SetCookie Expire Time

[alsaffar]

Hi everybody,

Subject: Setcookie expiration time.

Goal: To expire the cookie after 15 minutes (900 seconds) from setting.

Problem Description:
- When I set the expire parameter to time()+900, its taking the server timestamp where its in my case (time in GMT + 900).

(i.e. timestamp is 09:00AM GMT + 900 seconds -> expire at 09:15AM).

• If the user who is surfing my site is living in a country which its time is GMT+2, the cookie will not set (as I'm testing!) since the expiration time is in the past.

(i.e. User current loacl time is 09:00AM GMT + 2 -> 11:00AM) and the expire time of the cookie is 09:15AM as its returned from the setcookie function, which is in the past with respect to the user's browser local time.

Question:
- How can I overcome this problem? Since the user that surfing my site can be in any country in the world with its time is GMT+(X)hours, not necssary having the same server time. How can I set the cookie to the user's local time not the server time?

Please help my guys Im stucked 😉

[laserlight]

There should be no problem, time() is that of the server, not of the client.

EDIT:
hmm... I see your point, since there might be a problem since the client is the one deleting the cookie.

However, I dont remember having this problem at all, even on servers with many hours apart.

[laserlight]

Did a bit of research, and perhaps one reason why I never faced this problem would be because I started on PHP late, when browsers had a better method of determining cookie expiration time (or something like that).

In any case, one hack mentioned on phpbuilder (mailing list?) would be to use a semaphore file, or some other scratch file, to determine when to delete the cookie.

[yelvington]

This really isn't a problem.

Within PHP, you're working with GMT any time you call the time() function, regardless of the time zone of your server. If you do this:

$now = time();

... you get the number of seconds since Jan 1 1970 GMT. Construct your expiration time by adding to that.

If you need to explicitly set an expiration calendar date/time, use gmmktime().

The PHP set_cookie() function properly formats the timestamp as a string, again based on GMT.

It is the responsibility of the browser to know its own time zone and to do any necessary math to figure out when to expire the cookie.

If you have users for which this code is not working, then it is likely that their system clocks are not set properly, or their system is not properly configured for their time zones.

Judging from the number of stupid timestamps I see in my email inbox, that's actually a fairly common problem. But it's the user's problem to fix. Nothing you can do about it.