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)  2002-2018, 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:- use_module(library(readutil)).   64:- use_module(library(debug)).   65:- use_module(library(error)).   66:- use_module(library(option)).   67:- use_module(library(lists)).   68:- use_module(library(url)).   69:- use_module(library(uri)).   70:- use_module(library(memfile)).   71:- use_module(library(settings)).   72:- use_module(library(error)).   73:- use_module(library(pairs)).   74:- use_module(library(socket)).   75:- use_module(library(dcg/basics)).   76:- use_module(html_write).   77:- use_module(http_exception).   78:- use_module(mimetype).   79:- use_module(mimepack).   80
   81:- multifile
   82    http:status_page/3,             % +Status, +Context, -HTML
   83    http:status_reply/3,            % +Status, -Reply, +Options
   84    http:serialize_reply/2,         % +Reply, -Body
   85    http:post_data_hook/3,          % +Data, +Out, +HdrExtra
   86    http:mime_type_encoding/2.      % +MimeType, -Encoding
   87
   88% see http_update_transfer/4.
   89
   90:- setting(http:chunked_transfer, oneof([never,on_request,if_possible]),
   91           on_request, 'When to use Transfer-Encoding: Chunked').

  101:- discontiguous
  102    term_expansion/2.  103
  104
  105                 /*******************************
  106                 *          READ REQUEST        *
  107                 *******************************/

 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.

  115http_read_request(In, Request) :-
  116    catch(read_line_to_codes(In, Codes), E, true),
  117    (   var(E)
  118    ->  (   Codes == end_of_file
  119        ->  debug(http(header), 'end-of-file', []),
  120            Request = end_of_file
  121        ;   debug(http(header), 'First line: ~s', [Codes]),
  122            Request =  [input(In)|Request1],
  123            phrase(request(In, Request1), Codes),
  124            (   Request1 = [unknown(Text)|_]
  125            ->  string_codes(S, Text),
  126                syntax_error(http_request(S))
  127            ;   true
  128            )
  129        )
  130    ;   (   debugging(http(request))
  131        ->  message_to_string(E, Msg),
  132            debug(http(request), "Exception reading 1st line: ~s", [Msg])
  133        ;   true
  134        ),
  135        Request = end_of_file
  136    ).

 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.

  144http_read_reply_header(In, [input(In)|Reply]) :-
  145    read_line_to_codes(In, Codes),
  146    (   Codes == end_of_file
  147    ->  debug(http(header), 'end-of-file', []),
  148        throw(error(syntax(http_reply_header, end_of_file), _))
  149    ;   debug(http(header), 'First line: ~s~n', [Codes]),
  150        (   phrase(reply(In, Reply), Codes)
  151        ->  true
  152        ;   atom_codes(Header, Codes),
  153            syntax_error(http_reply_header(Header))
  154        )
  155    ).
  156
  157
  158                 /*******************************
  159                 *        FORMULATE REPLY       *
  160                 *******************************/

 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

  209http_reply(What, Out) :-
  210    http_reply(What, Out, [connection(close)], _).
  211
  212http_reply(Data, Out, HdrExtra) :-
  213    http_reply(Data, Out, HdrExtra, _Code).
  214
  215http_reply(Data, Out, HdrExtra, Code) :-
  216    http_reply(Data, Out, HdrExtra, [], Code).
  217
  218http_reply(Data, Out, HdrExtra, Context, Code) :-
  219    http_reply(Data, Out, HdrExtra, Context, [method(get)], Code).
  220
  221http_reply(Data, Out, HdrExtra, _Context, Request, Code) :-
  222    byte_count(Out, C0),
  223    memberchk(method(Method), Request),
  224    catch(http_reply_data(Data, Out, HdrExtra, Method, Code), E, true),
  225    !,
  226    (   var(E)
  227    ->  true
  228    ;   E = error(io_error(write, _), _)
  229    ->  byte_count(Out, C1),
  230        Sent is C1 - C0,
  231        throw(error(http_write_short(Data, Sent), _))
  232    ;   E = error(timeout_error(write, _), _)
  233    ->  throw(E)
  234    ;   map_exception_to_http_status(E, Status, NewHdr, NewContext),
  235        http_status_reply(Status, Out, NewHdr, NewContext, Request, Code)
  236    ).
  237http_reply(Status, Out, HdrExtra, Context, Request, Code) :-
  238    http_status_reply(Status, Out, HdrExtra, Context, Request, Code).
  239
  240:- meta_predicate
  241    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.

  250http_reply_data(Data, Out, HdrExtra, Method, Code) :-
  251    http_reply_data_(Data, Out, HdrExtra, Method, Code),
  252    flush_output(Out).
  253
  254http_reply_data_(html(HTML), Out, HdrExtra, Method, Code) :-
  255    !,
  256    phrase(reply_header(html(HTML), HdrExtra, Code), Header),
  257    format(Out, '~s', [Header]),
  258    if_no_head(print_html(Out, HTML), Method).
  259http_reply_data_(file(Type, File), Out, HdrExtra, Method, Code) :-
  260    !,
  261    phrase(reply_header(file(Type, File), HdrExtra, Code), Header),
  262    reply_file(Out, File, Header, Method).
  263http_reply_data_(gzip_file(Type, File), Out, HdrExtra, Method, Code) :-
  264    !,
  265    phrase(reply_header(gzip_file(Type, File), HdrExtra, Code), Header),
  266    reply_file(Out, File, Header, Method).
  267http_reply_data_(file(Type, File, Range), Out, HdrExtra, Method, Code) :-
  268    !,
  269    phrase(reply_header(file(Type, File, Range), HdrExtra, Code), Header),
  270    reply_file_range(Out, File, Header, Range, Method).
  271http_reply_data_(tmp_file(Type, File), Out, HdrExtra, Method, Code) :-
  272    !,
  273    phrase(reply_header(tmp_file(Type, File), HdrExtra, Code), Header),
  274    reply_file(Out, File, Header, Method).
  275http_reply_data_(bytes(Type, Bytes), Out, HdrExtra, Method, Code) :-
  276    !,
  277    phrase(reply_header(bytes(Type, Bytes), HdrExtra, Code), Header),
  278    format(Out, '~s', [Header]),
  279    if_no_head(format(Out, '~s', [Bytes]), Method).
  280http_reply_data_(stream(In, Len), Out, HdrExtra, Method, Code) :-
  281    !,
  282    phrase(reply_header(cgi_data(Len), HdrExtra, Code), Header),
  283    copy_stream(Out, In, Header, Method, 0, end).
  284http_reply_data_(cgi_stream(In, Len), Out, HdrExtra, Method, Code) :-
  285    !,
  286    http_read_header(In, CgiHeader),
  287    seek(In, 0, current, Pos),
  288    Size is Len - Pos,
  289    http_join_headers(HdrExtra, CgiHeader, Hdr2),
  290    phrase(reply_header(cgi_data(Size), Hdr2, Code), Header),
  291    copy_stream(Out, In, Header, Method, 0, end).
  292
  293if_no_head(_, head) :-
  294    !.
  295if_no_head(Goal, _) :-
  296    call(Goal).
  297
  298reply_file(Out, _File, Header, head) :-
  299    !,
  300    format(Out, '~s', [Header]).
  301reply_file(Out, File, Header, _) :-
  302    setup_call_cleanup(
  303        open(File, read, In, [type(binary)]),
  304        copy_stream(Out, In, Header, 0, end),
  305        close(In)).
  306
  307reply_file_range(Out, _File, Header, _Range, head) :-
  308    !,
  309    format(Out, '~s', [Header]).
  310reply_file_range(Out, File, Header, bytes(From, To), _) :-
  311    setup_call_cleanup(
  312        open(File, read, In, [type(binary)]),
  313        copy_stream(Out, In, Header, From, To),
  314        close(In)).
  315
  316copy_stream(Out, _, Header, head, _, _) :-
  317    !,
  318    format(Out, '~s', [Header]).
  319copy_stream(Out, In, Header, _, From, To) :-
  320    copy_stream(Out, In, Header, From, To).
  321
  322copy_stream(Out, In, Header, From, To) :-
  323    (   From == 0
  324    ->  true
  325    ;   seek(In, From, bof, _)
  326    ),
  327    peek_byte(In, _),
  328    format(Out, '~s', [Header]),
  329    (   To == end
  330    ->  copy_stream_data(In, Out)
  331    ;   Len is To - From,
  332        copy_stream_data(In, Out, Len)
  333    ).

 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)

  367http_status_reply(Status, Out, Options) :-
  368    _{header:HdrExtra, context:Context, code:Code, method:Method} :< Options,
  369    http_status_reply(Status, Out, HdrExtra, Context, [method(Method)], Code).
  370
  371http_status_reply(Status, Out, HdrExtra, Code) :-
  372    http_status_reply(Status, Out, HdrExtra, [], Code).
  373
  374http_status_reply(Status, Out, HdrExtra, Context, Code) :-
  375    http_status_reply(Status, Out, HdrExtra, Context, [method(get)], Code).
  376
  377http_status_reply(Status, Out, HdrExtra, Context, Request, Code) :-
  378    option(method(Method), Request, get),
  379    parsed_accept(Request, Accept),
  380    status_reply_flush(Status, Out,
  381                       _{ context: Context,
  382                          method:  Method,
  383                          code:    Code,
  384                          accept:  Accept,
  385                          header:  HdrExtra
  386                        }).
  387
  388parsed_accept(Request, Accept) :-
  389    memberchk(accept(Accept0), Request),
  390    http_parse_header_value(accept, Accept0, Accept1),
  391    !,
  392    Accept = Accept1.
  393parsed_accept(_, [ media(text/html, [], 0.1,  []),
  394                   media(_,         [], 0.01, [])
  395                 ]).
  396
  397status_reply_flush(Status, Out, Options) :-
  398    status_reply(Status, Out, Options),
  399    !,
  400    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

  413% Replies without content
  414status_reply(no_content, Out, Options) :-
  415    !,
  416    phrase(reply_header(status(no_content), Options), Header),
  417    format(Out, '~s', [Header]).
  418status_reply(switching_protocols(_Goal,SwitchOptions), Out, Options) :-
  419    !,
  420    (   option(headers(Extra1), SwitchOptions)
  421    ->  true
  422    ;   option(header(Extra1), SwitchOptions, [])
  423    ),
  424    http_join_headers(Options.header, Extra1, HdrExtra),
  425    phrase(reply_header(status(switching_protocols),
  426                        Options.put(header,HdrExtra)), Header),
  427    format(Out, '~s', [Header]).
  428status_reply(authorise(basic, ''), Out, Options) :-
  429    !,
  430    status_reply(authorise(basic), Out, Options).
  431status_reply(authorise(basic, Realm), Out, Options) :-
  432    !,
  433    status_reply(authorise(basic(Realm)), Out, Options).
  434status_reply(not_modified, Out, Options) :-
  435    !,
  436    phrase(reply_header(status(not_modified), Options), Header),
  437    format(Out, '~s', [Header]).
  438% aliases (compatibility)
  439status_reply(busy, Out, Options) :-
  440    status_reply(service_unavailable(busy), Out, Options).
  441status_reply(unavailable(Why), Out, Options) :-
  442    status_reply(service_unavailable(Why), Out, Options).
  443status_reply(resource_error(Why), Out, Options) :-
  444    status_reply(service_unavailable(Why), Out, Options).
  445% replies with content
  446status_reply(Status, Out, Options) :-
  447    status_has_content(Status),
  448    status_page_hook(Status, Reply, Options),
  449    serialize_body(Reply, Body),
  450    Status =.. List,
  451    append(List, [Body], ExList),
  452    ExStatus =.. ExList,
  453    phrase(reply_header(ExStatus, Options), Header),
  454    format(Out, '~s', [Header]),
  455    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.

  462status_has_content(created(_Location)).
  463status_has_content(moved(_To)).
  464status_has_content(moved_temporary(_To)).
  465status_has_content(see_other(_To)).
  466status_has_content(bad_request(_ErrorTerm)).
  467status_has_content(authorise(_Method)).
  468status_has_content(forbidden(_URL)).
  469status_has_content(not_found(_URL)).
  470status_has_content(method_not_allowed(_Method, _URL)).
  471status_has_content(not_acceptable(_Why)).
  472status_has_content(server_error(_ErrorTerm)).
  473status_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.

  484serialize_body(Reply, Body) :-
  485    http:serialize_reply(Reply, Body),
  486    !.
  487serialize_body(html_tokens(Tokens), body(text/html, utf8, Content)) :-
  488    !,
  489    with_output_to(string(Content), print_html(Tokens)).
  490serialize_body(Reply, Reply) :-
  491    Reply = body(_,_,_),
  492    !.
  493serialize_body(Reply, _) :-
  494    domain_error(http_reply_body, Reply).
  495
  496reply_status_body(_, _, Options) :-
  497    Options.method == head,
  498    !.
  499reply_status_body(Out, body(_Type, Encoding, Content), _Options) :-
  500    (   Encoding == octet
  501    ->  format(Out, '~s', [Content])
  502    ;   setup_call_cleanup(
  503            set_stream(Out, encoding(Encoding)),
  504            format(Out, '~s', [Content]),
  505            set_stream(Out, encoding(octet)))
  506    ).

 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 http: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

- http:status_page/3

  533status_page_hook(Term, Reply, Options) :-
  534    Context = Options.context,
  535    functor(Term, Name, _),
  536    status_number_fact(Name, Code),
  537    (   Options.code = Code,
  538        http:status_reply(Term, Reply, Options)
  539    ;   http:status_page(Term, Context, HTML),
  540        Reply = html_tokens(HTML)
  541    ;   http:status_page(Code, Context, HTML), % deprecated
  542        Reply = html_tokens(HTML)
  543    ),
  544    !.
  545status_page_hook(created(Location), html_tokens(HTML), _Options) :-
  546    phrase(page([ title('201 Created')
  547                ],
  548                [ h1('Created'),
  549                  p(['The document was created ',
  550                     a(href(Location), ' Here')
  551                    ]),
  552                  \address
  553                ]),
  554           HTML).
  555status_page_hook(moved(To), html_tokens(HTML), _Options) :-
  556    phrase(page([ title('301 Moved Permanently')
  557                ],
  558                [ h1('Moved Permanently'),
  559                  p(['The document has moved ',
  560                     a(href(To), ' Here')
  561                    ]),
  562                  \address
  563                ]),
  564           HTML).
  565status_page_hook(moved_temporary(To), html_tokens(HTML), _Options) :-
  566    phrase(page([ title('302 Moved Temporary')
  567                ],
  568                [ h1('Moved Temporary'),
  569                  p(['The document is currently ',
  570                     a(href(To), ' Here')
  571                    ]),
  572                  \address
  573                ]),
  574           HTML).
  575status_page_hook(see_other(To), html_tokens(HTML), _Options) :-
  576    phrase(page([ title('303 See Other')
  577                 ],
  578                 [ h1('See Other'),
  579                   p(['See other document ',
  580                      a(href(To), ' Here')
  581                     ]),
  582                   \address
  583                 ]),
  584            HTML).
  585status_page_hook(bad_request(ErrorTerm), html_tokens(HTML), _Options) :-
  586    '$messages':translate_message(ErrorTerm, Lines, []),
  587    phrase(page([ title('400 Bad Request')
  588                ],
  589                [ h1('Bad Request'),
  590                  p(\html_message_lines(Lines)),
  591                  \address
  592                ]),
  593           HTML).
  594status_page_hook(authorise(_Method), html_tokens(HTML), _Options):-
  595    phrase(page([ title('401 Authorization Required')
  596                ],
  597                [ h1('Authorization Required'),
  598                  p(['This server could not verify that you ',
  599                     'are authorized to access the document ',
  600                     'requested.  Either you supplied the wrong ',
  601                     'credentials (e.g., bad password), or your ',
  602                     'browser doesn\'t understand how to supply ',
  603                     'the credentials required.'
  604                    ]),
  605                  \address
  606                ]),
  607           HTML).
  608status_page_hook(forbidden(URL), html_tokens(HTML), _Options) :-
  609    phrase(page([ title('403 Forbidden')
  610                ],
  611                [ h1('Forbidden'),
  612                  p(['You don\'t have permission to access ', URL,
  613                     ' on this server'
  614                    ]),
  615                  \address
  616                ]),
  617           HTML).
  618status_page_hook(not_found(URL), html_tokens(HTML), _Options) :-
  619    phrase(page([ title('404 Not Found')
  620                ],
  621                [ h1('Not Found'),
  622                  p(['The requested URL ', tt(URL),
  623                     ' was not found on this server'
  624                    ]),
  625                  \address
  626                ]),
  627           HTML).
  628status_page_hook(method_not_allowed(Method,URL), html_tokens(HTML), _Options) :-
  629    upcase_atom(Method, UMethod),
  630    phrase(page([ title('405 Method not allowed')
  631                ],
  632                [ h1('Method not allowed'),
  633                  p(['The requested URL ', tt(URL),
  634                     ' does not support method ', tt(UMethod), '.'
  635                    ]),
  636                  \address
  637                ]),
  638           HTML).
  639status_page_hook(not_acceptable(WhyHTML), html_tokens(HTML), _Options) :-
  640    phrase(page([ title('406 Not Acceptable')
  641                ],
  642                [ h1('Not Acceptable'),
  643                  WhyHTML,
  644                  \address
  645                ]),
  646           HTML).
  647status_page_hook(server_error(ErrorTerm), html_tokens(HTML), _Options) :-
  648    '$messages':translate_message(ErrorTerm, Lines, []),
  649    phrase(page([ title('500 Internal server error')
  650                ],
  651                [ h1('Internal server error'),
  652                  p(\html_message_lines(Lines)),
  653                  \address
  654                ]),
  655           HTML).
  656status_page_hook(service_unavailable(Why), html_tokens(HTML), _Options) :-
  657    phrase(page([ title('503 Service Unavailable')
  658                ],
  659                [ h1('Service Unavailable'),
  660                  \unavailable(Why),
  661                  \address
  662                ]),
  663           HTML).
  664
  665unavailable(busy) -->
  666    html(p(['The server is temporarily out of resources, ',
  667            'please try again later'])).
  668unavailable(error(Formal,Context)) -->
  669    { '$messages':translate_message(error(Formal,Context), Lines, []) },
  670    html_message_lines(Lines).
  671unavailable(HTML) -->
  672    html(HTML).
  673
  674html_message_lines([]) -->
  675    [].
  676html_message_lines([nl|T]) -->
  677    !,
  678    html([br([])]),
  679    html_message_lines(T).
  680html_message_lines([flush]) -->
  681    [].
  682html_message_lines([Fmt-Args|T]) -->
  683    !,
  684    { format(string(S), Fmt, Args)
  685    },
  686    html([S]),
  687    html_message_lines(T).
  688html_message_lines([Fmt|T]) -->
  689    !,
  690    { format(string(S), Fmt, [])
  691    },
  692    html([S]),
  693    html_message_lines(T).

 http_join_headers(+Default, +Header, -Out)

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

  700http_join_headers([], H, H).
  701http_join_headers([H|T], Hdr0, Hdr) :-
  702    functor(H, N, A),
  703    functor(H2, N, A),
  704    member(H2, Hdr0),
  705    !,
  706    http_join_headers(T, Hdr0, Hdr).
  707http_join_headers([H|T], Hdr0, [H|Hdr]) :-
  708    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.

  720http_update_encoding(Header0, utf8, [content_type(Type)|Header]) :-
  721    select(content_type(Type0), Header0, Header),
  722    sub_atom(Type0, 0, _, _, 'text/'),
  723    !,
  724    (   sub_atom(Type0, S, _, _, ';')
  725    ->  sub_atom(Type0, 0, S, _, B)
  726    ;   B = Type0
  727    ),
  728    atom_concat(B, '; charset=UTF-8', Type).
  729http_update_encoding(Header, Encoding, Header) :-
  730    memberchk(content_type(Type), Header),
  731    (   (   sub_atom(Type, _, _, _, 'UTF-8')
  732        ;   sub_atom(Type, _, _, _, 'utf-8')
  733        )
  734    ->  Encoding = utf8
  735    ;   http:mime_type_encoding(Type, Encoding)
  736    ->  true
  737    ;   mime_type_encoding(Type, Encoding)
  738    ).
  739http_update_encoding(Header, octet, Header).

 mime_type_encoding(+MimeType, -Encoding) is semidet

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

  746mime_type_encoding('application/json',         utf8).
  747mime_type_encoding('application/jsonrequest',  utf8).
  748mime_type_encoding('application/x-prolog',     utf8).
  749mime_type_encoding('application/n-quads',      utf8).
  750mime_type_encoding('application/n-triples',    utf8).
  751mime_type_encoding('application/sparql-query', utf8).
  752mime_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.

  768http_update_connection(CgiHeader, Request, Connect,
  769                       [connection(Connect)|Rest]) :-
  770    select(connection(CgiConn), CgiHeader, Rest),
  771    !,
  772    connection(Request, ReqConnection),
  773    join_connection(ReqConnection, CgiConn, Connect).
  774http_update_connection(CgiHeader, Request, Connect,
  775                       [connection(Connect)|CgiHeader]) :-
  776    connection(Request, Connect).
  777
  778join_connection(Keep1, Keep2, Connection) :-
  779    (   downcase_atom(Keep1, 'keep-alive'),
  780        downcase_atom(Keep2, 'keep-alive')
  781    ->  Connection = 'Keep-Alive'
  782    ;   Connection = close
  783    ).

 connection(+Header, -Connection)

Extract the desired connection from a header.

  790connection(Header, Close) :-
  791    (   memberchk(connection(Connection), Header)
  792    ->  Close = Connection
  793    ;   memberchk(http_version(1-X), Header),
  794        X >= 1
  795    ->  Close = 'Keep-Alive'
  796    ;   Close = close
  797    ).

 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.

  816http_update_transfer(Request, CgiHeader, Transfer, Header) :-
  817    setting(http:chunked_transfer, When),
  818    http_update_transfer(When, Request, CgiHeader, Transfer, Header).
  819
  820http_update_transfer(never, _, CgiHeader, none, Header) :-
  821    !,
  822    delete(CgiHeader, transfer_encoding(_), Header).
  823http_update_transfer(_, _, CgiHeader, none, Header) :-
  824    memberchk(location(_), CgiHeader),
  825    !,
  826    delete(CgiHeader, transfer_encoding(_), Header).
  827http_update_transfer(_, Request, CgiHeader, Transfer, Header) :-
  828    select(transfer_encoding(CgiTransfer), CgiHeader, Rest),
  829    !,
  830    transfer(Request, ReqConnection),
  831    join_transfer(ReqConnection, CgiTransfer, Transfer),
  832    (   Transfer == none
  833    ->  Header = Rest
  834    ;   Header = [transfer_encoding(Transfer)|Rest]
  835    ).
  836http_update_transfer(if_possible, Request, CgiHeader, Transfer, Header) :-
  837    transfer(Request, Transfer),
  838    Transfer \== none,
  839    !,
  840    Header = [transfer_encoding(Transfer)|CgiHeader].
  841http_update_transfer(_, _, CgiHeader, none, CgiHeader).
  842
  843join_transfer(chunked, chunked, chunked) :- !.
  844join_transfer(_, _, none).

 transfer(+Header, -Connection)

Extract the desired connection from a header.

  851transfer(Header, Transfer) :-
  852    (   memberchk(transfer_encoding(Transfer0), Header)
  853    ->  Transfer = Transfer0
  854    ;   memberchk(http_version(1-X), Header),
  855        X >= 1
  856    ->  Transfer = chunked
  857    ;   Transfer = none
  858    ).

 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.

  867content_length_in_encoding(Enc, Stream, Bytes) :-
  868    stream_property(Stream, position(Here)),
  869    setup_call_cleanup(
  870        open_null_stream(Out),
  871        ( set_stream(Out, encoding(Enc)),
  872          catch(copy_stream_data(Stream, Out), _, fail),
  873          flush_output(Out),
  874          byte_count(Out, Bytes)
  875        ),
  876        ( close(Out, [force(true)]),
  877          set_stream_position(Stream, Here)
  878        )).
  879
  880
  881                 /*******************************
  882                 *          POST SUPPORT        *
  883                 *******************************/

 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.

  976http_post_data(Data, Out, HdrExtra) :-
  977    http:post_data_hook(Data, Out, HdrExtra),
  978    !.
  979http_post_data(html(HTML), Out, HdrExtra) :-
  980    !,
  981    phrase(post_header(html(HTML), HdrExtra), Header),
  982    format(Out, '~s', [Header]),
  983    print_html(Out, HTML).
  984http_post_data(xml(XML), Out, HdrExtra) :-
  985    !,
  986    http_post_data(xml(text/xml, XML, []), Out, HdrExtra).
  987http_post_data(xml(Type, XML), Out, HdrExtra) :-
  988    !,
  989    http_post_data(xml(Type, XML, []), Out, HdrExtra).
  990http_post_data(xml(Type, XML, Options), Out, HdrExtra) :-
  991    !,
  992    setup_call_cleanup(
  993        new_memory_file(MemFile),
  994        (   setup_call_cleanup(
  995                open_memory_file(MemFile, write, MemOut),
  996                xml_write(MemOut, XML, Options),
  997                close(MemOut)),
  998            http_post_data(memory_file(Type, MemFile), Out, HdrExtra)
  999        ),
 1000        free_memory_file(MemFile)).
 1001http_post_data(file(File), Out, HdrExtra) :-
 1002    !,
 1003    (   file_mime_type(File, Type)
 1004    ->  true
 1005    ;   Type = text/plain
 1006    ),
 1007    http_post_data(file(Type, File), Out, HdrExtra).
 1008http_post_data(file(Type, File), Out, HdrExtra) :-
 1009    !,
 1010    phrase(post_header(file(Type, File), HdrExtra), Header),
 1011    format(Out, '~s', [Header]),
 1012    setup_call_cleanup(
 1013        open(File, read, In, [type(binary)]),
 1014        copy_stream_data(In, Out),
 1015        close(In)).
 1016http_post_data(memory_file(Type, Handle), Out, HdrExtra) :-
 1017    !,
 1018    phrase(post_header(memory_file(Type, Handle), HdrExtra), Header),
 1019    format(Out, '~s', [Header]),
 1020    setup_call_cleanup(
 1021        open_memory_file(Handle, read, In, [encoding(octet)]),
 1022        copy_stream_data(In, Out),
 1023        close(In)).
 1024http_post_data(codes(Codes), Out, HdrExtra) :-
 1025    !,
 1026    http_post_data(codes(text/plain, Codes), Out, HdrExtra).
 1027http_post_data(codes(Type, Codes), Out, HdrExtra) :-
 1028    !,
 1029    phrase(post_header(codes(Type, Codes), HdrExtra), Header),
 1030    format(Out, '~s', [Header]),
 1031    setup_call_cleanup(
 1032        set_stream(Out, encoding(utf8)),
 1033        format(Out, '~s', [Codes]),
 1034        set_stream(Out, encoding(octet))).
 1035http_post_data(bytes(Type, Bytes), Out, HdrExtra) :-
 1036    !,
 1037    phrase(post_header(bytes(Type, Bytes), HdrExtra), Header),
 1038    format(Out, '~s~s', [Header, Bytes]).
 1039http_post_data(atom(Atom), Out, HdrExtra) :-
 1040    !,
 1041    http_post_data(atom(text/plain, Atom), Out, HdrExtra).
 1042http_post_data(atom(Type, Atom), Out, HdrExtra) :-
 1043    !,
 1044    phrase(post_header(atom(Type, Atom), HdrExtra), Header),
 1045    format(Out, '~s', [Header]),
 1046    setup_call_cleanup(
 1047        set_stream(Out, encoding(utf8)),
 1048        write(Out, Atom),
 1049        set_stream(Out, encoding(octet))).
 1050http_post_data(cgi_stream(In, _Len), Out, HdrExtra) :-
 1051    !,
 1052    debug(obsolete, 'Obsolete 2nd argument in cgi_stream(In,Len)', []),
 1053    http_post_data(cgi_stream(In), Out, HdrExtra).
 1054http_post_data(cgi_stream(In), Out, HdrExtra) :-
 1055    !,
 1056    http_read_header(In, Header0),
 1057    http_update_encoding(Header0, Encoding, Header),
 1058    content_length_in_encoding(Encoding, In, Size),
 1059    http_join_headers(HdrExtra, Header, Hdr2),
 1060    phrase(post_header(cgi_data(Size), Hdr2), HeaderText),
 1061    format(Out, '~s', [HeaderText]),
 1062    setup_call_cleanup(
 1063        set_stream(Out, encoding(Encoding)),
 1064        copy_stream_data(In, Out),
 1065        set_stream(Out, encoding(octet))).
 1066http_post_data(form(Fields), Out, HdrExtra) :-
 1067    !,
 1068    parse_url_search(Codes, Fields),
 1069    length(Codes, Size),
 1070    http_join_headers(HdrExtra,
 1071                      [ content_type('application/x-www-form-urlencoded')
 1072                      ], Header),
 1073    phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1074    format(Out, '~s', [HeaderChars]),
 1075    format(Out, '~s', [Codes]).
 1076http_post_data(form_data(Data), Out, HdrExtra) :-
 1077    !,
 1078    setup_call_cleanup(
 1079        new_memory_file(MemFile),
 1080        ( setup_call_cleanup(
 1081              open_memory_file(MemFile, write, MimeOut),
 1082              mime_pack(Data, MimeOut, Boundary),
 1083              close(MimeOut)),
 1084          size_memory_file(MemFile, Size, octet),
 1085          format(string(ContentType),
 1086                 'multipart/form-data; boundary=~w', [Boundary]),
 1087          http_join_headers(HdrExtra,
 1088                            [ mime_version('1.0'),
 1089                              content_type(ContentType)
 1090                            ], Header),
 1091          phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1092          format(Out, '~s', [HeaderChars]),
 1093          setup_call_cleanup(
 1094              open_memory_file(MemFile, read, In, [encoding(octet)]),
 1095              copy_stream_data(In, Out),
 1096              close(In))
 1097        ),
 1098        free_memory_file(MemFile)).
 1099http_post_data(List, Out, HdrExtra) :-          % multipart-mixed
 1100    is_list(List),
 1101    !,
 1102    setup_call_cleanup(
 1103        new_memory_file(MemFile),
 1104        ( setup_call_cleanup(
 1105              open_memory_file(MemFile, write, MimeOut),
 1106              mime_pack(List, MimeOut, Boundary),
 1107              close(MimeOut)),
 1108          size_memory_file(MemFile, Size, octet),
 1109          format(string(ContentType),
 1110                 'multipart/mixed; boundary=~w', [Boundary]),
 1111          http_join_headers(HdrExtra,
 1112                            [ mime_version('1.0'),
 1113                              content_type(ContentType)
 1114                            ], Header),
 1115          phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1116          format(Out, '~s', [HeaderChars]),
 1117          setup_call_cleanup(
 1118              open_memory_file(MemFile, read, In, [encoding(octet)]),
 1119              copy_stream_data(In, Out),
 1120              close(In))
 1121        ),
 1122        free_memory_file(MemFile)).

 post_header(+Data, +HeaderExtra)//

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

 1129post_header(html(Tokens), HdrExtra) -->
 1130    header_fields(HdrExtra, Len),
 1131    content_length(html(Tokens), Len),
 1132    content_type(text/html),
 1133    "\r\n".
 1134post_header(file(Type, File), HdrExtra) -->
 1135    header_fields(HdrExtra, Len),
 1136    content_length(file(File), Len),
 1137    content_type(Type),
 1138    "\r\n".
 1139post_header(memory_file(Type, File), HdrExtra) -->
 1140    header_fields(HdrExtra, Len),
 1141    content_length(memory_file(File), Len),
 1142    content_type(Type),
 1143    "\r\n".
 1144post_header(cgi_data(Size), HdrExtra) -->
 1145    header_fields(HdrExtra, Len),
 1146    content_length(Size, Len),
 1147    "\r\n".
 1148post_header(codes(Type, Codes), HdrExtra) -->
 1149    header_fields(HdrExtra, Len),
 1150    content_length(codes(Codes, utf8), Len),
 1151    content_type(Type, utf8),
 1152    "\r\n".
 1153post_header(bytes(Type, Bytes), HdrExtra) -->
 1154    header_fields(HdrExtra, Len),
 1155    content_length(bytes(Bytes), Len),
 1156    content_type(Type),
 1157    "\r\n".
 1158post_header(atom(Type, Atom), HdrExtra) -->
 1159    header_fields(HdrExtra, Len),
 1160    content_length(atom(Atom, utf8), Len),
 1161    content_type(Type, utf8),
 1162    "\r\n".
 1163
 1164
 1165                 /*******************************
 1166                 *       OUTPUT HEADER DCG      *
 1167                 *******************************/

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

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

 1174http_reply_header(Out, What, HdrExtra) :-
 1175    phrase(reply_header(What, HdrExtra, _Code), String),
 1176    !,
 1177    format(Out, '~s', [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.

 1201reply_header(Data, Dict) -->
 1202    { _{header:HdrExtra, code:Code} :< Dict },
 1203    reply_header(Data, HdrExtra, Code).
 1204
 1205reply_header(string(String), HdrExtra, Code) -->
 1206    reply_header(string(text/plain, String), HdrExtra, Code).
 1207reply_header(string(Type, String), HdrExtra, Code) -->
 1208    vstatus(ok, Code, HdrExtra),
 1209    date(now),
 1210    header_fields(HdrExtra, CLen),
 1211    content_length(codes(String, utf8), CLen),
 1212    content_type(Type, utf8),
 1213    "\r\n".
 1214reply_header(bytes(Type, Bytes), HdrExtra, Code) -->
 1215    vstatus(ok, Code, HdrExtra),
 1216    date(now),
 1217    header_fields(HdrExtra, CLen),
 1218    content_length(bytes(Bytes), CLen),
 1219    content_type(Type),
 1220    "\r\n".
 1221reply_header(html(Tokens), HdrExtra, Code) -->
 1222    vstatus(ok, Code, HdrExtra),
 1223    date(now),
 1224    header_fields(HdrExtra, CLen),
 1225    content_length(html(Tokens), CLen),
 1226    content_type(text/html),
 1227    "\r\n".
 1228reply_header(file(Type, File), HdrExtra, Code) -->
 1229    vstatus(ok, Code, HdrExtra),
 1230    date(now),
 1231    modified(file(File)),
 1232    header_fields(HdrExtra, CLen),
 1233    content_length(file(File), CLen),
 1234    content_type(Type),
 1235    "\r\n".
 1236reply_header(gzip_file(Type, File), HdrExtra, Code) -->
 1237    vstatus(ok, Code, HdrExtra),
 1238    date(now),
 1239    modified(file(File)),
 1240    header_fields(HdrExtra, CLen),
 1241    content_length(file(File), CLen),
 1242    content_type(Type),
 1243    content_encoding(gzip),
 1244    "\r\n".
 1245reply_header(file(Type, File, Range), HdrExtra, Code) -->
 1246    vstatus(partial_content, Code, HdrExtra),
 1247    date(now),
 1248    modified(file(File)),
 1249    header_fields(HdrExtra, CLen),
 1250    content_length(file(File, Range), CLen),
 1251    content_type(Type),
 1252    "\r\n".
 1253reply_header(tmp_file(Type, File), HdrExtra, Code) -->
 1254    vstatus(ok, Code, HdrExtra),
 1255    date(now),
 1256    header_fields(HdrExtra, CLen),
 1257    content_length(file(File), CLen),
 1258    content_type(Type),
 1259    "\r\n".
 1260reply_header(cgi_data(Size), HdrExtra, Code) -->
 1261    vstatus(ok, Code, HdrExtra),
 1262    date(now),
 1263    header_fields(HdrExtra, CLen),
 1264    content_length(Size, CLen),
 1265    "\r\n".
 1266reply_header(chunked_data, HdrExtra, Code) -->
 1267    vstatus(ok, Code, HdrExtra),
 1268    date(now),
 1269    header_fields(HdrExtra, _),
 1270    (   {memberchk(transfer_encoding(_), HdrExtra)}
 1271    ->  ""
 1272    ;   transfer_encoding(chunked)
 1273    ),
 1274    "\r\n".
 1275% non-200 replies without a body (e.g., 1xx, 204, 304)
 1276reply_header(status(Status), HdrExtra, Code) -->
 1277    vstatus(Status, Code),
 1278    header_fields(HdrExtra, Clen),
 1279    { Clen = 0 },
 1280    "\r\n".
 1281% non-200 replies with a body
 1282reply_header(Data, HdrExtra, Code) -->
 1283    { status_reply_headers(Data,
 1284                           body(Type, Encoding, Content),
 1285                           ReplyHeaders),
 1286      http_join_headers(ReplyHeaders, HdrExtra, Headers),
 1287      functor(Data, CodeName, _)
 1288    },
 1289    vstatus(CodeName, Code, Headers),
 1290    date(now),
 1291    header_fields(Headers, CLen),
 1292    content_length(codes(Content, Encoding), CLen),
 1293    content_type(Type, Encoding),
 1294    "\r\n".
 1295
 1296status_reply_headers(created(Location, Body), Body,
 1297                     [ location(Location) ]).
 1298status_reply_headers(moved(To, Body), Body,
 1299                     [ location(To) ]).
 1300status_reply_headers(moved_temporary(To, Body), Body,
 1301                     [ location(To) ]).
 1302status_reply_headers(see_other(To, Body), Body,
 1303                     [ location(To) ]).
 1304status_reply_headers(authorise(Method, Body), Body,
 1305                     [ www_authenticate(Method) ]).
 1306status_reply_headers(not_found(_URL, Body), Body, []).
 1307status_reply_headers(forbidden(_URL, Body), Body, []).
 1308status_reply_headers(method_not_allowed(_Method, _URL, Body), Body, []).
 1309status_reply_headers(server_error(_Error, Body), Body, []).
 1310status_reply_headers(service_unavailable(_Why, Body), Body, []).
 1311status_reply_headers(not_acceptable(_Why, Body), Body, []).
 1312status_reply_headers(bad_request(_Error, Body), Body, []).

 vstatus(+Status, -Code)// is det

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

Emit the HTTP header for Status

 1320vstatus(_Status, Code, HdrExtra) -->
 1321    {memberchk(status(Code), HdrExtra)},
 1322    !,
 1323    vstatus(_NewStatus, Code).
 1324vstatus(Status, Code, _) -->
 1325    vstatus(Status, Code).
 1326
 1327vstatus(Status, Code) -->
 1328    "HTTP/1.1 ",
 1329    status_number(Status, Code),
 1330    " ",
 1331    status_comment(Status),
 1332    "\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.

 1341status_number(Status, Code) -->
 1342    { var(Status) },
 1343    !,
 1344    integer(Code),
 1345    { status_number(Status, Code) },
 1346    !.
 1347status_number(Status, Code) -->
 1348    { status_number(Status, Code) },
 1349    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.

 1363% Unrecognized status codes that are within a defined code class.
 1364% RFC 7231 states:
 1365%   "[...] a client MUST understand the class of any status code,
 1366%    as indicated by the first digit, and treat an unrecognized status code
 1367%    as being equivalent to the `x00` status code of that class [...]
 1368%   "
 1369% @see http://tools.ietf.org/html/rfc7231#section-6
 1370
 1371status_number(Status, Code) :-
 1372    nonvar(Status),
 1373    !,
 1374    status_number_fact(Status, Code).
 1375status_number(Status, Code) :-
 1376    nonvar(Code),
 1377    !,
 1378    (   between(100, 599, Code)
 1379    ->  (   status_number_fact(Status, Code)
 1380        ->  true
 1381        ;   ClassCode is Code // 100 * 100,
 1382            status_number_fact(Status, ClassCode)
 1383        )
 1384    ;   domain_error(http_code, Code)
 1385    ).
 1386
 1387status_number_fact(continue,                   100).
 1388status_number_fact(switching_protocols,        101).
 1389status_number_fact(ok,                         200).
 1390status_number_fact(created,                    201).
 1391status_number_fact(accepted,                   202).
 1392status_number_fact(non_authoritative_info,     203).
 1393status_number_fact(no_content,                 204).
 1394status_number_fact(reset_content,              205).
 1395status_number_fact(partial_content,            206).
 1396status_number_fact(multiple_choices,           300).
 1397status_number_fact(moved,                      301).
 1398status_number_fact(moved_temporary,            302).
 1399status_number_fact(see_other,                  303).
 1400status_number_fact(not_modified,               304).
 1401status_number_fact(use_proxy,                  305).
 1402status_number_fact(unused,                     306).
 1403status_number_fact(temporary_redirect,         307).
 1404status_number_fact(bad_request,                400).
 1405status_number_fact(authorise,                  401).
 1406status_number_fact(payment_required,           402).
 1407status_number_fact(forbidden,                  403).
 1408status_number_fact(not_found,                  404).
 1409status_number_fact(method_not_allowed,         405).
 1410status_number_fact(not_acceptable,             406).
 1411status_number_fact(request_timeout,            408).
 1412status_number_fact(conflict,                   409).
 1413status_number_fact(gone,                       410).
 1414status_number_fact(length_required,            411).
 1415status_number_fact(payload_too_large,          413).
 1416status_number_fact(uri_too_long,               414).
 1417status_number_fact(unsupported_media_type,     415).
 1418status_number_fact(expectation_failed,         417).
 1419status_number_fact(upgrade_required,           426).
 1420status_number_fact(server_error,               500).
 1421status_number_fact(not_implemented,            501).
 1422status_number_fact(bad_gateway,                502).
 1423status_number_fact(service_unavailable,        503).
 1424status_number_fact(gateway_timeout,            504).
 1425status_number_fact(http_version_not_supported, 505).

 status_comment(+Code:atom)// is det

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

 1432status_comment(continue) -->
 1433    "Continue".
 1434status_comment(switching_protocols) -->
 1435    "Switching Protocols".
 1436status_comment(ok) -->
 1437    "OK".
 1438status_comment(created) -->
 1439    "Created".
 1440status_comment(accepted) -->
 1441    "Accepted".
 1442status_comment(non_authoritative_info) -->
 1443    "Non-Authoritative Information".
 1444status_comment(no_content) -->
 1445    "No Content".
 1446status_comment(reset_content) -->
 1447    "Reset Content".
 1448status_comment(created) -->
 1449    "Created".
 1450status_comment(partial_content) -->
 1451    "Partial content".
 1452status_comment(multiple_choices) -->
 1453    "Multiple Choices".
 1454status_comment(moved) -->
 1455    "Moved Permanently".
 1456status_comment(moved_temporary) -->
 1457    "Moved Temporary".
 1458status_comment(see_other) -->
 1459    "See Other".
 1460status_comment(not_modified) -->
 1461    "Not Modified".
 1462status_comment(use_proxy) -->
 1463    "Use Proxy".
 1464status_comment(unused) -->
 1465    "Unused".
 1466status_comment(temporary_redirect) -->
 1467    "Temporary Redirect".
 1468status_comment(bad_request) -->
 1469    "Bad Request".
 1470status_comment(authorise) -->
 1471    "Authorization Required".
 1472status_comment(payment_required) -->
 1473    "Payment Required".
 1474status_comment(forbidden) -->
 1475    "Forbidden".
 1476status_comment(not_found) -->
 1477    "Not Found".
 1478status_comment(method_not_allowed) -->
 1479    "Method Not Allowed".
 1480status_comment(not_acceptable) -->
 1481    "Not Acceptable".
 1482status_comment(request_timeout) -->
 1483    "Request Timeout".
 1484status_comment(conflict) -->
 1485    "Conflict".
 1486status_comment(gone) -->
 1487    "Gone".
 1488status_comment(length_required) -->
 1489    "Length Required".
 1490status_comment(payload_too_large) -->
 1491    "Payload Too Large".
 1492status_comment(uri_too_long) -->
 1493    "URI Too Long".
 1494status_comment(unsupported_media_type) -->
 1495    "Unsupported Media Type".
 1496status_comment(expectation_failed) -->
 1497    "Expectation Failed".
 1498status_comment(upgrade_required) -->
 1499    "Upgrade Required".
 1500status_comment(server_error) -->
 1501    "Internal Server Error".
 1502status_comment(not_implemented) -->
 1503    "Not Implemented".
 1504status_comment(bad_gateway) -->
 1505    "Bad Gateway".
 1506status_comment(service_unavailable) -->
 1507    "Service Unavailable".
 1508status_comment(gateway_timeout) -->
 1509    "Gateway Timeout".
 1510status_comment(http_version_not_supported) -->
 1511    "HTTP Version Not Supported".
 1512
 1513date(Time) -->
 1514    "Date: ",
 1515    (   { Time == now }
 1516    ->  now
 1517    ;   rfc_date(Time)
 1518    ),
 1519    "\r\n".
 1520
 1521modified(file(File)) -->
 1522    !,
 1523    { time_file(File, Time)
 1524    },
 1525    modified(Time).
 1526modified(Time) -->
 1527    "Last-modified: ",
 1528    (   { Time == now }
 1529    ->  now
 1530    ;   rfc_date(Time)
 1531    ),
 1532    "\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

 1542content_length(file(File, bytes(From, To)), Len) -->
 1543    !,
 1544    { size_file(File, Size),
 1545      (   To == end
 1546      ->  Len is Size - From,
 1547          RangeEnd is Size - 1
 1548      ;   Len is To+1 - From,       % To is index of last byte
 1549          RangeEnd = To
 1550      )
 1551    },
 1552    content_range(bytes, From, RangeEnd, Size),
 1553    content_length(Len, Len).
 1554content_length(Reply, Len) -->
 1555    { length_of(Reply, Len)
 1556    },
 1557    "Content-Length: ", integer(Len),
 1558    "\r\n".
 1559
 1560
 1561length_of(_, Len) :-
 1562    nonvar(Len),
 1563    !.
 1564length_of(codes(String, Encoding), Len) :-
 1565    !,
 1566    setup_call_cleanup(
 1567        open_null_stream(Out),
 1568        ( set_stream(Out, encoding(Encoding)),
 1569          format(Out, '~s', [String]),
 1570          byte_count(Out, Len)
 1571        ),
 1572        close(Out)).
 1573length_of(atom(Atom, Encoding), Len) :-
 1574    !,
 1575    setup_call_cleanup(
 1576        open_null_stream(Out),
 1577        ( set_stream(Out, encoding(Encoding)),
 1578          format(Out, '~a', [Atom]),
 1579          byte_count(Out, Len)
 1580        ),
 1581        close(Out)).
 1582length_of(file(File), Len) :-
 1583    !,
 1584    size_file(File, Len).
 1585length_of(memory_file(Handle), Len) :-
 1586    !,
 1587    size_memory_file(Handle, Len, octet).
 1588length_of(html_tokens(Tokens), Len) :-
 1589    !,
 1590    html_print_length(Tokens, Len).
 1591length_of(html(Tokens), Len) :-     % deprecated
 1592    !,
 1593    html_print_length(Tokens, Len).
 1594length_of(bytes(Bytes), Len) :-
 1595    !,
 1596    (   string(Bytes)
 1597    ->  string_length(Bytes, Len)
 1598    ;   length(Bytes, Len)          % assuming a list of 0..255
 1599    ).
 1600length_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.

 1608content_range(Unit, From, RangeEnd, Size) -->
 1609    "Content-Range: ", atom(Unit), " ",
 1610    integer(From), "-", integer(RangeEnd), "/", integer(Size),
 1611    "\r\n".
 1612
 1613content_encoding(Encoding) -->
 1614    "Content-Encoding: ", atom(Encoding), "\r\n".
 1615
 1616transfer_encoding(Encoding) -->
 1617    "Transfer-Encoding: ", atom(Encoding), "\r\n".
 1618
 1619content_type(Type) -->
 1620    content_type(Type, _).
 1621
 1622content_type(Type, Charset) -->
 1623    ctype(Type),
 1624    charset(Charset),
 1625    "\r\n".
 1626
 1627ctype(Main/Sub) -->
 1628    !,
 1629    "Content-Type: ",
 1630    atom(Main),
 1631    "/",
 1632    atom(Sub).
 1633ctype(Type) -->
 1634    !,
 1635    "Content-Type: ",
 1636    atom(Type).
 1637
 1638charset(Var) -->
 1639    { var(Var) },
 1640    !.
 1641charset(utf8) -->
 1642    !,
 1643    "; charset=UTF-8".
 1644charset(CharSet) -->
 1645    "; charset=",
 1646    atom(CharSet).

 header_field(-Name, -Value)// is det

 header_field(+Name, +Value) is det

Process an HTTP request property. Request properties appear as a single line in an HTTP header.

 1654header_field(Name, Value) -->
 1655    { var(Name) },                 % parsing
 1656    !,
 1657    field_name(Name),
 1658    ":",
 1659    whites,
 1660    read_field_value(ValueChars),
 1661    blanks_to_nl,
 1662    !,
 1663    {   field_to_prolog(Name, ValueChars, Value)
 1664    ->  true
 1665    ;   atom_codes(Value, ValueChars),
 1666        domain_error(Name, Value)
 1667    }.
 1668header_field(Name, Value) -->
 1669    field_name(Name),
 1670    ": ",
 1671    field_value(Name, Value),
 1672    "\r\n".

 read_field_value(-Codes)//

Read a field eagerly upto the next whitespace

 1678read_field_value([H|T]) -->
 1679    [H],
 1680    { \+ code_type(H, space) },
 1681    !,
 1682    read_field_value(T).
 1683read_field_value([]) -->
 1684    "".
 1685read_field_value([H|T]) -->
 1686    [H],
 1687    read_field_value(T).

 http_parse_header_value(+Field, +Value, -Prolog) is semidet

Translate Value in a meaningful Prolog term. Field denotes the HTTP request field for which we do the translation. Supported fields are:

content_length

Converted into an integer

status

Converted into an integer

cookie

Converted into a list with Name=Value by cookies//1.

set_cookie

Converted into a term set_cookie(Name, Value, Options). Options is a list consisting of Name=Value or a single atom (e.g., secure)

host

Converted to HostName:Port if applicable.

range

Converted into bytes(From, To), where From is an integer and To is either an integer or the atom end.

accept

Parsed to a list of media descriptions. Each media is a term media(Type, TypeParams, Quality, AcceptExts). The list is sorted according to preference.

content_disposition

Parsed into disposition(Name, Attributes), where Attributes is a list of Name=Value pairs.

content_type

Parsed into media(Type/SubType, Attributes), where Attributes is a list of Name=Value pairs.

As some fields are already parsed in the Request, this predicate is a no-op when called on an already parsed field.

Arguments:

Value

- is either an atom, a list of codes or an already parsed header value.

 1728http_parse_header_value(Field, Value, Prolog) :-
 1729    known_field(Field, _, Type),
 1730    (   already_parsed(Type, Value)
 1731    ->  Prolog = Value
 1732    ;   to_codes(Value, Codes),
 1733        parse_header_value(Field, Codes, Prolog)
 1734    ).
 1735
 1736already_parsed(integer, V)    :- !, integer(V).
 1737already_parsed(list(Type), L) :- !, is_list(L), maplist(already_parsed(Type), L).
 1738already_parsed(Term, V)       :- subsumes_term(Term, V).

 known_field(?FieldName, ?AutoConvert, -Type)

True if the value of FieldName is by default translated into a Prolog data structure.

 1746known_field(content_length,      true,  integer).
 1747known_field(status,              true,  integer).
 1748known_field(cookie,              true,  list(_=_)).
 1749known_field(set_cookie,          true,  list(set_cookie(_Name,_Value,_Options))).
 1750known_field(host,                true,  _Host:_Port).
 1751known_field(range,               maybe, bytes(_,_)).
 1752known_field(accept,              maybe, list(media(_Type, _Parms, _Q, _Exts))).
 1753known_field(content_disposition, maybe, disposition(_Name, _Attributes)).
 1754known_field(content_type,        false, media(_Type/_Sub, _Attributes)).
 1755
 1756to_codes(In, Codes) :-
 1757    (   is_list(In)
 1758    ->  Codes = In
 1759    ;   atom_codes(In, Codes)
 1760    ).