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From "Plüm, Rüdiger, VF-Group" <ruediger.pl...@vodafone.com>
Subject RE: DoS with mod_deflate & range requests
Date Thu, 25 Aug 2011 06:56:55 GMT
 

> -----Original Message-----
> From: Stefan Fritsch 
> Sent: Donnerstag, 25. August 2011 08:21
> To: dev@httpd.apache.org
> Subject: Re: DoS with mod_deflate & range requests
> 
> On Thursday 25 August 2011, Jim Jagielski wrote:
> > OK then... we seem to be coalescing into some consensus here...
> > basically, if the client sends stuff which is brain-dead stupid,
> > we simply 2000 and send the whole kit-and-kaboodle.
> > 
> > I'd like to propose that we update the byterange filter to perform
> > the following:
> > 
> >   o coalesce all adjacent ranges, whether overlapping or not.
> >     (eg: 200-250,251-300 & 200-250,220-300 both merge to 200-300)
> 
> This may still confuse a broken client. Maybe we could omit that from 
> the 2.2 patch for now and only commit to 2.3.

Sounds like a plan. Or make it configurable with a default of off in 2.2.x
and on in 2.3.x

> 
> >   o We count:
> >      > the number of times a gap between ranges is <80bytes
> >      > the number of times we hit a descendent range
> >        (eg: 200-1000,2000-3000,1200-1500,4000-5000 would count as
> > 1) > the number of ranges total (post ascending merge)
> >     If any >= some config-time limit, we send a 200
> > 
> > This is a start and was chosen simply for ease of implementation...
> > We can then expand it to be more functional...
> > 
> > Comments?


Looks good. Plus we should implement the patch from Stefan below and then we
should be good.

> 
> Please also look at the patch at
> 
> http://mail-archives.apache.org/mod_mbox/httpd-
> dev/201108.mbox/%3C201108250138.49474.sf@sfritsch.de%3E
> 
> which greatly reduces the memory needed for the range requests.
> BTW, I won't have time to beat that into shape today. If anyone else 
> has, please go ahead.
> 

Regards

Rüdiger

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