/* Part of SWI-Prolog Author: Jan Wielemaker, Matt Lilley E-mail: J.Wielemaker@cs.vu.nl WWW: http://www.swi-prolog.org Copyright (c) 2006-2017, University of Amsterdam VU University Amsterdam All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ :- module(http_session, [ http_set_session_options/1, % +Options http_set_session/1, % +Option http_set_session/2, % +SessionId, +Option http_session_option/1, % ?Option http_session_id/1, % -SessionId http_in_session/1, % -SessionId http_current_session/2, % ?SessionId, ?Data http_close_session/1, % +SessionId http_open_session/2, % -SessionId, +Options http_session_cookie/1, % -Cookie http_session_asserta/1, % +Data http_session_assert/1, % +Data http_session_retract/1, % ?Data http_session_retractall/1, % +Data http_session_data/1 % ?Data ]). :- use_module(http_wrapper). :- use_module(http_stream). :- use_module(library(error)). :- use_module(library(debug)). :- use_module(library(socket)). :- use_module(library(broadcast)). :- use_module(library(lists)). :- use_module(library(time)). :- predicate_options(http_open_session/2, 2, [renew(boolean)]). /** HTTP Session management This library defines session management based on HTTP cookies. Session management is enabled simply by loading this module. Details can be modified using http_set_session_options/1. By default, this module creates a session whenever a request is processes that is inside the hierarchy defined for session handling (see path option in http_set_session_options/1. Automatic creation of a session can be stopped using the option create(noauto). The predicate http_open_session/2 must be used to create a session if =noauto= is enabled. Sessions can be closed using http_close_session/1. If a session is active, http_in_session/1 returns the current session and http_session_assert/1 and friends maintain data about the session. If the session is reclaimed, all associated data is reclaimed too. Begin and end of sessions can be monitored using library(broadcast). The broadcasted messages are: * http_session(begin(SessionID, Peer)) Broadcasted if a session is started * http_session(end(SessionId, Peer)) Broadcasted if a session is ended. See http_close_session/1. For example, the following calls end_session(SessionId) whenever a session terminates. Please note that sessions ends are not scheduled to happen at the actual timeout moment of the session. Instead, creating a new session scans the active list for timed-out sessions. This may change in future versions of this library. == :- listen(http_session(end(SessionId, Peer)), end_session(SessionId)). == */ :- dynamic session_setting/1, % Name(Value) current_session/2, % SessionId, Peer last_used/2, % SessionId, Time session_data/2. % SessionId, Data session_setting(timeout(600)). % timeout in seconds session_setting(cookie('swipl_session')). session_setting(path(/)). session_setting(enabled(true)). session_setting(create(auto)). session_setting(proxy_enabled(false)). session_setting(gc(passive)). session_option(timeout, integer). session_option(cookie, atom). session_option(path, atom). session_option(create, oneof([auto,noauto])). session_option(route, atom). session_option(enabled, boolean). session_option(proxy_enabled, boolean). session_option(gc, oneof([active,passive])). %! http_set_session_options(+Options) is det. % % Set options for the session library. Provided options are: % % * timeout(+Seconds) % Session timeout in seconds. Default is 600 (10 min). % A timeout of `0` (zero) disables timeout. % % * cookie(+Cookiekname) % Name to use for the cookie to identify the session. % Default =swipl_session=. % % * path(+Path) % Path to which the cookie is associated. Default is % =|/|=. Cookies are only sent if the HTTP request path % is a refinement of Path. % % * route(+Route) % Set the route name. Default is the unqualified % hostname. To cancel adding a route, use the empty % atom. See route/1. % % * enabled(+Boolean) % Enable/disable session management. Sesion management % is enabled by default after loading this file. % % * create(+Atom) % Defines when a session is created. This is one of =auto= % (default), which creates a session if there is a request % whose path matches the defined session path or =noauto=, % in which cases sessions are only created by calling % http_open_session/2 explicitely. % % * proxy_enabled(+Boolean) % Enable/disable proxy session management. Proxy session % management associates the _originating_ IP address of % the client to the session rather than the _proxy_ IP % address. Default is false. % % * gc(+When) % When is one of `active`, which starts a thread that % performs session cleanup at close to the moment of the % timeout or `passive`, which runs session GC when a new % session is created. http_set_session_options([]). http_set_session_options([H|T]) :- http_set_session_option(H), http_set_session_options(T). http_set_session_option(Option) :- functor(Option, Name, Arity), arg(1, Option, Value), ( session_option(Name, Type) -> must_be(Type, Value) ; domain_error(http_session_option, Option) ), functor(Free, Name, Arity), ( clause(session_setting(Free), _, Ref) -> ( Free \== Value -> asserta(session_setting(Option)), erase(Ref), updated_session_setting(Name, Free, Value) ; true ) ; asserta(session_setting(Option)) ). %! http_session_option(?Option) is nondet. % % True if Option is a current option of the session system. http_session_option(Option) :- session_setting(Option). %! session_setting(+SessionID, ?Setting) is semidet. % % Find setting for SessionID. It is possible to overrule some % session settings using http_session_set(Setting). session_setting(SessionId, Setting) :- nonvar(Setting), functor(Setting, Name, 1), local_option(Name, Value, Term), session_data(SessionId, '$setting'(Term)), !, arg(1, Setting, Value). session_setting(_, Setting) :- session_setting(Setting). updated_session_setting(gc, _, passive) :- stop_session_gc_thread, !. updated_session_setting(_, _, _). % broadcast? %! http_set_session(Setting) is det. %! http_set_session(SessionId, Setting) is det. % % Overrule a setting for the current or specified session. % Currently, the only setting that can be overruled is =timeout=. % % @error permission_error(set, http_session, Setting) if setting % a setting that is not supported on per-session basis. http_set_session(Setting) :- http_session_id(SessionId), http_set_session(SessionId, Setting). http_set_session(SessionId, Setting) :- functor(Setting, Name, Arity), ( local_option(Name, _, _) -> true ; permission_error(set, http_session, Setting) ), arg(1, Setting, Value), ( session_option(Name, Type) -> must_be(Type, Value) ; domain_error(http_session_option, Setting) ), functor(Free, Name, Arity), retractall(session_data(SessionId, '$setting'(Free))), assert(session_data(SessionId, '$setting'(Setting))). local_option(timeout, X, timeout(X)). %! http_session_id(-SessionId) is det. % % True if SessionId is an identifier for the current session. % % @param SessionId is an atom. % @error existence_error(http_session, _) % @see http_in_session/1 for a version that fails if there is % no session. http_session_id(SessionID) :- ( http_in_session(ID) -> SessionID = ID ; throw(error(existence_error(http_session, _), _)) ). %! http_in_session(-SessionId) is semidet. % % True if SessionId is an identifier for the current session. The % current session is extracted from session(ID) from the current % HTTP request (see http_current_request/1). The value is cached % in a backtrackable global variable =http_session_id=. Using a % backtrackable global variable is safe because continuous worker % threads use a failure driven loop and spawned threads start % without any global variables. This variable can be set from the % commandline to fake running a goal from the commandline in the % context of a session. % % @see http_session_id/1 http_in_session(SessionID) :- nb_current(http_session_id, ID), ID \== [], !, debug(http_session, 'Session id from global variable: ~q', [ID]), ID \== no_session, SessionID = ID. http_in_session(SessionID) :- http_current_request(Request), http_in_session(Request, SessionID). http_in_session(Request, SessionID) :- memberchk(session(ID), Request), !, debug(http_session, 'Session id from request: ~q', [ID]), b_setval(http_session_id, ID), SessionID = ID. http_in_session(Request, SessionID) :- memberchk(cookie(Cookies), Request), session_setting(cookie(Cookie)), member(Cookie=SessionID0, Cookies), debug(http_session, 'Session id from cookie: ~q', [SessionID0]), peer(Request, Peer), valid_session_id(SessionID0, Peer), !, b_setval(http_session_id, SessionID0), SessionID = SessionID0. %! http_session(+RequestIn, -RequestOut, -SessionID) is semidet. % % Maintain the notion of a session using a client-side cookie. % This must be called first when handling a request that wishes to % do session management, after which the possibly modified request % must be used for further processing. % % This predicate creates a session if the setting create is % =auto=. If create is =noauto=, the application must call % http_open_session/1 to create a session. http_session(Request, Request, SessionID) :- memberchk(session(SessionID0), Request), !, SessionID = SessionID0. http_session(Request0, Request, SessionID) :- memberchk(cookie(Cookies), Request0), session_setting(cookie(Cookie)), member(Cookie=SessionID0, Cookies), peer(Request0, Peer), valid_session_id(SessionID0, Peer), !, SessionID = SessionID0, Request = [session(SessionID)|Request0], b_setval(http_session_id, SessionID). http_session(Request0, Request, SessionID) :- session_setting(create(auto)), session_setting(path(Path)), memberchk(path(ReqPath), Request0), sub_atom(ReqPath, 0, _, _, Path), !, create_session(Request0, Request, SessionID). create_session(Request0, Request, SessionID) :- http_gc_sessions, http_session_cookie(SessionID), session_setting(cookie(Cookie)), session_setting(path(Path)), debug(http_session, 'Created session ~q at path=~q', [SessionID, Path]), format('Set-Cookie: ~w=~w; Path=~w; Version=1\r\n', [Cookie, SessionID, Path]), Request = [session(SessionID)|Request0], peer(Request0, Peer), open_session(SessionID, Peer). %! http_open_session(-SessionID, +Options) is det. % % Establish a new session. This is normally used if the create % option is set to =noauto=. Options: % % * renew(+Boolean) % If =true= (default =false=) and the current request is part % of a session, generate a new session-id. By default, this % predicate returns the current session as obtained with % http_in_session/1. % % @see http_set_session_options/1 to control the =create= option. % @see http_close_session/1 for closing the session. % @error permission_error(open, http_session, CGI) if this call % is used after closing the CGI header. http_open_session(SessionID, Options) :- http_in_session(SessionID0), \+ option(renew(true), Options, false), !, SessionID = SessionID0. http_open_session(SessionID, _Options) :- ( in_header_state -> true ; current_output(CGI), permission_error(open, http_session, CGI) ), ( http_in_session(ActiveSession) -> http_close_session(ActiveSession, false) ; true ), http_current_request(Request), create_session(Request, _, SessionID). :- multifile http:request_expansion/2. http:request_expansion(Request0, Request) :- session_setting(enabled(true)), http_session(Request0, Request, _SessionID). %! peer(+Request, -Peer) is det. % % Find peer for current request. If unknown we leave it unbound. % Alternatively we should treat this as an error. peer(Request, Peer) :- ( session_setting(proxy_enabled(true)), http_peer(Request, Peer) -> true ; memberchk(peer(Peer), Request) -> true ; true ). %! open_session(+SessionID, +Peer) % % Open a new session. Uses broadcast/1 with the term % http_session(begin(SessionID, Peer)). open_session(SessionID, Peer) :- get_time(Now), assert(current_session(SessionID, Peer)), assert(last_used(SessionID, Now)), b_setval(http_session_id, SessionID), broadcast(http_session(begin(SessionID, Peer))). %! valid_session_id(+SessionID, +Peer) is semidet. % % Check if this sessionID is known. If so, check the idle time and % update the last_used for this session. valid_session_id(SessionID, Peer) :- current_session(SessionID, SessionPeer), get_time(Now), ( session_setting(SessionID, timeout(Timeout)), Timeout > 0 -> get_last_used(SessionID, Last), Idle is Now - Last, ( Idle =< Timeout -> true ; http_close_session(SessionID), fail ) ; Peer \== SessionPeer -> http_close_session(SessionID), fail ; true ), set_last_used(SessionID, Now, Timeout). get_last_used(SessionID, Last) :- atom(SessionID), !, once(last_used(SessionID, Last)). get_last_used(SessionID, Last) :- last_used(SessionID, Last). %! set_last_used(+SessionID, +Now, +TimeOut) % % Set the last-used notion for SessionID from the current time stamp. % The time is rounded down to 10 second intervals to avoid many % updates and simplify the scheduling of session GC. set_last_used(SessionID, Now, TimeOut) :- LastUsed is floor(Now/10)*10, ( clause(last_used(SessionID, CurrentLast), _, Ref) -> ( CurrentLast == LastUsed -> true ; asserta(last_used(SessionID, LastUsed)), erase(Ref), schedule_gc(LastUsed, TimeOut) ) ; asserta(last_used(SessionID, LastUsed)), schedule_gc(LastUsed, TimeOut) ). /******************************* * SESSION DATA * *******************************/ %! http_session_asserta(+Data) is det. %! http_session_assert(+Data) is det. %! http_session_retract(?Data) is nondet. %! http_session_retractall(?Data) is det. % % Versions of assert/1, retract/1 and retractall/1 that associate % data with the current HTTP session. http_session_asserta(Data) :- http_session_id(SessionId), asserta(session_data(SessionId, Data)). http_session_assert(Data) :- http_session_id(SessionId), assert(session_data(SessionId, Data)). http_session_retract(Data) :- http_session_id(SessionId), retract(session_data(SessionId, Data)). http_session_retractall(Data) :- http_session_id(SessionId), retractall(session_data(SessionId, Data)). %! http_session_data(?Data) is nondet. % % True if Data is associated using http_session_assert/1 to the % current HTTP session. % % @error existence_error(http_session,_) http_session_data(Data) :- http_session_id(SessionId), session_data(SessionId, Data). /******************************* * ENUMERATE * *******************************/ %! http_current_session(?SessionID, ?Data) is nondet. % % Enumerate the current sessions and associated data. There are % two _Pseudo_ data elements: % % * idle(Seconds) % Session has been idle for Seconds. % % * peer(Peer) % Peer of the connection. http_current_session(SessionID, Data) :- get_time(Now), get_last_used(SessionID, Last), % binds SessionID Idle is Now - Last, ( session_setting(SessionID, timeout(Timeout)), Timeout > 0 -> Idle =< Timeout ; true ), ( Data = idle(Idle) ; Data = peer(Peer), current_session(SessionID, Peer) ; session_data(SessionID, Data) ). /******************************* * GC SESSIONS * *******************************/ %! http_close_session(+SessionID) is det. % % Closes an HTTP session. This predicate can be called from any % thread to terminate a session. It uses the broadcast/1 service % with the message below. % % http_session(end(SessionId, Peer)) % % The broadcast is done *before* the session data is destroyed and % the listen-handlers are executed in context of the session that % is being closed. Here is an example that destroys a Prolog % thread that is associated to a thread: % % == % :- listen(http_session(end(SessionId, _Peer)), % kill_session_thread(SessionID)). % % kill_session_thread(SessionID) :- % http_session_data(thread(ThreadID)), % thread_signal(ThreadID, throw(session_closed)). % == % % Succeed without any effect if SessionID does not refer to an % active session. % % If http_close_session/1 is called from a handler operating in % the current session and the CGI stream is still in state % =header=, this predicate emits a =|Set-Cookie|= to expire the % cookie. % % @error type_error(atom, SessionID) % @see listen/2 for acting upon closed sessions http_close_session(SessionId) :- http_close_session(SessionId, true). http_close_session(SessionId, Expire) :- must_be(atom, SessionId), ( current_session(SessionId, Peer), ( b_setval(http_session_id, SessionId), broadcast(http_session(end(SessionId, Peer))), fail ; true ), ( Expire == true -> expire_session_cookie ; true ), retractall(current_session(SessionId, _)), retractall(last_used(SessionId, _)), retractall(session_data(SessionId, _)), fail ; true ). %! expire_session_cookie(+SessionId) is det. % % Emit a request to delete a session cookie. This is only done if % http_close_session/1 is still in `header mode'. expire_session_cookie :- in_header_state, session_setting(cookie(Cookie)), session_setting(path(Path)), !, format('Set-Cookie: ~w=; \c expires=Tue, 01-Jan-1970 00:00:00 GMT; \c path=~w\r\n', [Cookie, Path]). expire_session_cookie. in_header_state :- current_output(CGI), is_cgi_stream(CGI), cgi_property(CGI, state(header)), !. %! http_gc_sessions is det. %! http_gc_sessions(+TimeOut) is det. % % Delete dead sessions. Currently runs session GC if a new session % is opened and the last session GC was more than a TimeOut ago. :- dynamic last_gc/1. http_gc_sessions :- start_session_gc_thread, http_gc_sessions(60). http_gc_sessions(TimeOut) :- ( with_mutex(http_session_gc, need_sesion_gc(TimeOut)) -> do_http_gc_sessions ; true ). need_sesion_gc(TimeOut) :- get_time(Now), ( last_gc(LastGC), Now-LastGC < TimeOut -> true ; retractall(last_gc(_)), asserta(last_gc(Now)), do_http_gc_sessions ). do_http_gc_sessions :- debug(http_session(gc), 'Running HTTP session GC', []), get_time(Now), ( last_used(SessionID, Last), session_setting(SessionID, timeout(Timeout)), Timeout > 0, Idle is Now - Last, Idle > Timeout, http_close_session(SessionID, false), fail ; true ). %! start_session_gc_thread is det. %! stop_session_gc_thread is det. % % Create/stop a thread that listens for timeout-at timing and wakes up % to run http_gc_sessions/1 shortly after a session is scheduled to % timeout. :- dynamic session_gc_queue/1. start_session_gc_thread :- session_gc_queue(_), !. start_session_gc_thread :- session_setting(gc(active)), !, catch(thread_create(session_gc_loop, _, [ alias('__http_session_gc'), at_exit(retractall(session_gc_queue(_))) ]), error(permission_error(create, thread, _),_), true). start_session_gc_thread. stop_session_gc_thread :- retract(session_gc_queue(Id)), !, thread_send_message(Id, done), thread_join(Id, _). stop_session_gc_thread. session_gc_loop :- thread_self(GcQueue), asserta(session_gc_queue(GcQueue)), repeat, thread_get_message(Message), ( Message == done -> ! ; schedule(Message), fail ). schedule(at(Time)) :- current_alarm(At, _, _, _), Time == At, !. schedule(at(Time)) :- debug(http_session(gc), 'Schedule GC at ~p', [Time]), alarm_at(Time, http_gc_sessions(10), _, [ remove(true) ]). schedule_gc(LastUsed, TimeOut) :- nonvar(TimeOut), % var(TimeOut) means none session_gc_queue(Queue), !, At is LastUsed+TimeOut+5, % give some slack thread_send_message(Queue, at(At)). schedule_gc(_, _). /******************************* * UTIL * *******************************/ %! http_session_cookie(-Cookie) is det. % % Generate a random cookie that can be used by a browser to % identify the current session. The cookie has the format % XXXX-XXXX-XXXX-XXXX[.], where XXXX are random hexadecimal % numbers and [.] is the optionally added routing % information. http_session_cookie(Cookie) :- route(Route), !, random_4(R1,R2,R3,R4), format(atom(Cookie), '~`0t~16r~4|-~`0t~16r~9|-~`0t~16r~14|-~`0t~16r~19|.~w', [R1,R2,R3,R4,Route]). http_session_cookie(Cookie) :- random_4(R1,R2,R3,R4), format(atom(Cookie), '~`0t~16r~4|-~`0t~16r~9|-~`0t~16r~14|-~`0t~16r~19|', [R1,R2,R3,R4]). :- thread_local route_cache/1. %! route(-RouteID) is semidet. % % Fetch the route identifier. This value is added as . to % the session cookie and used by -for example- the apache load % balanching module. The default route is the local name of the % host. Alternatives may be provided using % http_set_session_options/1. route(Route) :- route_cache(Route), !, Route \== ''. route(Route) :- route_no_cache(Route), assert(route_cache(Route)), Route \== ''. route_no_cache(Route) :- session_setting(route(Route)), !. route_no_cache(Route) :- gethostname(Host), ( sub_atom(Host, Before, _, _, '.') -> sub_atom(Host, 0, Before, _, Route) ; Route = Host ). :- if(\+current_prolog_flag(windows, true)). %! urandom(-Handle) is semidet. % % Handle is a stream-handle for /dev/urandom. Originally, this % simply tried to open /dev/urandom, failing if this device does % not exist. It turns out that trying to open /dev/urandom can % block indefinitely on some Windows installations, so we no % longer try this on Windows. :- dynamic urandom_handle/1. urandom(Handle) :- urandom_handle(Handle), !, Handle \== []. urandom(Handle) :- catch(open('/dev/urandom', read, In, [type(binary)]), _, fail), !, assert(urandom_handle(In)), Handle = In. urandom(_) :- assert(urandom_handle([])), fail. get_pair(In, Value) :- get_byte(In, B1), get_byte(In, B2), Value is B1<<8+B2. :- endif. %! random_4(-R1,-R2,-R3,-R4) is det. % % Generate 4 2-byte random numbers. Uses =|/dev/urandom|= when % available to make prediction of the session IDs hard. :- if(current_predicate(urandom/1)). random_4(R1,R2,R3,R4) :- urandom(In), !, get_pair(In, R1), get_pair(In, R2), get_pair(In, R3), get_pair(In, R4). :- endif. random_4(R1,R2,R3,R4) :- R1 is random(65536), R2 is random(65536), R3 is random(65536), R4 is random(65536).