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/
37 $c->check_session_plugin_requirements;
43 sub check_session_plugin_requirements {
46 unless ( $c->isa("Catalyst::Plugin::Session::State")
47 && $c->isa("Catalyst::Plugin::Session::Store") )
50 ( "The Session plugin requires both Session::State "
51 . "and Session::Store plugins to be used as well." );
54 Catalyst::Exception->throw($err);
61 my $cfg = ( $c->config->{session} ||= {} );
69 $c->NEXT::setup_session();
75 if ( $c->config->{session}{flash_to_stash}
77 and my $flash_data = $c->flash )
79 @{ $c->stash }{ keys %$flash_data } = values %$flash_data;
82 $c->NEXT::prepare_action(@_);
91 $c->NEXT::finalize(@_);
97 if ( my $sid = $c->_sessionid ) {
99 # all sessions are extended at the end of the request
102 if ( my $expires = $c->session_expires ) {
103 $c->store_session_data( "expires:$sid" => $expires );
106 if ( my $session_data = $c->_session ) {
108 no warnings 'uninitialized';
109 if ( Object::Signature::signature($session_data) ne
110 $c->_session_data_sig )
112 $session_data->{__updated} = $now;
113 $c->store_session_data( "session:$sid" => $session_data );
122 if ( my $sid = $c->_sessionid ) {
123 if ( my $flash_data = $c->_flash ) {
124 delete @{$flash_data}{ @{ $c->_flash_stale_keys || [] } };
127 $c->store_session_data( "flash:$sid", $flash_data );
130 $c->delete_session_data("flash:$sid");
139 if ( my $sid = $c->_sessionid ) {
140 if ( $c->session_expires ) { # > 0
142 my $session_data = $c->get_session_data("session:$sid");
143 $c->_session($session_data);
145 no warnings 'uninitialized'; # ne __address
146 if ( $c->config->{session}{verify_address}
147 && $session_data->{__address} ne $c->request->address )
150 "Deleting session $sid due to address mismatch ("
151 . $session_data->{__address} . " != "
152 . $c->request->address . ")",
154 $c->delete_session("address mismatch");
158 $c->log->debug(qq/Restored session "$sid"/) if $c->debug;
159 $c->_session_data_sig(
160 Object::Signature::signature($session_data) );
161 $c->_expire_session_keys;
163 return $session_data;
173 if ( my $sid = $c->_sessionid ) {
174 if ( my $flash_data = $c->_flash
175 || $c->_flash( $c->get_session_data("flash:$sid") ) )
177 $c->_flash_stale_keys( [ keys %$flash_data ] );
185 sub _expire_session_keys {
186 my ( $c, $data ) = @_;
190 my $expiry = ( $data || $c->_session || {} )->{__expire_keys} || {};
191 foreach my $key ( grep { $expiry->{$_} < $now } keys %$expiry ) {
192 delete $c->_session->{$key};
193 delete $expiry->{$key};
198 my ( $c, $msg ) = @_;
200 # delete the session data
201 my $sid = $c->_sessionid || return;
202 $c->delete_session_data("${_}:${sid}") for qw/session expires flash/;
204 # reset the values in the context object
205 # see the BEGIN block
206 $c->$_(undef) for @session_data_accessors;
208 $c->_session_delete_reason($msg);
211 sub session_delete_reason {
215 if ( $c->_sessionid && !$c->_session ); # must verify session data
217 $c->_session_delete_reason(@_);
220 sub session_expires {
221 my ( $c, $should_create ) = @_;
223 $c->_session_expires || do {
224 if ( my $sid = $c->_sessionid ) {
227 if ( !$should_create ) {
228 if ( ( $c->get_session_data("expires:$sid") || 0 ) < $now ) {
231 $c->log->debug("Deleting session $sid (expired)")
233 $c->delete_session("session expired");
238 return $c->_session_expires(
239 $now + $c->config->{session}{expires} );
248 if($c->_sessionid()) {
249 $c->log->warn('Session ID already set, ignoring.');
250 return $c->_sessionid();
252 if ( $c->validate_session_id( my $sid = shift ) ) {
253 $c->_sessionid($sid);
254 return unless defined wantarray;
257 my $err = "Tried to set invalid session ID '$sid'";
258 $c->log->error($err);
259 Catalyst::Exception->throw($err);
264 if ( $c->_sessionid && !$c->_session ); # must verify session data
266 return $c->_sessionid;
269 sub validate_session_id {
270 my ( $c, $sid ) = @_;
272 $sid and $sid =~ /^[a-f\d]+$/i;
278 $c->_session || $c->_load_session || do {
279 $c->create_session_id;
281 $c->initialize_session_data;
287 $c->_flash || $c->_load_flash || do {
288 $c->create_session_id;
293 sub session_expire_key {
294 my ( $c, %keys ) = @_;
297 @{ $c->session->{__expire_keys} }{ keys %keys } =
298 map { $now + $_ } values %keys;
301 sub initialize_session_data {
312 $c->config->{session}{verify_address}
313 ? ( __address => $c->request->address )
320 sub generate_session_id {
323 my $digest = $c->_find_digest();
324 $digest->add( $c->session_hash_seed() );
325 return $digest->hexdigest;
328 sub create_session_id {
331 if ( !$c->_sessionid ) {
332 my $sid = $c->generate_session_id;
334 $c->log->debug(qq/Created session "$sid"/) if $c->debug;
337 $c->session_expires(1);
343 sub session_hash_seed {
346 return join( "", ++$counter, time, rand, $$, {}, overload::StrVal($c), );
351 sub _find_digest () {
353 foreach my $alg (qw/SHA-1 SHA-256 MD5/) {
354 if ( eval { Digest->new($alg) } ) {
359 Catalyst::Exception->throw(
360 "Could not find a suitable Digest module. Please install "
361 . "Digest::SHA1, Digest::SHA, or Digest::MD5" )
365 return Digest->new($usable);
372 $c->NEXT::dump_these(),
375 ? ( [ "Session ID" => $c->sessionid ], [ Session => $c->session ], )
388 Catalyst::Plugin::Session - Generic Session plugin - ties together server side
389 storage and client side state required to maintain session data.
393 # To get sessions to "just work", all you need to do is use these plugins:
397 Session::Store::FastMmap
398 Session::State::Cookie
401 # you can replace Store::FastMmap with Store::File - both have sensible
402 # default configurations (see their docs for details)
404 # more complicated backends are available for other scenarios (DBI storage,
408 # after you've loaded the plugins you can save session data
409 # For example, if you are writing a shopping cart, it could be implemented
412 sub add_item : Local {
413 my ( $self, $c ) = @_;
415 my $item_id = $c->req->param("item");
417 # $c->session is a hash ref, a bit like $c->stash
418 # the difference is that it' preserved across requests
420 push @{ $c->session->{items} }, $item_id;
422 $c->forward("MyView");
425 sub display_items : Local {
426 my ( $self, $c ) = @_;
428 # values in $c->session are restored
429 $c->stash->{items_to_display} =
430 [ map { MyModel->retrieve($_) } @{ $c->session->{items} } ];
432 $c->forward("MyView");
437 The Session plugin is the base of two related parts of functionality required
438 for session management in web applications.
440 The first part, the State, is getting the browser to repeat back a session key,
441 so that the web application can identify the client and logically string
442 several requests together into a session.
444 The second part, the Store, deals with the actual storage of information about
445 the client. This data is stored so that the it may be revived for every request
446 made by the same client.
448 This plugin links the two pieces together.
450 =head1 RECCOMENDED BACKENDS
454 =item Session::State::Cookie
456 The only really sane way to do state is using cookies.
458 =item Session::Store::File
460 A portable backend, based on Cache::File.
462 =item Session::Store::FastMmap
464 A fast and flexible backend, based on Cache::FastMmap.
474 An accessor for the session ID value.
478 Returns a hash reference that might contain unserialized values from previous
479 requests in the same session, and whose modified value will be saved for future
482 This method will automatically create a new session and session ID if none
485 =item session_expires
487 =item session_expires $reset
489 This method returns the time when the current session will expire, or 0 if
490 there is no current session. If there is a session and it already expired, it
491 will delete the session and return 0 as well.
493 If the C<$reset> parameter is true, and there is a session ID the expiry time
494 will be reset to the current time plus the time to live (see
495 L</CONFIGURATION>). This is used when creating a new session.
499 This is like Ruby on Rails' flash data structure. Think of it as a stash that
500 lasts for longer than one request, letting you redirect instead of forward.
502 The flash data will be cleaned up only on requests on which actually use
503 $c->flash (thus allowing multiple redirections), and the policy is to delete
504 all the keys which were present at the time the data was loaded just before the
508 my ( $self, $c ) = @_;
510 $c->flash->{beans} = 10;
511 $c->response->redirect( $c->uri_for("foo") );
515 my ( $self, $c ) = @_;
517 my $value = $c->flash->{beans};
521 $c->response->redirect( $c->uri_for("bar") );
525 my ( $self, $c ) = @_;
527 if ( exists $c->flash->{beans} ) { # false
532 =item session_delete_reason
534 This accessor contains a string with the reason a session was deleted. Possible
549 =item session_expire_key $key, $ttl
551 Mark a key to expire at a certain time (only useful when shorter than the
552 expiry time for the whole session).
556 __PACKAGE__->config->{session}{expires} = 1000000000000; # forever
560 $c->session_expire_key( __user => 3600 );
562 Will make the session data survive, but the user will still be logged out after
565 Note that these values are not auto extended.
569 =head1 INTERNAL METHODS
575 This method is extended to also make calls to
576 C<check_session_plugin_requirements> and C<setup_session>.
578 =item check_session_plugin_requirements
580 This method ensures that a State and a Store plugin are also in use by the
585 This method populates C<< $c->config->{session} >> with the default values
586 listed in L</CONFIGURATION>.
590 This methoid is extended.
592 It's only effect is if the (off by default) C<flash_to_stash> configuration
593 parameter is on - then it will copy the contents of the flash to the stash at
598 This method is extended and will extend the expiry time, as well as persist the
599 session data if a session exists.
601 =item delete_session REASON
603 This method is used to invalidate a session. It takes an optional parameter
604 which will be saved in C<session_delete_reason> if provided.
606 =item initialize_session_data
608 This method will initialize the internal structure of the session, and is
609 called by the C<session> method if appropriate.
611 =item create_session_id
613 Creates a new session id using C<generate_session_id> if there is no session ID
616 =item validate_session_id SID
618 Make sure a session ID is of the right format.
620 This currently ensures that the session ID string is any amount of case
621 insensitive hexadecimal characters.
623 =item generate_session_id
625 This method will return a string that can be used as a session ID. It is
626 supposed to be a reasonably random string with enough bits to prevent
627 collision. It basically takes C<session_hash_seed> and hashes it using SHA-1,
628 MD5 or SHA-256, depending on the availibility of these modules.
630 =item session_hash_seed
632 This method is actually rather internal to generate_session_id, but should be
633 overridable in case you want to provide more random data.
635 Currently it returns a concatenated string which contains:
649 One value from C<rand>.
653 The stringified value of a newly allocated hash reference
657 The stringified value of the Catalyst context object
661 In the hopes that those combined values are entropic enough for most uses. If
662 this is not the case you can replace C<session_hash_seed> with e.g.
664 sub session_hash_seed {
665 open my $fh, "<", "/dev/random";
666 read $fh, my $bytes, 20;
671 Or even more directly, replace C<generate_session_id>:
673 sub generate_session_id {
674 open my $fh, "<", "/dev/random";
675 read $fh, my $bytes, 20;
677 return unpack("H*", $bytes);
680 Also have a look at L<Crypt::Random> and the various openssl bindings - these
681 modules provide APIs for cryptographically secure random data.
685 See L<Catalyst/dump_these> - ammends the session data structure to the list of
686 dumped objects if session ID is defined.
690 =head1 USING SESSIONS DURING PREPARE
692 The earliest point in time at which you may use the session data is after
693 L<Catalyst::Plugin::Session>'s C<prepare_action> has finished.
695 State plugins must set $c->session ID before C<prepare_action>, and during
696 C<prepare_action> L<Catalyst::Plugin::Session> will actually load the data from
702 # don't touch $c->session yet!
704 $c->NEXT::prepare_action( @_ );
706 $c->session; # this is OK
707 $c->sessionid; # this is also OK
712 $c->config->{session} = {
716 All configuation parameters are provided in a hash reference under the
717 C<session> key in the configuration hash.
723 The time-to-live of each session, expressed in seconds. Defaults to 7200 (two
728 When true, C<<$c->request->address>> will be checked at prepare time. If it is
729 not the same as the address that initiated the session, the session is deleted.
733 This option makes it easier to have actions behave the same whether they were
734 forwarded to or redirected to. On prepare time it copies the contents of
735 C<flash> (if any) to the stash.
741 The hash reference returned by C<< $c->session >> contains several keys which
742 are automatically set:
748 This key no longer exists. Use C<session_expires> instead.
752 The last time a session was saved to the store.
756 The time when the session was first created.
760 The value of C<< $c->request->address >> at the time the session was created.
761 This value is only populated if C<verify_address> is true in the configuration.
767 =head2 Round the Robin Proxies
769 C<verify_address> could make your site inaccessible to users who are behind
770 load balanced proxies. Some ISPs may give a different IP to each request by the
771 same client due to this type of proxying. If addresses are verified these
772 users' sessions cannot persist.
774 To let these users access your site you can either disable address verification
775 as a whole, or provide a checkbox in the login dialog that tells the server
776 that it's OK for the address of the client to change. When the server sees that
777 this box is checked it should delete the C<__address> sepcial key from the
778 session hash when the hash is first created.
780 =head2 Race Conditions
782 In this day and age where cleaning detergents and dutch football (not the
783 american kind) teams roam the plains in great numbers, requests may happen
784 simultaneously. This means that there is some risk of session data being
785 overwritten, like this:
791 request a starts, request b starts, with the same session id
795 session data is loaded in request a
799 session data is loaded in request b
803 session data is changed in request a
807 request a finishes, session data is updated and written to store
811 request b finishes, session data is updated and written to store, overwriting
816 If this is a concern in your application, a soon to be developed locking
817 solution is the only safe way to go. This will have a bigger overhead.
819 For applications where any given user is only making one request at a time this
820 plugin should be safe enough.
828 =item Christian Hansen
830 =item Yuval Kogman, C<nothingmuch@woobling.org> (current maintainer)
832 =item Sebastian Riedel
836 And countless other contributers from #catalyst. Thanks guys!
838 =head1 COPYRIGHT & LICENSE
840 Copyright (c) 2005 the aforementioned authors. All rights
841 reserved. This program is free software; you can redistribute
842 it and/or modify it under the same terms as Perl itself.