Handling of Urlencoded string in URL in Varnish

Per Buer perbu at varnish-software.com
Mon Apr 7 11:25:35 CEST 2014

Hi Jason.

Docwilco from Fastly has written an URL encoder/decorder VMOD that you can
use. You could run it through it twice or patch it do uppcase/lowercase the


Varnish itself doesn't try to interpret the URL much.


On Mon, Apr 7, 2014 at 11:01 AM, Jason Woods <devel at jasonwoods.me.uk> wrote:

> Hi all,
> I apologise if this is the wrong place for a general question / request
> for advice about Varnish. If there's a better place, please do let me know!
> I have a URL (that I've modified) that has an url encoded sequence, e.g.
> /block/jason%E2%80%99s-first-blog
> That sequence is a fancy apostrophe. It must have snuck into the title
> through a copy and paste or something, but it brought up some caching issue
> with the encoding.
> We notice that when we printed the URL links in HTML, it was printed as
> above, %E2%80%99. But when some browsers appear to request the URL, it
> seems to lowercase the encoding to %e2%80%99. So we ended up with two
> instances of this page cached. Presumedly the browser decoded the URL and
> then re-encoded it for the request.
> This meant that when we modified the blog post we sent a PURGE for
> %E2%80%99 - but it only updated one instance of the cache, and there were
> many people seeing the old version. We ended up having to manually PURGE
> the other cache.
> Would I be right in saying that the following two URL are identical, and
> should have one instance of cache? I'm not sure if this is accounted for in
> RFC/ISO of anything. URLs are generally case-sensitive IIRC but is it true
> also for encodings?
> /block/jason%E2%80%99s-first-blog
> /block/jason%e2%80%99s-first-blog
> Is there a way for Varnish to decode the URL before hashing for the cache?
> Or is there a better approach?
> We are using varnish-3.0.3 revision 9e6a70f, which may be quite old, maybe
> this is fixed in a recent version?
> Thanks!
> Jason
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 <http://www.varnish-software.com/> *Per Buer*
CTO | Varnish Software
Phone: +47 958 39 117 | Skype: per.buer
We Make Websites Fly!

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