NAME Catalyst::Plugin::Session - Generic Session plugin - ties together server side storage and client side state required to maintain session data. SYNOPSIS # To get sessions to "just work", all you need to do is use these plugins: use Catalyst qw/ Session Session::Store::FastMmap Session::State::Cookie /; # you can replace Store::FastMmap with Store::File - both have sensible # default configurations (see their docs for details) # more complicated backends are available for other scenarios (DBI storage, # etc) # after you've loaded the plugins you can save session data # For example, if you are writing a shopping cart, it could be implemented # like this: sub add_item : Local { my ( $self, $c ) = @_; my $item_id = $c->req->param("item"); # $c->session is a hash ref, a bit like $c->stash # the difference is that it' preserved across requests push @{ $c->session->{items} }, $item_id; $c->forward("MyView"); } sub display_items : Local { my ( $self, $c ) = @_; # values in $c->session are restored $c->stash->{items_to_display} = [ map { MyModel->retrieve($_) } @{ $c->session->{items} } ]; $c->forward("MyView"); } DESCRIPTION The Session plugin is the base of two related parts of functionality required for session management in web applications. The first part, the State, is getting the browser to repeat back a session key, so that the web application can identify the client and logically string several requests together into a session. The second part, the Store, deals with the actual storage of information about the client. This data is stored so that the it may be revived for every request made by the same client. This plugin links the two pieces together. RECCOMENDED BACKENDS Session::State::Cookie The only really sane way to do state is using cookies. Session::Store::File A portable backend, based on Cache::File. Session::Store::FastMmap A fast and flexible backend, based on Cache::FastMmap. METHODS sessionid An accessor for the session ID value. session Returns a hash reference that might contain unserialized values from previous requests in the same session, and whose modified value will be saved for future requests. This method will automatically create a new session and session ID if none exists. session_delete_reason This accessor contains a string with the reason a session was deleted. Possible values include: * "address mismatch" * "session expired" INTERNAL METHODS setup This method is extended to also make calls to "check_session_plugin_requirements" and "setup_session". check_session_plugin_requirements This method ensures that a State and a Store plugin are also in use by the application. setup_session This method populates "$c->config->{session}" with the default values listed in "CONFIGURATION". prepare_action This methoid is extended, and will restore session data and check it for validity if a session id is defined. It assumes that the State plugin will populate the "sessionid" key beforehand. finalize This method is extended and will extend the expiry time, as well as persist the session data if a session exists. delete_session REASON This method is used to invalidate a session. It takes an optional parameter which will be saved in "session_delete_reason" if provided. initialize_session_data This method will initialize the internal structure of the session, and is called by the "session" method if appropriate. generate_session_id This method will return a string that can be used as a session ID. It is supposed to be a reasonably random string with enough bits to prevent collision. It basically takes "session_hash_seed" and hashes it using SHA-1, MD5 or SHA-256, depending on the availibility of these modules. session_hash_seed This method is actually rather internal to generate_session_id, but should be overridable in case you want to provide more random data. Currently it returns a concatenated string which contains: * A counter * The current time * One value from "rand". * The stringified value of a newly allocated hash reference * The stringified value of the Catalyst context object In the hopes that those combined values are entropic enough for most uses. If this is not the case you can replace "session_hash_seed" with e.g. sub session_hash_seed { open my $fh, "<", "/dev/random"; read $fh, my $bytes, 20; close $fh; return $bytes; } Or even more directly, replace "generate_session_id": sub generate_session_id { open my $fh, "<", "/dev/random"; read $fh, my $bytes, 20; close $fh; return unpack("H*", $bytes); } Also have a look at Crypt::Random and the various openssl bindings - these modules provide APIs for cryptographically secure random data. dump_these See "dump_these" in Catalyst - ammends the session data structure to the list of dumped objects if session ID is defined. USING SESSIONS DURING PREPARE The earliest point in time at which you may use the session data is after Catalyst::Plugin::Session's "prepare_action" has finished. State plugins must set $c->session ID before "prepare_action", and during "prepare_action" Catalyst::Plugin::Session will actually load the data from the store. sub prepare_action { my $c = shift; # don't touch $c->session yet! $c->NEXT::prepare_action( @_ ); $c->session; # this is OK $c->sessionid; # this is also OK } CONFIGURATION $c->config->{session} = { expires => 1234, }; All configuation parameters are provided in a hash reference under the "session" key in the configuration hash. expires The time-to-live of each session, expressed in seconds. Defaults to 7200 (two hours). verify_address When false, "$c->request->address" will be checked at prepare time. If it is not the same as the address that initiated the session, the session is deleted. SPECIAL KEYS The hash reference returned by "$c->session" contains several keys which are automatically set: __expires A timestamp whose value is the last second when the session is still valid. If a session is restored, and __expires is less than the current time, the session is deleted. __updated The last time a session was saved. This is the value of "$c->{session}{__expires} - $c->config->{session}{expires}". __created The time when the session was first created. __address The value of "$c->request->address" at the time the session was created. This value is only populated of "verify_address" is true in the configuration. CAVEATS "verify_address" could make your site inaccessible to users who are behind load balanced proxies. Some ISPs may give a different IP to each request by the same client due to this type of proxying. If addresses are verified these users' sessions cannot persist. To let these users access your site you can either disable address verification as a whole, or provide a checkbox in the login dialog that tells the server that it's OK for the address of the client to change. When the server sees that this box is checked it should delete the "__address" sepcial key from the session hash when the hash is first created. AUTHORS Andy Grundman Christian Hansen Yuval Kogman, "nothingmuch@woobling.org" Sebastian Riedel COPYRIGHT & LICNESE Copyright (c) 2005 the aforementioned authors. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.