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) 2010-2016, 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_host, 37 [ http_public_url/2, % +Request, -PublicURL 38 http_public_host_url/2, % +Request, -HostURL 39 http_public_host/4, % +Request, -Host, -Port, +Options 40 % deprecated 41 http_current_host/4 % +Request, -Host, -Port, +Options 42 ]). 43:- if(exists_source(library(http/thread_httpd))). 44:- use_module(library(http/thread_httpd)). 45:- endif. 46:- use_module(library(http/http_wrapper)). 47:- use_module(library(socket)). 48:- use_module(library(option)). 49:- use_module(library(settings)). 50 51:- setting(http:public_host, atom, '', 52 'Name the outside world can use to contact me'). 53:- setting(http:public_port, integer, 80, 54 'Port on the public server'). 55:- setting(http:public_scheme, oneof([http,https]), http, 56 'Default URL scheme to use'). 57 58:- predicate_options(http_public_host/4, 4, [global(boolean)]). 59:- predicate_options(http_current_host/4, 4, 60 [pass_to(http_public_host/4, 4)]). 61 62/** <module> Obtain public server location 63 64This library finds the public address of the running server. This can be 65used to construct URLs that are visible from anywhere on the internet. 66This module was introduced to deal with OpenID, where a request is 67redirected to the OpenID server, which in turn redirects to our server 68(see http_openid.pl). 69 70The address is established from the settings `http:public_host` and 71`http:public_port` if provided. Otherwise it is deduced from the request. 72*/ 73 74%! http_public_url(+Request, -URL) is det. 75% 76% True when URL is an absolute URL for the current request. 77% Typically, the login page should redirect to this URL to avoid 78% losing the session. 79 80http_public_url(Request, URL) :- 81 http_public_host_url(Request, HostURL), 82 option(request_uri(RequestURI), Request), 83 atomic_list_concat([HostURL, RequestURI], URL). 84 85 86%! http_public_host_url(+Request, -URL) is det. 87% 88% True when URL is the public URL at which this server can be 89% contacted. This value is not easy to obtain. See 90% http_public_host/4 for the hardest part: find the host and 91% port. 92 93http_public_host_url(Request, URL) :- 94 http_public_host(Request, Host, Port, 95 [ global(true) 96 ]), 97 setting(http:public_scheme, Scheme), 98 ( scheme_port(Scheme, Port) 99 -> format(atom(URL), '~w://~w', [Scheme, Host]) 100 ; format(atom(URL), '~w://~w:~w', [Scheme, Host, Port]) 101 ). 102 103scheme_port(http, 80). 104scheme_port(https, 443). 105 106%! http_public_host(?Request, -Hostname, -Port, +Options) is det. 107% 108% Current global host and port of the HTTP server. This is the 109% basis to form absolute address, which we need for redirection 110% based interaction such as the OpenID protocol. Options are: 111% 112% * global(+Bool) 113% If =true= (default =false=), try to replace a local hostname 114% by a world-wide accessible name. 115% 116% This predicate performs the following steps to find the host and 117% port: 118% 119% 1. Use the settings =http:public_host= and =http:public_port= 120% 2. Use =X-Forwarded-Host= header, which applies if this server 121% runs behind a proxy. 122% 3. Use the =Host= header, which applies for HTTP 1.1 if we are 123% contacted directly. 124% 4. Use gethostname/1 to find the host and 125% http_current_server/2 to find the port. 126% 127% @param Request is the current request. If it is left unbound, 128% and the request is needed, it is obtained with 129% http_current_request/1. 130 131http_public_host(_Request, Host, Port, _) :- 132 setting(http:public_host, PublicHost), PublicHost \== '', 133 !, 134 Host = PublicHost, 135 setting(http:public_port, Port). 136http_public_host(Request, Host, Port, Options) :- 137 ( var(Request) 138 -> http_current_request(Request) 139 ; true 140 ), 141 ( memberchk(x_forwarded_host(Forwarded), Request) 142 -> Port = 80, 143 primary_forwarded_host(Forwarded, Host) 144 ; memberchk(host(Host0), Request), 145 ( option(global(true), Options, false) 146 -> global_host(Host0, Host) 147 ; Host = Host0 148 ), 149 option(port(Port), Request, 80) 150 ), 151 !. 152:- if(current_predicate(http_current_server/2)). 153http_public_host(_Request, Host, Port, _Options) :- 154 gethostname(Host), 155 http_current_server(_:_Pred, Port). 156:- endif. 157 158%! http_current_host(?Request, -Hostname, -Port, +Options) is det. 159% 160% @deprecated Use http_public_host/4 (same semantics) 161 162http_current_host(Request, Hostname, Port, Options) :- 163 http_public_host(Request, Hostname, Port, Options). 164 165%! primary_forwarded_host(+Spec, -Host) is det. 166% 167% x_forwarded host contains multiple hosts separated by ', ' if 168% there are multiple proxy servers in between. The first one is 169% the one the user's browser knows about. 170 171primary_forwarded_host(Spec, Host) :- 172 sub_atom(Spec, B, _, _, ','), 173 !, 174 sub_atom(Spec, 0, B, _, Host). 175primary_forwarded_host(Host, Host). 176 177 178%! global_host(+HostIn, -Host) 179% 180% Globalize a hostname. Used if we need to pass our hostname to a 181% client and expect the client to be able to contact us. In this 182% case we cannot use a name such as `localhost' or the plain 183% hostname of the machine. We assume (possibly wrongly) that if 184% the host contains a '.', it is globally accessible. 185% 186% If the heuristics used by this predicate do not suffice, the 187% setting http:public_host can be used to override. 188 189global_host(_, Host) :- 190 setting(http:public_host, PublicHost), PublicHost \== '', 191 !, 192 Host = PublicHost. 193global_host(localhost, Host) :- 194 !, 195 gethostname(Host). 196global_host(Local, Host) :- 197 sub_atom(Local, _, _, _, '.'), 198 !, 199 Host = Local. 200global_host(Local, Host) :- 201 tcp_host_to_address(Local, IP), 202 tcp_host_to_address(Host, IP)