3 package Catalyst::Plugin::Session;
6 with 'MooseX::Emulate::Class::Accessor::Fast';
8 use Catalyst::Exception ();
11 use Object::Signature ();
14 use namespace::clean -except => 'meta';
16 our $VERSION = '0.28';
17 $VERSION = eval $VERSION;
19 my @session_data_accessors; # used in delete_session
21 __PACKAGE__->mk_accessors(
22 "_session_delete_reason",
23 @session_data_accessors = qw/
27 _extended_session_expires
32 _tried_loading_session_id
33 _tried_loading_session_data
34 _tried_loading_session_expires
35 _tried_loading_flash_data
39 sub _session_plugin_config {
41 # FIXME - Start warning once all the state/store modules have also been updated.
42 #$c->log->warn("Deprecated 'session' config key used, please use the key 'Plugin::Session' instead")
43 # if exists $c->config->{session}
44 #$c->config->{'Plugin::Session'} ||= delete($c->config->{session}) || {};
45 $c->config->{'Plugin::Session'} ||= $c->config->{session} || {};
51 $c->maybe::next::method(@_);
53 $c->check_session_plugin_requirements;
59 sub check_session_plugin_requirements {
62 unless ( $c->isa("Catalyst::Plugin::Session::State")
63 && $c->isa("Catalyst::Plugin::Session::Store") )
66 ( "The Session plugin requires both Session::State "
67 . "and Session::Store plugins to be used as well." );
70 Catalyst::Exception->throw($err);
77 my $cfg = $c->_session_plugin_config;
82 verify_user_agent => 0,
86 $c->maybe::next::method();
92 $c->maybe::next::method(@_);
94 if ( $c->_session_plugin_config->{flash_to_stash}
96 and my $flash_data = $c->flash )
98 @{ $c->stash }{ keys %$flash_data } = values %$flash_data;
102 sub finalize_headers {
105 # fix cookie before we send headers
106 $c->_save_session_expires;
108 return $c->maybe::next::method(@_);
114 # We have to finalize our session *before* $c->engine->finalize_xxx is called,
115 # because we do not want to send the HTTP response before the session is stored/committed to
116 # the session database (or whatever Session::Store you use).
117 $c->finalize_session;
119 return $c->maybe::next::method(@_);
122 sub finalize_session {
125 $c->maybe::next::method(@_);
127 $c->_save_session_id;
131 $c->_clear_session_instance_data;
134 sub _save_session_id {
137 # we already called set when allocating
138 # no need to tell the state plugins anything new
141 sub _save_session_expires {
144 if ( defined($c->_session_expires) ) {
145 my $expires = $c->session_expires; # force extension
147 my $sid = $c->sessionid;
148 $c->store_session_data( "expires:$sid" => $expires );
155 if ( my $session_data = $c->_session ) {
157 no warnings 'uninitialized';
158 if ( Object::Signature::signature($session_data) ne
159 $c->_session_data_sig )
161 $session_data->{__updated} = time();
162 my $sid = $c->sessionid;
163 $c->store_session_data( "session:$sid" => $session_data );
171 if ( my $flash_data = $c->_flash ) {
173 my $hashes = $c->_flash_key_hashes || {};
174 my $keep = $c->_flash_keep_keys || {};
175 foreach my $key ( keys %$hashes ) {
176 if ( !exists $keep->{$key} and Object::Signature::signature( \$flash_data->{$key} ) eq $hashes->{$key} ) {
177 delete $flash_data->{$key};
181 my $sid = $c->sessionid;
183 my $session_data = $c->_session;
185 $session_data->{__flash} = $flash_data;
188 delete $session_data->{__flash};
190 $c->_session($session_data);
195 sub _load_session_expires {
197 return $c->_session_expires if $c->_tried_loading_session_expires;
198 $c->_tried_loading_session_expires(1);
200 if ( my $sid = $c->sessionid ) {
201 my $expires = $c->get_session_data("expires:$sid") || 0;
203 if ( $expires >= time() ) {
204 $c->_session_expires( $expires );
207 $c->delete_session( "session expired" );
217 return $c->_session if $c->_tried_loading_session_data;
218 $c->_tried_loading_session_data(1);
220 if ( my $sid = $c->sessionid ) {
221 if ( $c->_load_session_expires ) { # > 0
223 my $session_data = $c->get_session_data("session:$sid") || return;
224 $c->_session($session_data);
226 no warnings 'uninitialized'; # ne __address
227 if ( $c->_session_plugin_config->{verify_address}
228 && $session_data->{__address} ne $c->request->address )
231 "Deleting session $sid due to address mismatch ("
232 . $session_data->{__address} . " != "
233 . $c->request->address . ")"
235 $c->delete_session("address mismatch");
238 if ( $c->_session_plugin_config->{verify_user_agent}
239 && $session_data->{__user_agent} ne $c->request->user_agent )
242 "Deleting session $sid due to user agent mismatch ("
243 . $session_data->{__user_agent} . " != "
244 . $c->request->user_agent . ")"
246 $c->delete_session("user agent mismatch");
250 $c->log->debug(qq/Restored session "$sid"/) if $c->debug;
251 $c->_session_data_sig( Object::Signature::signature($session_data) ) if $session_data;
252 $c->_expire_session_keys;
254 return $session_data;
263 return $c->_flash if $c->_tried_loading_flash_data;
264 $c->_tried_loading_flash_data(1);
266 if ( my $sid = $c->sessionid ) {
268 my $session_data = $c->session;
269 $c->_flash($session_data->{__flash});
271 if ( my $flash_data = $c->_flash )
273 $c->_flash_key_hashes({ map { $_ => Object::Signature::signature( \$flash_data->{$_} ) } keys %$flash_data });
282 sub _expire_session_keys {
283 my ( $c, $data ) = @_;
287 my $expire_times = ( $data || $c->_session || {} )->{__expire_keys} || {};
288 foreach my $key ( grep { $expire_times->{$_} < $now } keys %$expire_times ) {
289 delete $c->_session->{$key};
290 delete $expire_times->{$key};
294 sub _clear_session_instance_data {
296 $c->$_(undef) for @session_data_accessors;
297 $c->maybe::next::method(@_); # allow other plugins to hook in on this
300 sub change_session_id {
303 my $sessiondata = $c->session;
304 my $oldsid = $c->sessionid;
305 my $newsid = $c->create_session_id;
308 $c->log->debug(qq/change_sessid: deleting session data from "$oldsid"/) if $c->debug;
309 $c->delete_session_data("${_}:${oldsid}") for qw/session expires flash/;
312 $c->log->debug(qq/change_sessid: storing session data to "$newsid"/) if $c->debug;
313 $c->store_session_data( "session:$newsid" => $sessiondata );
319 my ( $c, $msg ) = @_;
321 $c->log->debug("Deleting session" . ( defined($msg) ? "($msg)" : '(no reason given)') ) if $c->debug;
323 # delete the session data
324 if ( my $sid = $c->sessionid ) {
325 $c->delete_session_data("${_}:${sid}") for qw/session expires flash/;
326 $c->delete_session_id($sid);
329 # reset the values in the context object
330 # see the BEGIN block
331 $c->_clear_session_instance_data;
333 $c->_session_delete_reason($msg);
336 sub session_delete_reason {
339 $c->session_is_valid; # check that it was loaded
341 $c->_session_delete_reason(@_);
344 sub session_expires {
347 if ( defined( my $expires = $c->_extended_session_expires ) ) {
349 } elsif ( defined( $expires = $c->_load_session_expires ) ) {
350 return $c->extend_session_expires( $expires );
356 sub extend_session_expires {
357 my ( $c, $expires ) = @_;
358 $c->_extended_session_expires( my $updated = $c->calculate_extended_session_expires( $expires ) );
359 $c->extend_session_id( $c->sessionid, $updated );
363 sub calculate_initial_session_expires {
365 return ( time() + $c->_session_plugin_config->{expires} );
368 sub calculate_extended_session_expires {
369 my ( $c, $prev ) = @_;
370 $c->calculate_initial_session_expires;
373 sub reset_session_expires {
374 my ( $c, $sid ) = @_;
376 my $exp = $c->calculate_initial_session_expires;
377 $c->_session_expires( $exp );
379 # since we're setting _session_expires directly, make load_session_expires
380 # actually use that value.
382 $c->_tried_loading_session_expires(1);
383 $c->_extended_session_expires( $exp );
390 return $c->_sessionid || $c->_load_sessionid;
393 sub _load_sessionid {
395 return if $c->_tried_loading_session_id;
396 $c->_tried_loading_session_id(1);
398 if ( defined( my $sid = $c->get_session_id ) ) {
399 if ( $c->validate_session_id($sid) ) {
400 # temporarily set the inner key, so that validation will work
401 $c->_sessionid($sid);
404 my $err = "Tried to set invalid session ID '$sid'";
405 $c->log->error($err);
406 Catalyst::Exception->throw($err);
413 sub session_is_valid {
416 # force a check for expiry, but also __address, etc
417 if ( $c->_load_session ) {
424 sub validate_session_id {
425 my ( $c, $sid ) = @_;
427 $sid and $sid =~ /^[a-f\d]+$/i;
433 $c->_session || $c->_load_session || do {
434 $c->create_session_id_if_needed;
435 $c->initialize_session_data;
440 my ( $c, @keys ) = @_;
441 my $href = $c->_flash_keep_keys || $c->_flash_keep_keys({});
442 (@{$href}{@keys}) = ((undef) x @keys);
447 $c->_flash || $c->_load_flash || do {
448 $c->create_session_id_if_needed;
456 my $items = @_ > 1 ? {@_} : $_[0];
457 croak('flash takes a hash or hashref') unless ref $items;
458 @{ $c->_flash }{ keys %$items } = values %$items;
472 #$c->delete_session_data("flash:" . $c->sessionid); # should this be in here? or delayed till finalization?
473 $c->_flash_key_hashes({});
474 $c->_flash_keep_keys({});
478 sub session_expire_key {
479 my ( $c, %keys ) = @_;
482 @{ $c->session->{__expire_keys} }{ keys %keys } =
483 map { $now + $_ } values %keys;
486 sub initialize_session_data {
497 $c->_session_plugin_config->{verify_address}
498 ? ( __address => $c->request->address||'' )
502 $c->_session_plugin_config->{verify_user_agent}
503 ? ( __user_agent => $c->request->user_agent||'' )
510 sub generate_session_id {
513 my $digest = $c->_find_digest();
514 $digest->add( $c->session_hash_seed() );
515 return $digest->hexdigest;
518 sub create_session_id_if_needed {
520 $c->create_session_id unless $c->sessionid;
523 sub create_session_id {
526 my $sid = $c->generate_session_id;
528 $c->log->debug(qq/Created session "$sid"/) if $c->debug;
530 $c->_sessionid($sid);
531 $c->reset_session_expires;
532 $c->set_session_id($sid);
539 sub session_hash_seed {
542 return join( "", ++$counter, time, rand, $$, {}, overload::StrVal($c), );
547 sub _find_digest () {
549 foreach my $alg (qw/SHA-1 SHA-256 MD5/) {
550 if ( eval { Digest->new($alg) } ) {
555 Catalyst::Exception->throw(
556 "Could not find a suitable Digest module. Please install "
557 . "Digest::SHA1, Digest::SHA, or Digest::MD5" )
561 return Digest->new($usable);
568 $c->maybe::next::method(),
571 ? ( [ "Session ID" => $c->sessionid ], [ Session => $c->session ], )
577 sub get_session_id { shift->maybe::next::method(@_) }
578 sub set_session_id { shift->maybe::next::method(@_) }
579 sub delete_session_id { shift->maybe::next::method(@_) }
580 sub extend_session_id { shift->maybe::next::method(@_) }
590 Catalyst::Plugin::Session - Generic Session plugin - ties together server side storage and client side state required to maintain session data.
594 # To get sessions to "just work", all you need to do is use these plugins:
598 Session::Store::FastMmap
599 Session::State::Cookie
602 # you can replace Store::FastMmap with Store::File - both have sensible
603 # default configurations (see their docs for details)
605 # more complicated backends are available for other scenarios (DBI storage,
609 # after you've loaded the plugins you can save session data
610 # For example, if you are writing a shopping cart, it could be implemented
613 sub add_item : Local {
614 my ( $self, $c ) = @_;
616 my $item_id = $c->req->param("item");
618 # $c->session is a hash ref, a bit like $c->stash
619 # the difference is that it' preserved across requests
621 push @{ $c->session->{items} }, $item_id;
623 $c->forward("MyView");
626 sub display_items : Local {
627 my ( $self, $c ) = @_;
629 # values in $c->session are restored
630 $c->stash->{items_to_display} =
631 [ map { MyModel->retrieve($_) } @{ $c->session->{items} } ];
633 $c->forward("MyView");
638 The Session plugin is the base of two related parts of functionality required
639 for session management in web applications.
641 The first part, the State, is getting the browser to repeat back a session key,
642 so that the web application can identify the client and logically string
643 several requests together into a session.
645 The second part, the Store, deals with the actual storage of information about
646 the client. This data is stored so that the it may be revived for every request
647 made by the same client.
649 This plugin links the two pieces together.
651 =head1 RECOMENDED BACKENDS
655 =item Session::State::Cookie
657 The only really sane way to do state is using cookies.
659 =item Session::Store::File
661 A portable backend, based on Cache::File.
663 =item Session::Store::FastMmap
665 A fast and flexible backend, based on Cache::FastMmap.
675 An accessor for the session ID value.
679 Returns a hash reference that might contain unserialized values from previous
680 requests in the same session, and whose modified value will be saved for future
683 This method will automatically create a new session and session ID if none
686 =item session_expires
688 =item session_expires $reset
690 This method returns the time when the current session will expire, or 0 if
691 there is no current session. If there is a session and it already expired, it
692 will delete the session and return 0 as well.
694 If the C<$reset> parameter is true, and there is a session ID the expiry time
695 will be reset to the current time plus the time to live (see
696 L</CONFIGURATION>). This is used when creating a new session.
700 This is like Ruby on Rails' flash data structure. Think of it as a stash that
701 lasts for longer than one request, letting you redirect instead of forward.
703 The flash data will be cleaned up only on requests on which actually use
704 $c->flash (thus allowing multiple redirections), and the policy is to delete
705 all the keys which haven't changed since the flash data was loaded at the end
709 my ( $self, $c ) = @_;
711 $c->flash->{beans} = 10;
712 $c->response->redirect( $c->uri_for("foo") );
716 my ( $self, $c ) = @_;
718 my $value = $c->flash->{beans};
722 $c->response->redirect( $c->uri_for("bar") );
726 my ( $self, $c ) = @_;
728 if ( exists $c->flash->{beans} ) { # false
735 Zap all the keys in the flash regardless of their current state.
737 =item keep_flash @keys
739 If you want to keep a flash key for the next request too, even if it hasn't
740 changed, call C<keep_flash> and pass in the keys as arguments.
742 =item delete_session REASON
744 This method is used to invalidate a session. It takes an optional parameter
745 which will be saved in C<session_delete_reason> if provided.
747 NOTE: This method will B<also> delete your flash data.
749 =item session_delete_reason
751 This accessor contains a string with the reason a session was deleted. Possible
766 =item session_expire_key $key, $ttl
768 Mark a key to expire at a certain time (only useful when shorter than the
769 expiry time for the whole session).
773 __PACKAGE__->config('Plugin::Session' => { expires => 1000000000000 }); # forever
777 $c->session_expire_key( __user => 3600 );
779 Will make the session data survive, but the user will still be logged out after
782 Note that these values are not auto extended.
784 =item change_session_id
786 By calling this method you can force a session id change while keeping all
787 session data. This method might come handy when you are paranoid about some
788 advanced variations of session fixation attack.
790 If you want to prevent this session fixation scenario:
792 0) let us have WebApp with anonymous and authenticated parts
793 1) a hacker goes to vulnerable WebApp and gets a real sessionid,
794 just by browsing anonymous part of WebApp
795 2) the hacker inserts (somehow) this values into a cookie in victim's browser
796 3) after the victim logs into WebApp the hacker can enter his/her session
798 you should call change_session_id in your login controller like this:
800 if ($c->authenticate( { username => $user, password => $pass } )) {
802 $c->change_session_id;
811 =head1 INTERNAL METHODS
817 This method is extended to also make calls to
818 C<check_session_plugin_requirements> and C<setup_session>.
820 =item check_session_plugin_requirements
822 This method ensures that a State and a Store plugin are also in use by the
827 This method populates C<< $c->config('Plugin::Session') >> with the default values
828 listed in L</CONFIGURATION>.
832 This method is extended.
834 Its only effect is if the (off by default) C<flash_to_stash> configuration
835 parameter is on - then it will copy the contents of the flash to the stash at
838 =item finalize_headers
840 This method is extended and will extend the expiry time before sending
845 This method is extended and will call finalize_session before the other
846 finalize_body methods run. Here we persist the session data if a session exists.
848 =item initialize_session_data
850 This method will initialize the internal structure of the session, and is
851 called by the C<session> method if appropriate.
853 =item create_session_id
855 Creates a new session ID using C<generate_session_id> if there is no session ID
858 =item validate_session_id SID
860 Make sure a session ID is of the right format.
862 This currently ensures that the session ID string is any amount of case
863 insensitive hexadecimal characters.
865 =item generate_session_id
867 This method will return a string that can be used as a session ID. It is
868 supposed to be a reasonably random string with enough bits to prevent
869 collision. It basically takes C<session_hash_seed> and hashes it using SHA-1,
870 MD5 or SHA-256, depending on the availability of these modules.
872 =item session_hash_seed
874 This method is actually rather internal to generate_session_id, but should be
875 overridable in case you want to provide more random data.
877 Currently it returns a concatenated string which contains:
883 =item * The current time
885 =item * One value from C<rand>.
887 =item * The stringified value of a newly allocated hash reference
889 =item * The stringified value of the Catalyst context object
893 in the hopes that those combined values are entropic enough for most uses. If
894 this is not the case you can replace C<session_hash_seed> with e.g.
896 sub session_hash_seed {
897 open my $fh, "<", "/dev/random";
898 read $fh, my $bytes, 20;
903 Or even more directly, replace C<generate_session_id>:
905 sub generate_session_id {
906 open my $fh, "<", "/dev/random";
907 read $fh, my $bytes, 20;
909 return unpack("H*", $bytes);
912 Also have a look at L<Crypt::Random> and the various openssl bindings - these
913 modules provide APIs for cryptographically secure random data.
915 =item finalize_session
917 Clean up the session during C<finalize>.
919 This clears the various accessors after saving to the store.
923 See L<Catalyst/dump_these> - ammends the session data structure to the list of
924 dumped objects if session ID is defined.
927 =item calculate_extended_session_expires
929 =item calculate_initial_session_expires
931 =item create_session_id_if_needed
933 =item delete_session_id
935 =item extend_session_expires
937 =item extend_session_id
941 =item reset_session_expires
943 =item session_is_valid
949 =head1 USING SESSIONS DURING PREPARE
951 The earliest point in time at which you may use the session data is after
952 L<Catalyst::Plugin::Session>'s C<prepare_action> has finished.
954 State plugins must set $c->session ID before C<prepare_action>, and during
955 C<prepare_action> L<Catalyst::Plugin::Session> will actually load the data from
961 # don't touch $c->session yet!
963 $c->NEXT::prepare_action( @_ );
965 $c->session; # this is OK
966 $c->sessionid; # this is also OK
971 $c->config('Plugin::Session' => {
975 All configuation parameters are provided in a hash reference under the
976 C<Plugin::Session> key in the configuration hash.
982 The time-to-live of each session, expressed in seconds. Defaults to 7200 (two
987 When true, C<<$c->request->address>> will be checked at prepare time. If it is
988 not the same as the address that initiated the session, the session is deleted.
992 =item verify_user_agent
994 When true, C<<$c->request->user_agent>> will be checked at prepare time. If it
995 is not the same as the user agent that initiated the session, the session is
1000 =item flash_to_stash
1002 This option makes it easier to have actions behave the same whether they were
1003 forwarded to or redirected to. On prepare time it copies the contents of
1004 C<flash> (if any) to the stash.
1010 The hash reference returned by C<< $c->session >> contains several keys which
1011 are automatically set:
1017 This key no longer exists. Use C<session_expires> instead.
1021 The last time a session was saved to the store.
1025 The time when the session was first created.
1029 The value of C<< $c->request->address >> at the time the session was created.
1030 This value is only populated if C<verify_address> is true in the configuration.
1034 The value of C<< $c->request->user_agent >> at the time the session was created.
1035 This value is only populated if C<verify_user_agent> is true in the configuration.
1041 =head2 Round the Robin Proxies
1043 C<verify_address> could make your site inaccessible to users who are behind
1044 load balanced proxies. Some ISPs may give a different IP to each request by the
1045 same client due to this type of proxying. If addresses are verified these
1046 users' sessions cannot persist.
1048 To let these users access your site you can either disable address verification
1049 as a whole, or provide a checkbox in the login dialog that tells the server
1050 that it's OK for the address of the client to change. When the server sees that
1051 this box is checked it should delete the C<__address> special key from the
1052 session hash when the hash is first created.
1054 =head2 Race Conditions
1056 In this day and age where cleaning detergents and Dutch football (not the
1057 American kind) teams roam the plains in great numbers, requests may happen
1058 simultaneously. This means that there is some risk of session data being
1059 overwritten, like this:
1065 request a starts, request b starts, with the same session ID
1069 session data is loaded in request a
1073 session data is loaded in request b
1077 session data is changed in request a
1081 request a finishes, session data is updated and written to store
1085 request b finishes, session data is updated and written to store, overwriting
1086 changes by request a
1090 If this is a concern in your application, a soon-to-be-developed locking
1091 solution is the only safe way to go. This will have a bigger overhead.
1093 For applications where any given user is only making one request at a time this
1094 plugin should be safe enough.
1102 Yuval Kogman, C<nothingmuch@woobling.org>
1106 Tomas Doran (t0m) C<bobtfish@bobtfish.net> (current maintainer)
1112 Florian Ragwitz (rafl) C<rafl@debian.org>
1114 Kent Fredric (kentnl)
1116 And countless other contributers from #catalyst. Thanks guys!
1118 =head1 COPYRIGHT & LICENSE
1120 Copyright (c) 2005 the aforementioned authors. All rights
1121 reserved. This program is free software; you can redistribute
1122 it and/or modify it under the same terms as Perl itself.