session_set_cookie_params

As PHP's Session Control does not handle session lifetimes correctly when using session_set_cookie_params(), we need to do something in order to change the session expiry time every time the user visits our site. So, here's the problem.<?php  $lifetime=600;  session_set_cookie_params($lifetime);  session_start();?>This code doesn't change the lifetime of the session when the user gets back at our site or refreshes the page. The session WILL expire after $lifetime seconds, no matter how many times the user requests the page. So we just overwrite the session cookie as follows:<?php  $lifetime=600;  session_start();  setcookie(session_name(),session_id(),time()+$lifetime);?>And now we have the same session cookie with the lifetime set to the proper value.

The following appears to work for setting the SameSite attribute on session cookies for PHP < 7.3.<?php    $secure = true; // if you only want to receive the cookie over HTTPS    $httponly = true; // prevent JavaScript access to session cookie    $samesite = 'lax';    if(PHP_VERSION_ID < 70300) {        session_set_cookie_params($maxlifetime, '/; samesite='.$samesite, $_SERVER['HTTP_HOST'], $secure, $httponly);    } else {        session_set_cookie_params([            'lifetime' => $maxlifetime,            'path' => '/',            'domain' => $_SERVER['HTTP_HOST'],            'secure' => $secure,            'httponly' => $httponly,            'samesite' => $samesite        ]);    }?>

As per version PHP 7 session_start can include an option array this function became obsolete. All cookie settings (and many more) can be included in an option array as a parameter to session_start():<?php    session_start( [         'cookie_path' => '/',        'cookie_lifetime' => 300,        'cookie_secure' => true,        'cookie_httponly' => true,        'cookie_samesite' => 'lax',    ] );

One might want to be noted that the browsers are case-sensitive to the $path parameter.

For example, if you do this:
<?php
session_set_cookie_params(0,"/webapp/");
session_start();
?>

and you visit your site in this way:
example.com/WebApp/

You would get a new session on every request.

I'm not sure if this is the standard, but I see this happens on IE 6, Firefox 12 (Palemoon, actually), Chrome 19 (Portable version), and on both IIS and Apache.

Setting the domain for cookies in session_set_cookie_params() only affects the domain used for the session cookie which is set by PHP.

All other cookies set by calling the function setcookie() either:
i) Use the domain set explicitly in the call to setcookie()
or 
ii) Don't set the domain at all on the cookie and so the browser assumes it's for the current domain.

So to make all your cookies be available across all sub-domains of your site you need to do this:

<?php
$currentCookieParams = session_get_cookie_params();

$rootDomain = '.example.com';

session_set_cookie_params(
    $currentCookieParams["lifetime"],
    $currentCookieParams["path"],
    $rootDomain,
    $currentCookieParams["secure"],
    $currentCookieParams["httponly"]
);

session_name('mysessionname');
session_start();

setcookie($cookieName, $cookieValue, time() + 3600, '/', $rootDomain);
?>

when setting the path that the cookie is valid for, always remember to have that trailing '/'.CORRECT:session_set_cookie_params (0, '/yourpath/');INCORRECT:session_set_cookie_params (0, '/yourpath');no comment on how long it took me to realize that this was the cause of my authentication/session problems...

Please take note of the garbage collection "feature" on systems like Ubuntu and Debian.apt-get installs a cron script at /etc/cron.d/php5 that checks the session.gc_maxlifetime variable and then deletes all old sessions every 9 and 39 minutes.The problem is: If you set the maxlifetime for a specific virtual host, those settings will be ignored. Lets say you want your server to store sessions for only 30 minutes, but for one special website you want all sessions to be 24 hours. If you set the session.gc_maxlifetime in .htaccess, your apache conf or use ini_set in your code, it won't work and sessions will still be destroyed after 30 minutes. That's because /usr/lib/php5/maxlifetime (found in that cron file) will always return the value in your php.ini, not the values you set in .htaccess.A workaround is to set the maxlifetime to the maximum your sites require, and then configure a shorter maxlifetime in your .htaccess for those sites that don't need it. Another solution is to give the php5 file in /etc/cron.d sane values, ie, only let it run at 3am in the morning, but you'll have to remember to block the replacement of this file it every time you update php.

REMEMBER, that if you have a multi-subdomain site, you must put the following to enable a session id on the whole website:

<?php
session_set_cookie_params(0, '/', '.example.com');
session_start();
?>

Otherwise, you'll have 2 diffrent sessions on e.g. news.example.com and download.example.com

Something that has taken me some time to debug: session_set_cookie_params() does not work when the domain param is just a one level domain, like it was a TLD.I have a site in an intranet and our internal domain is .local, so trying to set the cookie session to the .local domain does not work:session_set_cookie_params(0, '/', '.local'); // Does not workIn all test I've done, setting the domain only works for SLDs and above: session_set_cookie_params(0 , '/', '.sld.local'); Does workThis is nothing to do with PHP but the http protocol, witch does not permit setting cookies for TLDs for obvious security reasons.

The below note is an excellent example of how to 'reset' the session expiration time upon a page refresh.However, take care to compensate for when the session expires and doesn't renew itself (a bug I believe). If the below example is run every time a script is executed, it will give an 'Undefined index <session name> error' after the session fails to renew. Precede it with and if isset() condition.<?phpprivate function startSession($time = 3600, $ses = 'MYSES') {    session_set_cookie_params($time);    session_name($ses);    session_start();    // Reset the expiration time upon page load    if (isset($_COOKIE[$ses]))      setcookie($ses, $_COOKIE[$ses], time() + $time, "/");}?>The above example states that a session will last an hour without a page refresh until it is scrapped. Upon a page refresh, the expiration time is reset back to one hour again. If you wish to give users the option of 'staying logged in forever', just feed startSession a value of '99999999', which should last about 3 years.

In Response to RC>23-Apr-2008 04:45>For anyone looking for which browsers support the HTTPOnly >flag, per my research:>>IE 6 SP 1 and higher.>Firefox 3 and higher.>Opera 9.50 and higher.Firefox 2.0 also supports them, but only since version 2.0.0.5.http://bugzilla.mozilla.org/show_bug.cgi?id=178993

For complete session cookie control I use this snippit<?php    session_set_cookie_params( [         'lifetime' => 0,        'path' => '/',        'domain' => $_SERVER['HTTP_HOST'],        'samesite' => 'Strict',    ] );    session_start( [         'name' => 'SESSION',        'sid_length' => 96,        'sid_bits_per_character' => 6,        'use_strict_mode' => true,        'referer_check' => $_SERVER['HTTP_HOST'],    ] );?>This will set the params to the recommended ones and generates a cookie  id of reasonable quality.

Unfortunately session_set_cookie_params() cannot be called during an active session, it'll just E_WARNING and return false, which means calling session_regenerate_id() (eg, during login to prevent a session fixation attack) could end up using old cookie settings (eg, not "SameSite=Strict")To ensure any future sessions are being created with the right cookie settings, you're better off to use ini_set() to set the cookie parameters - which is all that session_set_cookie_params() does under the hood anyway

The information above about this function that it can only be used BEFORE session_start depends on how you use it. Because its also useful AFTER a session has started as follows:Example you wand to change an already set value of the session cookie expire time:<?php // Here we start as usualsession_set_cookie_params('3600'); // 1 hoursession_start();// More code...// Now we found in some database that the user whishes// the cookie to expire after for example 10 minutes// we can change it instantly ! session_set_cookie_params('600'); // 10 minutes.session_regenerate_id(true); // This will delete old cookie and adopt new expire settings and the// old cookie variables in a new cookie?>Please note i only explained the browser (client) side changes of session cookie's expire time.

The first argument to session_set_cookie_params is the number of seconds in the future (based on the server's current time) that the session will expire.  So if you want your sessions to last 100 days:$expireTime = 60*60*24*100; // 100 dayssession_set_cookie_params($expireTime);I was using time()+$expireTime, which is WRONG (a lot of the session_set_cookie_params() examples I found get this wrong, but probably don't care because they are just doing "infinite" sessions).

[Editor's Note:

Rasmus' Solution from the PHP-General list:

Just use a session cookie (by not providing an expiry time) and add the
server's expiry timestamp to the value of the cookie.  Then when you get
that cookie sent to you, check it against your server's time and make the
decision on whether to accept the cookie or not based on that.

That way you are immune from people not having their system clocks set
right.

-Rasmus

--zak@php.net]

A couple things I noticed when using this. I think it only works if you set the session_set_cookie_params() function BEFORE the session_start() function.

Also, when you set the "lifetime" on the cookie, it takes the seconds offset from the SERVER. it sends the cookie encoded to timeout at the SERVER time. So if your server is +2 minutes ahead of the client, and you set the cookie to timeout after 30 seconds, the client actually has 2 minutes and 30 seconds before the cookie times out. I don't know if there's any way that this can be patched in future versions, and the only alternative I think is setting cookies in javascript, which is hardly the point when using all these specific session functions.

"Info at xyzsite dot ru" writes that Internet Explorer does not correctly handle cookies whose domain contains an underscore character.However, There's a good reason for this apparently faulty behavior: the underscore character is forbidden in DNS names.  RFC 3696 says:"The labels ... that make up a domain name must consist of only the ASCII alphabetic and numeric characters, plus the hyphen.  No other symbols or punctuation characters are permitted, nor is blank space."If the underscore works in Mozilla or other browsers, it's only because they are being lenient in the validation of domain names.

Cross-domain Cookies do work in all browsers (path '/' server '.example.com'), except the case you try it in IE6/7 and the server name is retreived from :etc/hosts: file, in that case the cookie won't be even saved.

i found it somewhat difficult to work with sessions due to the documentation not really denoting the necessity for the session name to be set via session_name() in order for session_set_cookie_params() to be of any use.  i found no reference to session_name() in this article, and my session functions would have been a disastrous mess were it not for a friend familiar with session.so, in essence, for anybody wondering about where to start: declare a session name before using session_set_cookie_params(), otherwise you might agitate php to the point of committing some atrocity against your webserver.

Further to "info at xyzsite dot ru" and William Leslie, Safari on OS X also doesn't honour cookies with an underscore in the subdomain.The workaround I've found is to specify the parent domain as the cookie domain -- instead of "bad_name.example.com", set the path to ".example.com"; it's suboptimal, but gets the job done.