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) 2013, VU University Amsterdam 7 All rights reserved. 8 9 Redistribution and use in source and binary forms, with or without 10 modification, are permitted provided that the following conditions 11 are met: 12 13 1. Redistributions of source code must retain the above copyright 14 notice, this list of conditions and the following disclaimer. 15 16 2. Redistributions in binary form must reproduce the above copyright 17 notice, this list of conditions and the following disclaimer in 18 the documentation and/or other materials provided with the 19 distribution. 20 21 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 29 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 31 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32 POSSIBILITY OF SUCH DAMAGE. 33*/ 34 35:- module(yadis, 36 [ xrds_dom/2, % +URI, -XRDS_DOM 37 xrds_location/2 % +Xid, -URL 38 ]). 39:- use_module(library(http/http_open)). 40:- use_module(library(xpath)). 41:- use_module(library(uri)). 42:- use_module(library(sgml)).
49:- multifile
50 xrds_specified_location/2.
57xrds_dom(Xid, XRDS_DOM) :-
58 xrds_location(Xid, XRDSLocation),
59 xrds_load(XRDSLocation, XRDS_DOM).68xid_normalize(Xid, URL) :- 69 add_component(scheme, Xid, URL0, http), 70 add_component(path, URL0, URL, /). 71 72add_component(Field, URL0, URL, Default) :- 73 uri_components(URL0, Comp), 74 uri_data(Field, Comp, Value), 75 ( var(Value) 76 -> ( Field == scheme 77 -> atomic_list_concat([Default, '://', URL0], URL) 78 ; Value = Default, 79 uri_components(URL, Comp) 80 ) 81 ; Field == path, 82 Value = '' 83 -> uri_data(path, Comp, Default, Comp2), 84 uri_components(URL, Comp2) 85 ; URL = URL0 86 ).
93xrds_location(Xid, XRDSLocation) :- 94 xid_normalize(Xid, URL), 95 ( xrds_specified_location(URL, XRDSLocation) 96 -> XRDSLocation \== (-) 97 ; catch(xrds_location_direct(URL, XRDSLocation), 98 E, yadis_failed(E)) 99 -> true 100 ; catch(xrds_location_html(URL, XRDSLocation), 101 E, yadis_failed(E)) 102 ). 103 104yadis_failed(E) :- 105 ( debugging(yadis) 106 -> print_message(warning, E) 107 ; true 108 ), 109 fail. 110 111xrds_location_direct(URL, XRDSLocation) :- 112 setup_call_cleanup( 113 http_open(URL, In, 114 [ method(head), 115 request_header(accept='application/xrds+xml'), 116 header(x_xrds_location, Reply), 117 cert_verify_hook(ssl_verify) 118 ]), 119 true, 120 close(In)), 121 Reply \== '', 122 !, 123 XRDSLocation = Reply. 124 125xrds_location_html(URL, XRDSLocation) :- 126 setup_call_cleanup( 127 http_open(URL, In, 128 [ cert_verify_hook(ssl_verify) 129 ]), 130 html_head_dom(In, DOM), 131 close(In)), 132 xpath(DOM, meta(@'http-equiv'=Equiv, @content), Content), 133 downcase_atom(Equiv, 'x-xrds-location'), 134 !, 135 XRDSLocation = Content.
141xrds_load(XRDSLocation, XRDS_DOM) :- 142 setup_call_cleanup( 143 http_open(XRDSLocation, In, 144 [ request_header(accept='application/xrds+xml'), 145 cert_verify_hook(ssl_verify) 146 ]), 147 load_structure(In, XRDS_DOM, 148 [ dialect(xmlns), 149 space(remove) 150 ]), 151 close(In)). 152 153:- public ssl_verify/5.
159ssl_verify(_SSL,
160 _ProblemCertificate, _AllCertificates, _FirstCertificate,
161 _Error).169:- thread_local 170 html_head_dom/1. 171 172html_head_dom(Stream, HeadDOM) :- 173 dtd(html, DTD), 174 new_sgml_parser(Parser, [dtd(DTD)]), 175 call_cleanup( 176 sgml_parse(Parser, 177 [ source(Stream), 178 syntax_errors(quiet), 179 call(begin, on_begin) 180 ]), 181 free_sgml_parser(Parser)), 182 retract(html_head_dom(HeadDOM)). 183 184on_begin(head, Attrs, Parser) :- 185 sgml_parse(Parser, 186 [ document(DOM), 187 parse(content) 188 ]), 189 asserta(html_head_dom(element(head, Attrs, DOM))).
yadis:xrds_specified_location('http://google.com/',
'https://www.google.com/accounts/o8/id').
If this hook succeeds with XRDSLocation bound to - (minus), we
assume there is no XRDS document associated to URL. This can be
used to avoid retrieving misleading or broken XRDS documents.
Yadis discovery