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Date: Thu, 15 Mar 2007 13:12:15 +0100
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Subject: Re: [PHP-DEV] A request for code change : Repeated opening and closing
 the session leads to a LOT of Set-Cookie headers.
From: sesser@hardened-php.net (Stefan Esser)

Hello Richard,

your problem is a bug in the session extension.

My suggested but not tested workaround is that you simply call

ini_set("session.use_cookies", 0);

after the first time you call session_write_close(). This will stop the
session extension from sending further cookies during a single request.

Stefan Esser

Richard Quadling schrieb:
> Hi.
>
> I have a webapp which uses Ajax to initiate a process on the server
> which could take several minutes to complete and will go through many
> steps to before the task is finished.
>
> In that script, I update the session to indicate the current position
> of the process.
>
> When the user initiates the main process, another AJAX request is made
> which examines the state of the main process (via the session) and
> reports back to the client - keeps them interested. The user can also
> abort the process and closing the browser also triggers an abort.
>
> All works FINE in FF. In IE, I'm getting a "Page cannot be displayed"
> sort of errror (having to debug the response to see this). This SEEMS
> to relate to the fact that I am closing and opening the session in the
> first script as I want to keep the session file uptodate. The process
> script only has 1 output and that is the final result at the end of
> the script.
>
> I also tested this using a telnet connection to the webserver and sent
> the same headers that FireFox generated (captured via FireBub) and it
> bombed just before the data arrived (Lost connection).
>
> e.g.
>
> <?php
> function UpdateSession($s_Progress) {
> session_start();
> $_SESSION['Progress'] = $s_Progress;
> session_write_close();
> }
>
> //Stage 1
> UpdateSession('Loading preferences');
> ...
> //Stage 10
> UpdateSession('Report generated and is now available at <a href="' .
> MakeWebPath(realpath($s_PDFReport)) . '">here</a>.');
> echo rawurlencode(json_encode(array('SUCCESS' =>
> MakeWebPath(realpath($s_PDFReport)))));
> ?>
>
>
> As a consequence, I get ...
>
> Set-Cookie: PHPSESSID=uWPNRja2oT0PHPDCLqUiMzXiz1b; path=/
> Set-Cookie: PHPSESSID=uWPNRja2oT0PHPDCLqUiMzXiz1b; path=/
> Set-Cookie: PHPSESSID=uWPNRja2oT0PHPDCLqUiMzXiz1b; path=/
> ...
>
> LOTS of times followed by a "Page cannot be displayed". If I use
> Ethereal to examine the data, it is all there and is the same via IE
> and FF, it is just the IE doesn't like the REALLY long header.
>
> I accept this is normal behaviour and IE should "deal with it", but ...
>
> Is there any mileage in stopping session_start from sending the same
> header if it has already been sent? If the PHPSESSID is different,
> then fine, send it.
>
>> From looking at session.c and php_session.h, I think the following
> changes would suffice.
>
> 1 - The typedef struct _php_ps_globals {} needs to include ...
>
> char *prev_id;
>
>
> 2 - In PHP_GINIT_FUNCTION(ps) ...
>
> ps_globals->prev_id = NULL;
>
>
> 3 - In php_session_send_cookie(TSRMLS_D), do a comparison of prev_id
> and id (taking into account prev_id could be NULL) and if different,
> then allow the cookie to be set and to update prev_id with the id
> sent.
>
>
> Some other issues, if other parts of the cookie are altered, then
> maybe rather than just examining the ID, the entire cookie should be
> remembered.
>
>
> Assuming that the cookie would be identical, repeatedly sending it to
> the client when the session is repeatedly opened is a pain and I think
> can easily be fixed.
>
>
> Thank you for your time.
>
> Richard Quadling.
>
>
>