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From Abu Hurayrah <abu_huray...@almaghrib.org>
Subject Re: [users@httpd] Strange user-agents and requests causing Apache processes to explode!
Date Mon, 25 Apr 2005 08:37:45 GMT
Actually, I think I discovered my own solution.  It turns out by 
hijacking Apache's normal role of serving files and delegating it to my 
own PHP script, I've caused a bit of a confusion, and Apache still 
attempts to answer requests for partial content, while my script is only 
adept at deliver the whole thing from start to finish.

What ends up happening, I think, is that Apache will load the *entire* 
file into memory, and then take care of the partial-content requests - I 
don't know if it is successfully, because these requests are often 
repeated, much to the dismay of my memory controller!  This would 
explain why the processes were maxing out at 140+MB - that is, 
coincidentally, around the same size as the largest files I'm serving up.

What I have to do is rewrite my entire routine to handle the HTTP 
requests themselves, which shouldn't be amazingly hard - but it does 
through a wrench in the works.  I'll try and update this thread if I 
finish my solution.

I apologize, again, if I am violating any of the rules or ettiquettes of 
posting on this usergroup - I just imagine this issue might be a concern 
for others as well that might be in a similar situation as mine.

Abu Hurayrah wrote:

> Greets to all!
>
> I apologize in advance if I am violating some ettiquettes with regards 
> to this mailing list - I joined specifically because I have been 
> experiencing some strange behavior that is disrupting my server.
>
> I've included three chunks of my server log that chronicle the 
> requests that relate to my problem, each one with some different 
> information.  These are located at the end of my message (probably 
> should be left out of any replies)
>
> Essentially, what is happening is some kind of a request is causing my 
> server's Apache's processes to mushroom in size - going from a normal 
> 15 - 30 MB all the way up to 140+MB
>
> And with 10 - 20 Apache processes running on a system with 1GB of RAM, 
> this can be a problem. : -D
>
> The requests are occurring with a custom download script that I have 
> written, through which ALL download requests occur. I've optimized it 
> to use very little memory by reading in the files in small chunks.  I 
> rarely have any problems except with requests that follow a specific 
> pattern.  I thought the problem was in my script, but I highly doubt 
> it because I cannot duplicate it myself - plus "normal" requests, even 
> a barrage of them, trigger no issues whatsoever.
>
> I was previously running Apache 2.0.52, but after reading up on it, I 
> discovered there was a security hole that caused a problem similar to 
> what I was having:
>
> http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0942
>
> So I upgraded to the latest release (2.0.54) - and I'm STILL having 
> the same problem.
>
> The requests usually have a User-Agent string of the following: 
> "Mozilla/4.0 (compatible; MSIE 5.00; Windows 98)".  This is easy 
> enough to BrowserMatch out with an environmental variable, but not in 
> every case does this work.
>
> I think I've talked enough, so I want to see if anyone else is 
> experiencing the same problem or not.
>

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