[squid-users] Squid going through another forward proxy

[Amos Jeffries]

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On 14/11/2014 6:22 p.m., Hector Chan wrote:
> Hi Amos,
> 
>> those lines you specify above go in (C). *if* they are needed at
>> all.
> 
> But I don't have control over (C).  It's off limits.

Then you have to trust that the admin in charge of it set it up right.

> 
>> In (B) goes:
>> 
>> cache_peer forward-proxy.example.com parent 3128 0 name=C
>> 
>> acl sendToC dstdomain origin-x.example.com origin-y.example.com
> origin-z.example.com
>> cache_peer_access C sendToC
> 
> The requests reaching (B) (reverse-proxy.example.com) are in the
> form: http://reverse-proxy.example.com/goto-origin-x 
> http://reverse-proxy.example.com/goto-origin-y 
> http://reverse-proxy.example.com/goto-origin-z
> 
> and I have a couple of cache_peer_access acls (urlpath regex) to
> send them to origin-x, origin-y, and origin-z.  How would the above
> dstdomain acl work with these rules?

You have now stopped using HTTP and started using some strange
URL-embeded protocol.

An HTTP proxy cannot help you there. You require a proxy that
understands and acts on the URL-embeded protocol messages.

It is possible to extend Squid with URL-rewrite helpers that can
translate it into different HTTP URL for passing to (C). BUT, there is
no guarantee of what origin (C) will use to fetch that resource. You
have to *trust* that (C) uses the origin best suited to any request
that it is given, according to the criteria its own admin has set for
"best".

Amos
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