#25175 [Fbk->Bgs]: session.use_trans_sid causes ob_get_length() to return incorrect value

ID: 25175 Updated by: moriyoshi@php.net Reported By: phpbug at paypc dot com -Status: Feedback +Status: Bogus Bug Type: Session related Operating System: Linux 2.4 PHP Version: 4.3.2 New Comment: Technically, this is not a bug. Please see the following description. trans-sid (aka URL rewriter) utilises output buffering facility and it virtually works as a top level output buffer handler in the hanlder stack. Thus ob_get_length() might not reflect the actual length of the content being sent to the user-agent because trans-sid handler automatically rewrites all URL referrers of the tags that are specified by url_rewriter.tags in your php.ini so they contains session identifiers if the content includes any one of those tags. So, in any case ob_get_length() returns the size of the intact content, on which no URL transformation is applied yet. The same thing applies to zlib.output_compression. Then let me mark this PR bogus since this is not a bug in PHP. But this behaviour is rather confusing and will be addressed in the future versions. BTW, how on earth did you know I'm Japanese? :) Previous Comments: ------------------------------------------------------------------------ [2003-08-21 19:05:53] sniper@php.net Please try using this CVS snapshot: http://snaps.php.net/php4-STABLE-latest.tar.gz For Windows: http://snaps.php.net/win32/php4-win32-STABLE-latest.zip ------------------------------------------------------------------------ [2003-08-21 04:33:50] phpbug at paypc dot com *ARGH* I hate "thinkoes" -- it should be obvious from context (and perusing my phpconfig) that I've TURNED OFF enable_trans_sid, not turned it on. Upon re-reading my posting (naturally AFTER I'd hit submit), I noted the think-o. My apologies. =Apollyon= ------------------------------------------------------------------------ [2003-08-21 04:31:10] phpbug at paypc dot com OK, let me put forth some declarations so we're talking apples and apples. My test method: echo -e "GET /legal/tester.php HTTP/1.1\r\nHost: 127.0.0.1\r\n" | nc 127.0.0.1 80 > dump I wish to eliminate any possible "post-processing" or browser-variations. IE: "nc" is netcat, a commonly available network tool. OK, onto the results of my tests. I copied and pasted sniper's code *EXACTLY* as presented, with whitespaces and line spacing as entered. I obtained identical results with both lynx and my netcat method, though lynx probably doesn't support HTTP/1.1 because there was an additional header. With Lynx Version 2.8.3rel.1: HTTP/1.1 200 OK Date: Thu, 21 Aug 2003 09:10:16 GMT Server: Apache/1.3.27 Ben-SSL/1.48 Connection-Type: Keep-Alive Content-Length: 4 Connection: close <<<<<<<<<<<<< Additional header Content-Type: text/html With netcat: HTTP/1.1 200 OK Date: Thu, 21 Aug 2003 09:10:55 GMT Server: Apache/1.3.27 Ben-SSL/1.48 Connection-Type: Keep-Alive Content-Length: 4 Content-Type: text/html In comparing the actual bytes sent over the wire against the advertised content-length, the Content-Length header is correct. If you wish to inspect my PHP build and setup configuration, you may do so at: <http://hollywood.paypc.com/config4phpbugmasters> (I will be removing this after 24 hours.) And yes, it's pretty loaded. And yes, trans_sid is enabled, but in all of my test harnesses which employ sessions, I've enabled cookies - and they are created/used by the browsers involved. ******* AHHHHHHAAAA ******* Arigatoo gozaimashita to Moriyoshi-san for cautioning me to turn on trans_sid, because when I disable it in my global php.ini, the discrepancy disappears! For my "complex" web-application which formerly reported bad sizing, I received the following header (after turning off trans_sid): ---------------------------- HTTP/1.1 200 OK Date: Thu, 21 Aug 2003 09:20:47 GMT Server: Apache/1.3.27 Ben-SSL/1.48 Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Pragma: no-cache Set-Cookie: PHPSESSID=a1c8bfb3f409580e57206d7c19eac473; path=/ Expires: Thu, 19 Nov 1981 08:52:00 GMT Content-Length: 2825 Content-Type: text/html -------------------------------- And doing a wc -c on the content-portion matches this size exactly (with my netcat test). Third-party validation via usage of <http://www.ircache.net/cgi-bin/cacheability.py> confirms an exact match of advertised Content-Length and what's actually received. And lastly, and most importantly, the IE "hang" bug while accessing this web application via an intranet is gone. OK, fine, trans_sid broke it. Why? And should it have? I'm suspicious that the Esteemed Moriyoshi-san nailed this specific setting in advance, as if to suspect it being a potential cause for buggage. Inquiring minds want to know - if it's by design, please add it to the documentation and FAQ. I know alot of things about the ob_ functions are unusual and cause some people hardship (of their own making). This one came out of left field. =Apollyon= ------------------------------------------------------------------------ [2003-08-21 00:10:00] moriyoshi@php.net > Set-Cookie: PHPSESSID=2989258979bd07405999448563ef4bfc; path=/ Perhaps you seem to have enabled session.use_trans_sid. If so, first turn it off before trying the above script provided by sniper. ------------------------------------------------------------------------ [2003-08-20 22:54:00] sniper@php.net try this script: <?php ob_start(); ?> foo <?php header("Connection-Type: Keep-Alive"); header('Content-Length: ' . ob_get_length()); ob_end_flush(); echo ob_get_length(); ?> And access it with this command: # lynx -head lynx -dump -head http://localhost/test.php I get this (correct) output: HTTP/1.1 200 OK Date: Thu, 21 Aug 2003 03:52:44 GMT Server: Apache/1.3.27 (Unix) PHP/4.3.3RC5-dev X-Powered-By: PHP/4.3.3RC5-dev Connection-Type: Keep-Alive Content-Length: 4 Connection: close Content-Type: text/html ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/25175 -- Edit this bug report at http://bugs.php.net/?id=25175&edit=1