On Fri, Oct 10, 2008 at 12:30 PM, Amos Jeffries <squid3@xxxxxxxxxxxxx> wrote: > Richard Wall wrote: >> >> Hi, >> >> I've been reading through the archive looking for information about >> squid 2.6 and windows update caching. The FAQ mentions problems with >> range offsets but it's not really clear which versions of Squid this >> applies to. > > All versions. The FAQ was the result of my experiments mid last year. With > some tweaks made early his year since Vista came out. > We haven't done a intensive experiments with Vista yet. Hi Amos, I'm still investigating Windows Update caching (with 2.6.STABLE17/18) First of all, I have been doing some tests to try and find out the problem with Squid and Content-Range requests. * I watch the squid logs as a vista box does its automatic updates and I can see that *some* of its requests use ranges. (so far I have only seen these when it requests .psf files...some of which seem to be very large files...so the range request makes sense) See: http://groups.google.hr/group/microsoft.public.windowsupdate/browse_thread/thread/af5db07dc2db9713 # zcat squid.log.192.168.1.119.2008-10-16.gz | grep "multipart/byteranges" | awk '{print $7}' | uniq | while read URL; do echo $URL; wget --spider $URL 2>&1 | grep Length; done http://www.download.windowsupdate.com/msdownload/update/software/secu/2008/10/windows6.0-kb956390-x86_2d03c4b14b5bad88510380c14acd2bffc26436a7.psf Length: 91,225,471 (87M) [application/octet-stream] http://www.download.windowsupdate.com/msdownload/update/software/secu/2008/05/windows6.0-kb950762-x86_0cc2989b92bc968e143e1eeae8817f08907fd715.psf Length: 834,868 (815K) [application/octet-stream] http://www.download.windowsupdate.com/msdownload/update/software/secu/2008/03/windows6.0-kb948590-x86_ed27763e42ee2e20e676d9f6aa13f18b84d7bc96.psf Length: 755,232 (738K) [application/octet-stream] http://www.download.windowsupdate.com/msdownload/update/software/crup/2008/09/windows6.0-kb955302-x86_1e40fd3ae8f95723dbd76f837ba096adb25f3829.psf Length: 7,003,447 (6.7M) [application/octet-stream] ... * I have found that curl can make range requests so I've been using it to test how Squid behaves....and it seems to do the right thing. eg - First ask for a range : The correct range is returned X-Cache: MISS - Repeat the range request : The correct range is returned X-Cache: MISS - Request the entire file: The entire file is correctly returned X-Cache: MISS - Repeat the request: X-Cache: HIT - Repeat the previous range request: X-Cache: HIT - Request a different range: X-Cache: HIT curl --range 1000-1002 --header Pragma: -v -x http://127.0.0.1:3128 http://www.download.windowsupdate.com/msdownload/update/software/secu/2008/05/windows6.0-kb950762-x86_0cc2989b92bc968e143e1eeae8817f08907fd715.psf > /dev/null Looking back through the archive I find this conversation from 2005: http://www.squid-cache.org/mail-archive/squid-users/200504/0669.html ...but the behaviour there sounds like a result of setting: range_offset_limit -1 Seems to me that Squid should do a good job of Windows Update caching. There is another thread discussing how to override MS update cache control headers: http://www.squid-cache.org/mail-archive/squid-users/200508/0596.html ....but I don't see anything evil in the server response headers today. I guess the client may be sending no-cache headers...I'll double check that later. Is there some other case that I'm missing? >> I'm going to experiment, but if anyone has any positive or >> negative experience of Squid and windows update caching, I'd be really >> interested to hear from you. >> >> In case Squid cannot do windows update caching by its self, I'm also >> looking at integrating Update Accelerator >> (http://update-accelerator.advproxy.net/) script with standard squid >> 2.6 and wondered if anyone else had any experience of this. >> The update accelerator script is just a perl wrapper around wget which >> is configured as a Squid url_rewrite_program. It's not clear to me >> what this script is doing that Squid wouldn't do by its self. > > Strange indeed. I got update accelerator working with Squid but I'm still not convinced that it's necessary (see above). -RichardW.
