Re: Modifying Set-Cookie header in Squid 3.3.9

On 04/25/2014 03:19 AM, Peter Belau wrote:

> Also, just for my own understanding, what's fundamentally wrong with
> modifying the StoreEntry?

Fundamentally, StoreEntry and StoreEntry's HttpReply is a temporary
reflection of the response that was received from the server (and
possibly adapted and/or cached). If your intent is to modify the cached
information, affecting all from-cache responses, it should be done
pre-cache (http.cc and friends). If your intent is to adjust a single
to-client response, it should be done post-cache without StoreEntry
modifications (clientReplyContext::buildReplyHeader and friends).

Needless to say, there are exceptions and violations of the fundamental
principles sketched above.

HTH,

Alex.

> On Thursday, April 24, 2014 7:20 AM, Alex Rousskov wrote:
> On 04/24/2014 04:33 AM, Peter Belau wrote:
>
>
>> I'm trying to modify the Set-Cookie header from within
>> client_side_reply.cc. Currently my code looks like this:
>
>> HttpReply *rep = http->storeEntry()->getReply()->clone();
>> http->storeEntry()->releaseRequest();
>> rep->header.putStr(HDR_SET_COOKIE, "FOO=bar");
>> http->storeEntry()->replaceHttpReply(rep);
>> http->storeEntry()->complete();
>
>> This seems to corrupt storeEntry in ways that I don't understand. I
>> imagine that I'm missing something fundamental here. If someone could
>> point me in the right direct, I would much appreciate it.
>
>
> Hi Peter,
>
> There are at least two fundamental problems here:
>
> * As Eliezer has already noted, you should be using one of the many
> available adaptation interfaces instead of modifying sources directly.
> If the available interfaces do not do what you want, they usually can be
> enhanced (or new interfaces can be added). As you said, we all have
> specific reasons for doing the wrong thing, of course.
>
> * If you want to adjust each response, including HIT responses, you
> should be modifying the response as it goes out, not the Store entry
> itself. See clientReplyContext::buildReplyHeader(). If you want to
> adjust the response before it may be cached (so that a cached response
> is adjusted just once and served many times), then you should be doing
> that in http.cc instead.
>
>
> HTH,
>
> Alex.
>
Received on Fri Apr 25 2014 - 14:41:43 MDT