Ubuntu Manpage: CGI::Simple::Cookie - Interface to HTTP cookies

Provided by: libcgi-simple-perl_1.281-1_all

NAME

       CGI::Simple::Cookie - Interface to HTTP cookies

SYNOPSIS

           use CGI::Simple::Standard qw(header);
           use CGI::Simple::Cookie;

           # Create new cookies and send them
           $cookie1 = CGI::Simple::Cookie->new( -name=>'ID', -value=>123456 );
           $cookie2 = CGI::Simple::Cookie->new( -name=>'preferences',
                                               -value=>{ font => Helvetica,
                                                         size => 12 }
                                             );
           print header( -cookie=>[$cookie1,$cookie2] );

           # fetch existing cookies
           %cookies = CGI::Simple::Cookie->fetch;
           $id = $cookies{'ID'}->value;

           # create cookies returned from an external source
           %cookies = CGI::Simple::Cookie->parse($ENV{COOKIE});

DESCRIPTION

       CGI::Simple::Cookie is an interface to HTTP/1.1 cookies, a mechanism that allows Web servers to store
       persistent information on the browser's side of the connection. Although CGI::Simple::Cookie is intended
       to be used in conjunction with CGI::Simple (and is in fact used by it internally), you can use this
       module independently.

       For full information on cookies see:

           http://tools.ietf.org/html/rfc2109
           http://tools.ietf.org/html/rfc2965
           https://dcthetall.github.io/CHIPS-spec/draft-cutler-httpbis-partitioned-cookies.html

USING CGI::Simple::Cookie

CGI::Simple::Cookie is object oriented. Each cookie object has a name and a value. The name is any
scalar value. The value is any scalar or array value (associative arrays are also allowed). Cookies
also have several optional attributes, including:

1. expiration date
The expiration date tells the browser how long to hang on to the cookie. If the cookie specifies an
expiration date in the future, the browser will store the cookie information in a disk file and
return it to the server every time the user reconnects (until the expiration date is reached). If
the cookie species an expiration date in the past, the browser will remove the cookie from the disk
file. If the expiration date is not specified, the cookie will persist only until the user quits the
browser.

2. domain
This is a partial or complete domain name for which the cookie is valid. The browser will return the
cookie to any host that matches the partial domain name. For example, if you specify a domain name
of ".capricorn.com", then the browser will return the cookie to web servers running on any of the
machines "www.capricorn.com", "ftp.capricorn.com", "feckless.capricorn.com", etc. Domain names must
contain at least two periods to prevent attempts to match on top level domains like ".edu". If no
domain is specified, then the browser will only return the cookie to servers on the host the cookie
originated from.

3. path
If you provide a cookie path attribute, the browser will check it against your script's URL before
returning the cookie. For example, if you specify the path "/cgi-bin", then the cookie will be
returned to each of the scripts "/cgi-bin/tally.pl", "/cgi-bin/order.pl", and
"/cgi-bin/customer_service/complain.pl", but not to the script "/cgi-private/site_admin.pl". By
default, the path is set to "/", so that all scripts at your site will receive the cookie.

4. secure flag
If the "secure" attribute is set, the cookie will only be sent to your script if the CGI request is
occurring on a secure channel, such as SSL.

5. HttpOnly flag
If the "httponly" attribute is set, the cookie will only be accessible through HTTP Requests. This
cookie will be inaccessible via JavaScript (to prevent XSS attacks).

See this URL for more information including supported browsers:

<http://www.owasp.org/index.php/HTTPOnly>

6. samesite flag
Allowed settings are "Strict", "Lax" and "None".

As of April 2018, support is limited mostly to recent releases of Chrome and Opera.

<https://tools.ietf.org/html/draft-west-first-party-cookies-07>

7. priority flag
This attribute allows servers to specify a retention priority for HTTP cookies that will be respected
by user agents during cookie eviction.

Allowed settings are "Low", "Medium" and "High".

8. partitioned flag
If the "partitioned" attribute is set, the cookie is restricted to the contexts in which a cookie is
available to only those whose top-level document is same-site with the top-level document that
initiated the request that created the cookie.

<https://dcthetall.github.io/CHIPS-spec/draft-cutler-httpbis-partitioned-cookies.html>

Creating New Cookies
$c = CGI::Simple::Cookie->new( -name => 'foo',
-value => 'bar',
-expires => '+3M',
-max-age => '+3M',
-domain => '.capricorn.com',
-path => '/cgi-bin/database',
-secure => 1,
-samesite => 'Lax',
);

Create cookies from scratch with the new method. The -name and -value parameters are required. The name
must be a scalar value. The value can be a scalar, an array reference, or a hash reference. (At some
point in the future cookies will support one of the Perl object serialization protocols for full
generality).

-expires accepts any of the relative or absolute date formats recognized by CGI::Simple, for example
"+3M" for three months in the future. See CGI::Simple's documentation for details.

-max-age accepts the same data formats as -expires, but sets a relative value instead of an absolute like
-expires. This is intended to be more secure since a clock could be changed to fake an absolute time. In
practice, as of 2011, "-max-age" still does not enjoy the widespread support that "-expires" has. You can
set both, and browsers that support "-max-age" should ignore the "Expires" header. The drawback to this
approach is the bit of bandwidth for sending an extra header on each cookie.

-domain points to a domain name or to a fully qualified host name. If not specified, the cookie will be
returned only to the Web server that created it.

-path points to a partial URL on the current server. The cookie will be returned to all URLs beginning
with the specified path. If not specified, it defaults to '/', which returns the cookie to all pages at
your site.

-secure if set to a true value instructs the browser to return the cookie only when a cryptographic
protocol is in use.

-httponly if set to a true value, the cookie will not be accessible via JavaScript.

-samesite may be "Lax", "Strict" or "None" and is an evolving part of the standards for cookies. Please
refer to current documentation regarding it.

Sending the Cookie to the Browser
Within a CGI script you can send a cookie to the browser by creating one or more Set-Cookie: fields in
the HTTP header. Here is a typical sequence:

$c = CGI::Simple::Cookie->new( -name => 'foo',
-value => ['bar','baz'],
-expires => '+3M'
);

print "Set-Cookie: $c\n";
print "Content-Type: text/html\n\n";

To send more than one cookie, create several Set-Cookie: fields. Alternatively, you may concatenate the
cookies together with "; " and send them in one field.

If you are using CGI::Simple, you send cookies by providing a -cookie argument to the header() method:

print header( -cookie=>$c );

Mod_perl users can set cookies using the request object's header_out() method:

$r->header_out('Set-Cookie',$c);

Internally, Cookie overloads the "" operator to call its as_string() method when incorporated into the
HTTP header. as_string() turns the Cookie's internal representation into an RFC-compliant text
representation. You may call as_string() yourself if you prefer:

print "Set-Cookie: ",$c->as_string,"\n";

Recovering Previous Cookies
%cookies = CGI::Simple::Cookie->fetch;

fetch returns an associative array consisting of all cookies returned by the browser. The keys of the
array are the cookie names. You can iterate through the cookies this way:

%cookies = CGI::Simple::Cookie->fetch;
foreach (keys %cookies) {
do_something($cookies{$_});
}

In a scalar context, fetch() returns a hash reference, which may be more efficient if you are
manipulating multiple cookies.

CGI::Simple uses the URL escaping methods to save and restore reserved characters in its cookies. If you
are trying to retrieve a cookie set by a foreign server, this escaping method may trip you up. Use
raw_fetch() instead, which has the same semantics as fetch(), but performs no unescaping.

You may also retrieve cookies that were stored in some external form using the parse() class method:

$COOKIES = `cat /usr/tmp/Cookie_stash`;
%cookies = CGI::Simple::Cookie->parse($COOKIES);

Manipulating Cookies
Cookie objects have a series of accessor methods to get and set cookie attributes. Each accessor has a
similar syntax. Called without arguments, the accessor returns the current value of the attribute.
Called with an argument, the accessor changes the attribute and returns its new value.

name()
Get or set the cookie's name. Example:

$name = $c->name;
$new_name = $c->name('fred');

value()
Get or set the cookie's value. Example:

$value = $c->value;
@new_value = $c->value(['a','b','c','d']);

value() is context sensitive. In a list context it will return the current value of the cookie as an
array. In a scalar context it will return the first value of a multivalued cookie.

domain()
Get or set the cookie's domain.

path()
Get or set the cookie's path.

expires()
Get or set the cookie's expiration time.

max_age()
Get or set the cookie's maximum age.

secure()
Get or set the cookie's secure flag.

httponly()
Get or set the cookie's HttpOnly flag.

samesite()
Get or set the cookie's samesite value.

priority()
Get or set the cookie's priority value.

partitioned()
Get or set the cookies partitioned flag.

AUTHOR INFORMATION

       Original  version copyright 1997-1998, Lincoln D. Stein.  All rights reserved.  Originally copyright 2001
       Dr James Freeman <jfreeman@tassie.net.au> This release by Andy Armstrong <andy@hexten.net>

       This library is free software; you can redistribute it and/or modify it under  the  same  terms  as  Perl
       itself.

       Address bug reports and comments to: andy@hexten.net

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