3 package Catalyst::Plugin::Session;
4 use base qw/Class::Accessor::Fast/;
10 use Catalyst::Exception ();
13 use Object::Signature ();
15 our $VERSION = "0.05";
17 my @session_data_accessors; # used in delete_session
19 __PACKAGE__->mk_accessors(
20 "_session_delete_reason",
21 @session_data_accessors = qw/
38 $c->check_session_plugin_requirements;
44 sub check_session_plugin_requirements {
47 unless ( $c->isa("Catalyst::Plugin::Session::State")
48 && $c->isa("Catalyst::Plugin::Session::Store") )
51 ( "The Session plugin requires both Session::State "
52 . "and Session::Store plugins to be used as well." );
55 Catalyst::Exception->throw($err);
62 my $cfg = ( $c->config->{session} ||= {} );
70 $c->NEXT::setup_session();
76 if ( $c->config->{session}{flash_to_stash}
78 and my $flash_data = $c->flash )
80 @{ $c->stash }{ keys %$flash_data } = values %$flash_data;
83 $c->NEXT::prepare_action(@_);
92 $c->NEXT::finalize(@_);
98 if ( my $sid = $c->_sessionid ) {
100 # all sessions are extended at the end of the request
103 if ( my $expires = $c->session_expires ) {
104 $c->store_session_data( "expires:$sid" => $expires );
107 if ( my $session_data = $c->_session ) {
109 no warnings 'uninitialized';
110 if ( Object::Signature::signature($session_data) ne
111 $c->_session_data_sig )
113 $session_data->{__updated} = $now;
114 $c->store_session_data( "session:$sid" => $session_data );
123 if ( my $sid = $c->_sessionid ) {
124 if ( my $flash_data = $c->_flash ) {
126 my $hashes = $c->_flash_key_hashes || {};
127 my $keep = $c->_flash_keep_keys || {};
128 foreach my $key ( keys %$hashes ) {
129 if ( !exists $keep->{$key} and Object::Signature::signature( \$flash_data->{$key} ) eq $hashes->{$key} ) {
130 delete $flash_data->{$key};
135 $c->store_session_data( "flash:$sid", $flash_data );
138 $c->delete_session_data("flash:$sid");
147 if ( my $sid = $c->_sessionid ) {
148 if ( $c->session_expires ) { # > 0
150 my $session_data = $c->get_session_data("session:$sid") || return;
151 $c->_session($session_data);
153 no warnings 'uninitialized'; # ne __address
154 if ( $c->config->{session}{verify_address}
155 && $session_data->{__address} ne $c->request->address )
158 "Deleting session $sid due to address mismatch ("
159 . $session_data->{__address} . " != "
160 . $c->request->address . ")" . Carp::longmess,
162 $c->delete_session("address mismatch");
166 $c->log->debug(qq/Restored session "$sid"/) if $c->debug;
167 $c->_session_data_sig( Object::Signature::signature($session_data) ) if $session_data;
168 $c->_expire_session_keys;
170 return $session_data;
180 if ( my $sid = $c->_sessionid ) {
181 if ( my $flash_data = $c->_flash
182 || $c->_flash( $c->get_session_data("flash:$sid") ) )
184 $c->_flash_key_hashes({ map { $_ => Object::Signature::signature( \$flash_data->{$_} ) } keys %$flash_data });
192 sub _expire_session_keys {
193 my ( $c, $data ) = @_;
197 my $expiry = ( $data || $c->_session || {} )->{__expire_keys} || {};
198 foreach my $key ( grep { $expiry->{$_} < $now } keys %$expiry ) {
199 delete $c->_session->{$key};
200 delete $expiry->{$key};
205 my ( $c, $msg ) = @_;
207 # delete the session data
208 my $sid = $c->_sessionid || return;
209 $c->delete_session_data("${_}:${sid}") for qw/session expires flash/;
211 # reset the values in the context object
212 # see the BEGIN block
213 $c->$_(undef) for @session_data_accessors;
215 $c->_session_delete_reason($msg);
218 sub session_delete_reason {
222 if ( $c->_sessionid && !$c->_session ); # must verify session data
224 $c->_session_delete_reason(@_);
227 sub session_expires {
228 my ( $c, $should_create ) = @_;
230 $c->_session_expires || do {
231 if ( my $sid = $c->_sessionid ) {
234 if ( !$should_create ) {
235 if ( ( $c->get_session_data("expires:$sid") || 0 ) < $now ) {
238 $c->log->debug("Deleting session $sid (expired)")
240 $c->delete_session("session expired");
245 return $c->_session_expires(
246 $now + $c->config->{session}{expires} );
255 if($c->_sessionid()) {
256 $c->log->warn('Session ID already set, ignoring.');
257 return $c->_sessionid();
259 if ( $c->validate_session_id( my $sid = shift ) ) {
260 $c->_sessionid($sid);
261 return unless defined wantarray;
264 my $err = "Tried to set invalid session ID '$sid'";
265 $c->log->error($err);
266 Catalyst::Exception->throw($err);
271 if ( $c->_sessionid && !$c->_session ); # must verify session data
273 return $c->_sessionid;
276 sub validate_session_id {
277 my ( $c, $sid ) = @_;
279 $sid and $sid =~ /^[a-f\d]+$/i;
285 $c->_session || $c->_load_session || do {
286 $c->create_session_id;
288 $c->initialize_session_data;
293 my ( $c, @keys ) = @_;
294 my $href = $c->_flash_keep_keys || $c->_flash_keep_keys({});
295 (@{$href}{@keys}) = ((undef) x @keys);
300 $c->_flash || $c->_load_flash || do {
301 $c->create_session_id;
306 sub session_expire_key {
307 my ( $c, %keys ) = @_;
310 @{ $c->session->{__expire_keys} }{ keys %keys } =
311 map { $now + $_ } values %keys;
314 sub initialize_session_data {
325 $c->config->{session}{verify_address}
326 ? ( __address => $c->request->address )
333 sub generate_session_id {
336 my $digest = $c->_find_digest();
337 $digest->add( $c->session_hash_seed() );
338 return $digest->hexdigest;
341 sub create_session_id {
344 if ( !$c->_sessionid ) {
345 my $sid = $c->generate_session_id;
347 $c->log->debug(qq/Created session "$sid"/) if $c->debug;
350 $c->session_expires(1);
356 sub session_hash_seed {
359 return join( "", ++$counter, time, rand, $$, {}, overload::StrVal($c), );
364 sub _find_digest () {
366 foreach my $alg (qw/SHA-1 SHA-256 MD5/) {
367 if ( eval { Digest->new($alg) } ) {
372 Catalyst::Exception->throw(
373 "Could not find a suitable Digest module. Please install "
374 . "Digest::SHA1, Digest::SHA, or Digest::MD5" )
378 return Digest->new($usable);
385 $c->NEXT::dump_these(),
388 ? ( [ "Session ID" => $c->sessionid ], [ Session => $c->session ], )
401 Catalyst::Plugin::Session - Generic Session plugin - ties together server side
402 storage and client side state required to maintain session data.
406 # To get sessions to "just work", all you need to do is use these plugins:
410 Session::Store::FastMmap
411 Session::State::Cookie
414 # you can replace Store::FastMmap with Store::File - both have sensible
415 # default configurations (see their docs for details)
417 # more complicated backends are available for other scenarios (DBI storage,
421 # after you've loaded the plugins you can save session data
422 # For example, if you are writing a shopping cart, it could be implemented
425 sub add_item : Local {
426 my ( $self, $c ) = @_;
428 my $item_id = $c->req->param("item");
430 # $c->session is a hash ref, a bit like $c->stash
431 # the difference is that it' preserved across requests
433 push @{ $c->session->{items} }, $item_id;
435 $c->forward("MyView");
438 sub display_items : Local {
439 my ( $self, $c ) = @_;
441 # values in $c->session are restored
442 $c->stash->{items_to_display} =
443 [ map { MyModel->retrieve($_) } @{ $c->session->{items} } ];
445 $c->forward("MyView");
450 The Session plugin is the base of two related parts of functionality required
451 for session management in web applications.
453 The first part, the State, is getting the browser to repeat back a session key,
454 so that the web application can identify the client and logically string
455 several requests together into a session.
457 The second part, the Store, deals with the actual storage of information about
458 the client. This data is stored so that the it may be revived for every request
459 made by the same client.
461 This plugin links the two pieces together.
463 =head1 RECCOMENDED BACKENDS
467 =item Session::State::Cookie
469 The only really sane way to do state is using cookies.
471 =item Session::Store::File
473 A portable backend, based on Cache::File.
475 =item Session::Store::FastMmap
477 A fast and flexible backend, based on Cache::FastMmap.
487 An accessor for the session ID value.
491 Returns a hash reference that might contain unserialized values from previous
492 requests in the same session, and whose modified value will be saved for future
495 This method will automatically create a new session and session ID if none
498 =item session_expires
500 =item session_expires $reset
502 This method returns the time when the current session will expire, or 0 if
503 there is no current session. If there is a session and it already expired, it
504 will delete the session and return 0 as well.
506 If the C<$reset> parameter is true, and there is a session ID the expiry time
507 will be reset to the current time plus the time to live (see
508 L</CONFIGURATION>). This is used when creating a new session.
512 This is like Ruby on Rails' flash data structure. Think of it as a stash that
513 lasts for longer than one request, letting you redirect instead of forward.
515 The flash data will be cleaned up only on requests on which actually use
516 $c->flash (thus allowing multiple redirections), and the policy is to delete
517 all the keys which haven't changed since the flash data was loaded at the end
521 my ( $self, $c ) = @_;
523 $c->flash->{beans} = 10;
524 $c->response->redirect( $c->uri_for("foo") );
528 my ( $self, $c ) = @_;
530 my $value = $c->flash->{beans};
534 $c->response->redirect( $c->uri_for("bar") );
538 my ( $self, $c ) = @_;
540 if ( exists $c->flash->{beans} ) { # false
545 =item keep_flash @keys
547 If you wawnt to keep a flash key for the next request too, even if it hasn't
548 changed, call C<keep_flash> and pass in the keys as arguments.
550 =item session_delete_reason
552 This accessor contains a string with the reason a session was deleted. Possible
567 =item session_expire_key $key, $ttl
569 Mark a key to expire at a certain time (only useful when shorter than the
570 expiry time for the whole session).
574 __PACKAGE__->config->{session}{expires} = 1000000000000; # forever
578 $c->session_expire_key( __user => 3600 );
580 Will make the session data survive, but the user will still be logged out after
583 Note that these values are not auto extended.
587 =head1 INTERNAL METHODS
593 This method is extended to also make calls to
594 C<check_session_plugin_requirements> and C<setup_session>.
596 =item check_session_plugin_requirements
598 This method ensures that a State and a Store plugin are also in use by the
603 This method populates C<< $c->config->{session} >> with the default values
604 listed in L</CONFIGURATION>.
608 This methoid is extended.
610 It's only effect is if the (off by default) C<flash_to_stash> configuration
611 parameter is on - then it will copy the contents of the flash to the stash at
616 This method is extended and will extend the expiry time, as well as persist the
617 session data if a session exists.
619 =item delete_session REASON
621 This method is used to invalidate a session. It takes an optional parameter
622 which will be saved in C<session_delete_reason> if provided.
624 =item initialize_session_data
626 This method will initialize the internal structure of the session, and is
627 called by the C<session> method if appropriate.
629 =item create_session_id
631 Creates a new session id using C<generate_session_id> if there is no session ID
634 =item validate_session_id SID
636 Make sure a session ID is of the right format.
638 This currently ensures that the session ID string is any amount of case
639 insensitive hexadecimal characters.
641 =item generate_session_id
643 This method will return a string that can be used as a session ID. It is
644 supposed to be a reasonably random string with enough bits to prevent
645 collision. It basically takes C<session_hash_seed> and hashes it using SHA-1,
646 MD5 or SHA-256, depending on the availibility of these modules.
648 =item session_hash_seed
650 This method is actually rather internal to generate_session_id, but should be
651 overridable in case you want to provide more random data.
653 Currently it returns a concatenated string which contains:
667 One value from C<rand>.
671 The stringified value of a newly allocated hash reference
675 The stringified value of the Catalyst context object
679 In the hopes that those combined values are entropic enough for most uses. If
680 this is not the case you can replace C<session_hash_seed> with e.g.
682 sub session_hash_seed {
683 open my $fh, "<", "/dev/random";
684 read $fh, my $bytes, 20;
689 Or even more directly, replace C<generate_session_id>:
691 sub generate_session_id {
692 open my $fh, "<", "/dev/random";
693 read $fh, my $bytes, 20;
695 return unpack("H*", $bytes);
698 Also have a look at L<Crypt::Random> and the various openssl bindings - these
699 modules provide APIs for cryptographically secure random data.
703 See L<Catalyst/dump_these> - ammends the session data structure to the list of
704 dumped objects if session ID is defined.
708 =head1 USING SESSIONS DURING PREPARE
710 The earliest point in time at which you may use the session data is after
711 L<Catalyst::Plugin::Session>'s C<prepare_action> has finished.
713 State plugins must set $c->session ID before C<prepare_action>, and during
714 C<prepare_action> L<Catalyst::Plugin::Session> will actually load the data from
720 # don't touch $c->session yet!
722 $c->NEXT::prepare_action( @_ );
724 $c->session; # this is OK
725 $c->sessionid; # this is also OK
730 $c->config->{session} = {
734 All configuation parameters are provided in a hash reference under the
735 C<session> key in the configuration hash.
741 The time-to-live of each session, expressed in seconds. Defaults to 7200 (two
746 When true, C<<$c->request->address>> will be checked at prepare time. If it is
747 not the same as the address that initiated the session, the session is deleted.
751 This option makes it easier to have actions behave the same whether they were
752 forwarded to or redirected to. On prepare time it copies the contents of
753 C<flash> (if any) to the stash.
759 The hash reference returned by C<< $c->session >> contains several keys which
760 are automatically set:
766 This key no longer exists. Use C<session_expires> instead.
770 The last time a session was saved to the store.
774 The time when the session was first created.
778 The value of C<< $c->request->address >> at the time the session was created.
779 This value is only populated if C<verify_address> is true in the configuration.
785 =head2 Round the Robin Proxies
787 C<verify_address> could make your site inaccessible to users who are behind
788 load balanced proxies. Some ISPs may give a different IP to each request by the
789 same client due to this type of proxying. If addresses are verified these
790 users' sessions cannot persist.
792 To let these users access your site you can either disable address verification
793 as a whole, or provide a checkbox in the login dialog that tells the server
794 that it's OK for the address of the client to change. When the server sees that
795 this box is checked it should delete the C<__address> sepcial key from the
796 session hash when the hash is first created.
798 =head2 Race Conditions
800 In this day and age where cleaning detergents and dutch football (not the
801 american kind) teams roam the plains in great numbers, requests may happen
802 simultaneously. This means that there is some risk of session data being
803 overwritten, like this:
809 request a starts, request b starts, with the same session id
813 session data is loaded in request a
817 session data is loaded in request b
821 session data is changed in request a
825 request a finishes, session data is updated and written to store
829 request b finishes, session data is updated and written to store, overwriting
834 If this is a concern in your application, a soon to be developed locking
835 solution is the only safe way to go. This will have a bigger overhead.
837 For applications where any given user is only making one request at a time this
838 plugin should be safe enough.
846 =item Christian Hansen
848 =item Yuval Kogman, C<nothingmuch@woobling.org> (current maintainer)
850 =item Sebastian Riedel
854 And countless other contributers from #catalyst. Thanks guys!
856 =head1 COPYRIGHT & LICENSE
858 Copyright (c) 2005 the aforementioned authors. All rights
859 reserved. This program is free software; you can redistribute
860 it and/or modify it under the same terms as Perl itself.