session_set_cookie_params()

(PHP 4, PHP 5, PHP 7)

设置会话 cookie 参数

说明

session_set_cookie_params(int $lifetime[,string $path[,string $domain[,bool $secure=FALSE[,bool $httponly=FALSE]]]]): bool

session_set_cookie_params(array $options): bool

Cookie 参数可以在php.ini文件中定义，本函数仅在当前脚本执行过程中有效。因此，如果要通过函数修改 cookie 参数，需要对每个请求都要在调用session_start()函数之前调用session_set_cookie_params()函数。

本函数会修改运行期 ini 设置值，可以通过ini_get()函数获取这些值。

参数

$lifetime

Cookie 的生命周期，以秒为单位。

$path

此 cookie 的有效路径。 on the domain where 设置为“/”表示对于本域上所有的路径此 cookie 都可用。

$domain

Cookie 的作用域。例如：“www.php.net”。如果要让 cookie 在所有的子域中都可用，此参数必须以点（.）开头，例如：“.php.net”。

$secure

设置为TRUE表示 cookie 仅在使用安全链接时可用。

$httponly

设置为TRUE表示 PHP 发送 cookie 的时候会使用httponly标记。

$options

此参数为一个键值对关联array，可能包含的键有：lifetime，path，domain,secure，httponly以及samesite。这些键对应的值和上面所述的一样。samesite键对应的值可以是Lax或者Strict。如果可以接受的键在传入的数组中不存在，那么会采用这些键对应的默认值作为运行时的值。如果不提供samesite键，那么就设置 SameSite cookie 属性。

返回值

成功时返回TRUE，或者在失败时返回FALSE。

更新日志

参见

• session.cookie_lifetime
• session.cookie_path
• session.cookie_domain
• session.cookie_secure
• session.cookie_httponly
• session.cookie_samesite
• session_get_cookie_params() 获取会话 cookie 参数

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.

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);
?>

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.

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

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.

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 work
In all test I've done, setting the domain only works for SLDs and above: 
session_set_cookie_params(0 , '/', '.sld.local'); Does work
This is nothing to do with PHP but the http protocol, witch does not permit setting cookies for TLDs for obvious security reasons.

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

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 usual
session_set_cookie_params('3600'); // 1 hour
session_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.

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.

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.
<?php
private 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.

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.

[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.

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:
$expireTime = 60*60*24*100; // 100 days
session_set_cookie_params($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).

Just one more bad situation - cookies in Internet Explorer do not work with '_' in domain name. FF and Opera are O.K. So if your hostname is like test_host.example.com, IE cookies will not function correctly/

It appears that if you are setting a session cookie on https://subdomain123.example.com for .example.com that the default of the secure cookie is not false but true.
So your cookie won't work on http://subdomainxyz.example.com unless you set the secure option to false.

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.
As of Safari 3.1.1 (April 2008), Safari did not yet support this flag.
This cookie flag was developed by Microsoft and is slowly making its way into other browsers: http://msdn2.microsoft.com/en-us/library/ms533046.aspx