I'm creating my own (multi threaded) ISAPI based website in C++ and I'm trying to implement correct session management.
The problem is that when a new session should be created, the session is created twice when using subsequent requests in the generated web page.
Here's how it works: - Client requests http://localhost and sends either no cookie or a cookie with an old session ID in it. - Server looks at the session cookie and feels that it needs to create a new one because it no longer exists: it prepares a header with a cookie in it with a new session ID and sends the complete header to the client (I tracked this with http live headers plugin in firefox and it is correct). It also prepares some data like the page and and stuff like that (not yet body data, as it is still processing data from the database and stuff like that) and sends what it has back to the client. - Client should have this new session cookie now, and sees the stylesheet link and immediately sends the stylesheet request http://localhost/css to my server. But... he still does this with the old session ID for some reason, not with the newly received one! - Server sees this request (with again an no longer existing session id), generates another new session and sends the new session id with a cookie along with the stylesheet data.
So the client has received two session id's now and will from now on keep using the second one as the first one is overwritten, but nevertheless the first page has used the wrong session (or actually, the second page has).
You could say that this is not a problem, but when I start using personalized stylesheets, I will have the wrong stylesheet on the first page and as the page will use AJAX to refresh the content (if available), it is possible that the stylesheet is never reloaded unless the client refreshes.
So, is this a problem that is always there when doing this kind of thing? Will the browser always send an old cookie although it has already received a new one but is still processing the page? Is this a problem that, for example PHP, also has?
Note: before all the discussions start about "use php instead" or something: I am rewriting a website that I had first written in PHP, it became popular, had thousands of (real) visitors every hour and started killing my server (the website doesn't make that kind of money that I can throw lots of servers at it). By writing it in C++, requests take 2ms instead of 200ms in PHP... I can optimize everything. By taking my time to develop this ISAPI correctly, it is safely multi-threaded and can be multi-processed, multi-servered. And most of all, I like the challenge.
Added note: It seems that the problem is only there when an old session exists in the cookies, because when I completely clear all cookies from my browser, and a new one is created and sent back to the client, the subsequent stylesheet request immediately uses the given session id. This seems to be some kind of proof that I'm doing something wrong when an old session id is sent... Should an existing cookie be deleted first? How?
Added note: The cookie is written with an expire-date one year ahead.
I have found out what the problem was, I was in the assumption that setting a cookie without specifying a path would result in making the session work on all paths on that domain. By using http://foo.bar/home as main page and http://foo.bar/home/css as stylesheet, internally translating that url to ?s1=home and ?s1=home&css=y, I was actually using two different paths according to the browser which did not pass the cookie to the css-request.
For some reason, they actually got together afterwards, I don't fully understand why.
Isn't this silly? Will people not often have a http://foo.bar/index.php and a http://foo.bar/css/style.css.php , just because they use subdirectories to keep their structure clean?
If anyone knows of a way to fix it, to make subpaths also work with the same cookies, let me know, but as I understand it from the definition of cookies, they are stuck within a specific path (although, it seems that if you specifically add a path other than /, it will work on subdirectories as well?)