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    format(Out, '~s', [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    format(Out, '~s', [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    format(Out, '~s', [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    format(Out, '~s', [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    format(Out, '~s', [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    format(Out, '~s', [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    format(Out, '~s', [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    format(Out, '~s', [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    format(Out, '~s', [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    format(Out, '~s', [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([Fmt-Args|T]) -->
  711    !,
  712    { format(string(S), Fmt, Args)
  713    },
  714    html([S]),
  715    html_message_lines(T).
  716html_message_lines([Fmt|T]) -->
  717    !,
  718    { format(string(S), Fmt, [])
  719    },
  720    html([S]),
  721    html_message_lines(T).

 http_join_headers(+Default, +Header, -Out)

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

  728http_join_headers([], H, H).
  729http_join_headers([H|T], Hdr0, Hdr) :-
  730    functor(H, N, A),
  731    functor(H2, N, A),
  732    member(H2, Hdr0),
  733    !,
  734    http_join_headers(T, Hdr0, Hdr).
  735http_join_headers([H|T], Hdr0, [H|Hdr]) :-
  736    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.

  748http_update_encoding(Header0, utf8, [content_type(Type)|Header]) :-
  749    select(content_type(Type0), Header0, Header),
  750    sub_atom(Type0, 0, _, _, 'text/'),
  751    !,
  752    (   sub_atom(Type0, S, _, _, ';')
  753    ->  sub_atom(Type0, 0, S, _, B)
  754    ;   B = Type0
  755    ),
  756    atom_concat(B, '; charset=UTF-8', Type).
  757http_update_encoding(Header, Encoding, Header) :-
  758    memberchk(content_type(Type), Header),
  759    (   (   sub_atom(Type, _, _, _, 'UTF-8')
  760        ;   sub_atom(Type, _, _, _, 'utf-8')
  761        )
  762    ->  Encoding = utf8
  763    ;   http:mime_type_encoding(Type, Encoding)
  764    ->  true
  765    ;   mime_type_encoding(Type, Encoding)
  766    ).
  767http_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.

  774mime_type_encoding('application/json',         utf8).
  775mime_type_encoding('application/jsonrequest',  utf8).
  776mime_type_encoding('application/x-prolog',     utf8).
  777mime_type_encoding('application/n-quads',      utf8).
  778mime_type_encoding('application/n-triples',    utf8).
  779mime_type_encoding('application/sparql-query', utf8).
  780mime_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.

  796http_update_connection(CgiHeader, Request, Connect,
  797                       [connection(Connect)|Rest]) :-
  798    select(connection(CgiConn), CgiHeader, Rest),
  799    !,
  800    connection(Request, ReqConnection),
  801    join_connection(ReqConnection, CgiConn, Connect).
  802http_update_connection(CgiHeader, Request, Connect,
  803                       [connection(Connect)|CgiHeader]) :-
  804    connection(Request, Connect).
  805
  806join_connection(Keep1, Keep2, Connection) :-
  807    (   downcase_atom(Keep1, 'keep-alive'),
  808        downcase_atom(Keep2, 'keep-alive')
  809    ->  Connection = 'Keep-Alive'
  810    ;   Connection = close
  811    ).

 connection(+Header, -Connection)

Extract the desired connection from a header.

  818connection(Header, Close) :-
  819    (   memberchk(connection(Connection), Header)
  820    ->  Close = Connection
  821    ;   memberchk(http_version(1-X), Header),
  822        X >= 1
  823    ->  Close = 'Keep-Alive'
  824    ;   Close = close
  825    ).

 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.

  844http_update_transfer(Request, CgiHeader, Transfer, Header) :-
  845    setting(http:chunked_transfer, When),
  846    http_update_transfer(When, Request, CgiHeader, Transfer, Header).
  847
  848http_update_transfer(never, _, CgiHeader, none, Header) :-
  849    !,
  850    delete(CgiHeader, transfer_encoding(_), Header).
  851http_update_transfer(_, _, CgiHeader, none, Header) :-
  852    memberchk(location(_), CgiHeader),
  853    !,
  854    delete(CgiHeader, transfer_encoding(_), Header).
  855http_update_transfer(_, Request, CgiHeader, Transfer, Header) :-
  856    select(transfer_encoding(CgiTransfer), CgiHeader, Rest),
  857    !,
  858    transfer(Request, ReqConnection),
  859    join_transfer(ReqConnection, CgiTransfer, Transfer),
  860    (   Transfer == none
  861    ->  Header = Rest
  862    ;   Header = [transfer_encoding(Transfer)|Rest]
  863    ).
  864http_update_transfer(if_possible, Request, CgiHeader, Transfer, Header) :-
  865    transfer(Request, Transfer),
  866    Transfer \== none,
  867    !,
  868    Header = [transfer_encoding(Transfer)|CgiHeader].
  869http_update_transfer(_, _, CgiHeader, none, CgiHeader).
  870
  871join_transfer(chunked, chunked, chunked) :- !.
  872join_transfer(_, _, none).

 transfer(+Header, -Connection)

Extract the desired connection from a header.

  879transfer(Header, Transfer) :-
  880    (   memberchk(transfer_encoding(Transfer0), Header)
  881    ->  Transfer = Transfer0
  882    ;   memberchk(http_version(1-X), Header),
  883        X >= 1
  884    ->  Transfer = chunked
  885    ;   Transfer = none
  886    ).

 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.

  895content_length_in_encoding(Enc, Stream, Bytes) :-
  896    stream_property(Stream, position(Here)),
  897    setup_call_cleanup(
  898        open_null_stream(Out),
  899        ( set_stream(Out, encoding(Enc)),
  900          catch(copy_stream_data(Stream, Out), _, fail),
  901          flush_output(Out),
  902          byte_count(Out, Bytes)
  903        ),
  904        ( close(Out, [force(true)]),
  905          set_stream_position(Stream, Here)
  906        )).
  907
  908
  909                 /*******************************
  910                 *          POST SUPPORT        *
  911                 *******************************/

 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.

 1004http_post_data(Data, Out, HdrExtra) :-
 1005    http:post_data_hook(Data, Out, HdrExtra),
 1006    !.
 1007http_post_data(html(HTML), Out, HdrExtra) :-
 1008    !,
 1009    phrase(post_header(html(HTML), HdrExtra), Header),
 1010    format(Out, '~s', [Header]),
 1011    print_html(Out, HTML).
 1012http_post_data(xml(XML), Out, HdrExtra) :-
 1013    !,
 1014    http_post_data(xml(text/xml, XML, []), Out, HdrExtra).
 1015http_post_data(xml(Type, XML), Out, HdrExtra) :-
 1016    !,
 1017    http_post_data(xml(Type, XML, []), Out, HdrExtra).
 1018http_post_data(xml(Type, XML, Options), Out, HdrExtra) :-
 1019    !,
 1020    setup_call_cleanup(
 1021        new_memory_file(MemFile),
 1022        (   setup_call_cleanup(
 1023                open_memory_file(MemFile, write, MemOut),
 1024                xml_write(MemOut, XML, Options),
 1025                close(MemOut)),
 1026            http_post_data(memory_file(Type, MemFile), Out, HdrExtra)
 1027        ),
 1028        free_memory_file(MemFile)).
 1029http_post_data(file(File), Out, HdrExtra) :-
 1030    !,
 1031    (   file_mime_type(File, Type)
 1032    ->  true
 1033    ;   Type = text/plain
 1034    ),
 1035    http_post_data(file(Type, File), Out, HdrExtra).
 1036http_post_data(file(Type, File), Out, HdrExtra) :-
 1037    !,
 1038    phrase(post_header(file(Type, File), HdrExtra), Header),
 1039    format(Out, '~s', [Header]),
 1040    setup_call_cleanup(
 1041        open(File, read, In, [type(binary)]),
 1042        copy_stream_data(In, Out),
 1043        close(In)).
 1044http_post_data(memory_file(Type, Handle), Out, HdrExtra) :-
 1045    !,
 1046    phrase(post_header(memory_file(Type, Handle), HdrExtra), Header),
 1047    format(Out, '~s', [Header]),
 1048    setup_call_cleanup(
 1049        open_memory_file(Handle, read, In, [encoding(octet)]),
 1050        copy_stream_data(In, Out),
 1051        close(In)).
 1052http_post_data(codes(Codes), Out, HdrExtra) :-
 1053    !,
 1054    http_post_data(codes(text/plain, Codes), Out, HdrExtra).
 1055http_post_data(codes(Type, Codes), Out, HdrExtra) :-
 1056    !,
 1057    phrase(post_header(codes(Type, Codes), HdrExtra), Header),
 1058    format(Out, '~s', [Header]),
 1059    setup_call_cleanup(
 1060        set_stream(Out, encoding(utf8)),
 1061        format(Out, '~s', [Codes]),
 1062        set_stream(Out, encoding(octet))).
 1063http_post_data(bytes(Type, Bytes), Out, HdrExtra) :-
 1064    !,
 1065    phrase(post_header(bytes(Type, Bytes), HdrExtra), Header),
 1066    format(Out, '~s~s', [Header, Bytes]).
 1067http_post_data(atom(Atom), Out, HdrExtra) :-
 1068    !,
 1069    http_post_data(atom(text/plain, Atom), Out, HdrExtra).
 1070http_post_data(atom(Type, Atom), Out, HdrExtra) :-
 1071    !,
 1072    phrase(post_header(atom(Type, Atom), HdrExtra), Header),
 1073    format(Out, '~s', [Header]),
 1074    setup_call_cleanup(
 1075        set_stream(Out, encoding(utf8)),
 1076        write(Out, Atom),
 1077        set_stream(Out, encoding(octet))).
 1078http_post_data(cgi_stream(In, _Len), Out, HdrExtra) :-
 1079    !,
 1080    debug(obsolete, 'Obsolete 2nd argument in cgi_stream(In,Len)', []),
 1081    http_post_data(cgi_stream(In), Out, HdrExtra).
 1082http_post_data(cgi_stream(In), Out, HdrExtra) :-
 1083    !,
 1084    http_read_header(In, Header0),
 1085    http_update_encoding(Header0, Encoding, Header),
 1086    content_length_in_encoding(Encoding, In, Size),
 1087    http_join_headers(HdrExtra, Header, Hdr2),
 1088    phrase(post_header(cgi_data(Size), Hdr2), HeaderText),
 1089    format(Out, '~s', [HeaderText]),
 1090    setup_call_cleanup(
 1091        set_stream(Out, encoding(Encoding)),
 1092        copy_stream_data(In, Out),
 1093        set_stream(Out, encoding(octet))).
 1094http_post_data(form(Fields), Out, HdrExtra) :-
 1095    !,
 1096    parse_url_search(Codes, Fields),
 1097    length(Codes, Size),
 1098    http_join_headers(HdrExtra,
 1099                      [ content_type('application/x-www-form-urlencoded')
 1100                      ], Header),
 1101    phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1102    format(Out, '~s', [HeaderChars]),
 1103    format(Out, '~s', [Codes]).
 1104http_post_data(form_data(Data), Out, HdrExtra) :-
 1105    !,
 1106    setup_call_cleanup(
 1107        new_memory_file(MemFile),
 1108        ( setup_call_cleanup(
 1109              open_memory_file(MemFile, write, MimeOut),
 1110              mime_pack(Data, MimeOut, Boundary),
 1111              close(MimeOut)),
 1112          size_memory_file(MemFile, Size, octet),
 1113          format(string(ContentType),
 1114                 'multipart/form-data; boundary=~w', [Boundary]),
 1115          http_join_headers(HdrExtra,
 1116                            [ mime_version('1.0'),
 1117                              content_type(ContentType)
 1118                            ], Header),
 1119          phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1120          format(Out, '~s', [HeaderChars]),
 1121          setup_call_cleanup(
 1122              open_memory_file(MemFile, read, In, [encoding(octet)]),
 1123              copy_stream_data(In, Out),
 1124              close(In))
 1125        ),
 1126        free_memory_file(MemFile)).
 1127http_post_data(List, Out, HdrExtra) :-          % multipart-mixed
 1128    is_list(List),
 1129    !,
 1130    setup_call_cleanup(
 1131        new_memory_file(MemFile),
 1132        ( setup_call_cleanup(
 1133              open_memory_file(MemFile, write, MimeOut),
 1134              mime_pack(List, MimeOut, Boundary),
 1135              close(MimeOut)),
 1136          size_memory_file(MemFile, Size, octet),
 1137          format(string(ContentType),
 1138                 'multipart/mixed; boundary=~w', [Boundary]),
 1139          http_join_headers(HdrExtra,
 1140                            [ mime_version('1.0'),
 1141                              content_type(ContentType)
 1142                            ], Header),
 1143          phrase(post_header(cgi_data(Size), Header), HeaderChars),
 1144          format(Out, '~s', [HeaderChars]),
 1145          setup_call_cleanup(
 1146              open_memory_file(MemFile, read, In, [encoding(octet)]),
 1147              copy_stream_data(In, Out),
 1148              close(In))
 1149        ),
 1150        free_memory_file(MemFile)).

 post_header(+Data, +HeaderExtra)//

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

 1157post_header(html(Tokens), HdrExtra) -->
 1158    header_fields(HdrExtra, Len),
 1159    content_length(html(Tokens), Len),
 1160    content_type(text/html),
 1161    "\r\n".
 1162post_header(file(Type, File), HdrExtra) -->
 1163    header_fields(HdrExtra, Len),
 1164    content_length(file(File), Len),
 1165    content_type(Type),
 1166    "\r\n".
 1167post_header(memory_file(Type, File), HdrExtra) -->
 1168    header_fields(HdrExtra, Len),
 1169    content_length(memory_file(File), Len),
 1170    content_type(Type),
 1171    "\r\n".
 1172post_header(cgi_data(Size), HdrExtra) -->
 1173    header_fields(HdrExtra, Len),
 1174    content_length(Size, Len),
 1175    "\r\n".
 1176post_header(codes(Type, Codes), HdrExtra) -->
 1177    header_fields(HdrExtra, Len),
 1178    content_length(codes(Codes, utf8), Len),
 1179    content_type(Type, utf8),
 1180    "\r\n".
 1181post_header(bytes(Type, Bytes), HdrExtra) -->
 1182    header_fields(HdrExtra, Len),
 1183    content_length(bytes(Bytes), Len),
 1184    content_type(Type),
 1185    "\r\n".
 1186post_header(atom(Type, Atom), HdrExtra) -->
 1187    header_fields(HdrExtra, Len),
 1188    content_length(atom(Atom, utf8), Len),
 1189    content_type(Type, utf8),
 1190    "\r\n".
 1191
 1192
 1193                 /*******************************
 1194                 *       OUTPUT HEADER DCG      *
 1195                 *******************************/

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

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

 1202http_reply_header(Out, What, HdrExtra) :-
 1203    phrase(reply_header(What, HdrExtra, _Code), String),
 1204    !,
 1205    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.

 1229reply_header(Data, Dict) -->
 1230    { _{header:HdrExtra, code:Code} :< Dict },
 1231    reply_header(Data, HdrExtra, Code).
 1232
 1233reply_header(string(String), HdrExtra, Code) -->
 1234    reply_header(string(text/plain, String), HdrExtra, Code).
 1235reply_header(string(Type, String), HdrExtra, Code) -->
 1236    vstatus(ok, Code, HdrExtra),
 1237    date(now),
 1238    header_fields(HdrExtra, CLen),
 1239    content_length(codes(String, utf8), CLen),
 1240    content_type(Type, utf8),
 1241    "\r\n".
 1242reply_header(bytes(Type, Bytes), HdrExtra, Code) -->
 1243    vstatus(ok, Code, HdrExtra),
 1244    date(now),
 1245    header_fields(HdrExtra, CLen),
 1246    content_length(bytes(Bytes), CLen),
 1247    content_type(Type),
 1248    "\r\n".
 1249reply_header(html(Tokens), HdrExtra, Code) -->
 1250    vstatus(ok, Code, HdrExtra),
 1251    date(now),
 1252    header_fields(HdrExtra, CLen),
 1253    content_length(html(Tokens), CLen),
 1254    content_type(text/html),
 1255    "\r\n".
 1256reply_header(file(Type, File), HdrExtra, Code) -->
 1257    vstatus(ok, Code, HdrExtra),
 1258    date(now),
 1259    modified(file(File)),
 1260    header_fields(HdrExtra, CLen),
 1261    content_length(file(File), CLen),
 1262    content_type(Type),
 1263    "\r\n".
 1264reply_header(gzip_file(Type, File), HdrExtra, Code) -->
 1265    vstatus(ok, Code, HdrExtra),
 1266    date(now),
 1267    modified(file(File)),
 1268    header_fields(HdrExtra, CLen),
 1269    content_length(file(File), CLen),
 1270    content_type(Type),
 1271    content_encoding(gzip),
 1272    "\r\n".
 1273reply_header(file(Type, File, Range), HdrExtra, Code) -->
 1274    vstatus(partial_content, Code, HdrExtra),
 1275    date(now),
 1276    modified(file(File)),
 1277    header_fields(HdrExtra, CLen),
 1278    content_length(file(File, Range), CLen),
 1279    content_type(Type),
 1280    "\r\n".
 1281reply_header(tmp_file(Type, File), HdrExtra, Code) -->
 1282    vstatus(ok, Code, HdrExtra),
 1283    date(now),
 1284    header_fields(HdrExtra, CLen),
 1285    content_length(file(File), CLen),
 1286    content_type(Type),
 1287    "\r\n".
 1288reply_header(cgi_data(Size), HdrExtra, Code) -->
 1289    vstatus(ok, Code, HdrExtra),
 1290    date(now),
 1291    header_fields(HdrExtra, CLen),
 1292    content_length(Size, CLen),
 1293    "\r\n".
 1294reply_header(chunked_data, HdrExtra, Code) -->
 1295    vstatus(ok, Code, HdrExtra),
 1296    date(now),
 1297    header_fields(HdrExtra, _),
 1298    (   {memberchk(transfer_encoding(_), HdrExtra)}
 1299    ->  ""
 1300    ;   transfer_encoding(chunked)
 1301    ),
 1302    "\r\n".
 1303% non-200 replies without a body (e.g., 1xx, 204, 304)
 1304reply_header(status(Status), HdrExtra, Code) -->
 1305    vstatus(Status, Code),
 1306    header_fields(HdrExtra, Clen),
 1307    { Clen = 0 },
 1308    "\r\n".
 1309% non-200 replies with a body
 1310reply_header(Data, HdrExtra, Code) -->
 1311    { status_reply_headers(Data,
 1312                           body(Type, Encoding, Content),
 1313                           ReplyHeaders),
 1314      http_join_headers(ReplyHeaders, HdrExtra, Headers),
 1315      functor(Data, CodeName, _)
 1316    },
 1317    vstatus(CodeName, Code, Headers),
 1318    date(now),
 1319    header_fields(Headers, CLen),
 1320    content_length(codes(Content, Encoding), CLen),
 1321    content_type(Type, Encoding),
 1322    "\r\n".
 1323
 1324status_reply_headers(created(Location, Body), Body,
 1325                     [ location(Location) ]).
 1326status_reply_headers(moved(To, Body), Body,
 1327                     [ location(To) ]).
 1328status_reply_headers(moved_temporary(To, Body), Body,
 1329                     [ location(To) ]).
 1330status_reply_headers(gone(_URL, Body), Body, []).
 1331status_reply_headers(see_other(To, Body), Body,
 1332                     [ location(To) ]).
 1333status_reply_headers(authorise(Method, Body), Body,
 1334                     [ www_authenticate(Method) ]).
 1335status_reply_headers(not_found(_URL, Body), Body, []).
 1336status_reply_headers(forbidden(_URL, Body), Body, []).
 1337status_reply_headers(method_not_allowed(_Method, _URL, Body), Body, []).
 1338status_reply_headers(server_error(_Error, Body), Body, []).
 1339status_reply_headers(service_unavailable(_Why, Body), Body, []).
 1340status_reply_headers(not_acceptable(_Why, Body), Body, []).
 1341status_reply_headers(bad_request(_Error, Body), Body, []).

 vstatus(+Status, -Code)// is det

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

Emit the HTTP header for Status

 1349vstatus(_Status, Code, HdrExtra) -->
 1350    {memberchk(status(Code), HdrExtra)},
 1351    !,
 1352    vstatus(_NewStatus, Code).
 1353vstatus(Status, Code, _) -->
 1354    vstatus(Status, Code).
 1355
 1356vstatus(Status, Code) -->
 1357    "HTTP/1.1 ",
 1358    status_number(Status, Code),
 1359    " ",
 1360    status_comment(Status),
 1361    "\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.

 1370status_number(Status, Code) -->
 1371    { var(Status) },
 1372    !,
 1373    integer(Code),
 1374    { status_number(Status, Code) },
 1375    !.
 1376status_number(Status, Code) -->
 1377    { status_number(Status, Code) },
 1378    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.

 1392% Unrecognized status codes that are within a defined code class.
 1393% RFC 7231 states:
 1394%   "[...] a client MUST understand the class of any status code,
 1395%    as indicated by the first digit, and treat an unrecognized status code
 1396%    as being equivalent to the `x00` status code of that class [...]
 1397%   "
 1398% @see http://tools.ietf.org/html/rfc7231#section-6
 1399
 1400status_number(Status, Code) :-
 1401    nonvar(Status),
 1402    !,
 1403    status_number_fact(Status, Code).
 1404status_number(Status, Code) :-
 1405    nonvar(Code),
 1406    !,
 1407    (   between(100, 599, Code)
 1408    ->  (   status_number_fact(Status, Code)
 1409        ->  true
 1410        ;   ClassCode is Code // 100 * 100,
 1411            status_number_fact(Status, ClassCode)
 1412        )
 1413    ;   domain_error(http_code, Code)
 1414    ).
 1415
 1416status_number_fact(continue,                   100).
 1417status_number_fact(switching_protocols,        101).
 1418status_number_fact(ok,                         200).
 1419status_number_fact(created,                    201).
 1420status_number_fact(accepted,                   202).
 1421status_number_fact(non_authoritative_info,     203).
 1422status_number_fact(no_content,                 204).
 1423status_number_fact(reset_content,              205).
 1424status_number_fact(partial_content,            206).
 1425status_number_fact(multiple_choices,           300).
 1426status_number_fact(moved,                      301).
 1427status_number_fact(moved_temporary,            302).
 1428status_number_fact(see_other,                  303).
 1429status_number_fact(not_modified,               304).
 1430status_number_fact(use_proxy,                  305).
 1431status_number_fact(unused,                     306).
 1432status_number_fact(temporary_redirect,         307).
 1433status_number_fact(bad_request,                400).
 1434status_number_fact(authorise,                  401).
 1435status_number_fact(payment_required,           402).
 1436status_number_fact(forbidden,                  403).
 1437status_number_fact(not_found,                  404).
 1438status_number_fact(method_not_allowed,         405).
 1439status_number_fact(not_acceptable,             406).
 1440status_number_fact(request_timeout,            408).
 1441status_number_fact(conflict,                   409).
 1442status_number_fact(gone,                       410).
 1443status_number_fact(length_required,            411).
 1444status_number_fact(payload_too_large,          413).
 1445status_number_fact(uri_too_long,               414).
 1446status_number_fact(unsupported_media_type,     415).
 1447status_number_fact(expectation_failed,         417).
 1448status_number_fact(upgrade_required,           426).
 1449status_number_fact(server_error,               500).
 1450status_number_fact(not_implemented,            501).
 1451status_number_fact(bad_gateway,                502).
 1452status_number_fact(service_unavailable,        503).
 1453status_number_fact(gateway_timeout,            504).
 1454status_number_fact(http_version_not_supported, 505).

 status_comment(+Code:atom)// is det

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

 1461status_comment(continue) -->
 1462    "Continue".
 1463status_comment(switching_protocols) -->
 1464    "Switching Protocols".
 1465status_comment(ok) -->
 1466    "OK".
 1467status_comment(created) -->
 1468    "Created".
 1469status_comment(accepted) -->
 1470    "Accepted".
 1471status_comment(non_authoritative_info) -->
 1472    "Non-Authoritative Information".
 1473status_comment(no_content) -->
 1474    "No Content".
 1475status_comment(reset_content) -->
 1476    "Reset Content".
 1477status_comment(created) -->
 1478    "Created".
 1479status_comment(partial_content) -->
 1480    "Partial content".
 1481status_comment(multiple_choices) -->
 1482    "Multiple Choices".
 1483status_comment(moved) -->
 1484    "Moved Permanently".
 1485status_comment(moved_temporary) -->
 1486    "Moved Temporary".
 1487status_comment(see_other) -->
 1488    "See Other".
 1489status_comment(not_modified) -->
 1490    "Not Modified".
 1491status_comment(use_proxy) -->
 1492    "Use Proxy".
 1493status_comment(unused) -->
 1494    "Unused".
 1495status_comment(temporary_redirect) -->
 1496    "Temporary Redirect".
 1497status_comment(bad_request) -->
 1498    "Bad Request".
 1499status_comment(authorise) -->
 1500    "Authorization Required".
 1501status_comment(payment_required) -->
 1502    "Payment Required".
 1503status_comment(forbidden) -->
 1504    "Forbidden".
 1505status_comment(not_found) -->
 1506    "Not Found".
 1507status_comment(method_not_allowed) -->
 1508    "Method Not Allowed".
 1509status_comment(not_acceptable) -->
 1510    "Not Acceptable".
 1511status_comment(request_timeout) -->
 1512    "Request Timeout".
 1513status_comment(conflict) -->
 1514    "Conflict".
 1515status_comment(gone) -->
 1516    "Gone".
 1517status_comment(length_required) -->
 1518    "Length Required".
 1519status_comment(payload_too_large) -->
 1520    "Payload Too Large".
 1521status_comment(uri_too_long) -->
 1522    "URI Too Long".
 1523status_comment(unsupported_media_type) -->
 1524    "Unsupported Media Type".
 1525status_comment(expectation_failed) -->
 1526    "Expectation Failed".
 1527status_comment(upgrade_required) -->
 1528    "Upgrade Required".
 1529status_comment(server_error) -->
 1530    "Internal Server Error".
 1531status_comment(not_implemented) -->
 1532    "Not Implemented".
 1533status_comment(bad_gateway) -->
 1534    "Bad Gateway".
 1535status_comment(service_unavailable) -->
 1536    "Service Unavailable".
 1537status_comment(gateway_timeout) -->
 1538    "Gateway Timeout".
 1539status_comment(http_version_not_supported) -->
 1540    "HTTP Version Not Supported".
 1541
 1542date(Time) -->
 1543    "Date: ",
 1544    (   { Time == now }
 1545    ->  now
 1546    ;   rfc_date(Time)
 1547    ),
 1548    "\r\n".
 1549
 1550modified(file(File)) -->
 1551    !,
 1552    { time_file(File, Time)
 1553    },
 1554    modified(Time).
 1555modified(Time) -->
 1556    "Last-modified: ",
 1557    (   { Time == now }
 1558    ->  now
 1559    ;   rfc_date(Time)
 1560    ),
 1561    "\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

 1571content_length(file(File, bytes(From, To)), Len) -->
 1572    !,
 1573    { size_file(File, Size),
 1574      (   To == end
 1575      ->  Len is Size - From,
 1576          RangeEnd is Size - 1
 1577      ;   Len is To+1 - From,       % To is index of last byte
 1578          RangeEnd = To
 1579      )
 1580    },
 1581    content_range(bytes, From, RangeEnd, Size),
 1582    content_length(Len, Len).
 1583content_length(Reply, Len) -->
 1584    { length_of(Reply, Len)
 1585    },
 1586    "Content-Length: ", integer(Len),
 1587    "\r\n".
 1588
 1589
 1590length_of(_, Len) :-
 1591    nonvar(Len),
 1592    !.
 1593length_of(codes(String, Encoding), Len) :-
 1594    !,
 1595    setup_call_cleanup(
 1596        open_null_stream(Out),
 1597        ( set_stream(Out, encoding(Encoding)),
 1598          format(Out, '~s', [String]),
 1599          byte_count(Out, Len)
 1600        ),
 1601        close(Out)).
 1602length_of(atom(Atom, Encoding), Len) :-
 1603    !,
 1604    setup_call_cleanup(
 1605        open_null_stream(Out),
 1606        ( set_stream(Out, encoding(Encoding)),
 1607          format(Out, '~a', [Atom]),
 1608          byte_count(Out, Len)
 1609        ),
 1610        close(Out)).
 1611length_of(file(File), Len) :-
 1612    !,
 1613    size_file(File, Len).
 1614length_of(memory_file(Handle), Len) :-
 1615    !,
 1616    size_memory_file(Handle, Len, octet).
 1617length_of(html_tokens(Tokens), Len) :-
 1618    !,
 1619    html_print_length(Tokens, Len).
 1620length_of(html(Tokens), Len) :-     % deprecated
 1621    !,
 1622    html_print_length(Tokens, Len).
 1623length_of(bytes(Bytes), Len) :-
 1624    !,
 1625    (   string(Bytes)
 1626    ->  string_length(Bytes, Len)
 1627    ;   length(Bytes, Len)          % assuming a list of 0..255
 1628    ).
 1629length_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.

 1637content_range(Unit, From, RangeEnd, Size) -->
 1638    "Content-Range: ", atom(Unit), " ",
 1639    integer(From), "-", integer(RangeEnd), "/", integer(Size),
 1640    "\r\n".
 1641
 1642content_encoding(Encoding) -->
 1643    "Content-Encoding: ", atom(Encoding), "\r\n".
 1644
 1645transfer_encoding(Encoding) -->
 1646    "Transfer-Encoding: ", atom(Encoding), "\r\n".
 1647
 1648content_type(Type) -->
 1649    content_type(Type, _).
 1650
 1651content_type(Type, Charset) -->
 1652    ctype(Type),
 1653    charset(Charset),
 1654    "\r\n".
 1655
 1656ctype(Main/Sub) -->
 1657    !,
 1658    "Content-Type: ",
 1659    atom(Main),
 1660    "/",
 1661    atom(Sub).
 1662ctype(Type) -->
 1663    !,
 1664    "Content-Type: ",
 1665    atom(Type).
 1666
 1667charset(Var) -->
 1668    { var(Var) },
 1669    !.
 1670charset(utf8) -->
 1671    !,
 1672    "; charset=UTF-8".
 1673charset(CharSet) -->
 1674    "; charset=",
 1675    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.

 1683header_field(Name, Value) -->
 1684    { var(Name) },                 % parsing
 1685    !,
 1686    field_name(Name),
 1687    ":",
 1688    whites,
 1689    read_field_value(ValueChars),
 1690    blanks_to_nl,
 1691    !,
 1692    {   field_to_prolog(Name, ValueChars, Value)
 1693    ->  true
 1694    ;   atom_codes(Value, ValueChars),
 1695        domain_error(Name, Value)
 1696    }.
 1697header_field(Name, Value) -->
 1698    field_name(Name),
 1699    ": ",
 1700    field_value(Name, Value),
 1701    "\r\n".