Some HTTP clients only receive first 4k

Scott Stevenson scott at maxify.com
Mon May 23 12:06:07 PDT 2005


This is a follow-up to a post back in February.
<http://www.monkey.org/freebsd/archive/freebsd-questions/200502/ 
msg03071.html>


Summary: Certain HTTP clients only receive partial file contents. The  
majority of visitors have no problems, but those that do seem to  
experience it 100% of the time.

After looking into this further, I've discovered some interesting  
data points:


1. Affected clients consistently receive only the first 4096 bytes  
of .html and .css files. After that, they encounter a single garbage  
character (looks like a memory stomp), and then nothing.

2. At least two of the sites hosted on the machine are affected.

3. The issue can be reproduced via the W3 validator:

<http://validator.w3.org/check?uri=http%3A%2F%2Fcocoadevcentral.com% 
2Farticles%2F000085-test.html&charset=%28detect+automatically% 
29&doctype=%28detect+automatically%29&ss=1>

The bottom of this page shows the first 4k that was successfully  
fetched. It stops right in the middle of a tag. The same thing  
happens with this css file:

<http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F% 
2Fcocoadevcentral.com%2Fcss% 
2Fcocoadevcentral-20050401.css&usermedium=all>


4. At least in the case of the validator, the requests don't show up  
in Apache's access or error logs! This is consistently reproducible.

5. For some reason, clients consistently only get to byte 3883 (or  
perhaps 3884) in .php files, and then get the garbage character.


These same sites were previously running on the same network with the  
same version of apache. I've done hours of googling and also searched  
the freebsd-questions mailing list archives. I've gone out of my way  
to keep the installation as vanilla as possible. The system  
configuration is essentially:

FreeBSD 5.3-Release
Apache 2.0.50
PHP 5.0.2


Thanks,

    - Scott




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