/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (C): 2007-2014, University of Amsterdam, VU University Amsterdam This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA As a special exception, if you link this library with other files, compiled with a Free Software compiler, to produce an executable, this library does not by itself cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License. */ :- module(http_host, [ http_public_url/2, % +Request, -PublicURL http_public_host_url/2, % +Request, -HostURL http_public_host/4, % +Request, -Host, -Port, +Options % deprecated http_current_host/4 % +Request, -Host, -Port, +Options ]). :- use_module(library(http/thread_httpd)). :- use_module(library(http/http_wrapper)). :- use_module(library(socket)). :- use_module(library(option)). :- use_module(library(settings)). :- setting(http:public_host, atom, '', 'Name the outside world can use to contact me'). :- setting(http:public_port, integer, 80, 'Port on the public server'). :- setting(http:public_scheme, oneof([http,https]), http, 'Default URL scheme to use'). :- predicate_options(http_public_host/4, 4, [global(boolean)]). :- predicate_options(http_current_host/4, 4, [pass_to(http_public_host/4, 4)]). /** Obtain public server location This library finds the public address of the running server. This can be used to construct URLs that are visible from anywhere on the internet. This module was introduced to deal with OpenID, where a reques is redirected to the OpenID server, which in turn redirects to our server (see http_openid.pl). The address is established from the settings http:public_host and http:public_port if provided. Otherwise it is deduced from the request. */ %% http_public_url(+Request, -URL) is det. % % True when URL is an absolute URL for the current request. % Typically, the login page should redirect to this URL to avoid % loosing the session. http_public_url(Request, URL) :- http_public_host_url(Request, HostURL), option(request_uri(RequestURI), Request), atomic_list_concat([HostURL, RequestURI], URL). %% http_public_host_url(+Request, -URL) is det. % % True when URL is the public URL at which this server can be % contacted. This value is not easy to obtain. See % http_public_host/4 for the hardest part: find the host and % port. http_public_host_url(Request, URL) :- http_public_host(Request, Host, Port, [ global(true) ]), setting(http:public_scheme, Scheme), ( scheme_port(Scheme, Port) -> format(atom(URL), '~w://~w', [Scheme, Host]) ; format(atom(URL), '~w://~w:~w', [Scheme, Host, Port]) ). scheme_port(http, 80). scheme_port(https, 443). %% http_public_host(?Request, -Hostname, -Port, +Options) is det. % % Current global host and port of the HTTP server. This is the % basis to form absolute address, which we need for redirection % based interaction such as the OpenID protocol. Options are: % % * global(+Bool) % If =true= (default =false=), try to replace a local hostname % by a world-wide accessible name. % % This predicate performs the following steps to find the host and % port: % % 1. Use the settings =http:public_host= and =http:public_port= % 2. Use =X-Forwarded-Host= header, which applies if this server % runs behind a proxy. % 3. Use the =Host= header, which applies for HTTP 1.1 if we are % contacted directly. % 4. Use gethostname/1 to find the host and % http_current_server/2 to find the port. % % @param Request is the current request. If it is left unbound, % and the request is needed, it is obtained with % http_current_request/1. http_public_host(_Request, Host, Port, _) :- setting(http:public_host, PublicHost), PublicHost \== '', !, Host = PublicHost, setting(http:public_port, Port). http_public_host(Request, Host, Port, Options) :- ( var(Request) -> http_current_request(Request) ; true ), ( memberchk(x_forwarded_host(Forwarded), Request) -> Port = 80, primary_forwarded_host(Forwarded, Host) ; memberchk(host(Host0), Request), ( option(global(true), Options, false) -> global_host(Host0, Host) ; Host = Host0 ), option(port(Port), Request, 80) ), !. http_public_host(_Request, Host, Port, _Options) :- gethostname(Host), http_current_server(_:_Pred, Port). %% http_current_host(?Request, -Hostname, -Port, +Options) is det. % % @deprecated Use http_public_host/4 (same semantics) http_current_host(Request, Hostname, Port, Options) :- http_public_host(Request, Hostname, Port, Options). %% primary_forwarded_host(+Spec, -Host) is det. % % x_forwarded host contains multiple hosts seperated by ', ' if % there are multiple proxy servers in between. The first one is % the one the user's browser knows about. primary_forwarded_host(Spec, Host) :- sub_atom(Spec, B, _, _, ','), !, sub_atom(Spec, 0, B, _, Host). primary_forwarded_host(Host, Host). %% global_host(+HostIn, -Host) % % Globalize a hostname. Used if we need to pass our hostname to a % client and expect the client to be able to contact us. In this % case we cannot use a name such as `localhost' or the plain % hostname of the machine. We assume (possibly wrongly) that if % the host contains a '.', it is globally accessible. % % If the heuristics used by this predicate do not suffice, the % setting http:public_host can be used to override. global_host(_, Host) :- setting(http:public_host, PublicHost), PublicHost \== '', !, Host = PublicHost. global_host(localhost, Host) :- !, gethostname(Host). global_host(Local, Host) :- sub_atom(Local, _, _, _, '.'), !, Host = Local. global_host(Local, Host) :- tcp_host_to_address(Local, IP), tcp_host_to_address(Host, IP).