase(post_header(memory_file(Type, Handle), HdrExtra), Header),
 1070    send_request_header(Out, Header),
 1071    setup_call_cleanup(
 1072        open_memory_file(Handle, read, In, [encoding(octet)]),
 1073        copy_stream_data(In, Out),
 1074        close(In)).
 1075http_post_data(codes(Codes), Out, HdrExtra) :-
 1076    !,
 1077    http_post_data(codes(text/plain, Codes), Out, HdrExtra).
 1078http_post_data(codes(Type, Codes), Out, HdrExtra) :-
 1079    !,
 1080    phrase(post_header(codes(Type, Codes), HdrExtra), Header),
 1081    send_request_header(Out, Header),
 1082    setup_call_cleanup(
 1083        set_stream(Out, encoding(utf8)),
 1084        format(Out, '~s', [Codes]),
 1085        set_stream(Out, encoding(octet))).
 1086http_post_data(bytes(Type, Bytes), Out, HdrExtra) :-
 1087    !,
 1088    phrase(post_header(bytes(Type, Bytes), HdrExtra), Header),
 1089    send_request_header(Out, Header),
 1090    format(Out, '~s', [Bytes]).
 1091http_post_data(atom(Atom), Out, HdrExtra) :-
 1092    !,
 1093    http_post_data(atom(text/plain, Atom), Out, HdrExtra).
 1094http_post_data(atom(Type, Atom), Out, HdrExtra) :-
 1095    !,
 1096    phrase(post_header(atom(Type, Atom), HdrExtra), Header),
 1097    send_request_header(Out, Header),
 1098    setup_call_cleanup(
 1099        set_stream(Out, encoding(utf8)),
 1100        write(Out, Atom),
 1101        set_stream(Out, encoding(octet))).
 1102http_post_data(string(String), Out, HdrExtra) :-
 1103    !,
 1104    http_post_data(atom(text/plain, String), Out, HdrExtra).
 1105http_post_data(string(Type, String), Out, HdrExtra) :-
 1106    !,
 1107    phrase(post_header(string(Type, String), HdrExtra), Header),
 1108    send_request_header(Out, Header),
 1109    setup_call_cleanup(
 1110        set_stream(Out, encoding(utf8)),
 1111        write(Out, String),
 1112        set_stream(Out, encoding(octet))).
 1113http_post_data(cgi_stream(In, _Len), Out, HdrExtra) :-
 1114    !,
 1115    debug(obsolete, 'Obsolete 2nd argument in cgi_stream(In,Len)', []),
 1116    http_post_data(cgi_stream(In), Out, HdrExtra).
 1117http_post_data(cgi_stream(In), Out, HdrExtra) :-
 1118    !,
 1119    http_read_header(In, Header0),
 1120    http_update_encoding(Header0, Encoding, Header),
 1121    content_length_in_encoding(Encoding, In, Size),
 1122    http_join_headers(HdrExtra, Header, Hdr2),
 1123    phrase(post_header(cgi_data(Size), Hdr2), HeaderText),
 1124    send_request_header(Out, HeaderText),
 1125    setup_call_cleanup(
 1126        set_stream(Out, encoding(Encoding)),
 1127        copy_stream_data(In, Out),
 1128        set_stream(Out, encoding(octet))).
 1129http_post_data(form(Fields), Out, HdrExtra) :-
 1130    !,
 1131    parse_url_search(Codes, Fields),
 1132    length(Codes, Size),
 1133    http_join_headers(HdrExtra,
 1134                      [ content_type('application/x-www-form-urlencoded')
 1135                      ], Header),
 1136    phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1137    send_request_header(Out, HeaderChars),
 1138    format(Out, '~s', [Codes]).
 1139http_post_data(form_data(Data), Out, HdrExtra) :-
 1140    !,
 1141    setup_call_cleanup(
 1142        new_memory_file(MemFile),
 1143        ( setup_call_cleanup(
 1144              open_memory_file(MemFile, write, MimeOut),
 1145              mime_pack(Data, MimeOut, Boundary),
 1146              close(MimeOut)),
 1147          size_memory_file(MemFile, Size, octet),
 1148          format(string(ContentType),
 1149                 'multipart/form-data; boundary=~w', [Boundary]),
 1150          http_join_headers(HdrExtra,
 1151                            [ mime_version('1.0'),
 1152                              content_type(ContentType)
 1153                            ], Header),
 1154          phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1155          send_request_header(Out, HeaderChars),
 1156          setup_call_cleanup(
 1157              open_memory_file(MemFile, read, In, [encoding(octet)]),
 1158              copy_stream_data(In, Out),
 1159              close(In))
 1160        ),
 1161        free_memory_file(MemFile)).
 1162http_post_data(List, Out, HdrExtra) :-          % multipart-mixed
 1163    is_list(List),
 1164    !,
 1165    setup_call_cleanup(
 1166        new_memory_file(MemFile),
 1167        ( setup_call_cleanup(
 1168              open_memory_file(MemFile, write, MimeOut),
 1169              mime_pack(List, MimeOut, Boundary),
 1170              close(MimeOut)),
 1171          size_memory_file(MemFile, Size, octet),
 1172          format(string(ContentType),
 1173                 'multipart/mixed; boundary=~w', [Boundary]),
 1174          http_join_headers(HdrExtra,
 1175                            [ mime_version('1.0'),
 1176                              content_type(ContentType)
 1177                            ], Header),
 1178          phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1179          send_request_header(Out, HeaderChars),
 1180          setup_call_cleanup(
 1181              open_memory_file(MemFile, read, In, [encoding(octet)]),
 1182              copy_stream_data(In, Out),
 1183              close(In))
 1184        ),
 1185        free_memory_file(MemFile)).

 post_header(+Data, +HeaderExtra)//

Generate the POST header, emitting HeaderExtra, followed by the HTTP Content-length and Content-type fields.

 1192post_header(html(Tokens), HdrExtra) -->
 1193    header_fields(HdrExtra, Len),
 1194    content_length(html(Tokens), Len),
 1195    content_type(text/html),
 1196    "\r\n".
 1197post_header(file(Type, File), HdrExtra) -->
 1198    header_fields(HdrExtra, Len),
 1199    content_length(file(File), Len),
 1200    content_type(Type),
 1201    "\r\n".
 1202post_header(memory_file(Type, File), HdrExtra) -->
 1203    header_fields(HdrExtra, Len),
 1204    content_length(memory_file(File), Len),
 1205    content_type(Type),
 1206    "\r\n".
 1207post_header(cgi_data(Size), HdrExtra) -->
 1208    header_fields(HdrExtra, Len),
 1209    content_length(Size, Len),
 1210    "\r\n".
 1211post_header(codes(Type, Codes), HdrExtra) -->
 1212    header_fields(HdrExtra, Len),
 1213    content_length(codes(Codes, utf8), Len),
 1214    content_type(Type, utf8),
 1215    "\r\n".
 1216post_header(bytes(Type, Bytes), HdrExtra) -->
 1217    header_fields(HdrExtra, Len),
 1218    content_length(bytes(Bytes), Len),
 1219    content_type(Type),
 1220    "\r\n".
 1221post_header(atom(Type, Atom), HdrExtra) -->
 1222    header_fields(HdrExtra, Len),
 1223    content_length(atom(Atom, utf8), Len),
 1224    content_type(Type, utf8),
 1225    "\r\n".
 1226post_header(string(Type, String), HdrExtra) -->
 1227    header_fields(HdrExtra, Len),
 1228    content_length(string(String, utf8), Len),
 1229    content_type(Type, utf8),
 1230    "\r\n".
 1231
 1232
 1233                 /*******************************
 1234                 *       OUTPUT HEADER DCG      *
 1235                 *******************************/

 http_reply_header(+Out:stream, +What, +HdrExtra) is det

Create a reply header using reply_header//3 and send it to Stream.

 1242http_reply_header(Out, What, HdrExtra) :-
 1243    phrase(reply_header(What, HdrExtra, _Code), String),
 1244    !,
 1245    send_reply_header(Out, String).

 reply_header(+Data, +HdrExtra, -Code)// is det

Grammar that realises the HTTP handler for sending Data. Data is a real data object as described with http_reply/2 or a not-200-ok HTTP status reply. The following status replies are defined.

• created(+URL, +HTMLTokens)
• moved(+URL, +HTMLTokens)
• moved_temporary(+URL, +HTMLTokens)
• see_other(+URL, +HTMLTokens)
• status(+Status)
• status(+Status, +HTMLTokens)
• authorise(+Method, +Realm, +Tokens)
• authorise(+Method, +Tokens)
• not_found(+URL, +HTMLTokens)
• server_error(+Error, +Tokens)
• resource_error(+Error, +Tokens)
• service_unavailable(+Why, +Tokens)

See also

- http_status_reply/4 formulates the not-200-ok HTTP replies.

 1269reply_header(Data, Dict) -->
 1270    { _{header:HdrExtra, code:Code} :< Dict },
 1271    reply_header(Data, HdrExtra, Code).
 1272
 1273reply_header(string(String), HdrExtra, Code) -->
 1274    reply_header(string(text/plain, String), HdrExtra, Code).
 1275reply_header(string(Type, String), HdrExtra, Code) -->
 1276    vstatus(ok, Code, HdrExtra),
 1277    date(now),
 1278    header_fields(HdrExtra, CLen),
 1279    content_length(codes(String, utf8), CLen),
 1280    content_type(Type, utf8),
 1281    "\r\n".
 1282reply_header(bytes(Type, Bytes), HdrExtra, Code) -->
 1283    vstatus(ok, Code, HdrExtra),
 1284    date(now),
 1285    header_fields(HdrExtra, CLen),
 1286    content_length(bytes(Bytes), CLen),
 1287    content_type(Type),
 1288    "\r\n".
 1289reply_header(html(Tokens), HdrExtra, Code) -->
 1290    vstatus(ok, Code, HdrExtra),
 1291    date(now),
 1292    header_fields(HdrExtra, CLen),
 1293    content_length(html(Tokens), CLen),
 1294    content_type(text/html),
 1295    "\r\n".
 1296reply_header(file(Type, File), HdrExtra, Code) -->
 1297    vstatus(ok, Code, HdrExtra),
 1298    date(now),
 1299    modified(file(File)),
 1300    header_fields(HdrExtra, CLen),
 1301    content_length(file(File), CLen),
 1302    content_type(Type),
 1303    "\r\n".
 1304reply_header(gzip_file(Type, File), HdrExtra, Code) -->
 1305    vstatus(ok, Code, HdrExtra),
 1306    date(now),
 1307    modified(file(File)),
 1308    header_fields(HdrExtra, CLen),
 1309    content_length(file(File), CLen),
 1310    content_type(Type),
 1311    content_encoding(gzip),
 1312    "\r\n".
 1313reply_header(file(Type, File, Range), HdrExtra, Code) -->
 1314    vstatus(partial_content, Code, HdrExtra),
 1315    date(now),
 1316    modified(file(File)),
 1317    header_fields(HdrExtra, CLen),
 1318    content_length(file(File, Range), CLen),
 1319    content_type(Type),
 1320    "\r\n".
 1321reply_header(tmp_file(Type, File), HdrExtra, Code) -->
 1322    vstatus(ok, Code, HdrExtra),
 1323    date(now),
 1324    header_fields(HdrExtra, CLen),
 1325    content_length(file(File), CLen),
 1326    content_type(Type),
 1327    "\r\n".
 1328reply_header(cgi_data(Size), HdrExtra, Code) -->
 1329    vstatus(ok, Code, HdrExtra),
 1330    date(now),
 1331    header_fields(HdrExtra, CLen),
 1332    content_length(Size, CLen),
 1333    "\r\n".
 1334reply_header(chunked_data, HdrExtra, Code) -->
 1335    vstatus(ok, Code, HdrExtra),
 1336    date(now),
 1337    header_fields(HdrExtra, _),
 1338    (   {memberchk(transfer_encoding(_), HdrExtra)}
 1339    ->  ""
 1340    ;   transfer_encoding(chunked)
 1341    ),
 1342    "\r\n".
 1343% non-200 replies without a body (e.g., 1xx, 204, 304)
 1344reply_header(status(Status), HdrExtra, Code) -->
 1345    vstatus(Status, Code),
 1346    header_fields(HdrExtra, Clen),
 1347    { Clen = 0 },
 1348    "\r\n".
 1349% non-200 replies with a body
 1350reply_header(Data, HdrExtra, Code) -->
 1351    { status_reply_headers(Data,
 1352                           body(Type, Encoding, Content),
 1353                           ReplyHeaders),
 1354      http_join_headers(ReplyHeaders, HdrExtra, Headers),
 1355      functor(Data, CodeName, _)
 1356    },
 1357    vstatus(CodeName, Code, Headers),
 1358    date(now),
 1359    header_fields(Headers, CLen),
 1360    content_length(codes(Content, Encoding), CLen),
 1361    content_type(Type, Encoding),
 1362    "\r\n".
 1363
 1364status_reply_headers(created(Location, Body), Body,
 1365                     [ location(Location) ]).
 1366status_reply_headers(moved(To, Body), Body,
 1367                     [ location(To) ]).
 1368status_reply_headers(moved_temporary(To, Body), Body,
 1369                     [ location(To) ]).
 1370status_reply_headers(gone(_URL, Body), Body, []).
 1371status_reply_headers(see_other(To, Body), Body,
 1372                     [ location(To) ]).
 1373status_reply_headers(authorise(Method, Body), Body,
 1374                     [ www_authenticate(Method) ]).
 1375status_reply_headers(not_found(_URL, Body), Body, []).
 1376status_reply_headers(forbidden(_URL, Body), Body, []).
 1377status_reply_headers(method_not_allowed(_Method, _URL, Body), Body, []).
 1378status_reply_headers(server_error(_Error, Body), Body, []).
 1379status_reply_headers(service_unavailable(_Why, Body), Body, []).
 1380status_reply_headers(not_acceptable(_Why, Body), Body, []).
 1381status_reply_headers(bad_request(_Error, Body), Body, []).

 vstatus(+Status, -Code)// is det

 vstatus(+Status, -Code, +HdrExtra)// is det

Emit the HTTP header for Status

 1389vstatus(_Status, Code, HdrExtra) -->
 1390    {memberchk(status(Code), HdrExtra)},
 1391    !,
 1392    vstatus(_NewStatus, Code).
 1393vstatus(Status, Code, _) -->
 1394    vstatus(Status, Code).
 1395
 1396vstatus(Status, Code) -->
 1397    "HTTP/1.1 ",
 1398    status_number(Status, Code),
 1399    " ",
 1400    status_comment(Status),
 1401    "\r\n".

 status_number(?Status, ?Code)// is semidet

Parse/generate the HTTP status numbers and map them to the proper name.

See also

- See the source code for supported status names and codes.

 1410status_number(Status, Code) -->
 1411    { var(Status) },
 1412    !,
 1413    integer(Code),
 1414    { status_number(Status, Code) },
 1415    !.
 1416status_number(Status, Code) -->
 1417    { status_number(Status, Code) },
 1418    integer(Code).

 status_number(+Status:atom, -Code:nonneg) is det

status_number(-Status:atom, +Code:nonneg) is det

Relates a symbolic HTTP status names to their integer Code. Each code also needs a rule for status_comment//1.

throws

- type_error If Code is instantiated with something other than an integer.

- domain_error If Code is instantiated with an integer outside of the range [100-599] of defined HTTP status codes.

 1432% Unrecognized status codes that are within a defined code class.
 1433% RFC 7231 states:
 1434%   "[...] a client MUST understand the class of any status code,
 1435%    as indicated by the first digit, and treat an unrecognized status code
 1436%    as being equivalent to the `x00` status code of that class [...]
 1437%   "
 1438% @see http://tools.ietf.org/html/rfc7231#section-6
 1439
 1440status_number(Status, Code) :-
 1441    nonvar(Status),
 1442    !,
 1443    status_number_fact(Status, Code).
 1444status_number(Status, Code) :-
 1445    nonvar(Code),
 1446    !,
 1447    (   between(100, 599, Code)
 1448    ->  (   status_number_fact(Status, Code)
 1449        ->  true
 1450        ;   ClassCode is Code // 100 * 100,
 1451            status_number_fact(Status, ClassCode)
 1452        )
 1453    ;   domain_error(http_code, Code)
 1454    ).
 1455
 1456status_number_fact(continue,                   100).
 1457status_number_fact(switching_protocols,        101).
 1458status_number_fact(ok,                         200).
 1459status_number_fact(created,                    201).
 1460status_number_fact(accepted,                   202).
 1461status_number_fact(non_authoritative_info,     203).
 1462status_number_fact(no_content,                 204).
 1463status_number_fact(reset_content,              205).
 1464status_number_fact(partial_content,            206).
 1465status_number_fact(multiple_choices,           300).
 1466status_number_fact(moved,                      301).
 1467status_number_fact(moved_temporary,            302).
 1468status_number_fact(see_other,                  303).
 1469status_number_fact(not_modified,               304).
 1470status_number_fact(use_proxy,                  305).
 1471status_number_fact(unused,                     306).
 1472status_number_fact(temporary_redirect,         307).
 1473status_number_fact(bad_request,                400).
 1474status_number_fact(authorise,                  401).
 1475status_number_fact(payment_required,           402).
 1476status_number_fact(forbidden,                  403).
 1477status_number_fact(not_found,                  404).
 1478status_number_fact(method_not_allowed,         405).
 1479status_number_fact(not_acceptable,             406).
 1480status_number_fact(request_timeout,            408).
 1481status_number_fact(conflict,                   409).
 1482status_number_fact(gone,                       410).
 1483status_number_fact(length_required,            411).
 1484status_number_fact(payload_too_large,          413).
 1485status_number_fact(uri_too_long,               414).
 1486status_number_fact(unsupported_media_type,     415).
 1487status_number_fact(expectation_failed,         417).
 1488status_number_fact(upgrade_required,           426).
 1489status_number_fact(server_error,               500).
 1490status_number_fact(not_implemented,            501).
 1491status_number_fact(bad_gateway,                502).
 1492status_number_fact(service_unavailable,        503).
 1493status_number_fact(gateway_timeout,            504).
 1494status_number_fact(http_version_not_supported, 505).

 status_comment(+Code:atom)// is det

Emit standard HTTP human-readable comment on the reply-status.

 1501status_comment(continue) -->
 1502    "Continue".
 1503status_comment(switching_protocols) -->
 1504    "Switching Protocols".
 1505status_comment(ok) -->
 1506    "OK".
 1507status_comment(created) -->
 1508    "Created".
 1509status_comment(accepted) -->
 1510    "Accepted".
 1511status_comment(non_authoritative_info) -->
 1512    "Non-Authoritative Information".
 1513status_comment(no_content) -->
 1514    "No Content".
 1515status_comment(reset_content) -->
 1516    "Reset Content".
 1517status_comment(created) -->
 1518    "Created".
 1519status_comment(partial_content) -->
 1520    "Partial content".
 1521status_comment(multiple_choices) -->
 1522    "Multiple Choices".
 1523status_comment(moved) -->
 1524    "Moved Permanently".
 1525status_comment(moved_temporary) -->
 1526    "Moved Temporary".
 1527status_comment(see_other) -->
 1528    "See Other".
 1529status_comment(not_modified) -->
 1530    "Not Modified".
 1531status_comment(use_proxy) -->
 1532    "Use Proxy".
 1533status_comment(unused) -->
 1534    "Unused".
 1535status_comment(temporary_redirect) -->
 1536    "Temporary Redirect".
 1537status_comment(bad_request) -->
 1538    "Bad Request".
 1539status_comment(authorise) -->
 1540    "Authorization Required".
 1541status_comment(payment_required) -->
 1542    "Payment Required".
 1543status_comment(forbidden) -->
 1544    "Forbidden".
 1545status_comment(not_found) -->
 1546    "Not Found".
 1547status_comment(method_not_allowed) -->
 1548    "Method Not Allowed".
 1549status_comment(not_acceptable) -->
 1550    "Not Acceptable".
 1551status_comment(request_timeout) -->
 1552    "Request Timeout".
 1553status_comment(conflict) -->
 1554    "Conflict".
 1555status_comment(gone) -->
 1556    "Gone".
 1557status_comment(length_required) -->
 1558    "Length Required".
 1559status_comment(payload_too_large) -->
 1560    "Payload Too Large".
 1561status_comment(uri_too_long) -->
 1562    "URI Too Long".
 1563status_comment(unsupported_media_type) -->
 1564    "Unsupported Media Type".
 1565status_comment(expectation_failed) -->
 1566    "Expectation Failed".
 1567status_comment(upgrade_required) -->
 1568    "Upgrade Required".
 1569status_comment(server_error) -->
 1570    "Internal Server Error".
 1571status_comment(not_implemented) -->
 1572    "Not Implemented".
 1573status_comment(bad_gateway) -->
 1574    "Bad Gateway".
 1575status_comment(service_unavailable) -->
 1576    "Service Unavailable".
 1577status_comment(gateway_timeout) -->
 1578    "Gateway Timeout".
 1579status_comment(http_version_not_supported) -->
 1580    "HTTP Version Not Supported".
 1581
 1582date(Time) -->
 1583    "Date: ",
 1584    (   { Time == now }
 1585    ->  now
 1586    ;   rfc_date(Time)
 1587    ),
 1588    "\r\n".
 1589
 1590modified(file(File)) -->
 1591    !,
 1592    { time_file(File, Time)
 1593    },
 1594    modified(Time).
 1595modified(Time) -->
 1596    "Last-modified: ",
 1597    (   { Time == now }
 1598    ->  now
 1599    ;   rfc_date(Time)
 1600    ),
 1601    "\r\n".

 content_length(+Object, ?Len)// is det

Emit the content-length field and (optionally) the content-range field.

Arguments:

Len	- Number of bytes specified

 1611content_length(file(File, bytes(From, To)), Len) -->
 1612    !,
 1613    { size_file(File, Size),
 1614      (   To == end
 1615      ->  Len is Size - From,
 1616          RangeEnd is Size - 1
 1617      ;   Len is To+1 - From,       % To is index of last byte
 1618          RangeEnd = To
 1619      )
 1620    },
 1621    content_range(bytes, From, RangeEnd, Size),
 1622    content_length(Len, Len).
 1623content_length(Reply, Len) -->
 1624    { length_of(Reply, Len)
 1625    },
 1626    "Content-Length: ", integer(Len),
 1627    "\r\n".
 1628
 1629
 1630length_of(_, Len) :-
 1631    nonvar(Len),
 1632    !.
 1633length_of(string(String, Encoding), Len) :-
 1634    length_of(codes(String, Encoding), Len).
 1635length_of(codes(String, Encoding), Len) :-
 1636    !,
 1637    setup_call_cleanup(
 1638        open_null_stream(Out),
 1639        ( set_stream(Out, encoding(Encoding)),
 1640          format(Out, '~s', [String]),
 1641          byte_count(Out, Len)
 1642        ),
 1643        close(Out)).
 1644length_of(atom(Atom, Encoding), Len) :-
 1645    !,
 1646    setup_call_cleanup(
 1647        open_null_stream(Out),
 1648        ( set_stream(Out, encoding(Encoding)),
 1649          format(Out, '~a', [Atom]),
 1650          byte_count(Out, Len)
 1651        ),
 1652        close(Out)).
 1653length_of(file(File), Len) :-
 1654    !,
 1655    size_file(File, Len).
 1656length_of(memory_file(Handle), Len) :-
 1657    !,
 1658    size_memory_file(Handle, Len, octet).
 1659length_of(html_tokens(Tokens), Len) :-
 1660    !,
 1661    html_print_length(Tokens, Len).
 1662length_of(html(Tokens), Len) :-     % deprecated
 1663    !,
 1664    html_print_length(Tokens, Len).
 1665length_of(bytes(Bytes), Len) :-
 1666    !,
 1667    (   string(Bytes)
 1668    ->  string_length(Bytes, Len)
 1669    ;   length(Bytes, Len)          % assuming a list of 0..255
 1670    ).
 1671length_of(Len, Len).

 content_range(+Unit:atom, +From:int, +RangeEnd:int, +Size:int)// is det

Emit the Content-Range header for partial content (206) replies.

 1679content_range(Unit, From, RangeEnd, Size) -->
 1680    "Content-Range: ", atom(Unit), " ",
 1681    integer(From), "-", integer(RangeEnd), "/", integer(Size),
 1682    "\r\n".
 1683
 1684content_encoding(Encoding) -->
 1685    "Content-Encoding: ", atom(Encoding), "\r\n".
 1686
 1687transfer_encoding(Encoding) -->
 1688    "Transfer-Encoding: ", atom(Encoding), "\r\n".
 1689
 1690content_type(Type) -->
 1691    content_type(Type, _).
 1692
 1693content_type(Type, Charset) -->
 1694    ctype(Type),
 1695    charset(Charset),
 1696    "\r\n".
 1697
 1698ctype(Main/Sub) -->
 1699    !,
 1700    "Content-Type: ",
 1701    atom(Main),
 1702    "/",
 1703    atom(Sub).
 1704ctype(Type) -->
 1705    !,
 1706    "Content-Type: ",
 1707    atom(Type).
 1708
 1709charset(Var) -->
 1710    { var(Var) },
 1711    !.
 1712charset(utf8) -->
 1713    !,
 1714    "; charset=UTF-8".
 1715charset(CharSet) -->
 1716    "; charset=",
 1717    atom(CharSet).