CGI::Application::PlugUserSContributed PerCGI::Application::Plugin::Session(3)NAMECGI::Application::Plugin::Session - Add CGI::Session support to
CGI::Application
SYNOPSIS
use CGI::Application::Plugin::Session;
my $language = $self->session->param('language');
DESCRIPTIONCGI::Application::Plugin::Session seamlessly adds session support to
your CGI::Application modules by providing a CGI::Session object that
is accessible from anywhere in the application.
Lazy loading is used to prevent expensive file system or database calls
from being made if the session is not needed during this request. In
other words, the Session object is not created until it is actually
needed. Also, the Session object will act as a singleton by always
returning the same Session object for the duration of the request.
This module aims to be as simple and non obtrusive as possible. By not
requiring any changes to the inheritance tree of your modules, it can
be easily added to existing applications. Think of it as a plugin
module that adds a couple of new methods directly into the
CGI::Application namespace simply by loading the module.
METHODS
session
This method will return the current CGI::Session object. The
CGI::Session object is created on the first call to this method, and
any subsequent calls will return the same object. This effectively
creates a singleton session object for the duration of the request.
CGI::Session will look for a cookie or param containing the session ID,
and create a new session if none is found. If "session_config" has not
been called before the first call to "session", then it will choose
some sane defaults to create the session object.
# retrieve the session object
my $session = $self->session;
- or -
# use the session object directly
my $language = $self->session->param('language');
session_config
This method can be used to customize the functionality of the
CGI::Application::Plugin::Session module. Calling this method does not
mean that a new session object will be immediately created. The
session object will not be created until the first call to
$self->session. This 'lazy loading' can prevent expensive file system
or database calls from being made if the session is not needed during
this request.
The recommended place to call "session_config" is in the "cgiapp_init"
stage of CGI::Application. If this method is called after the session
object has already been accessed, then it will die with an error
message.
If this method is not called at all then a reasonable set of defaults
will be used (the exact default values are defined below).
The following parameters are accepted:
CGI_SESSION_OPTIONS
This allows you to customize how the CGI::Session object is created
by providing a list of options that will be passed to the
CGI::Session constructor. Please see the documentation for
CGI::Session for the exact syntax of the parameters.
DEFAULT_EXPIRY
CGI::Session Allows you to set an expiry time for the session. You
can set the DEFAULT_EXPIRY option to have a default expiry time set
for all newly created sessions. It takes the same format as the
$session->expiry method of CGI::Session takes. Note that it is
only set for new session, not when a session is reloaded from the
store.
COOKIE_PARAMS
This allows you to customize the options that are used when
creating the session cookie. For example you could provide an
expiry time for the cookie by passing -expiry => '+24h'. The -name
and -value parameters for the cookie will be added automatically
unless you specifically override them by providing -name and/or
-value parameters. See the CGI::Cookie docs for the exact syntax
of the parameters.
NOTE: If you change the name of the cookie by passing a -name
parameter, remember to notify CGI::Session of the change by calling
CGI::Session->name('new_cookie_name').
SEND_COOKIE
If set to a true value, the module will automatically add a cookie
header to the outgoing headers if a new session is created (Since
the session module is lazy loaded, this will only happen if you
make a call to $self->session at some point to create the session
object). This option defaults to true. If it is set to false,
then no session cookies will be sent, which may be useful if you
prefer URL based sessions (it is up to you to pass the session ID
in this case).
The following example shows what options are set by default (ie this is
what you would get if you do not call session_config).
$self->session_config(
CGI_SESSION_OPTIONS => [ "driver:File", $self->query, {Directory=>'/tmp'} ],
COOKIE_PARAMS => {
-path => '/',
},
SEND_COOKIE => 1,
);
Here is a more customized example that uses the PostgreSQL driver and
sets an expiry and domain on the cookie.
$self->session_config(
CGI_SESSION_OPTIONS => [ "driver:PostgreSQL;serializer:Storable", $self->query, {Handle=>$dbh} ],
COOKIE_PARAMS => {
-domain => 'mydomain.com',
-expires => '+24h',
-path => '/',
-secure => 1,
},
);
session_cookie
This method will add a cookie to the outgoing headers containing the
session ID that was assigned by the CGI::Session module.
This method is called automatically the first time $self->session is
accessed if SEND_COOKIE was set true, which is the default, so it will
most likely never need to be called manually.
NOTE that if you do choose to call it manually that a session object
will automatically be created if it doesn't already exist. This
removes the lazy loading benefits of the plugin where a session is only
created/loaded when it is required.
It could be useful if you want to force the cookie header to be sent
out even if the session is not used on this request, or if you want to
manage the headers yourself by turning SEND_COOKIE to false.
# Force the cookie header to be sent including some
# custom cookie parameters
$self->session_cookie(-secure => 1, -expires => '+1w');
session_loaded
This method will let you know if the session object has been loaded
yet. In other words, it lets you know if $self->session has been
called.
sub cgiapp_postrun {
my $self = shift;
$self->session->flush if $self->session_loaded;;
}
session_recreate
This method will delete the existing session, and create a brand new
one for you with a new session ID. It copies over all existing
parameters into the new session.
This can be useful to protect against some login attacks when storing
authentication tokens in the session. Very briefly, an attacker loads
a page on your site and creates a session, then tries to trick a victim
into loading this page with the same session ID (possibly by embedding
it in a URL). Then if the victim follows the link and subsequently
logs into their account, the attacker will have a valid session ID
where the session is now logged in, and hence the attacker has access
to the victims account.
sub mylogin {
my $self = shift;
if ($newly_authenticated) {
$self->session_recreate;
}
}
session_delete
This method will perform a more comprehensive clean-up of the session,
calling both the CGI::Session delete() method, but also deleting the
cookie from the client, if you are using cookies.
sub logout {
my $self = shift;
$self->session_delete;
# what now? redirect user back to the homepage?
}
EXAMPLE
In a CGI::Application module:
# configure the session once during the init stage
sub cgiapp_init {
my $self = shift;
# Configure the session
$self->session_config(
CGI_SESSION_OPTIONS => [ "driver:PostgreSQL;serializer:Storable", $self->query, {Handle=>$self->dbh} ],
DEFAULT_EXPIRY => '+1w',
COOKIE_PARAMS => {
-expires => '+24h',
-path => '/',
},
SEND_COOKIE => 1,
);
}
sub cgiapp_prerun {
my $self = shift;
# Redirect to login, if necessary
unless ( $self->session->param('~logged-in') ) {
$self->prerun_mode('login');
}
}
sub my_runmode {
my $self = shift;
# Load the template
my $template = $self->load_tmpl('my_runmode.tmpl');
# Add all the session parameters to the template
$template->param($self->session->param_hashref());
# return the template output
return $template->output;
}
TODO
· I am considering adding support for other session modules in the
future, like Apache::Session and possibly others if there is a
demand.
· Possibly add some tests to make sure cookies are accepted by the
client.
· Allow a callback to be executed right after a session has been
created
SEE ALSO
CGI::Application, CGI::Session, perl(1)AUTHOR
Cees Hek <ceeshek@gmail.com>
LICENSE
Copyright (C) 2004, 2005 Cees Hek <ceeshek@gmail.com>
This library is free software. You can modify and or distribute it
under the same terms as Perl itself.
perl v5.14.12011-07-CGI::Application::Plugin::Session(3)
