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 = '0.25';
18 my @session_data_accessors; # used in delete_session
20 __PACKAGE__->mk_accessors(
21 "_session_delete_reason",
22 @session_data_accessors = qw/
26 _extended_session_expires
31 _tried_loading_session_id
32 _tried_loading_session_data
33 _tried_loading_session_expires
34 _tried_loading_flash_data
42 $c->maybe::next::method(@_);
44 $c->check_session_plugin_requirements;
50 sub check_session_plugin_requirements {
53 unless ( $c->isa("Catalyst::Plugin::Session::State")
54 && $c->isa("Catalyst::Plugin::Session::Store") )
57 ( "The Session plugin requires both Session::State "
58 . "and Session::Store plugins to be used as well." );
61 Catalyst::Exception->throw($err);
68 my $cfg = ( $c->config->{session} ||= {} );
73 verify_user_agent => 0,
77 $c->maybe::next::method();
83 if ( $c->config->{session}{flash_to_stash}
85 and my $flash_data = $c->flash )
87 @{ $c->stash }{ keys %$flash_data } = values %$flash_data;
90 $c->maybe::next::method(@_);
93 sub finalize_headers {
96 # fix cookie before we send headers
97 $c->_save_session_expires;
99 return $c->maybe::next::method(@_);
105 # We have to finalize our session *before* $c->engine->finalize_xxx is called,
106 # because we do not want to send the HTTP response before the session is stored/committed to
107 # the session database (or whatever Session::Store you use).
108 $c->finalize_session;
110 return $c->maybe::next::method(@_);
113 sub finalize_session {
116 $c->maybe::next::method(@_);
118 $c->_save_session_id;
122 $c->_clear_session_instance_data;
125 sub _save_session_id {
128 # we already called set when allocating
129 # no need to tell the state plugins anything new
132 sub _save_session_expires {
135 if ( defined($c->_session_expires) ) {
136 my $expires = $c->session_expires; # force extension
138 my $sid = $c->sessionid;
139 $c->store_session_data( "expires:$sid" => $expires );
146 if ( my $session_data = $c->_session ) {
148 no warnings 'uninitialized';
149 if ( Object::Signature::signature($session_data) ne
150 $c->_session_data_sig )
152 $session_data->{__updated} = time();
153 my $sid = $c->sessionid;
154 $c->store_session_data( "session:$sid" => $session_data );
162 if ( my $flash_data = $c->_flash ) {
164 my $hashes = $c->_flash_key_hashes || {};
165 my $keep = $c->_flash_keep_keys || {};
166 foreach my $key ( keys %$hashes ) {
167 if ( !exists $keep->{$key} and Object::Signature::signature( \$flash_data->{$key} ) eq $hashes->{$key} ) {
168 delete $flash_data->{$key};
172 my $sid = $c->sessionid;
174 my $session_data = $c->_session;
176 $session_data->{__flash} = $flash_data;
179 delete $session_data->{__flash};
181 $c->_session($session_data);
186 sub _load_session_expires {
188 return $c->_session_expires if $c->_tried_loading_session_expires;
189 $c->_tried_loading_session_expires(1);
191 if ( my $sid = $c->sessionid ) {
192 my $expires = $c->get_session_data("expires:$sid") || 0;
194 if ( $expires >= time() ) {
195 $c->_session_expires( $expires );
198 $c->delete_session( "session expired" );
208 return $c->_session if $c->_tried_loading_session_data;
209 $c->_tried_loading_session_data(1);
211 if ( my $sid = $c->sessionid ) {
212 if ( $c->_load_session_expires ) { # > 0
214 my $session_data = $c->get_session_data("session:$sid") || return;
215 $c->_session($session_data);
217 no warnings 'uninitialized'; # ne __address
218 if ( $c->config->{session}{verify_address}
219 && $session_data->{__address} ne $c->request->address )
222 "Deleting session $sid due to address mismatch ("
223 . $session_data->{__address} . " != "
224 . $c->request->address . ")"
226 $c->delete_session("address mismatch");
229 if ( $c->config->{session}{verify_user_agent}
230 && $session_data->{__user_agent} ne $c->request->user_agent )
233 "Deleting session $sid due to user agent mismatch ("
234 . $session_data->{__user_agent} . " != "
235 . $c->request->user_agent . ")"
237 $c->delete_session("user agent mismatch");
241 $c->log->debug(qq/Restored session "$sid"/) if $c->debug;
242 $c->_session_data_sig( Object::Signature::signature($session_data) ) if $session_data;
243 $c->_expire_session_keys;
245 return $session_data;
254 return $c->_flash if $c->_tried_loading_flash_data;
255 $c->_tried_loading_flash_data(1);
257 if ( my $sid = $c->sessionid ) {
259 my $session_data = $c->session;
260 $c->_flash($session_data->{__flash});
262 if ( my $flash_data = $c->_flash )
264 $c->_flash_key_hashes({ map { $_ => Object::Signature::signature( \$flash_data->{$_} ) } keys %$flash_data });
273 sub _expire_session_keys {
274 my ( $c, $data ) = @_;
278 my $expire_times = ( $data || $c->_session || {} )->{__expire_keys} || {};
279 foreach my $key ( grep { $expire_times->{$_} < $now } keys %$expire_times ) {
280 delete $c->_session->{$key};
281 delete $expire_times->{$key};
285 sub _clear_session_instance_data {
287 $c->$_(undef) for @session_data_accessors;
288 $c->maybe::next::method(@_); # allow other plugins to hook in on this
291 sub change_session_id {
294 my $sessiondata = $c->session;
295 my $oldsid = $c->sessionid;
296 my $newsid = $c->create_session_id;
299 $c->log->debug(qq/change_sessid: deleting session data from "$oldsid"/) if $c->debug;
300 $c->delete_session_data("${_}:${oldsid}") for qw/session expires flash/;
303 $c->log->debug(qq/change_sessid: storing session data to "$newsid"/) if $c->debug;
304 $c->store_session_data( "session:$newsid" => $sessiondata );
310 my ( $c, $msg ) = @_;
312 $c->log->debug("Deleting session" . ( defined($msg) ? "($msg)" : '(no reason given)') ) if $c->debug;
314 # delete the session data
315 if ( my $sid = $c->sessionid ) {
316 $c->delete_session_data("${_}:${sid}") for qw/session expires flash/;
317 $c->delete_session_id($sid);
320 # reset the values in the context object
321 # see the BEGIN block
322 $c->_clear_session_instance_data;
324 $c->_session_delete_reason($msg);
327 sub session_delete_reason {
330 $c->session_is_valid; # check that it was loaded
332 $c->_session_delete_reason(@_);
335 sub session_expires {
338 if ( defined( my $expires = $c->_extended_session_expires ) ) {
340 } elsif ( defined( $expires = $c->_load_session_expires ) ) {
341 return $c->extend_session_expires( $expires );
347 sub extend_session_expires {
348 my ( $c, $expires ) = @_;
349 $c->_extended_session_expires( my $updated = $c->calculate_extended_session_expires( $expires ) );
350 $c->extend_session_id( $c->sessionid, $updated );
354 sub calculate_initial_session_expires {
356 return ( time() + $c->config->{session}{expires} );
359 sub calculate_extended_session_expires {
360 my ( $c, $prev ) = @_;
361 $c->calculate_initial_session_expires;
364 sub reset_session_expires {
365 my ( $c, $sid ) = @_;
367 my $exp = $c->calculate_initial_session_expires;
368 $c->_session_expires( $exp );
369 $c->_extended_session_expires( $exp );
376 return $c->_sessionid || $c->_load_sessionid;
379 sub _load_sessionid {
381 return if $c->_tried_loading_session_id;
382 $c->_tried_loading_session_id(1);
384 if ( defined( my $sid = $c->get_session_id ) ) {
385 if ( $c->validate_session_id($sid) ) {
386 # temporarily set the inner key, so that validation will work
387 $c->_sessionid($sid);
390 my $err = "Tried to set invalid session ID '$sid'";
391 $c->log->error($err);
392 Catalyst::Exception->throw($err);
399 sub session_is_valid {
402 # force a check for expiry, but also __address, etc
403 if ( $c->_load_session ) {
410 sub validate_session_id {
411 my ( $c, $sid ) = @_;
413 $sid and $sid =~ /^[a-f\d]+$/i;
419 $c->_session || $c->_load_session || do {
420 $c->create_session_id_if_needed;
421 $c->initialize_session_data;
426 my ( $c, @keys ) = @_;
427 my $href = $c->_flash_keep_keys || $c->_flash_keep_keys({});
428 (@{$href}{@keys}) = ((undef) x @keys);
433 $c->_flash || $c->_load_flash || do {
434 $c->create_session_id_if_needed;
442 my $items = @_ > 1 ? {@_} : $_[0];
443 croak('flash takes a hash or hashref') unless ref $items;
444 @{ $c->_flash }{ keys %$items } = values %$items;
458 #$c->delete_session_data("flash:" . $c->sessionid); # should this be in here? or delayed till finalization?
459 $c->_flash_key_hashes({});
460 $c->_flash_keep_keys({});
464 sub session_expire_key {
465 my ( $c, %keys ) = @_;
468 @{ $c->session->{__expire_keys} }{ keys %keys } =
469 map { $now + $_ } values %keys;
472 sub initialize_session_data {
483 $c->config->{session}{verify_address}
484 ? ( __address => $c->request->address||'' )
488 $c->config->{session}{verify_user_agent}
489 ? ( __user_agent => $c->request->user_agent||'' )
496 sub generate_session_id {
499 my $digest = $c->_find_digest();
500 $digest->add( $c->session_hash_seed() );
501 return $digest->hexdigest;
504 sub create_session_id_if_needed {
506 $c->create_session_id unless $c->sessionid;
509 sub create_session_id {
512 my $sid = $c->generate_session_id;
514 $c->log->debug(qq/Created session "$sid"/) if $c->debug;
516 $c->_sessionid($sid);
517 $c->reset_session_expires;
518 $c->set_session_id($sid);
525 sub session_hash_seed {
528 return join( "", ++$counter, time, rand, $$, {}, overload::StrVal($c), );
533 sub _find_digest () {
535 foreach my $alg (qw/SHA-1 SHA-256 MD5/) {
536 if ( eval { Digest->new($alg) } ) {
541 Catalyst::Exception->throw(
542 "Could not find a suitable Digest module. Please install "
543 . "Digest::SHA1, Digest::SHA, or Digest::MD5" )
547 return Digest->new($usable);
554 $c->maybe::next::method(),
557 ? ( [ "Session ID" => $c->sessionid ], [ Session => $c->session ], )
563 sub get_session_id { shift->maybe::next::method(@_) }
564 sub set_session_id { shift->maybe::next::method(@_) }
565 sub delete_session_id { shift->maybe::next::method(@_) }
566 sub extend_session_id { shift->maybe::next::method(@_) }
576 Catalyst::Plugin::Session - Generic Session plugin - ties together server side storage and client side state required to maintain session data.
580 # To get sessions to "just work", all you need to do is use these plugins:
584 Session::Store::FastMmap
585 Session::State::Cookie
588 # you can replace Store::FastMmap with Store::File - both have sensible
589 # default configurations (see their docs for details)
591 # more complicated backends are available for other scenarios (DBI storage,
595 # after you've loaded the plugins you can save session data
596 # For example, if you are writing a shopping cart, it could be implemented
599 sub add_item : Local {
600 my ( $self, $c ) = @_;
602 my $item_id = $c->req->param("item");
604 # $c->session is a hash ref, a bit like $c->stash
605 # the difference is that it' preserved across requests
607 push @{ $c->session->{items} }, $item_id;
609 $c->forward("MyView");
612 sub display_items : Local {
613 my ( $self, $c ) = @_;
615 # values in $c->session are restored
616 $c->stash->{items_to_display} =
617 [ map { MyModel->retrieve($_) } @{ $c->session->{items} } ];
619 $c->forward("MyView");
624 The Session plugin is the base of two related parts of functionality required
625 for session management in web applications.
627 The first part, the State, is getting the browser to repeat back a session key,
628 so that the web application can identify the client and logically string
629 several requests together into a session.
631 The second part, the Store, deals with the actual storage of information about
632 the client. This data is stored so that the it may be revived for every request
633 made by the same client.
635 This plugin links the two pieces together.
637 =head1 RECOMENDED BACKENDS
641 =item Session::State::Cookie
643 The only really sane way to do state is using cookies.
645 =item Session::Store::File
647 A portable backend, based on Cache::File.
649 =item Session::Store::FastMmap
651 A fast and flexible backend, based on Cache::FastMmap.
661 An accessor for the session ID value.
665 Returns a hash reference that might contain unserialized values from previous
666 requests in the same session, and whose modified value will be saved for future
669 This method will automatically create a new session and session ID if none
672 =item session_expires
674 =item session_expires $reset
676 This method returns the time when the current session will expire, or 0 if
677 there is no current session. If there is a session and it already expired, it
678 will delete the session and return 0 as well.
680 If the C<$reset> parameter is true, and there is a session ID the expiry time
681 will be reset to the current time plus the time to live (see
682 L</CONFIGURATION>). This is used when creating a new session.
686 This is like Ruby on Rails' flash data structure. Think of it as a stash that
687 lasts for longer than one request, letting you redirect instead of forward.
689 The flash data will be cleaned up only on requests on which actually use
690 $c->flash (thus allowing multiple redirections), and the policy is to delete
691 all the keys which haven't changed since the flash data was loaded at the end
695 my ( $self, $c ) = @_;
697 $c->flash->{beans} = 10;
698 $c->response->redirect( $c->uri_for("foo") );
702 my ( $self, $c ) = @_;
704 my $value = $c->flash->{beans};
708 $c->response->redirect( $c->uri_for("bar") );
712 my ( $self, $c ) = @_;
714 if ( exists $c->flash->{beans} ) { # false
721 Zap all the keys in the flash regardless of their current state.
723 =item keep_flash @keys
725 If you want to keep a flash key for the next request too, even if it hasn't
726 changed, call C<keep_flash> and pass in the keys as arguments.
728 =item delete_session REASON
730 This method is used to invalidate a session. It takes an optional parameter
731 which will be saved in C<session_delete_reason> if provided.
733 NOTE: This method will B<also> delete your flash data.
735 =item session_delete_reason
737 This accessor contains a string with the reason a session was deleted. Possible
752 =item session_expire_key $key, $ttl
754 Mark a key to expire at a certain time (only useful when shorter than the
755 expiry time for the whole session).
759 __PACKAGE__->config->{session}{expires} = 1000000000000; # forever
763 $c->session_expire_key( __user => 3600 );
765 Will make the session data survive, but the user will still be logged out after
768 Note that these values are not auto extended.
770 =item change_session_id
772 By calling this method you can force a session id change while keeping all
773 session data. This method might come handy when you are paranoid about some
774 advanced variations of session fixation attack.
776 If you want to prevent this session fixation scenario:
778 0) let us have WebApp with anonymous and authenticated parts
779 1) a hacker goes to vulnerable WebApp and gets a real sessionid,
780 just by browsing anonymous part of WebApp
781 2) the hacker inserts (somehow) this values into a cookie in victim's browser
782 3) after the victim logs into WebApp the hacker can enter his/her session
784 you should call change_session_id in your login controller like this:
786 if ($c->authenticate( { username => $user, password => $pass } )) {
788 $c->change_session_id;
797 =head1 INTERNAL METHODS
803 This method is extended to also make calls to
804 C<check_session_plugin_requirements> and C<setup_session>.
806 =item check_session_plugin_requirements
808 This method ensures that a State and a Store plugin are also in use by the
813 This method populates C<< $c->config->{session} >> with the default values
814 listed in L</CONFIGURATION>.
818 This method is extended.
820 Its only effect is if the (off by default) C<flash_to_stash> configuration
821 parameter is on - then it will copy the contents of the flash to the stash at
824 =item finalize_headers
826 This method is extended and will extend the expiry time before sending
831 This method is extended and will call finalize_session before the other
832 finalize_body methods run. Here we persist the session data if a session exists.
834 =item initialize_session_data
836 This method will initialize the internal structure of the session, and is
837 called by the C<session> method if appropriate.
839 =item create_session_id
841 Creates a new session ID using C<generate_session_id> if there is no session ID
844 =item validate_session_id SID
846 Make sure a session ID is of the right format.
848 This currently ensures that the session ID string is any amount of case
849 insensitive hexadecimal characters.
851 =item generate_session_id
853 This method will return a string that can be used as a session ID. It is
854 supposed to be a reasonably random string with enough bits to prevent
855 collision. It basically takes C<session_hash_seed> and hashes it using SHA-1,
856 MD5 or SHA-256, depending on the availability of these modules.
858 =item session_hash_seed
860 This method is actually rather internal to generate_session_id, but should be
861 overridable in case you want to provide more random data.
863 Currently it returns a concatenated string which contains:
869 =item * The current time
871 =item * One value from C<rand>.
873 =item * The stringified value of a newly allocated hash reference
875 =item * The stringified value of the Catalyst context object
879 in the hopes that those combined values are entropic enough for most uses. If
880 this is not the case you can replace C<session_hash_seed> with e.g.
882 sub session_hash_seed {
883 open my $fh, "<", "/dev/random";
884 read $fh, my $bytes, 20;
889 Or even more directly, replace C<generate_session_id>:
891 sub generate_session_id {
892 open my $fh, "<", "/dev/random";
893 read $fh, my $bytes, 20;
895 return unpack("H*", $bytes);
898 Also have a look at L<Crypt::Random> and the various openssl bindings - these
899 modules provide APIs for cryptographically secure random data.
901 =item finalize_session
903 Clean up the session during C<finalize>.
905 This clears the various accessors after saving to the store.
909 See L<Catalyst/dump_these> - ammends the session data structure to the list of
910 dumped objects if session ID is defined.
913 =item calculate_extended_session_expires
915 =item calculate_initial_session_expires
917 =item create_session_id_if_needed
919 =item delete_session_id
921 =item extend_session_expires
923 =item extend_session_id
927 =item reset_session_expires
929 =item session_is_valid
935 =head1 USING SESSIONS DURING PREPARE
937 The earliest point in time at which you may use the session data is after
938 L<Catalyst::Plugin::Session>'s C<prepare_action> has finished.
940 State plugins must set $c->session ID before C<prepare_action>, and during
941 C<prepare_action> L<Catalyst::Plugin::Session> will actually load the data from
947 # don't touch $c->session yet!
949 $c->NEXT::prepare_action( @_ );
951 $c->session; # this is OK
952 $c->sessionid; # this is also OK
957 $c->config->{session} = {
961 All configuation parameters are provided in a hash reference under the
962 C<session> key in the configuration hash.
968 The time-to-live of each session, expressed in seconds. Defaults to 7200 (two
973 When true, C<<$c->request->address>> will be checked at prepare time. If it is
974 not the same as the address that initiated the session, the session is deleted.
978 =item verify_user_agent
980 When true, C<<$c->request->user_agent>> will be checked at prepare time. If it
981 is not the same as the user agent that initiated the session, the session is
988 This option makes it easier to have actions behave the same whether they were
989 forwarded to or redirected to. On prepare time it copies the contents of
990 C<flash> (if any) to the stash.
996 The hash reference returned by C<< $c->session >> contains several keys which
997 are automatically set:
1003 This key no longer exists. Use C<session_expires> instead.
1007 The last time a session was saved to the store.
1011 The time when the session was first created.
1015 The value of C<< $c->request->address >> at the time the session was created.
1016 This value is only populated if C<verify_address> is true in the configuration.
1020 The value of C<< $c->request->user_agent >> at the time the session was created.
1021 This value is only populated if C<verify_user_agent> is true in the configuration.
1027 =head2 Round the Robin Proxies
1029 C<verify_address> could make your site inaccessible to users who are behind
1030 load balanced proxies. Some ISPs may give a different IP to each request by the
1031 same client due to this type of proxying. If addresses are verified these
1032 users' sessions cannot persist.
1034 To let these users access your site you can either disable address verification
1035 as a whole, or provide a checkbox in the login dialog that tells the server
1036 that it's OK for the address of the client to change. When the server sees that
1037 this box is checked it should delete the C<__address> special key from the
1038 session hash when the hash is first created.
1040 =head2 Race Conditions
1042 In this day and age where cleaning detergents and Dutch football (not the
1043 American kind) teams roam the plains in great numbers, requests may happen
1044 simultaneously. This means that there is some risk of session data being
1045 overwritten, like this:
1051 request a starts, request b starts, with the same session ID
1055 session data is loaded in request a
1059 session data is loaded in request b
1063 session data is changed in request a
1067 request a finishes, session data is updated and written to store
1071 request b finishes, session data is updated and written to store, overwriting
1072 changes by request a
1076 If this is a concern in your application, a soon-to-be-developed locking
1077 solution is the only safe way to go. This will have a bigger overhead.
1079 For applications where any given user is only making one request at a time this
1080 plugin should be safe enough.
1088 Yuval Kogman, C<nothingmuch@woobling.org>
1092 Tomas Doran (t0m) C<bobtfish@bobtfish.net> (current maintainer)
1098 And countless other contributers from #catalyst. Thanks guys!
1100 =head1 COPYRIGHT & LICENSE
1102 Copyright (c) 2005 the aforementioned authors. All rights
1103 reserved. This program is free software; you can redistribute
1104 it and/or modify it under the same terms as Perl itself.