[squid-users] Re: Squid Issues and Problems

It's Trend Micro way of telling the ICAP server (IWSS) that the ICAP
client (the proxy) is capable of forwarding the response from the ICAP
server before the entire object has been sent to the ICAP Server.

Most others assume this by default without requiring the private "X-TE:
trailers" header.

The ICAP standard do not cover explicit how ICAP clients should behave
in this regard.

This is used by IWSS both for showing a download progress bar, and also
in trickle mode where the data is slowly sent to the requestor while
scanned for viruses.

I do not know who proposed the "X-TE: trailers" name. It's a very odd
name for the feature as it

a) Does not have anything to do with transfer encoding (TE)

b) Does not have anything to do with trailers.

But with it being an X-* header it's free to mean anyting implementation
specific, as long as everyone involved privately agrees on what the
meaning actually is...

Regards
Henrik

On mån, 2008-07-07 at 11:01 -0400, Jeremy Hall wrote:
> What do X-TE headers do?
>
> _J
>
> >>> <jerome_law_at_trendmicro.co.uk> 7/7/2008 5:28 AM >>>
> Hi there all,
>
> Firstly many thanks for all your work on Squid thus far :)
>
> I have been testing Squid 3.0 since PRE6 in various configurations, and one
> of the more notable issues I have found is that when Squid is running in
> ICAP mode, coupled with Trend Micro IWSx (InterScan Web Security) - IWSx
> reports that Squid does not support the X-TE trailers for data trickling.
> The error is usually logged when dealing with video from CNN (at first I
> thought all flash video, but YouTube is unaffected) and downloading certain
> MS Hotfixes. There might be other triggers as well - but these seem to be
> the main ones. When I configure IWSx to use a different ICAP server - say
> NetCache or other, there is no issue or error logged and things work as
> expected.
>
> A quick search of the squid source provided no answers, however a search of
> the archives show that there was a patch for Squid 2.5 ICAP dealing with
> X-TE trailers:
>
> http://www.squid-cache.org/mail-archive/squid-dev/200311/att-0018/squid-icap
> -2_5-x-auth-user.diff
> http://www.squid-cache.org/~hno/changesets/squid/patches/7972.patch <http://www.squid-cache.org/%7Ehno/changesets/squid/patches/7972.patch>
>
> Looking at ICAPModXact.cc I can see that there are some similar references
> to the area's above, however most certainly the code is above my level of
> expertise to have a play around with to cobble something together.
>
> I was wondering if there were any plans to include support for X-TE trailers
> in this version? If you could let me know that would be greatly appreciated.
>
> Best Regards,
>
> Jerome
>
>
>
> <http://websecurity.trendmicro.com/>
>
>
>
> Jerome Law | Solutions Architect, Regional Marketing EMEA
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